tag:blogger.com,1999:blog-65780358419826029342024-03-21T21:17:52.137+08:00RadTechOnDutyRadTechOnDuty is an educational blog for Technicians.iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.comBlogger353125tag:blogger.com,1999:blog-6578035841982602934.post-38916778332745015692019-11-20T11:57:00.000+08:002019-11-20T12:10:05.577+08:00Facial Bone Xray Positioning<br />
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<span style="font-family: "calibri light" , sans-serif;">Facial Bone</span></h4>
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<span style="font-family: "calibri light" , sans-serif;">The function of the facial bone is to protect our brain and other sensitive organs situated in our face like an organ of smell, sight, hearing, taste and equilibrium. The facial bone also provides attachment of muscles that is responsible for movement of the head and controlling our facial expression which may also play a role in understanding in a written language.</span></div>
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<span style="font-family: "calibri light" , sans-serif;">Facial Bone Anatomy</span></h4>
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<span style="font-family: "calibri light" , sans-serif;">The facial bone composes of 14 bones that is:</span></div>
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<span style="font-family: "calibri light" , sans-serif;"><b>1 vomer</b> – it can be found in the midsagittal line of the head, and articulates with the sphenoid, the ethmoid, the left and right palatine bones, and the left and right maxillary bones.</span></div>
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<span style="font-family: "calibri light" , sans-serif;"><b>2 Maxilla</b> – it also known as the upper jaw. It is also a vital viscerocranium structure of the skull. The two maxillary bones are fused in midline by the intermaxillary suture to form the upper jaw.</span></div>
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<span style="font-family: "calibri light" , sans-serif;"><b>1 Mandible</b> – it is the lower jaw or known as jawbone. It is the largest, strongest and lowest bone in the facial bone. It forms the lower jaw and attached our teeth to hold in placed.</span></div>
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<span style="font-family: "calibri light" , sans-serif;"><b>2 Nasal Bones</b> – our nose is supported by the nasal bones. </span></div>
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<span style="font-family: "calibri light" , sans-serif;"><b>2 Palatine Bone</b> – The palatine bone is a paired, L-shaped bone that forms part of the nasal cavity.</span></div>
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<span style="font-family: "calibri light" , sans-serif;"><b>2 Lacrimal Bones</b> – is a small and fragile bone of the facial bone. It is roughly the size of the little fingernail. It is located at the front part of the medial wall of the orbit.</span></div>
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<span style="font-family: "calibri light" , sans-serif;"><b>2 Zygomatic Bones</b> – it is called cheekbone or malar bone. It’s a diamond shaped bone below and lateral to the orbit, or eye socket, at the widest part of the cheek.</span></div>
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<span style="font-family: "calibri light" , sans-serif;"><b>2 Inferior nasal conchae</b> – it is one of the three paired nasal conchae in the nose. It extends horizontally along the lateral wall of the nasal cavity and consists of a lamina of spongy bone, curled upon itself like a scroll.</span></div>
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<span style="font-family: "calibri light" , sans-serif;">Radiographic Positioning of Facial bone</span></h3>
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<span style="font-family: "calibri light" , sans-serif;"><a href="https://www.radtechonduty.com/2013/12/lateral-position-right-or-left-lateral_5.html" rel="nofollow" target="_blank">Facial Bone Lateral</a></span></div>
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<span style="font-family: "calibri light" , sans-serif;">Facial Bone Parietoacanthial (Waters and Modified Waters)</span></div>
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<span style="font-family: "calibri light" , sans-serif;">Facial Bone PA axial or Caldwell Method</span></div>
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<span style="font-family: "calibri light" , sans-serif;">Facial Bone PA axial 15º Caudad Caldwell</span></div>
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<span style="font-family: "calibri light" , sans-serif;">Facial Bone Trauma Series</span></div>
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<br />iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.com0tag:blogger.com,1999:blog-6578035841982602934.post-9797613259706893582018-09-29T13:28:00.000+08:002018-09-29T13:30:34.264+08:00The First World's Color Xray Image<div class="separator" style="clear: both; text-align: center;">
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A father and son tandem from New Zealand has introduced the first ever colored x-ray scanner adapted from technology used in finding the Higgs boson.<br />
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Phil (father) and Anthony (son) Butler from Canterbury and Otago Universities, dedicated full 10 years to build their 3D x-ray scanner. Finally, on July 10, they released the world's first x-rays of the very first human to have been scanned by the technology.<br />
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The machine called the MARS spectral x-ray scanner is expected to assist medical professionals in the diagnosis and treatment of cancer, as well as heart diseases through providing colored images that are much closer to what the human body looks like internally.<br />
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The MARS x-ray can show the fat, water, calcium, and other disease markers in the body parts that are being scanned.<br />
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In the next few months, the x-ray scanner will undergo its first clinical trial with orthopedic and rheumatology patients in Christchurch, New Zealand.<br />
Colored X-Ray Technology<br />
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The first person to have been scanned using the breakthrough technology is no other than Phil himself. He scanned his ankle and wrist. The scan of his wrist was incredibly detailed, it even included the watch he was wearing.<br />
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The scan of his feet was equally précise as well and even showed the yellowish soft tissue in his sole.<br />
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"Traditional black-and-white x-rays only allow measurement of the density and shape of an object," said Anthony, highlighting MARS's advantage over the traditional x-ray machine.<br />
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Anthony mentioned that researchers are currently using a smaller version of the MARS scanner to study cancer and other vascular diseases. Initial results from these studies suggested that MARS scanners will provide more accurate diagnosis and personalized treatment.<br />
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Phil and Anthony said they are currently developing a machine that can scan the whole body.<br />
CERN Medipix3 Technology<br />
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The Butlers applied the Medipix3 technology used by the European Organization for Nuclear Research in the hunt for the "God particle" or the Higgs boson.<br />
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The Medipix chip was originally developed to help the Large Hadron Collider with its particle acceleration processes. Over the course of 20 years from the first time the chip was introduced, it has undergone different improvements.<br />
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In more recent years, the chip has been significant in other fields of sciences outside of the study of high-energy physics. In the case of the MARS scanner, the CERN Medipix3 chip sees its relevance in the medical field.<br />
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Medipix3 is the most advanced version of the chip. Philip said the technology sets the MARS scanner apart because it produces images no other x-ray machine tool can achieve.</div>
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Source: <a href="https://www.techtimes.com/articles/232239/20180713/world-s-first-colored-human-x-ray-applies-cern-technology-used-in-search-of-god-particle.htm" rel="nofollow">www.techtimes.com</a></div>
iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.com1tag:blogger.com,1999:blog-6578035841982602934.post-23707645836606041372018-09-27T15:49:00.000+08:002018-09-27T15:49:01.277+08:00UK’s first MR Linac, combining MRI and radiotherapy technology<div class="separator" style="clear: both; text-align: center;">
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The first <a href="https://www.royalmarsden.nhs.uk/mrlinac">MR linac to be commissioned in the UK</a> is starting to be used to treat patients.<div>
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The benefit of the <a href="https://mrrt.elekta.com/">Elekta Unity</a> magnetic resonance radiation therapy (MR/RT) linac is that it precisely locates tumours, tailors the shape of high energy x-ray beams following real time adaptation of the dosimetric plan and accurately delivers radiation.</div>
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Combining the precise soft-tissue contrast of MRI scanning (1.5 Tesla) with precision radiotherapy in a single treatment technology has been an aspiration for radiotherapy research. A stringent physics commissioning programme has demonstrated that the MR linac can be calibrated to deliver x-rays accurately in the presence of the distorting magnetic field used to generate MRI images.</div>
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In doing so, researchers have overcome a key scientific challenge. This technology could be especially effective for cancers which move during radiotherapy or change position between scanning and treatment. For example, because of breathing, bladder filling or bowel changes. This is particularly useful for radiotherapy for lung, cervical, prostate, bowel and bladder cancer.</div>
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It also could support significant reductions in overall number of treatments as radiotherapy moves towards increasing use of stereotactic ablation treatments..</div>
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"This really is ground-breaking technology which will provide enormous benefits for patients and their families," Sarah Helyer, radiotherapy services manager, at The Royal Marsden, said.</div>
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"Having one of the first MR linacs in the UK at the Marsden has brought together all the main professions in radiotherapy, working as a team to bring this technology into the clinic." Sarah continued.</div>
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“This is especially good for therapeutic radiographers, who have worked alongside their diagnostic colleagues, to gain the skills and experience necessary to take on MRI technology in radiotherapy in the future.”</div>
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Dr Alison Tree, a consultant oncologist, explained the impact for prostate cancer patients: “Prostate cancer responds most effectively to large doses of radiation delivered over a short period. However, because the prostate lies close to the rectum, high doses risk damaging the rectum and increasing side effects.</div>
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“With the MR linac we can better target treatment, so we can safely deliver higher doses of radiation. Treatment time could be reduced to five days, or even just one, which will save time and money for patients and the NHS.”</div>
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The Royal Marsden and the Institute of Cancer Research have been developing the technology for several years as part of an international consortium of seven cancer treatment centres working with Elekta, which makes the MR linac, and MR partner Phillips.</div>
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The first patient<br /> Barry Dolling from Surrey: “I was diagnosed with prostate cancer in April this year. I was told about the clinical trial on the MR linac when I was referred to The Royal Marsden for radiotherapy. I jumped at the chance because I believe the treatment will give me a better quality of life and minimal side effects in comparison to other treatments.</div>
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"I will be having 20 treatments on the MR linac and Iam hoping to keep up with my swimming and golf. It was important to me to have treatment that had minimal side effects. I am lucky the timings worked out for me as the trial just opened at the time I would have been starting standard radiotherapy treatment. I was really excited when they told me I would be the first patient in the UK. I feel very privileged.”</div>
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Source: <a href="https://www.sor.org/news/first-patient-uk-treated-using-magnetic-resonance-radiation-therapy" rel="nofollow">sor.org</a></div>
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iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.com2tag:blogger.com,1999:blog-6578035841982602934.post-90780150696670781892018-09-25T21:57:00.000+08:002018-09-25T21:57:22.261+08:00Computed Tomography of the Brain<h3>
CT Scan of the Brain</h3>
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Indications</h4>
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CT is the imaging modality most commonly used in triaging acute neurological disease. For non emergency indications CT is second best to MR, but is still widely used, often because it is more broadly available and simpler to interpret. The indications include the following:</div>
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Following major head injury (if the patient has lost consciousness, has impaired consciousness, or has a neurological deficit). The presence of a skull fracture also justifies the use of CT. NICE (National Institute for Health and Care Excellence) guidance has been issued on the use of imaging for the head injuries for adults and children, specifically CT, listing the criteria for assessment based on best relevant data and consensus recommendations.</div>
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In suspected intracranial infection ( the use of contrast enhancement is recommended).</div>
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<li>For suspected intracranial haemorrhage and cases of ischaemic and haemorrhagic stroke.</li>
<li>In suspected raised intracranial pressure, and as a precaution before lumbar puncture once certain criteria are fulfilled. These would include reduced consciousness ( a Glasgow coma score of less than 15), definite papilloedema, focal neurological deficit, immune suppression and bleeding dyscrasia.</li>
<li>In other situations, such as epilepsy, migraine, suspected tumour, demyelination, dementia and psyschosis, CT is a poorer quality tool. If imaging can be justified, MRI is greatly preferable and is recommended by NICE in these situation except for the first episode of psychosis.</li>
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Brain CT scan Technique</h3>
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<li>Most clinical indications are adequately covered by 3 mm sections parallel to the floor of the anterior cranial fossa, from the foramen magnum to the midbrain, with 7 mm sections to the vertex (or contigious 3 mm slices throughout). In all trauma cases, window width and level should be adjusted to examine bone and any haemorrhagic, space occupying lesions. Review of all trauma studies should be done on brain windows, bone and blood windows.</li>
<li>In suspected infection, tumours, vascular malformations and subacute infactions, the sections should be repeated following intravenous (i.v) contrast enhancement, if MRI is not available. Standard precautions with regard to possible adverse reactions to contrast medium should be taken.</li>
<li>Dynamic studies using iodinated contrast are increasingly being used as a routine in high velocity head trauma, the assessment of ruptured arteriovenous shunts and dural venous sinus thrombosis. CT angiography (CTA) on a typical 64 slice multidetector scanner is performed using 70-100 ml of contrast and 50 ml saline chaser, injected at 4 ml/s with a delay of 15s or triggered by bolus tracking with ROI in the aortic arch. Overlapping slices of 0.75 – 1.25 mm are reconstructed. CT venography (CVT) involves injecting 90-100 ml of contrast with a delay of 40s. Images are usually reviewed both as three dimensional rendered data and multiplanar reformats (MPRs).</li>
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iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.com0tag:blogger.com,1999:blog-6578035841982602934.post-30992909320632976562018-09-18T21:05:00.001+08:002018-09-18T21:07:48.266+08:00Methods of Radiographic Imaging the Brain<br />
Imaging the brain’s structure and examining its physiology, both in the acute and elective setting, are now the domain of multiplanar, computer-assisted imaging. The imaging modalities in use today include the following:<br />
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Computed Tomography CT</h3>
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This is the technique of choice for investigation of serious head injury; for suspected intracranial haemorrhage, stroke, infection and other acute neurological emergencies. CT is quick, efficient and safer to use in the emergency situation than MRI.</div>
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Magnetic Resonance Imaging MRI</h3>
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This is the best and most versatile imaging modality for the brain, constrained only by availability, patient acceptability, and the logistics and safety of patient handling in emergency situations. New protocols and higher field strength magnets have raised the sensitivity of MRI in epilepsy imaging, acute stroke, aneurysm detection and follow - up post treatment of neoplastic and vascular disorders. It is the only effective way of diagnosing multiple sclerosis.</div>
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Angiography</h3>
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This is very important in intracranial haemorrhage (ICH), especially subarachnoid haemorrahage (SAH) and, increasing, in intra-arterial management of ischaemic stroke. However, with the widespread availability of multi detector CT scanners, CT angiography CTA is now preferentially used in ischaemic stroke, SAH and ICH. Angiography is still requested for pre-operative assessment of tumors, vascular malformations and angiographic expertise is vital for the performance of many neurointerventional procedures.</div>
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Radionuclide Imaging</h3>
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There are two principal methods. The first is regional cerebral blood flow scanning, still more used in research than in clinical management, especially in the dementias and in movement disorders such as Parkinsonism; second is position emission tomography (PET). By this method focal hyper-metabolism may be shown using <sup style="background-color: white; color: #545454; font-family: arial, sans-serif; line-height: 0.9;">18</sup><span style="background-color: white; color: #545454; font-family: "arial" , sans-serif; font-size: x-small;">F</span> fluorodeoxyglucose (<sup style="background-color: white; color: #545454; font-family: arial, sans-serif; line-height: 0.9;">18</sup><span style="background-color: white; color: #545454; font-family: "arial" , sans-serif; font-size: x-small;">F</span>DG), for example in epilepcy, and cell turnover may be shown using <sup style="background-color: white; color: #545454; font-family: arial, sans-serif; line-height: 0.9;">11</sup><span style="background-color: white; color: #545454; font-family: "arial" , sans-serif; font-size: x-small;">C</span>-methionine, for example in tumour studies.</div>
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Ultrasound US</h3>
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This is particularly helpful in neonates and during the first year of life to image haemorrhagic and ischemic syndromes, developmental malformations, and hydrocephalus using the fontanelles as acoustic windows. In adults, transcranial Doppler used for intracerebral arterial velocity studies to assess the severity of vapospasm.</div>
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Plain films of the skull</h3>
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These film are of little value except in head injury.</div>
iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.com0tag:blogger.com,1999:blog-6578035841982602934.post-63088894658746296352018-07-31T16:42:00.001+08:002018-07-31T16:42:19.170+08:00Health Care Insurance and Benefits System: HMOs, Medicare and Medicaid<h4>
Health Care Insurance and Benefits System </h4>
More than 30 years ago up to the present, most health care was delivered on a fee-for-service basis. In this system, insurance companies repay patients for the expenses of their health care within the perimeters of the policy and the patient is responsible for any charges that are not covered. Patients can seek care from their choice of doctors and hospitals. Because private doctors may offer a more personal service and superior continuity of care in this system, many people find this kind of care soothing and are ready to pay a high premium for this type of insurance coverage.<div>
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<h4>
Medicare and Medicaid</h4>
<div>
Medicare, a federal health insurance program in the United States, covers a percentage of the medical care costs for those over the age of 65. The federal government also offers funds to aid the medically indigent through a program named Medicaid.</div>
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<h4>
Health Maintenance Organization (HMO)</h4>
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As health care and hospital amenities became more technical and more lavish, health insurance premiums and uninsured charges started to cost more than many persons could afford. In an effort to bring more affordable care, health maintenance organizations (HMOs) were made. These organizations offer a complete and comprehensive health care for the cost of the premium and a small fee called a co-payment for each visit. HMOs control costs by upholding good health and by providing care only in specified facilities. The physicians and other professionals who offer care may be salaried employees of the organization. Physician assistants and nurse practitioners may provide many aspects of care formerly provided only by physicians.</div>
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If you go to an HMO and have a health concern, the first person you see is your primary health care provider. This might be a physician or perhaps a nurse practitioner (a nurse with progressive education and credentials for providing primary care). If your condition requires additional diagnostic attention or care, you will be referred to a secondary provider. The provider they have refer, might be a doctor such as an ophthalmologist, a gynecologist, or a radiologist. Sometimes, your condition might be serious enough to demand care within the hospital setting, which is called tertiary care. Your primary health care provider will manage your treatment and provide follow-up check-ups after you are discharged from the hospital.</div>
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By stimulating good health, the HMO tries to lessen the average cost of health care for all its members.</div>
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Regular physical examinations, immunizations, weight control, treatment for hypertension, and other forms of preventive care, such as fitness programs and classes on health-related topics, are normally included among benefits of these organizations. This preventive care system is in direct distinction to crisis intervention or episodic care, in which you see your doctor only when you are ill. An essential part of an HMO system is that patients are anticipated to become more involved in meeting their specific health care needs. They rarely have the ongoing, one-to-one association with a primary care provider that was once common with a family specialist.</div>
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As HMOs have flourished and become more prevalent, many private doctors and hospitals have work together to form managed care systems. These systems permit private hospitals and doctors to deliver private services while as well providing care over insurance plans alike to HMOs. Managed care systems save money by restrictive access to expensive services when they are not required. Their benefits differ from altered fee-for-service programs to inclusive HMOs.</div>
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Unluckily, even HMOs have had difficulties managing with the escalating charge of diagnostic procedures and hospital care. Health insurance rates have flew, and the number of families are incapable to afford health care has augmented dramatically. One consequence is that many low-income families have turned to emergency departments to deliver care for all kinds of illnesses. This crisis intervention model of care is costly on a per-patient basis, and since many of these patients are unable to pay, the cost is feast over the whole span of hospital care.</div>
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To get rid of the pressure on hospital emergency departments and deliver more cost-effective care, a system raised to meet the needs of patients who need vital care or minor surgery for circumstances that are not immediately life-threatening. These services are called immediate or urgent care clinics. Patients are seen without waiting several days for an appointment. These centers cope with acute but minor illnesses and accidents. Conditions such as broken fingers, middle ear infections, and severe upper respiratory infections can be seen rapidly and cured effectively in such centers.</div>
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Outpatient surgical services are also common. In these "surgicenters," we call, patients are admitted in the early morning for minor techniques such as simple hernia repair and are released to home care the same evening. Once again, the impulsion for such centers remained the need to cut costs. In this case, the payment involved are less than those for the use of a major medical suite and a following overnight hospital stay.</div>
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Clients need to know how to use the treatment available, because insurance programs differ greatly and are often subject to modification. Must you be referred to an emergency section for an unexpected illness, or is there a vital care center? Does your program cover x-rays and medications? If welfares are not used correctly, the insurance may not cover the care established and patients may be confronted with large, unforeseen bills. It pays to be an knowledgeable and confident consumer.</div>
iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.com0tag:blogger.com,1999:blog-6578035841982602934.post-50729455268046409372018-07-27T23:10:00.002+08:002018-07-27T23:48:07.564+08:00Personal Monitoring Device, Radiation Badge, Dosimeter, TLD and OSL<br />
<h4>
Dosimeters</h4>
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<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">Devices for monitoring radiation
exposure to personnel are called <b>dosimeters. </b>Radiation workers who are issued
single badges for monitoring whole-body dose should wear them in the region of
the collar with the label facing out. When a lead apron is worn, the dosimeter should
be outside of the lead apron. Technologists who work with fluoroscopy may wear
two badges, one on collar outside the lead apron and one at the waist that is
under the apron. The two dosimeters should be distinguished by color or icons
indicating their specific locations. Personnel who are issued dosimeters should
wear them at all times when working in radiation areas, and should keep them in
a safe place, away from radiation and heat, when off duty. In addition to
wholebody badges, ring dosimeters may be worn by nuclear medicine technologists
and others whose work results in more exposure to the hands than to the body.<o:p></o:p></span></div>
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<h4>
<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">Film Badges</span></h4>
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<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">Film badges were once the principal
type of dosimeter. They are still in use today, but are much less common. They
consist of one or two pieces of dental film, paper-wrapped and enclosed in a
badgelike holder. Several filters are incorporated in the badge so that if the
unfiltered exposure exceeds the capacity of the film, additional exposure can
be measured in the filtered area. The disadvantage of this type of personal monitor
is that the dental film is subject to fog when exposed to heat or fumes, and this
exposure could result in a false reading. The film is also ruined if it is laundered!
After a period of use, the film is returned to a laboratory that processes it
and measures the OD of the film. The exposure is calculated and reported based
on this measurement. Many radiographers still refer to their dosimeters as
"film badges," but today they are more likely to be TLDs or OSLs.<o:p></o:p></span></div>
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<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">Thermoluminescent Dosimeter (TLD)</span></h4>
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<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">TLD stands for <i>thermoluminescent
dosimeter. </i>The roots of this term mean "dose-measuring device that gives
off light when heated." The TLD is a type of personal monitor commonly
used by radiographer 36). It consists of a plastic badge or ring containing one
or more lithium fluoride crystals. These crystals (and several others with
similar characteristics) absorb x-ray energy and, when heated, give off the
energy again in the form of light. The TLD is more durable than the film badge
insert and responds only to ionizing radiation exposure. At the end of the
measurement period, the badge is sent to a laboratory where the crystals are
placed in a special tray and inserted into the TLD analyzer. This instrument
heats the crystals to the required temperature, measures the light emitted, and
transmits the data to a computer.<o:p></o:p></span></div>
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<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;"><o:p><br /></o:p></span></div>
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<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">Optical Stimulated Luminescence (OSL)</span></h4>
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<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">OSL stands for <i>optically stimulated
luminescence </i>and refers to the most recently developed monitoring<i> </i>dosimeter.
Aluminum oxide is the radiation detector in this device. The dosimeter is
processed using a laser rather than heat as for TLDs. OSLs have several
advantages over TLDs. They can measure very </span>small doses more precisely and can be
reanalyzed to confirm results. They are accurate over a wide dose range and
have excellent long-term stability.</div>
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<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">Radiation Monitor Badge Service
Laboratories</span></h4>
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<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">Radiation monitor badge service
laboratories provide dosimeters, processing services, and reports, and keep
permanent records of the radiation exposure of each person monitored. Service
may be arranged on a weekly, monthly, bimonthly, or quarterly basis. Personnel who
receive relatively high doses of occupational exposure change their badges most
frequently. With the exception of OSL badges, dosimeters cannot accurately
measure total exposures of less than 5 mrem (0.05 mSv). For this reason,
personnel who receive very small amounts of exposure will get more accurate
measurements with less frequent badge changes. Personnel involved in diagnostic
radiography who are always or nearly always in a control booth during exposures
are usually best monitored with quarterly service. Monthly service is a better
choice for those who work in fluoroscopy and those who perform bedside
radiography.<o:p></o:p></span></div>
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<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">Service companies provide an extra
dosimeter in every batch that is marked "CONTROL." The purpose of
this dosimeter is to measure any radiation exposure to the entire batch while in
transit. Any amount of exposure measured from the control badge will be
subtracted from the amounts measured from the other badges in the batch. The
control badge should be kept in a safe place, away from any possibility of
x-ray exposure. It should never be used to measure occupational dose or for any
other purpose.<o:p></o:p></span></div>
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<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">Radiation badge service companies will
want to know the name, birth date, and Social Security number of all persons to
be monitored so that all records can be accurately identified. If there has been
a history of previous occupational radiation exposure and the dose is known,
this information should also be provided so that the record will be complete
and accurate. Exposure reports are sent to the subscriber for each batch, and
an annual summary of personal exposure is also provided. Radiation workers
should be advised of the radiation exposure reported from their badges and should
be provided with copies of the annual reports for their own records. Employees
exposed to ionizing radiation should not leave their employment without a
complete record of their radiation exposure history. Employers are required to
provide this information.<o:p></o:p></span></div>
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<br />iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.com0tag:blogger.com,1999:blog-6578035841982602934.post-49323463670156626242018-07-27T21:26:00.000+08:002018-07-27T21:26:04.139+08:00Effects of Radiation to Human<br />
<h4>
Biologic Effect of Radiation</h4>
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<o:p></o:p></div>
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As a radiographer, we all know that xray can ionize
substance by removing electrons from their orbits. This process results in a
free, negatively charged electron and leaves the remainder of the atom with
positive charge. When human beings are irradiated, ionization may occur to any
part of a living cell, such as the material that makes up it membrane, the
water within the membrane, or the DNA that makes up the cell’s chromosomes and
directs its activity. The initial ionization may produce a “domino effect”,
causing ionization in the surrounding area. Exposure also creates free radicals
(temporary molecules and parts of molecules with electrical charges). Free
radicals may interact directly with the DNA or may produce toxic substance that
are injurious to DNA.<o:p></o:p></div>
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Most effects of exposure are extremely short-lived because
electrons find new homes in the orbits of other atoms and the balance of
charges returns to normal. Free radicals combine to form more stable compounds.
Occasionally, however, the damage is not instantly resolved. A cell may be so
damaged that is cannot sustain itself and dies. Cell death is an insignificant
injury unless a large number of cells is involved. Cells may sustain damage that
requires several days for the body to make repairs. The body produces special
enzymes that function to repair the DNA protein molecules. A cell may be
damaged in such a way that is DNA “programming” is changed, and the cell no
longer behaves normally. This type of injury may eventually result in the
runaway production of new, abnormal cells, causing a tumor or malignant blood
disease.<o:p></o:p></div>
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<h4>
Law of Bergonie and Tribondeau</h4>
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<o:p></o:p></div>
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The relative sensitivy of different types of cells is
summarized in the Law of Bergonie and Tribondeau, which state that cell
sensitivity to radiation exposure depends on four characteristic of the cell:</div>
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<ul>
<li>Age. Younger cells are more sensitive than older ones.</li>
<li>Differentiation. Non-specialized cell are more sensitive
than highly complex ones.</li>
<li>Metabolic rate. Cells that use energy rapidly are more
sensitive than those with a slower metabolism.</li>
<li>Mitotic rate. Cells that divide and multiply rapidly are
more sensitive than those that replicate slowly.</li>
</ul>
<o:p></o:p><br />
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<o:p></o:p></div>
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<o:p></o:p></div>
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According to this laws, we see that blood cells and
blood-producing cells are very sensitive. Cells in contact with the environment
are quite simple, have relatively short lives, and are quite sensitive. These include
the cells of the skin and the mucosal lining of the mouth, nose, and
gastrointestinal tract. Some glandular tissue is also particularly sensitive,
especially that of the thyroid gland and the female breast. The tissue of embryos,
fetuses, infants, children, and adolescents tend to be more sensitive that
adult tissue because of their younger age and their higher metabolic and
mitotic rates. Nerve cells, which have a long life and are quite complex, are
much less vulnerable to radiation injury. Cortical bone cells are relatively
insensitive.<o:p></o:p></div>
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<h4>
Classification of Radiation Effects</h4>
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<o:p></o:p></div>
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Radiation effects are classified in various ways. Short-term
effects are those observed within 3 months of exposure. They are associated
with relatively high radiation doses ( greater than 50 rad). Short term effects
may be further categorized according to the body system affected:<o:p></o:p></div>
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<ul>
<li>Central nervous System (CNS)</li>
<li>Gatrointestinal (GI)</li>
<li>Hematologic effects</li>
</ul>
<o:p></o:p><br />
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<o:p></o:p></div>
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<o:p></o:p></div>
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Long-term effect, sometimes referred to as latend effects,
may not be apparent for as many as 30 years. Somatic effects are those that
effect the body of the irradiated individual directly, whereas genetic effects
occur as a result of damage to the reproductive cells of the irradiated person
and are observed as defects on the children or grandchildren of the irradiated
individual.<o:p></o:p></div>
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<h4>
Short-Term Somatic Effects</h4>
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<o:p></o:p></div>
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<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">Short-term radiation effects are
predictable, and the quantity of exposure required to produce them is well documented.
These are termed <b>nonstochastic </b>effects. Nonstochastic effects occur only
after a certain amount of exposure has been received, and the severity of the
effect depends upon the dose. One observable short-term effect reddening of the
skin called <b>erythema</b></span><b><span style="font-family: "Times New Roman",serif; font-size: 10.0pt;">. </span></b><span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">This phenomenon is sometimes called a
"radiation burn." In the very early days of radiation use, the amount
of radiation necessary to produce reddening of the skin was called the "erythema
dose." It was the first unit used to measure radiation exposure. <o:p></o:p></span></div>
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<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">Other short-term effects from doses in
excess of <i>50 </i>rad have been observed and studied in radiation therapy
patients and in the victims of radiation accidents and atomic bomb blasts. This
is vastly more exposure than is delivered by diagnostic x-ray machines. Extremely
high doses produce CNS effects, seizures, and coma that can result in death in
a short period of time. Lesser doses will result in "radiation
sickness," a Gastro Intestinal effect in which the mucosal lining of the
digestive tract is damaged, breaks down, and becomes infected by the bacteria
that normally inhabit the bowel.<o:p></o:p></span></div>
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<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">These victims also have a compromised
immune system because of the death of white blood cells and are unable to fight
the infection. Radiation sickness is usually fatal, and suffering may be
prolonged. A lesser dose, affecting primarily the blood and blood-forming
organs, results in hematologic effects, including anemia and compromise of the
immune system. These victims are prone to infectious diseases that may or may
not be fatal, depending on the radiation dose and the severity of the disease
process. One way that scientists describe the risk of high-level radiation
exposures is to calculate the whole-body radiation dose that is lethal to <i>50%
</i>of the irradiated population within <i>30 </i>days, a calculation that is
abbreviated as LD <i>50/30. </i>The LD <i>50/30 </i>for humans is approximately
<i>300 </i>rad (3 Gy).</span> </div>
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<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">Long-Term Somatic Effects</span></h4>
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<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;"><br /></span></div>
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<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">“Long-term" here refers to the
length of time between exposure and observation of the effect. The time required
for long-term effects to manifest is generally considered to be <i>5 </i>to <i>30
</i>years, with the greatest percentage occurring between <i>10 </i>and <i>15 </i>years.
In contrast to the predictable nature of short-term effects, longterm effects are
apparently random, and there is no threshold amount of exposure that must be
received in order for them to occur. These effects are termed <b>stochastic.</b>
The likelihood of stochastic effects is greater when the dose is increased, but
there is no correlation between the dose and the severity of the effects. They may
occur as the result of repeated small doses, such as those used in radiography.<o:p></o:p></span></div>
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<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">The percentage of observable effects
from the radiation involved in typical x-ray examinations is extremely low and
the risk to any single patient is minimal. Most of us take greater risks when
we drive a car or cross a busy street. Nevertheless, there is a risk of
long-term effects that has been demonstrated by studying large populations over
long periods. The incidence of certain conditions is greater when results for
irradiated groups are compared to those of nonirradiated control groups.<o:p></o:p></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; mso-layout-grid-align: none; text-autospace: none;">
<br /></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: 0.0001pt; text-align: justify;">
<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">Long-term radiation effects are not
easily identified as such because they occur years after the initial exposure
and because these same effects also occur in the absence of radiation exposure.
Only extensive research with large populations (epidemiologic studies) and
computer analysis can demonstrate the role of radiation in causing these
effects. In other words, radiation causes increased risk of these effects, but
the effects cannot be predicted with respect to any one individual. While the
individual risk may be extremely small, increasing exposure to the entire
population poses public health risks that require the attention and concern of
everyone involved in applying ionizing radiation to human beings.<o:p></o:p></span></div>
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<br /></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; mso-layout-grid-align: none; text-autospace: none;">
<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">The documented latent effects of low
doses of ionizing radiation include the following:<o:p></o:p></span></div>
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<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;"><br /></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; mso-layout-grid-align: none; text-autospace: none;">
</div>
<ul>
<li><b>Cataractogenesis.
</b>The
formation of cataracts, or clouding of the lens of the eye. This effect
concerns radiologists and radiographers who work extensively in fluoroscopy and
those who perform other work that involves repeated exposure to the eyes.</li>
<li><b>Carcinogenesis.
</b>Increased
risk of malignant disease; particularly cancer of the skin, thyroid, and breast;
and leukemia, a malignant blood disease associated with radiation exposure.</li>
<li><b>Life span
shortening. </b>A<b> </b>study of the life span of radiologists
who died during a 3-year period before 1945 showed that they had shorter life spans
than physicians who did not use radiation in their practices. This group
included radiologists who had used radiation since the early days of x-ray
science. More recent studies show that occupational exposure no longer has a
measurable effect on the life span of radiologists. Nevertheless, because
radiation exposure has been linked to life span shortening, it is a public
health concern and another reason to practice a high level of radiation safety.</li>
<li> </li>
</ul>
<br />
<h4 style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; mso-layout-grid-align: none; text-autospace: none;">
<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">Genetic Effects</span></h4>
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<br /></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: 0.0001pt; text-align: justify;">
<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">Genetic effects in the form of changes
or mutations to the genes may be caused when the ovaries or testes are exposed
to ionizing radiation. In the female, all of the ova cells that an individual
will ever produce are present in an immature state at birth. Because no new egg
cells are produced as the individual ages, the effect of radiation exposure to
the ovaries is cumulative. The genetic effects of radiation to the testes also
have a longer- term effect than may at first be presumed, because damage to the
stem cells that produce the sperm may result in continued production of sperm
with the genetic mutation. The majority of genetic mutations are considered
negative, or less well suited to survival of the individual than nonmutated
cells.<o:p></o:p></span></div>
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<br /></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: 0.0001pt; text-align: justify;">
<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">Because reproductive cells have only
half the number of chromosomes found in all other cells, each parent contributes
one chromosome to each pair in the new individual, and nature makes the choice
as to which gene of each pair will affect the characteristics of the offspring.
Those genes that are expressed are said to be dominant, and those that are not
expressed are called recessive. Mutated genes are usually recessive and
therefore do not manifest their characteristics in the offspring. Both dominant
and recessive genes, however, occur in the reproductive cells of the offspring
and may be passed on to future generations.<o:p></o:p></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; mso-layout-grid-align: none; text-autospace: none;">
<br /></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; mso-layout-grid-align: none; text-autospace: none;">
<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">As an increasing percentage of the
population is exposed to radiation from natural, occupational, and<o:p></o:p></span></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: 0.0001pt; text-align: justify;">
<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">health care sources, the likelihood
increases that individuals will be conceived with a mutation of both genes in a
strategic pair, resulting in some type of deformity or maladaption. Public
health officials and </span>governments are very concerned about
preserving the integrity of the population's gene pool by minimizing harmful,
defect-causing radiation. This concern should motivate those who apply ionizing
radiation to humans to minimize gonad doses in every way possible. Gonadal shielding
would be the best option to minimize radiation exposure to the reproductive
system.</div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: .0001pt; margin-bottom: 0cm; mso-layout-grid-align: none; text-autospace: none;">
<br /></div>
<div class="MsoNormal" style="line-height: normal; margin-bottom: 0.0001pt; text-align: justify;">
<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">Genetic effects from mutations caused
by x-ray exposure have long been demonstrated in animal research. Interestingly,
very little genetic effect has been confirmed by the continuing research of the
Japanese populations affected by the atomic bombs dropped on Hiroshima and
Nagasaki during World War I1 or in other studies of human populations.</span></div>
iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.com0tag:blogger.com,1999:blog-6578035841982602934.post-42239533873527724742018-07-27T19:38:00.000+08:002018-07-27T19:38:13.330+08:00Radiation Units and Measurements<h4>
Radiation Measurements</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal">
<div style="text-align: justify;">
Radiation Measurements can be made in two different but
related, system: the traditional (Britist) system, still commonly used in the
United states, and the Systeme Internationale (SI) units established by the
International Commission on Radiation Units in 1981. These units and their
relationships are summarized in below.<o:p></o:p></div>
<div style="text-align: justify;">
<br /></div>
</div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5NO0Zq-_-LSBr5LxmALklHzLo-PE8IOQkvZJwEDOwURVMiE61LQXbTFbriRRhyphenhyphenpP8ywa2yTmjWJmMUNTDAGj-TqIW8cA0JmonPasjY03FuyOHDi0ZdSScbq02jE4UHOg1UKapsZlYZ1Ht/s1600/Radiation+Units.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="" border="0" data-original-height="305" data-original-width="1043" height="93" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj5NO0Zq-_-LSBr5LxmALklHzLo-PE8IOQkvZJwEDOwURVMiE61LQXbTFbriRRhyphenhyphenpP8ywa2yTmjWJmMUNTDAGj-TqIW8cA0JmonPasjY03FuyOHDi0ZdSScbq02jE4UHOg1UKapsZlYZ1Ht/s320/Radiation+Units.JPG" title="radiation measurement and units" width="320" /></a></div>
<div class="MsoNormal">
<br /><br /></div>
<div class="MsoNormal">
<div style="text-align: justify;">
The traditional unit of radiation exposure is the <b>roentgen (R)</b>,
a measurement of radiation intensity in air. The roentgen is equal to the
quantity of radiation that will produce 2.08 x 10<sup>9 </sup>(more than 2
billion) ion pairs in 1 cm<sup>3 </sup>of dry air. The SI unit for measuring
radiation intensity is coulombs per kilogram (C/kg), specifying the quantity of
electrical charge in coulombs produced by the exposure of 1 kg of dry air. Once
roentgen equals 2.58 x 10<sup>-4 </sup>(.000258) C/kg.<o:p></o:p></div>
<div style="text-align: justify;">
<br /></div>
</div>
<div class="MsoNormal">
<div style="text-align: justify;">
The <b>roentgen</b> is useful for measuring the quantity of
radiation present but is not a useful dose measument. Dose varies with the
depth of measurement and the quantity of radiation energy absorbed in the
exposed tissue. The measure therapeutic radiation doses as well as specific
tissue doses received in diagnostic applications, the traditional unit is the
rad. <b>Rad</b> stands for radiation absorbed dose and equal to 100 ergs (an energy
unit) per gram of tissue. One roentgen of exposure will result in approximately
1 rad of absorbed dose in muscle tissue. The SI unit for dose measurement is
the Gray (Gy). One Grey equals 100 rad, and conversely, 1 rad equals to 1
centigray.<o:p></o:p></div>
<div style="text-align: justify;">
<br /></div>
</div>
<div class="MsoNormal">
<h3>
Biologic Effect of Radiation</h3>
<o:p></o:p></div>
<div class="MsoNormal">
<div style="text-align: justify;">
The biologic effect of radiation exposure varies according
to the type of radiation involved and its energy. Equal doses of various types
of radiation, as measured in rad or Gy, will not necessarily result in equal
biologic effects. Some radiation workers, such as engineers in nuclear power
plants, nuclear submarine construction workers, or technologist in nuclear
medicine laboratories may be exposed to several types of radiation with unequal
level of biologic effect. Neither the roentgen not the rad is a useful unit for
measuring the occupational dose of combined radiations with different levels of
effects.<o:p></o:p></div>
<div style="text-align: justify;">
<br /></div>
</div>
<div class="MsoNormal">
<div style="text-align: justify;">
To simplify the process of measuring occupational dose, a
weighting factor (WF) number is assigned to each type of radiation based upon
its absorbed energy in a mass of tissue and its relative biologic effect as
compared to xrays. Formerly, weighting factors were called quality factors. The
weighting factors for different types of ionizing radiation are listed below.<o:p></o:p></div>
<div style="text-align: justify;">
<br /></div>
</div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj2QnxPQ1hlYUNeArhTGx7hm1yI4yKQ-0jaqUiiceLNWYqFmxaLZVaFXcsKU-vVNv0QkOFYnfg9uB1ffDwm0LcudGwFC2jfqDElUxABDmiXlZ4VV_HRgDFirvOkul2za4xQ-hm3U1Xr0ZPE/s1600/Radiation+Weighting+factors.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="" border="0" data-original-height="455" data-original-width="512" height="284" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj2QnxPQ1hlYUNeArhTGx7hm1yI4yKQ-0jaqUiiceLNWYqFmxaLZVaFXcsKU-vVNv0QkOFYnfg9uB1ffDwm0LcudGwFC2jfqDElUxABDmiXlZ4VV_HRgDFirvOkul2za4xQ-hm3U1Xr0ZPE/s320/Radiation+Weighting+factors.JPG" title="radiation weighted factors" width="320" /></a></div>
<div class="MsoNormal">
<br /><br /></div>
<div class="MsoNormal">
<div style="text-align: justify;">
For example, note that alpha particles have a WF of 20. This
is because 1 rad of alpha particles causes biologic effects that are
approximately equal to those produced by 20 rad of xray energy. The absorbed
dose is multiplied by the WF to obtain the dose equivalent. The resulting unit
is called the <b>rem</b>, which stands for roentgen equivalent in man. Thus, the
worker exposed to 1 rad of alpha particles would receive 20 rem of occupational
exposure.<o:p></o:p></div>
<br /></div>
<div class="MsoNormal">
<div style="text-align: justify;">
Because the radiation quantities involved in diagnostic
radiology are so small, radiographers commonly use units that are 1 / 1000 of the
common unit (example, milliroentgens [mR], millirad [mrad], and millirem
[mrem]). For example, a chest radiograph may result in a skin entrance dose of
15 mrad, or 0.015 rad.<o:p></o:p></div>
<div style="text-align: justify;">
<br /></div>
</div>
<div class="MsoNormal">
<div style="text-align: justify;">
Students often find it confusing to determine which
radiation units should be used in a given situation. This is made more
difficult by the tendency of many radiographers to use the traditional
roentgen, rad, and rem units interchangeable. This does not cause serious
inaccuracy when speaking only of diagnostic xray, because exposure to 1
roentgen of xray energy will result in approximately 1 rad of absorbed dose on
muscle. Because the WF of diagnostic xray equals one, 1 rad is also equal to 1
rem.<o:p></o:p></div>
<div style="text-align: justify;">
<br /></div>
</div>
<div class="MsoNormal">
<div style="text-align: justify;">
In general, the reason for the measument determines which
unit is most appropriate. The R and C/kg units are used to measure the presence
of x-radiation without any reference to its absorption or attenuation (that is,
the quantity of radiation present in air). The rad and the Gy are used to
measure radiation dose. These units are used to prescribe radiation therapy. The
amount absorbed by a specific tissue is what is being measured, so a statement
indicating the part of the body involved usually modifies the rad dosage. For example,
a radiation oncologist may prescribe a treatment involving 150 centigray to the
liver, or a research report might state that the average patient who has a
routine chest radiograph receives a thyroid dose of 4 mrad. The laboratory that
processes personal radiation monitor badges will report occupational dose in
dose equivalent units: rem, mrem, or mSv.</div>
</div>
iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.com0tag:blogger.com,1999:blog-6578035841982602934.post-65527818947192798122018-07-26T21:22:00.000+08:002018-07-26T21:22:11.696+08:00Radiographic Image Quality: Optical Density, Image Detail and Distortion<br />
<h4>
Image Quality</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
The more exposure received by a specific portion of the
image receptor, the darker that portion of the image will be. The visibility of
the radiographic image depends on two factors: the overall blackness of the
image and the differences in blackness between the various portions of the
image. The clarity and sharpness of the image is a true representation of the
subject. These features make up the four elements of radiographic quality:
density, contrast, detail, and distortion.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<h4>
Radiographic or Optical Density</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
The overall blackness of the image is referred to as the
radiographic density or optical density (OD). When the radiographic density is
optimum, the image is both dark enough and light enough for you to see the
anatomic details clearly on the viewbox. In conventional film / screen system,
density is controlled by the exposure factors, primarily the mAs. Because
exposure darkens the image, an increase in mAs will result in a darker
radiograph, while a decrease will cause it to be lighter. In filmless
radiographic systems the radiographic density of the image is controlled by the
computer; an increase or decrease in mAs will not darken or lighten the image.
An increase or decrease in exposure can only be detected by looking at the
exposure indicator number.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<div class="MsoNormal" style="text-align: justify;">
Take care not to confuse radiographic density with tissue
density, which refers to the mass density of anatomic parts. While increased
optical or radiographic density indicates that the image is darker, an increase
in tissue density will result in an image that is lighter. To avoid errors, try
not to use the word density without an appropriate descriptor.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<h4>
Radiographic Contrast</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
The difference in the optical density of adjacent structures
within the image is referred to as the radiographic contrast. Even when a radiograph
has the proper optical density, it is possible that structures may be too
similar in density to be easily distinguished from one another. Image below
shows radiographs with high, low-contrast image has a black and white appearance.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
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<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<div class="MsoNormal" style="text-align: justify;">
Structures in the
grey areas are easily distinguished, but no details can be seen in the very
dark or the very light portions of the image. The low contrast image has an
overall grey appearance, and the structures tend to blend into one another. The
optimum contrast image shows details within all areas of the image, although
the contrast in some areas is less pronounced.</div>
<h4>
Kilovoltage</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
Kilovoltage is the primary contrast control factor, but
radiographic contrast is influenced by a number of other factors as well. These
include the nature of the subject, the characteristics of the film and or the
image receptor, and the amount of scatter radiation impacting the image
receptor. High kilovoltage produces an xray beam that penetrates more
completely, leaving no white areas in the image. The dark, easily penetrated
portions of the subject are not quite as dark when the kVp is high because less
mAs is needed to obtain the desired radiographic density. When more (higher)
contrast is desired, the kVp is decreased. Because this will result in less
penetration by the xray beam, a beam of greater intensity is needed, and the mAs
must be increased. Contrast is best evaluated when the overall radiographic
density is optimum.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<h4>
Image Detail</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
The third element of image quality is image detail. This refers
to the sharpness of the image. When detail is high, the edges and lines that
make up the image are crisp and precise; with low detail, these lines and edges
are less distinct and appear somewhat blurred or “out of focus”. Among the
factors that affect image detail are the distance between the source of xray
and the image receptor, referred to as the source/image distance (SID); the
distance between the object and the image receptor, referred to as the object/
image distance (OID); the size of the screen crystals and the thickness of the phosphor
layer when intensifying screens are used, or the size of the pixels in digital
systems; the focal spot size ( the smaller the focal spot the greater the
detail); and whether the patient is able to hold still during the exposure.</div>
<h4>
Distortion</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
The fourth element of image quality is distortion. This refers
to a variation in size or shape of the image in comparison to the object in
represents. Size distortion is always in the form of magnification, and all
radiographic images are magnified to some degree. The factors that affect
magnification are the OID and the SID. The angulation of the diverging xray that
define the edges of a subject affects the degree of magnification. <o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
When the image tube is farther from the image receptor, the
central, more parallel rays will define the subject, resulting in less
magnification. When the SID is shorter, the rays that define the subject are
those that diverge at a greater angle, increasing the magnification. The closer
the object to the receptor, the less magnification there will be.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<h4 style="tab-stops: center 225.65pt;">
Shape Distortion</h4>
<div class="MsoNormal" style="tab-stops: center 225.65pt;">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
Shape distortion is the result of unequal magnification of
various parts of the subject. The least shape distortion occurs when the plane
of the object is parallel to the plane of the image receptor and the central
ray is perpendicular to it. Angulation of the xray beam, the image receptor, or
the object in relation to the image receptor will all cause some degree of
distiortion.</div>
iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.com0tag:blogger.com,1999:blog-6578035841982602934.post-25230315040877901222018-07-26T16:16:00.003+08:002018-07-26T16:16:59.991+08:00Image Receptor Systems, Computed Radiography, Digital Radiography and PACS<br />
<h4>
Cassettes and Intensifying Screens</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
The cassettes serves as the film holder during the
radiographic procedure. It provides a light-tight, rigid structure to protect
the film and also houses the intensifying screens. Most cassettes contain two
intensifying screens, one front and one at the back, and the film is places
between them. Instensifying screens are plates coated with phosphors
(fluorescent crystals) that give off light when exposed to xrays. Their purpose
is to reduce the amount of exposure required to produce an image. Without intensifying
screens, as much as 50 to 100 times more exposure would be needed to adequately
expose film. Intensifying screens greatly reduce patient dose and also reduce
the output capacity requirements of xray generators and xray tubes.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<h4>
Intensifying Screens Phosphor</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
Most phosphor in common use today are salts from rare earth
elements. When exposed to xrays, they give off green, blue, blue violet, or
ultraviolet light, depending on the specific phosphor. The size of crystal and
thickness of the phosphor layer determine the amount of exposure required. Larger
crystals and/or thicker layers require less exposure. Screens with finer
crystals and thinner layer produce sharper image detail. Most radiography
departments that use screens have at least two types: fast screens with larger
crystal for routine use, and detail or extremity screens that have smaller
crystals and require more exposure. The detail screens are used only for
relatively small parts, such as hand and feet, where fine detail is most
important. They are used only on the tabletop, not with grids or buckys. The third
type may be used in some departments for chest radiography, where the
screen-film combination produces low contrast images (images with more shades
of gray) to improve visualization of the lungs, airway, and vascular
structures.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<h4>
Marker side of the Cassette</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
Each cassette has a small area where there is no
intensifying screen and where exposure is blocked from the film by lead foil. This
area is reserved for the photographic imprint of the patient identification. It
is indicated on the front of the cassette by the position of the identifying
label.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<h4>
Handling</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
It is important that you become familiar with the types of intensifying
screens used in your department so that you can select cassettes correctly and
use them with the appropriate exposure factors. Cassettes are marked according
to the type of screens they contain, and the technique chart will state which
screens are appropriate with a given set of exposures.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<div class="MsoNormal" style="text-align: justify;">
Intensifying screens are quite expensive and are easily damaged.
Damaged areas, dirt, or stains on the screens prevent light from exposing the
film and result in artifacts on the image. For these reasons, it is important
to avoid touching the screen and to keep the film processing are free of dust
and dirt.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<h4>
Radiographic Film</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
Radiographic film is manufactured with a particular
sensitivity to the light emitted by intensifying screens. Green sensitive film
is used with screens that emit green light, blue sensitive film is matched with
blue emitting screens, and ultraviolet light emitting screens are paired with
film that is sensitive to ultraviolet light.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<h4>
Double Emulsion Film</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
Film for routine radiography has emulsion coated on both
sides of the base so that the film responds to the light from both intensifying
screens. This system decreases the required exposure by half. Both side of the
film are therefore identical; there is no right or wrong side to a sheet of
double emulsion film.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<h4>
Film and Cassettes Sizes</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
Film and cassettes (as well as other image receptors) come
in standard sizes. You will work more effectively in the clinical area when you
have learned to recognize them at a glance. The most common sizes are the following:<o:p></o:p></div>
<div class="MsoNormal">
</div>
<ul>
<li>8 X 10 in ( 20 x 25 cm)</li>
<li>9 X 9 in (23 x 23 cm)</li>
<li>10 X 12 in (25 X 30 cm)</li>
<li>11 X 14 in (28 X 35 cm)</li>
<li>7 X 17 in ( 18 X 43 cm)</li>
<li>14 X 14 in ( 35 X 35 cm)</li>
<li>14 X 17 in ( 35 X 43 cm)</li>
</ul>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjy-Xzq91_ryrG8NIA08P-0QXlGOEyPU0tdXmNZ4vkGF8Pz67PbP2XPFvcyaND2IhKhkiw8SE9iZZ-rzqnb7McdduSxcxndMq_dVu4krid4jbmr7HyZT6XG_lmOVJc7OJfkJIRXZ29ACLUh/s1600/cassettes.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="" border="0" data-original-height="550" data-original-width="546" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjy-Xzq91_ryrG8NIA08P-0QXlGOEyPU0tdXmNZ4vkGF8Pz67PbP2XPFvcyaND2IhKhkiw8SE9iZZ-rzqnb7McdduSxcxndMq_dVu4krid4jbmr7HyZT6XG_lmOVJc7OJfkJIRXZ29ACLUh/s320/cassettes.JPG" title="cassettes" width="317" /></a></div>
<div>
<br /></div>
<br />
<h4>
Film Storage and Handling</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
Film must be stored correctly to avoid fog, a generalized
exposure that reduces film contrast. A good storage area is clean, cool, and
dry, and is protected from radiation and processing chemical fumes. Film boxes
should stand on edge with the expiration date visible. This date is checked to
be sure older film is used before its expiration date.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<h4>
Proper Film Handling</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
To avoid artifacts from improper film handling, be sure your
hand are clean and dry, and touch only the corners of the film when removing it
from the cassette. Avoid bending and crimping the film by allowing it to hand
vertically when holding it with only one hand. To place it horizontally, use
both hands and hold the film on opposite corners.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<h4>
Processing the Film</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
In a conventional processing system, the exposed cassette is
taken to the darkroom where the film is removed and fed into the automatic
processor in near darkness. Patient identification may be stamped on the film
using a daylight system that identifies the film outside the darkroom while it
is still in the cassette, or inside the darkroom after the film is removed from
the cassette. After the film has entered the processor, the cassette is
reloaded with fresh film from the film bin, a storage unit located under the
counter.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<h4>
Safelight Indicator on Processor</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
A safelight provides just enough illumination to see where
things are located. A tone or a red light on the processor will indicate when
it is safe to feed another film or to turn on the lights.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<h4>
Passbox</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
Cassettes are often passed to and from the dark room without
opening the door by using a passbox. This compartment is installed in the
darkroom and one set in the outside wall. Because the inner and outer doors
cannot be opened at the same time, cassettes can be transferred while the
darkroom remains dark. The passbox has two compartments: one for exposed
cassettes awaiting processing, and one for the unexposed cassettes that have been
reloaded and are ready for use. Correct locations for cassettes are essential,
because it is not possible to determine by looking at the cassettes whether the
film is exposed. Only by following the established routings can radiographer be
confident that a cassette is unexposed and ready for use.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<h4>
Filmless Radiography</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
Most major imaging centers have converted to filmless
systems for much of their radiographic imaging. Filmless systems are expensive,
but when the savings in space, time and processing chemicals are added to the
advantages of digital electronic images, the conversion is more than
worthwhile. There are two basic types of filmless radiography: Computed
Radiography (CR) and digital radiography (DR).<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<h4>
Image Receptor in Computed Radiography</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
The image receptor for computed radiography is an imaging
plate that consists of photostimulable phosphors. It is exposed in a special
cassette using conventional radiographic equipment. The radiographer inserts
the exposed cassette into a special processor and selects the type of examination
from a menu so that the image will be processed correctly. A small beam from a
high intensity laser in the processor converts the latent image to a visible
one that is captured by a photomultiplier tube similar to those used in
fluoroscopic image intensifiers. The photomultiplier tube emits an electronic
signal that is digitized and stored in a computer. The image can then be
displayed on a high resolution monitor. Hard copies can be produced using a
laser film printer.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<h4>
Digital Radiography Filmless Imaging System</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
The other type of filmless imaging system, DR, does not use
conventional equipment. Special radiographic tables and upright cabinets
contain radiation receptors that react to the pattern of the remnant radiation
and transmit a digital signal directly to the computer system, producing an
image instantaneously on a monitor. No cassettes and no processing are
involved.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<div class="MsoNormal" style="text-align: justify;">
Because both the CR and DR imaging systems automatically
adjust the visual quality of the image, there is not tell-tale darkness or
lightness of the image that indicates overexposure or underexposure as in
conventional imaging systems. For this reason, these processing systems usually
display an exposure indicator number on the monitor, also referred to as an
exposure index number, S number, or other number, depending on the equipment. This
number must be monitored by radiographer to ensure that exposure are not
excessive.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<div class="MsoNormal" style="text-align: justify;">
While digital radiography has for some time been used for
special applications such as fluoroscopy and angiography. Technical limitations
and cost factors have prevented widespread adoption of digital systems for general
radiography. As these technical limitations are conquered, digital radiography
is becoming more and more feasible for general radiographic applications.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<h4>
Storage, Archiving of
Digital Images / PACS</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
Once stored in the compter system, digital images from
either CR or DR systems are organized and catalogued and can be accessed on
monitors from multiple locations connected to the system network. These digital
images can be manipulated electronically to enhance visibility. Analog image
(conventional radiographs) can be added to the system by scanning them with a
laser device called a film digitizer.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<h4>
Computer Hardware and Software in Radiography</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
The computer hardware and software technology used to manage
digital images in hospital and large health care facilities is called a picture
archiving and communication system (PACS). This system provide archives for the
storage of images from all imaging modalities, connect images with patient
database information, facilities laser printing of images or transfer them to
CR-ROM media, and display both images and information at work stations throughout
the network as needed. PACS may include transmission equipment for tele radiology,
allowing images to be viewed in remote location such as a physician’s home, and
receiving images from remote locations such as outlying clinics. PACS technology
can transmit images directly over telephone lines and via the internet.</div>
iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.com0tag:blogger.com,1999:blog-6578035841982602934.post-85419165177222791782018-07-24T19:45:00.003+08:002018-07-24T19:45:51.675+08:00Factors of Radiographic Exposure<br />
<h4>
Exposure Time</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
Exposure time is a measure of how long the exposure will
continue and is measured in units of seconds, fractions of seconds, or
milliseconds. Electronic timers provide a wide range of possible settings,
allowing the operator to precisely control the length of exposure. Together
with the milliamperage, exposure time determines the total quantity of
radiation that will be produced. When a variation in the quantity of exposure
is desired, the exposure time is varied. Because a longer exposure time results
in the production of more xrays, when all other factors are equal, a longer
exposure time will produce a darker radiographic image. A decrease in exposure
time will result in less radiation exposure and a lighter image. Patient dose
is directly proportional to exposure time.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<div class="MsoNormal" style="text-align: justify;">
Exposure time settings may vary from a short as 1
millisecond to as long as several seconds. Some units have AECs. These
automatic exposure timers terminate the exposure when a specific quantity of
radiation has reached the image receptor. Machine with AEC have special
controls related to this process.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<h4>
Milliamperage</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
Milliamperage (mA) is a measure of the current flow rate in
the xray tube circuit. It determines the number of electron available to cross
the tube and thus the rate at which xrays are produced. You can think of mA as
an indication of the number of xray photons that will be produced per second. Thus
the mA setting will determine how much time is required to produce a given
amount of xray exposure. High mA settings are used to shorten the needed
exposure time when motion during a longer exposure would like cause blurring of
the radiographic image.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<div class="MsoNormal" style="text-align: justify;">
The number of possible mA settings is limited and is usually
in whole number that are divisible by 50 or 100. For example, a typical
radiographic unit may have the following mA settings: 50, 100, 200, 300, 400
and 500 mA. Some xray machine are capable of producing as much as 1000 or 1500
mA.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<div class="MsoNormal" style="text-align: justify;">
The relationship between mA and exposure time is simple. The
product of mA and time is milliampereseconds (mAs), which is an indicator of
the total quantity of radiation produced in the exposure. This relationship is
presented by the mAs formula:<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<div class="MsoNormal" style="text-align: center;">
mA x Time (seconds) = mAs<o:p></o:p></div>
<div class="MsoNormal" style="text-align: center;">
<br /></div>
<div class="MsoNormal" style="text-align: justify;">
Most control consoles today provide the option of setting
the mAs directly, while older models usually require the operator to set mA and
exposure time separately. The mAs settings for varous applications commonly
range between 1 and 300.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<div class="MsoNormal" style="text-align: justify;">
Changing the mA has other effects as well. In dual focus
tubes, specific mA stations control each filament. In general, mA settings of
150 or lower utilize the small filament and the small focal spot, while mA
settings of 200 or higher are associated with the large filament and large
focal spot. On controls that permits the operator to select the mA setting,
each setting will have an indication of which focal spot is associated with it.
Controls that provide mAs selection without specific mA settings will have a
separate mean of selecting focal spot size.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<div class="MsoNormal" style="text-align: justify;">
In addition to varying the focal spot size, changes in mA
will affect the amount of heat that accumulates in the anode during the
exposure and will be a cause for concern when large exposures are required. As
a rule, an xray tube can handle larger exposures when the desired mAs is
obtained with a lower mA setting and a longer exposure time.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<h4>
Kilovoltage</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
The kilovoltage or kilovoltage peak (kVp) is a measure of
the potential difference across the xray tube and determines the speed of the
electron in the electron stream. This determines the amount of kinetic energy
each electron has when it collides with the target and therefore determines the
amount of energy in the resulting xray beam. This energy is expressed by the
wavelengths have more energy and are more penetrating than those with longer
wavelengths. For this reason, an increase in kVp results in a more penetrating
xray beam. This will cause more exposure to the image receptor, because a
higher percentage of the xrays produced will pass through the patient and reach
the IR. An increase in kVp will produce a darker image, while a decrease in kVp
will produce a lighter image.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<div class="MsoNormal" style="text-align: justify;">
Changes in kilovoltage will also cause other changes to the
image. Because the differential penetration of the xray beam will be affected
by wavelength, the contrast of the image will also change. This means that the
degree of difference between the darker and lighter areas of the image will be
affected. Somewhere between no penetration and total penetration of the subject
is the optimum amount of diffetential penetration that will show a contrast in
exposure between the various features of the subject. The amount of kVp that
produces optimum penetration varies with the examination.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<div class="MsoNormal" style="text-align: justify;">
Kilovoltage settings for typical radiographic units range between
40 kVp and 150 kVp in increments of 1 or 2 kilovolts. Low kVp settings are used
for small body parts. For example, 50 to 60 kVp is commonly used for
radiographic examinations of the hand, wrist, or foot. Spine radiography
typically utilizes settings between 75 and 100 kVp, while settings above 100
kVp may be used for chest radiography and for studies of the digestive tract
that employ barium sulfate as a contrast agent.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<h4>
Distance</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
The distance between the source of the xray beam (the tube
target) and the image receptor is referred to as the source-image distance
(SID). This distance is a prime factor of exposure because it affect the
intensity of the xray beam. Radiation intensity might be thought of as the
number of photons per square inch striking the surface of the image receptor.
Because the xray beam diverges from its source, the size of the beam expands as
the distance from the source increases. As the total quantity of xray photons
in the beam spread out, there are fewer photons in any given area.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgUhKgSDf2GK8RtEuuulT2mL1iJEoJfvQaQ_QnwOkpz4KCVlg5FyqTERmj3qv_plbIOLY6JjojiKUb-UAidxp5SioeWbjqexGc2nASeMRCuLDznO1nYFykOHoRVqP1aaZp2-x3Ypk7-sRX9/s1600/SID.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="695" data-original-width="354" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgUhKgSDf2GK8RtEuuulT2mL1iJEoJfvQaQ_QnwOkpz4KCVlg5FyqTERmj3qv_plbIOLY6JjojiKUb-UAidxp5SioeWbjqexGc2nASeMRCuLDznO1nYFykOHoRVqP1aaZp2-x3Ypk7-sRX9/s320/SID.JPG" width="162" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Source-image distance affects radiation field size and intensity</td></tr>
</tbody></table>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<div class="MsoNormal" style="text-align: justify;">
The change in xray beam intensity that results from changes
in the SID is expressed by the inverse square law, which states that the
intensity of the radiation is inversely proportional to the square of the
distance. The inverse square law is expressed mathematically in this equation:<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgtOLFV9G3PVFF-ajiwxqkDDONLXmXLsXfTyf0GYQIOI76RRz4mnMJDgZ3l8en0eRoeJdTkiibJVgvxqM7-DBjrK0MQTKSh2MYpDX1tzHA-sRX02ElhoJWwHRzYDHGDvadbGsJv5QnQr1zc/s1600/Inverse+square+law.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="" border="0" data-original-height="71" data-original-width="157" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgtOLFV9G3PVFF-ajiwxqkDDONLXmXLsXfTyf0GYQIOI76RRz4mnMJDgZ3l8en0eRoeJdTkiibJVgvxqM7-DBjrK0MQTKSh2MYpDX1tzHA-sRX02ElhoJWwHRzYDHGDvadbGsJv5QnQr1zc/s1600/Inverse+square+law.JPG" title="inverse square law" /></a></div>
<br />
<div class="MsoNormal" style="text-align: justify;">
You will note in the picture above that, as the distance is
double, each dimension of the radiation filed is doubled; so the radiation
field is four times greater in area. Therefore, the intensity, the number of
photons per unit area within the field, is one fourth of the original amount.
Likewise, if the distance were tripled, the field area would be one ninth of
the original amount.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<div class="MsoNormal" style="text-align: justify;">
Of course, as the radiation intensity decrease, exposure to
the image receptor will also decrease. In order to maintain the same optical
density (degree of image darkness) when the SID changes, the mAs must be
adjusted corresponding. The formula for this adjustment is:<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEijkchp3HAYuj3zX2DDzq-OuZlAZhLm201ozqyzz7mWjyGZLQGJpAGKxB_2gSN0HOnW5gg0oY2Izm9eo4seoBj7tlK2EWwUmzOHQz9H6wMRN6VND73pKnVCKLWLlifIldubMFeF8wpUNuA1/s1600/optical+density.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="" border="0" data-original-height="70" data-original-width="194" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEijkchp3HAYuj3zX2DDzq-OuZlAZhLm201ozqyzz7mWjyGZLQGJpAGKxB_2gSN0HOnW5gg0oY2Izm9eo4seoBj7tlK2EWwUmzOHQz9H6wMRN6VND73pKnVCKLWLlifIldubMFeF8wpUNuA1/s1600/optical+density.JPG" title="optical density" /></a></div>
<br />
<div class="MsoNormal" style="text-align: justify;">
As you learn later when you study xray technique
calculations in more detail, this formula will enable you to maintain a given
radiation intensity, and therefore a given radiographic appearance, when
changing the SID. For example, this formula will result in a fourfold increase
in mAs compensates for the reduction in radiation intensity that occurs with
the SID increase, with the result that the radiation intensity is unchanged.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<h4>
Technique Charts</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
A technique chart located near the control console usually
provides the radiographer with a listing of recommended mAs and kVp settings,
as well as the SID, for each of the various body parts for different sizes of
patients. Some control consoles have “anatomical programming.” These
computerized units are preprogrammed with the required exposure settings for
the selected body part and size.</div>
iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.com0tag:blogger.com,1999:blog-6578035841982602934.post-77568908627596416502018-07-23T21:25:00.002+08:002018-07-23T21:25:49.255+08:00Fluorocospy - Radiography Machine<br />
<h4>
Fluoroscopy</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
While routine radiography procedures still or static images,
fluoroscopy permits the viewing of dynamic images or xray images in motion.
Fluoroscopy is usually performed by radiologists who are assisted by
radiographers. Fluoroscopic procedure are a routine aspect of every
radiographer’s clinical education. <o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjOW82OSMvIcqlmLXIfwvoV8Mjzmjgv9eDSCD9aHDbGuRFXANUXxABX1eLhLhUn4siUOWOgdapT1j0IsodQ0hJ-GKlPy6oXAsAZHrsfHhTyoyUn0cZy-LeAEjHbv-ZxvgpCWK-fBBjxZULZ/s1600/digital+fluoroscopy.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="" border="0" data-original-height="491" data-original-width="906" height="173" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjOW82OSMvIcqlmLXIfwvoV8Mjzmjgv9eDSCD9aHDbGuRFXANUXxABX1eLhLhUn4siUOWOgdapT1j0IsodQ0hJ-GKlPy6oXAsAZHrsfHhTyoyUn0cZy-LeAEjHbv-ZxvgpCWK-fBBjxZULZ/s320/digital+fluoroscopy.JPG" title="fluoroscopy machine" width="320" /></a></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<h4>
Fluoroscopic Equipment</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
A fluoroscope is an xray machine designed for direct viewing
of the xray image. Early fluoroscopes consisted simply of an xray tube mounted
under the xray table and a fluorescent screen mounted over the patient. The
physician watched the xray image on the screen while turning the patient into
the desired positions to view various anatomic areas. The fluoroscopic image
was very dim, dark adaptation was required, and the procedure was carried out
in a dark room.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<div class="MsoNormal" style="text-align: justify;">
Today’s equipment is far more sophisticated. Most
fluoroscopic units are properly called radiographic / fluoroscopic (R/F) units
because they can be used for both radiography and fluoroscopy. This is
convenient because most fluoroscopic examination also have a radiographic
component. <o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<h4>
Spot Films</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
Spot Films are taken during fluoroscopy to record the image
as seen on the fluoroscope. Depending on the age of equipment, cassettes, roll
film, or digital systems may be used to record fluoroscopic images.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<h4>
Fluoroscopic Tube</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
The fluoroscopic tube is used to expose spot films and
images areas of interest. After the fluoroscopic portion of the study is
completed, additional images may be taken using an overhead tube for comprehensive
visualization of the entire anatomic region.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<h4>
Digital Fluoroscopy</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
The radiation required for a fluoroscopic study has been
greatly reduced by the use of the image intensifier. This electronic device is
in the form of a tower that fits over the fluoroscopic screen. Inside is a
series of photomultiplier tube that brighten and enhance the image formerly
seen by looking directly at the fluoroscopic screen. <o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<div class="MsoNormal" style="text-align: justify;">
The enhanced image is digitized or photographed by a video
monitor. A Computer or videotape recorder can be used to make a record of the
entire study.<o:p></o:p></div>
<div class="MsoNormal">
Some towers can be removed from the fluoroscope and moved
away from the table when they are not needed. The fluoroscope and spot film
device can also be moved out of the way when the table is used for radiography.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal" style="text-align: justify;">
The control console of an R/F unit is more complex than that
of a basic radiography unit. There may be separate mA and kVp settings for the
control of the radiographic (overhead) and fluoroscopic (under table) tubes,
and special settings for spot film radiography. A timer on the control advances
when the fluoroscope is on, and an alarm sounds after a preset period, usually
5 minutes.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<h4>
Radiographer’s Duty in Fluoroscopy Examinations</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal">
For a fluoroscopy examination, the duties of the
radiographer include the following:<o:p></o:p></div>
<div class="MsoNormal">
</div>
<ul>
<li>Taking the patient’s history, including information on the
success of dietary and/or bowel cleansing preparation</li>
<li>Getting the patient gowned</li>
<li>Explaining the procedure to the
patient</li>
<li>Taking and processing any required
preliminary images</li>
<li>Setting the control panel correctly
for fluoroscopy and spot film radiography</li>
<li>Positioning the patient for the
start of the procedure</li>
<li>Preparing the equipment for
fluoroscopy</li>
<li>Entering patient data into the
computer for digital imaging, if applicable</li>
<li>Loading the spot film device, if
applicable</li>
<li>Preparing contrast agents as needed</li>
<li>Assisting the radiologist as
needed. This may involve helping the patient assume various positions;
assisting the patient and / or the radiologist with the contrast medium;
changing spot film cassettes as needed; loading, unloading, and identifying
roll films; or electronically managing digital images</li>
<li>Taking follow up radiographs</li>
<li>Providing post procedural care and instructions.</li>
</ul>
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<br />iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.com0tag:blogger.com,1999:blog-6578035841982602934.post-84797491063643582512018-07-23T17:54:00.001+08:002018-07-23T17:54:10.685+08:00Radiographic Equipments - Radiography<br />
<h4>
Radiographic Equipments</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
Xray rooms vary in design, depending on their purpose. For example,
a room dedicated to upright chest radiography might not have an xray table
because the patients in this room would be standing for their examinations, not
lying down. A room designed for doing gastrointestinal examinations would be
equipped for both radiography and fluoroscopy. A typical room designed for
general radiography is suitable for many different types of xray examinations. In
a hospital setting, the room will be fairly large, perhaps 18 x 20 feet in
size, with wide doors to accommodate hospital beds and stretchers. Physical
features will include the radiographic table, the xray tube and its support
system, an upright image receptor cabinet against one wall, and a shielded
control booth that contains the control console.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<h4>
The Xray Tube</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
The xray tube is the source of radiation. Modern multipurpose
xray tube are dual focus tubes. Their cathode assemblies contain two filaments,
one large and one small. It situated in the focusing cup that directs its
electrons toward the same general area on the target portion of the anode. When
the small filament is activated, its electron are directed to a tiny focal spot
on the target. The small filament and focal spot provide finer image detail
when a relatively small exposure is appropriate, for example, when imaging a
small body part such as a toe or wrist. The large filament provides more
electrons and is aimed at a larger target area.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
The combination of large filament and large focal spot is
used when a large exposure is required, such as for radiographs of the lumbar
spine or the abdomen, because the large filament provides more electrons and
the large focal spot can better handle the resulting heat at the anode. The anode
is disk-shaped and rotates during the exposure, distributing the anode heat
over a larger area and increasing the heat capacity of the tube. It is the rotation
of the anode that causes the whirring sound just before and after the exposure.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<h4>
Xray Tube Housing</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
The xray tube is located inside a protective barel-shaped
housing. The housing incorporates shielding that absorbs radiation that is not
a part of the useful xray beam. The housing protects and insulates the xray
tube itself while providing a base for attachment that allows radiographer to
manipulate the xray tube and to control the size and shape of the xray beam.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<h4>
Xray Tube Support</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
The tube housing may either be attached to a ceiling mount
tube hanger or mounted on a tube stand. Both type of mountings provide support
and mobility for the tube. A tube hanger is suspended from ceiling on a system
of tracks to allow positioning of the tube at locations throughout the room. This
ceiling mount is useful when positioning the tube over a stretcher or when
moving the tube for use in different locations. A tube stand is a vertical
support with a horizontal arm that supports the tube over the radiographic
table. The tube stand rolls along a track that is secured to the floor (and sometimes
also the ceiling or wall), permitting horizontal motion.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
A system of electric locks holds the tube support in
position. The control system for all, or most, of these locks is an attachment
on the front of the tube housing. To move the tube in any direction, the
locking device must be released. Moving the tube without first releasing the
lock may damage the lock, making it impossible to secure the tube in position. Do
not attempt to move the tube without first releasing the appropriate lock.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<div class="MsoNormal">
Typical tube motions include the following:<o:p></o:p></div>
<div class="MsoNormal">
</div>
<ul>
<li style="text-align: justify;">Longitudinal – along the long axis of the table</li>
<li style="text-align: justify;">Transverse – across the table, at the right angles to
longitudinal</li>
<li style="text-align: justify;">Vertical – up and down, increasing or decreasing the
distance between the tube and the table</li>
<li style="text-align: justify;">Rotation- allows the entire tube support to turn on its
axis, changing the direction in which the tube arm is extended</li>
<li style="text-align: justify;">Roll (tilt, angle)- permits angulation of the tube along the
longitudinal axis and also allows the tube to be aimed at the wall rather than
the table.</li>
</ul>
<h4 style="text-align: justify;">
Detend</h4>
<div style="text-align: justify;">
A <b>detent</b> is a special mechanism that tends to stop a moving part in a specific location. Detents are built into tube supports to facilitate placement at standard locations. For example, a vertical detent will indicate when the distance from tube to image receptor is 40 inches, a common standard distance. Other detents provide “stop” when the transverse tube position is centered to the table and when the tilt motion is such that the central ray is perpendicular to the table or to the upright image receptor cabinet against the wall.</div>
<o:p></o:p><br />
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<div class="MsoNormal" style="text-align: justify;">
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<h4 style="text-align: justify;">
Collimator</h4>
<div class="MsoNormal" style="text-align: justify;">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
Another attachment to the tube housing is the collimator, a
boxlike device mounted beneath the port, the opening of the housing. Collimators
allow the radiographer to vary the size of the radiation field and to indicate
with a light beam the size, location, and center of the field. There is usually
a centering light that also helps align the image receptor. Controls on the
front of the collimator allow the radiographer to adjust the size of each
dimension of the radiation field. The collimator has a scale that indicates each
dimension of the field at specific source-image distances. A timer controls the
collimator light, turning it off after a certain length of time, usually 30
seconds. This helps to avoid accidental overheating of the unit by prolonged use
of its high intensity light.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
While many collimators are manually controlled, some are
equipped with a feature called positive beam limitation (PBL). These collimators
have sensors that detect the size of the image receptor. Some automatically
adjust the radiation field size to the size of the image receptor; others
prevent exposure until the field has been manually adjusted to the size of the
image receptor or smaller. These PBL devices were legally required, for reasons
of radiation safety, to be installed on machines manufactured, moved, sold, or
significantly upgraded during the years between 1970 and 1993. This requirement
no longer exists, but many collimators with PBL features are still in use.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<h4>
Radiographic Table</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
The radiographic table is a specialized unit that is more
than just a support for the patient. While the table is usually secured to the
floor, it may be capable of several types of motion: vertical, tilt, and
floating tabletop.<o:p></o:p></div>
<div style="text-align: justify;">
<br /></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjc0VA6_HJamYBDndRqQdyuXR-mjaCm6JKRlEnr56bJALpUh2VtByEFanPuq8RvaYPzGDHnHt9opXASLulxJ2ZT9FRbCoczjdI2Iadnf8jW_JFvuIZU8q-Ob49LinjmS05-94KuRIE_rr7I/s1600/Radiographic+Table.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="" border="0" data-original-height="454" data-original-width="337" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjc0VA6_HJamYBDndRqQdyuXR-mjaCm6JKRlEnr56bJALpUh2VtByEFanPuq8RvaYPzGDHnHt9opXASLulxJ2ZT9FRbCoczjdI2Iadnf8jW_JFvuIZU8q-Ob49LinjmS05-94KuRIE_rr7I/s320/Radiographic+Table.JPG" title="radiographic table" width="237" /></a></div>
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<div class="MsoNormal" style="text-align: justify;">
For vertical table motion, a hydraulic motor, activated by a
hand, foot, or knee switch, raises or lowers the height of the table. This allows
lowering of the table so that the patient can sit down on it easily and also
permits the table to rise to a comfortable working height for the radiographer.
Adjustment to exact stretcher height can be made to facilitate patient
transfers. There will be a detent or standard position for routine radiography.
This standard table height corresponds to indicated distances from the xray
tube. Because it is important that standard tube/IR distances be used, it is
necessary to return the table to the detent position after lowering it for
patient access. Not all table are capable of vertical motion.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<h4>
Tilting Table</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
A tilting table also uses a hydraulic motor to change
position. In this case, the table turns on a central axis to attain a vertical
position. This allows the patient to be placed in a horizontal or vertical
position or at any angle in between. The table may also tilt in the opposite
direction, allowing the patient’s head to be lowered at least 15 degrees into
the Trendelenburg position. A detent stops the table in the horizontal
position. Tilting is an essential feature of most fluoroscopic tables and may
also be a feature of a radiographic unit.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
Special attachment for the tilting table including a
footboard and a shoulder guard to provide safety for the patient when tilting
the table. Pay particular attention to the attachment mechanism so that you
will be able to apply these attachments correctly when needed. Before tilting a
patient on the table, always test the footboard or shoulder guard to be certain
that it is securely attached.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<h4>
Motor of Tilting Table</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
The motor that tilts the table is quite powerful and can
overcome the resistance of obstacle placed in the way. Many step stool and
other pieces of movable equipment have been damaged because they were under the
end of the table and out of view when the table motor was activated. Such a
collision can also damage the table motor. Be certain that the spaces under the
head and foot of the table are clear before activating the tilt motor.<o:p></o:p></div>
<h4>
Floating Tabletop</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
A floating tabletop allows the top of the table to move
independently of the remainder of the table for ease in aligning the patient to
the xray tube and the image receptor. This motion may involve a mechanical
release, allowing the radiographer to shift the position of the tabletop, or
the movement may be power-assisted, activated by a small control pad with
directional switches. Power assisted movement is common for fluoroscopic table.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<h4>
Grids and Buckys</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
When primary
radiation encounters matter, such as the patient or the xray table, the
resulting interaction produces scatter radiation. Most of the scatter radiation produced
during an exposure originates within the patient. This scatter radiation causes
fog on the radiographic image, a generalized exposure that compromises the
visibility of the anatomic structures. Grids and buckys are devices to prevent
scatter radiation from reaching the image receptor and degrading the image.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<h4>
Bucky</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal">
A <b>bucky</b> is usually located beneath the table surface. It is
a moving grid device that incorporates a tray that holds the Image receptor. The
entire unit can be moved along the length of the table and locked into position
where desired. </div>
<div class="MsoNormal">
<br /></div>
<h4>
Grid</h4>
<div class="MsoNormal" style="text-align: justify;">
The <b>grid</b> that is incorporated into the bucky device is situated between
the tabletop and the image receptor. It is a plate made of tissue-thin lead
strip, mounted on edge, with radiolucent interspacing material. The strips must
be carefully aligned to the path of the primary xray beam, so precise alignment
of the xray tube is essential. In most radiographic units, the grid moves during the exposure. The purpose of moving the grid is to blur
the image of the thin lead strips so that they are not visible on the
radiograph. When the table has a floating tabletop, the bucky mechanism and
image receptor do not move with the tabletop.</div>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal" style="text-align: justify;">
Stationary grids that do not move during the exposure serve
the same purpose as a bucky. A grid may also be incorporated into a device
called a grid cap, which is a grid mounted in a frame that can be attached to
the front of an image receptor for mobile radiography and other special
applications.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal" style="text-align: justify;">
Grid or bucky are generally used only for body parts that
measure more than 10 to 12 cm in thickness. (The average adult’s neck or knee
measures 12 cm). when a grid is not needed, the image receptor is placed on the
tabletop.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<h4>
Upright Image Receptor Units</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
The upright bucky or the grid cabinet is a device that holds
the image receptor in the upright position for radiography. It is adjustable in
height and may incorporate either a bucky or a stationary grid. When a
stationary grid is included, this device may be referred to as a grid cabinet;
when the grid moves during the exposure, the device is called an upright bucky.
Even when the table tilts to the upright position, it is common to have a
separate upright unit for some examinations such as the cervical spine and the
chest. When the patient is sitting or standing at the upright bucky, the tube
is angled to direct the xray beam toward the image receptor. The distance may
be adjusted to 40 or 72 inches, depending on the requirements of the procedure.<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<h4>
Transformer</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
Cables from the tube housing connect the xray tube to the
transformer, which provides the high voltage necessary for xray production. Some
transformers look like a large box or cabinet, which may or may not be located
within the xray room. Newer transformer designs are much smaller and may be
incorporated into the control console.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<h4>
Control Console</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal">
The control console, located in the control booth, is the
access point for the radiographer to determine the exposure factors and to
initiate the exposure.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Radiographic control consoles have buttons, switches, dials,
or digital readouts for some or all of the following functions:<o:p></o:p></div>
<div class="MsoNormal">
</div>
<ul>
<li><b>Off/On</b> – controls the power to the control panel</li>
<li><b>mA</b> – allows the operator to set the milliamperage, the rate
at which the xrays are produced; determines the focal spot size</li>
<li><b>kVp</b> – controls the kilovoltage, and thereby the wavelength
and penetrating power, of the xray beam.</li>
<li><b>Timer</b> – controls the duration of the exposure</li>
<li><b>mAs</b> – some units have an mAs control instead of mA and time
settings. The mAs ( the product of mA and time) determines the total quantity
of radiation produced during an exposure</li>
<li><b>Bucky</b> – Activates the motor control of the bucky device so
that the grid will move during the exposure</li>
<li><b>Automatic exposure controls (AECs)</b> – special settings
available on certain units that allows termination of exposure when a certain
quantity of radiation has reached the image receptor</li>
<li><b>Meters or digital readouts</b> - to indicate the status of the
settings</li>
<li><b>Prep (ready or rotor ) switch</b> – prepares the tube for
exposure and must be continuously activated until exposure is complete</li>
<li><b>Exposure switch</b> – initiates the exposure and must be
continuously activated until the exposure is complete</li>
<li><b>Accessories</b> – other controls may also be present, depending
on the equipment and its specific features</li>
</ul>
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Continue reading on Fluoroscopy Xray Equipment<o:p></o:p></div>
<br />iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.com0tag:blogger.com,1999:blog-6578035841982602934.post-78379072267658934382018-07-22T10:52:00.000+08:002018-07-22T10:52:20.551+08:00Characteristic of Xray, Primary Xray and Scatter Radiation<h4>
Characteristic of Radiation</h4>
<div style="text-align: justify;">
Because xrays and visible light are both forms of electromagnetic energy, they share some similar characteristics. Both travel in straight lines, and both have an effect on photographic emulsions. When film is used, the photographic effect of xrays is important in the production of radiographic images. It is also important to remember because accidental exposure can occur when film is placed near xray sources.</div>
<div style="text-align: justify;">
Both xray and light have a biologic effect; that is, they can cause changes in living organisms. Because of their greater energy, xrays are capable of producing more harmful effects than light. Unlike light, xray cannot be refracted by lens. The xray beam diverges into space from its source until it is absorbed by matter.</div>
<div style="text-align: justify;">
Unlike light, xray cannot be detected by the human senses. This fact may seem obvious, but it is important to consider. If xray could be seen, felt or heard, we would have an increased awareness of their presence and radiation safety might be much simpler. Because they are undetectable, however, safety requires that you learn to know when and where xrays are present without being able to perceive them.</div>
<div>
<br /></div>
<div style="text-align: justify;">
Xrays can penetrate matter that is opaque to light. This penetration is differential and depends on the density and thickness of the matter. For example, xrays penetrate air very readily. There is less penetration of fat or oil, even less of water, which is about the same density as muscle tissue, and still less of bone. Xrays that have passed through the body are referred to as remnant radiation or exit radiation. Remnant radiation has a pattern of intensity that reflects the absorption characteristics of the body. It is pattern that is recorded to form the image.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
Xray cause certain crystal to fluoresce, giving off light when they are exposed. Among crystals that respond in this way are <b>barium platinocyanide</b>, <b>barium lead sulfate</b>, <b>calcium tungstate</b>, and <b>several salts consisting of rare earth elements</b>. These crystal are used to convert xray pattern into a visible image that can be viewed directly, as in fluoroscopy, or recorded on photographic film. The use of fluorescent intensifying screens to expose radiographs greatly reduces the quantity of radiation needed. The combination of film and intensifying screens has been the conventional image receptor (IR) for decades, but is now being replaced by filmless technology that produces digital images.</div>
<div style="text-align: justify;">
<br /></div>
<h4>
The Primary Xray Beam</h4>
<div style="text-align: justify;">
Xrays are formed within a very small area on the target (anode) called a focal spot. The actual size of the largest focal spot is no more than a few millimetres in diameter. From the focal spot, the xray diverge into space, forming the cone-shaped primary xray beam.</div>
<div>
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjdU12FlpDyOJ7Krzda2avF5iuAY0Djjyp2lMkuF2EHteVlVaiYWPJrD5JMlo_M-12iebhRjNMr0CQc0s4QyWGqIu5GMKLYrwDgqp4T5CxX88RAZ3Z9bKL2C46OEKMfWi0kMiw7Tq_L05Rz/s1600/xRay+source.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="" border="0" data-original-height="522" data-original-width="451" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjdU12FlpDyOJ7Krzda2avF5iuAY0Djjyp2lMkuF2EHteVlVaiYWPJrD5JMlo_M-12iebhRjNMr0CQc0s4QyWGqIu5GMKLYrwDgqp4T5CxX88RAZ3Z9bKL2C46OEKMfWi0kMiw7Tq_L05Rz/s320/xRay+source.JPG" title="xray tube" width="276" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Cross section of xray beam is called the radiation field.<br />imaginary perpendicular ray at its center is called central ray.</td></tr>
</tbody></table>
<div>
<br /></div>
<div>
<br /></div>
<div style="text-align: justify;">
The cross section of the xray beam at the point where it is utilized is called the radiation field. A photon in the center of the primary beam and perpendicular to long axis of the xray tube called the central ray.</div>
<div style="text-align: justify;">
The xray beam size is restricted by the size of the port, the opening in the tube housing. Attached to the housing is the collimator, a device that enables the radiographer to further control the size of the radiation field.</div>
<div>
<br /></div>
<h4>
Scatter Radiation</h4>
<div style="text-align: justify;">
When the primary xray beam encounters any solid matter, such as the patient or the xray table, a portion of its energy is absorbed. This results in the production of scatter radiation.</div>
<div>
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiu0YKemHocY-x6tWhu0HtvR0xpgT6iJOQMnNioRr2IWY9EhYPdCV_qZeOmGm8OyQOnFwg07oKi4IkX9gsEknQbteL9QODiIF0pXJ7A5AgDFalzS004c3jBAPg4wGWIUBrzdXAuXskoGDw4/s1600/Scatter+radiation.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="" border="0" data-original-height="562" data-original-width="490" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiu0YKemHocY-x6tWhu0HtvR0xpgT6iJOQMnNioRr2IWY9EhYPdCV_qZeOmGm8OyQOnFwg07oKi4IkX9gsEknQbteL9QODiIF0pXJ7A5AgDFalzS004c3jBAPg4wGWIUBrzdXAuXskoGDw4/s320/Scatter+radiation.JPG" title="scatter radiation" width="279" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Scatter radiation forms when the primary xray beam<br />interacts with matter</td></tr>
</tbody></table>
<div>
<br /></div>
<div style="text-align: justify;">
This scatter radiation is generally has less energy than the primary xray beam, but it is not easily controlled. It emanate from the source in all directions, causing unwanted exposure to the image receptor and posing a radiation hazard to anyone in the room. Scatter radiation is the principal source of occupational exposure to radiographers.</div>
<div style="text-align: justify;">
The characteristic of primary radiation, scatter radiation and remnant radiation are summarized for comparison below.</div>
<div style="text-align: justify;">
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhKnEnYun-X7zw6aK6JuA-QgwHXyiEb7R1MJILOxv03ZZ8ZO1OYzQY0NIvhmdK-6Snr5GJv8LbgBpTloNLbJadh8jOTggqVdKIPP9fKQjoL69uBhnEjYCMzfviT-A-YT6wVulpVHrRDIWpo/s1600/xray+beam+attenuation+table.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="339" data-original-width="1045" height="102" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhKnEnYun-X7zw6aK6JuA-QgwHXyiEb7R1MJILOxv03ZZ8ZO1OYzQY0NIvhmdK-6Snr5GJv8LbgBpTloNLbJadh8jOTggqVdKIPP9fKQjoL69uBhnEjYCMzfviT-A-YT6wVulpVHrRDIWpo/s320/xray+beam+attenuation+table.JPG" width="320" /></a></div>
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iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.com0tag:blogger.com,1999:blog-6578035841982602934.post-41860848156537324152018-07-21T22:39:00.000+08:002018-07-22T10:53:09.137+08:00Electromagnetic Energy Xray Production<br />
<h4>
Electromagnetic Energy</h4>
<div class="MsoNormal">
<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
Xrays are among several types of energy described as
electromagnetic energy, or electromagnetic wave radiation. They have both
electrical and magnetic properties, changing the field through which they pass
both electrically and magnetically. These changes in the field occur in the
form of a repeating wave, a pattern that scientists call a <b>sinusoidal form</b> or <b>sine wave</b>.<o:p></o:p></div>
<div class="MsoNormal">
Several types of this waveform are significant. The distance
between the crest and valley of the wave (it’s height) is called the amplitude. </div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6jj10kssqqhBizZnKCIC67uimC_pWrJW6tdHT4USIDt71qof42hjTGs6Kictl5QqXpCSTMJGzH5JGlFD9b5Jg5v6GkBvrHhyphenhypheng0P_rMXG5kZVSPru_cpuYA3hxOik65OKi5vhOAdEPod5T/s1600/Amplitude.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="380" data-original-width="494" height="246" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj6jj10kssqqhBizZnKCIC67uimC_pWrJW6tdHT4USIDt71qof42hjTGs6Kictl5QqXpCSTMJGzH5JGlFD9b5Jg5v6GkBvrHhyphenhypheng0P_rMXG5kZVSPru_cpuYA3hxOik65OKi5vhOAdEPod5T/s320/Amplitude.JPG" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">The three sine waves are identical except for their amplitudes.</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
More important to the radiographer is the distance from one crest to the next
or wavelength.</div>
<div class="MsoNormal">
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirhySzRnSygchE945KfeUHyuqMzw_imkzi4gUaMEgd-bjtUZSEyRy-7KzTMdlsj5EM6s6k1EdhJDmaO3aORODpwMKrZr-6tNvZdshO435TGqlrPzM0kWT3teQQnARsEdDjQNGmcGR5H8V0/s1600/wavelength.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="403" data-original-width="456" height="282" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirhySzRnSygchE945KfeUHyuqMzw_imkzi4gUaMEgd-bjtUZSEyRy-7KzTMdlsj5EM6s6k1EdhJDmaO3aORODpwMKrZr-6tNvZdshO435TGqlrPzM0kWT3teQQnARsEdDjQNGmcGR5H8V0/s320/wavelength.JPG" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Three sine waves have different wavelengths. The shorter the wavelength,<br />
the higher the frequency.</td></tr>
</tbody></table>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
The frequency of the waves is the number of times per seconds
that a crest passes a given point.</div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal" style="text-align: justify;">
Because all electromagnetic energy moves through space at
the same velocity, at approximately 186,000 miles per seconds, which is 30
billion (3 x <span style="background: white;">10</span><sup style="-webkit-text-stroke-width: 0px; font-variant-caps: normal; font-variant-ligatures: normal; orphans: 2; text-align: start; text-decoration-color: initial; text-decoration-style: initial; widows: 2; word-spacing: 0px;">10</sup>) centimetre per second, it is apparent that a relationship
exist between wavelength and frequency. When the wavelength is short, the crest
are closer together, so more of them will pass a given point each second,
resulting in a higher frequency. Longer wavelengths will have a lower
frequency. This may be expressed mathematically as follows:<o:p></o:p></div>
<div class="MsoNormal" style="text-align: justify;">
<br /></div>
<div class="MsoNormal" style="text-align: center;">
Velocity (v) = Wavelength (<span style="background: white; color: #222222;">λ</span>)
x Frequency (f)<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="background: white; color: #222222;"> The more energy the wave has, the
greater will be its frequency and the shorter its wavelength. We can therefore
use either wavelength or frequency to describe the energy of the wave. In radiologic
science, wavelength is more often used to describe the energy of the xray beam.
The average wavelength of a diagnostic xray beam is approximately 0.1
nanometer, which is 10<sup>-10</sup> (0.00000000001) meters, or about a
billionth of an inch.<o:p></o:p></span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="background: white; color: #222222;"><br /></span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="background: white; color: #222222;"> The wavelength of electromagnetic
radiation varies from exceedingly short ( shorter than that of diagnostic
xrays) to very long ( more than 5 miles). This range of energies is known as
the electromagnetic spectrum. It includes xray, gamma rays, visible light,
microwaves, and radio waves.</span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="background: white; color: #222222;"><br /></span></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiDhKnqiEcm3ao6m39uhkkqcXqVpcx5uvV_pJBwREbCEl4QmSaFXZHaoEOWZou06MHcJtyOOJmt2N5CVHZEwJAOgJn53yyah3qdzpWkUoKsijMuyAneZBefi1YTaShkg9Q96WalqSlYtpjY/s1600/Electromagnetic+spectrum.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" data-original-height="515" data-original-width="555" height="296" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiDhKnqiEcm3ao6m39uhkkqcXqVpcx5uvV_pJBwREbCEl4QmSaFXZHaoEOWZou06MHcJtyOOJmt2N5CVHZEwJAOgJn53yyah3qdzpWkUoKsijMuyAneZBefi1YTaShkg9Q96WalqSlYtpjY/s320/Electromagnetic+spectrum.JPG" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Electromagnetic Spectrum</td></tr>
</tbody></table>
<div class="MsoNormal" style="text-align: justify;">
<span style="background: white; color: #222222;"><br /></span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="background: white; color: #222222;"><br /></span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="background: white; color: #222222;"> Radiation with a wavelength shorter than one
nanometer (10<sup>-9 </sup></span><span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;">meters) is said to be ionizing radiation
because it has sufficient energy to remove an electron from an atomic orbit. Xray
are one type of ionizing radiation.<o:p></o:p></span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;"><br /></span></div>
<div class="MsoNormal" style="text-align: justify;">
<span style="mso-bidi-font-family: Calibri; mso-bidi-theme-font: minor-latin;"> The smallest possible unit of electromagnetic energy (analogous to
the atom with respect to matter) is the photon, which may be thought of as a
minute “bullet” of energy. Photons occur in group or “bundles” called quanta or
quantum (singular).<o:p></o:p></span></div>
<br />iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.com0tag:blogger.com,1999:blog-6578035841982602934.post-32257819588064808232018-07-21T18:12:00.000+08:002018-07-22T10:53:29.692+08:00Xray Production - Xray Tube<h4>
Xray Production</h4>
<h4>
How Xray Produce?</h4>
<div style="text-align: justify;">
In this section will include a close look at a number of pieces of xray equipment. To better appreciate their purposes, it will be helpful to understand how xray are produced. There are 4 basic requirements for the production of xrays:</div>
<div>
<br /></div>
<div>
<ul>
<li>A vacuum</li>
<li>A source of electrons</li>
<li>A target for the electrons</li>
<li>A high potential difference (voltage) between the electron source and the target.</li>
</ul>
</div>
<div>
<br /></div>
<div style="text-align: justify;">
The container of the vacuum is the xray tube itself, sometimes referred to as a glass envelope. It is made of borosilicate glass (PYREX) to withstand heat and is fitted on both ends with connection for the electrical supply. All of the air is removed from the tube so that gas molecules will not interfere with the process of xray production.</div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhMV6puFkAn6OG7DEBLnyelCF7TBobNAD88eDMnK4skZ9AFJZIQOlQGZh6VtRspH59t4GDjuMXg5k5gRjh33sIcR52AFiFAYyCmIYIvbcQ3ORFJFJ7uLgfQBT8CaWwdFVhbXFY6c9POe4ck/s1600/xray+production.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="" border="0" data-original-height="505" data-original-width="579" height="278" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhMV6puFkAn6OG7DEBLnyelCF7TBobNAD88eDMnK4skZ9AFJZIQOlQGZh6VtRspH59t4GDjuMXg5k5gRjh33sIcR52AFiFAYyCmIYIvbcQ3ORFJFJ7uLgfQBT8CaWwdFVhbXFY6c9POe4ck/s320/xray+production.JPG" title="xray tube" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Coolidge Tube: simplified understanding of xray production</td></tr>
</tbody></table>
<div>
<br /></div>
<h4>
Source of Xray</h4>
<div style="text-align: justify;">
The source of electron is a wire filament at the electrically negative cathode end of the tube. It is made of the element tungsten, a large atom with 74 electrons orbiting around its nucleus. An electric current flows through the filament to heat it. This speeds up the movement of the electron and increases their distance from the nucleus. Electrons in the outermost orbital shells get so far from the nucleus that they are no longer in orbit but are instead flung out of the atom, forming an electron cloud around the filament. These free electron, called a <b>space charge</b>, provide the needed electrons for xray production.</div>
<div>
<br /></div>
<h4>
Target</h4>
<div style="text-align: justify;">
The target is at the electrically positive anode end of the tube, the end opposite the filament. The smooth, hard surface of the target is the site to which the electrons travels, and is the place where the xrays are generated. The target is also made of tungsten, which has a high melting point to withstand the heat produced at the anode during xray exposure.</div>
<div>
<br /></div>
<h4>
High Voltage Transformer</h4>
<div style="text-align: justify;">
The voltage required for xray production is provided by a high voltage transformer. The two ends of the xray tube are connected in the transformer circuit so that during an exposure, the filament or cathode end is negative and the target or anode end is positive. The high positive electrical potential at the target attract the negatively charge electrons of the electron cloud, which move rapidly across the tube, forming an <b>electron stream</b>. When these fast moving electrons collide with the target, the kinetic energy of their motion must be converted into a different form of energy. The great majority of this kinetic energy is converted into heat (>99%), but a small amount is converted into the energy form that we know as <b>xrays</b>.</div>
iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.com0tag:blogger.com,1999:blog-6578035841982602934.post-7700617826193497862018-06-06T21:54:00.000+08:002018-06-06T21:54:33.953+08:00Biliary Gas – Xray, Ultrasound and CT Scan Examination <h4>
Clinical Characteristics of Biliary Gas</h4>
<div>
Gas within the biliary tree is often an incidental finding secondary to medical intervention, such as a sphincterotomy or cholecystoenterostomy.</div>
<div>
<br /></div>
<div>
Other cause include:</div>
<div>
<ul>
<li>A lax sphincter of oddi in the elderly.</li>
<li>Passage of a gallstone</li>
<li>Bialiary fistulae caused by stones, neoplasia or duodenal ulceration.</li>
<li>Biliary gas may result in gas within gallbladder.</li>
<li>Gas within the gallbladder may be secondary to emphysematous cholecystitis. This is an infection with gas forming organisms, seen in diabetics and leading to mural and intraluminal gallbladder gas.</li>
</ul>
</div>
<div>
<br /></div>
<h4>
Radiological Examinations - Biliary Gas</h4>
<h4>
Xray Examination</h4>
<div>
A branching radiolucencies are seen within the liver. These radiolucencies do not extend to the liver edge: a feature that helps to differentiate biliary gas from gas in the portal vien. Gas in the gallbladder may result in a gas-fluid level on an erect radiographic film.</div>
<div>
<br /></div>
<h4>
Ultasound Examination – Biliary Gad</h4>
<div>
Linear echogenic shadows, paralleling the portal venous system, are the characteristic appearance of biliary gas. Biliary calculi in ultrasound may be identified.</div>
<div>
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgTKjinTRBDJ5n3FciDPwslpC7DNC55Et0GYG7bX4L7YgN8_1vhcDn8C9-tOlZLJwjYIiPzM9tFLpXHFDCwoHlgAGU-iLDT8Mg-KCzHLOHvD-SwAix8En2MSbapz7Vow1aLtXnLuzvMYLlR/s1600/utz+biliary+gas.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="" border="0" data-original-height="445" data-original-width="488" height="291" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgTKjinTRBDJ5n3FciDPwslpC7DNC55Et0GYG7bX4L7YgN8_1vhcDn8C9-tOlZLJwjYIiPzM9tFLpXHFDCwoHlgAGU-iLDT8Mg-KCzHLOHvD-SwAix8En2MSbapz7Vow1aLtXnLuzvMYLlR/s320/utz+biliary+gas.JPG" title="biliary gas" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Air in the biliary tree seen as linear echogenic shadow<br />paralleling the portal venous system ( arrowhead).</td></tr>
</tbody></table>
<div>
<br /></div>
<h4>
Computed Tomography Examination</h4>
<div>
Branching air densities that parallel the portal system will be seen. Calculi, fistulae or neoplastic masses may be identified.</div>
<div>
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTprt7ApDeRhX4mpaWAeF9jo3jGO_pIxrK0WCFISyDZNP1S7Q-LKDHwgM0tqhoio1QOHqIsg-p5q2Mb6asJ5PtDgrwGRHehCwAAtokFu8G_1zXtdNZb821ZNbsOTDWbywXicT2Q3vWZdGX/s1600/Biliary+gas+ct+scan.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="" border="0" data-original-height="397" data-original-width="485" height="261" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhTprt7ApDeRhX4mpaWAeF9jo3jGO_pIxrK0WCFISyDZNP1S7Q-LKDHwgM0tqhoio1QOHqIsg-p5q2Mb6asJ5PtDgrwGRHehCwAAtokFu8G_1zXtdNZb821ZNbsOTDWbywXicT2Q3vWZdGX/s320/Biliary+gas+ct+scan.JPG" title="CT scan biliary gas" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Air in the biliary tree. CT scan elegantly demonstrates the air (arrows).<br />The relationship to the portal venous system is clear.</td></tr>
</tbody></table>
iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.com0tag:blogger.com,1999:blog-6578035841982602934.post-60926677912458985092018-06-06T11:08:00.003+08:002018-06-06T11:08:39.430+08:00Bezoar – Xray, Barium Studies, and CT Scan Examination <h3>
What is Bezoar?</h3>
<div>
<ul>
<li>Bezoar is an intestinal mass caused by the accumulation of ingested material.</li>
<li>A phytobezoar is formed from poorly digested plant fibre.</li>
<li>A trichobezoar is formed from ingested hair, almost always in females.</li>
<li>Bezoar can lead to obstruction or ulceration.</li>
</ul>
</div>
<div>
<br /></div>
<h4>
Radiological Procedures Usually Perform</h4>
<h4>
Xray of the Abdomen with Bezoar</h4>
<div>
If bezoar is present a mass may be seen within the stomach, and may demonstrate bowel obstruction.</div>
<div>
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9Gm657E8aWszES1Hf-On-BYnunrTCJ2-Lb95578kJ20ZvaaiTv-7LPXkKDmzgnjZJgW0ZEpxfbJGFHycVtUpj4wpvCE0HYRuC9NfEB7698_JFYEkR_pptyqPZmKxnpBXKDTGpoqbFUIhy/s1600/bezoar+xray+plain.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="bezoar" border="0" data-original-height="801" data-original-width="541" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9Gm657E8aWszES1Hf-On-BYnunrTCJ2-Lb95578kJ20ZvaaiTv-7LPXkKDmzgnjZJgW0ZEpxfbJGFHycVtUpj4wpvCE0HYRuC9NfEB7698_JFYEkR_pptyqPZmKxnpBXKDTGpoqbFUIhy/s320/bezoar+xray+plain.JPG" title="bezoar" width="216" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Trichobezoar. Large hair ball mass completely filling the stomach (arrow)</td></tr>
</tbody></table>
<div>
<br /></div>
<div>
<br /></div>
<h4>
Barium Studies of Bezoar</h4>
<div>
This examination may demonstrate an intraluminal filing defect that does not have a fixed site of attachment to the bowe wall.</div>
<div>
Barium may flow into crevices within the bezoar.</div>
<div>
<br /></div>
<h4>
CT studies on Bezoar</h4>
<div>
In this examination it may demonstrate a low density mass containing pockets of air.</div>
<div>
As on barium studies, oral contrast may intersperse with the mass though gaps between the ingested materials.</div>
<div>
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgAMKjncGu92UGGKSQwz1r-WHg0EDl1o6hHmriHGCgyiGbIh9JbfvX3KCWt7fDP6YUMjIZW8JgMvxv8SHW8qAepUl5lkYk21et65skEl2ujBkb2sWLXgqWCRuGQyKLVHru8wIxjCisS_DbM/s1600/bezoar+ct+scan+image.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="" border="0" data-original-height="773" data-original-width="543" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgAMKjncGu92UGGKSQwz1r-WHg0EDl1o6hHmriHGCgyiGbIh9JbfvX3KCWt7fDP6YUMjIZW8JgMvxv8SHW8qAepUl5lkYk21et65skEl2ujBkb2sWLXgqWCRuGQyKLVHru8wIxjCisS_DbM/s320/bezoar+ct+scan+image.JPG" title="bezoar" width="224" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Trichobezoar on same patient in coronal CT scan reformat. <br />Oral contrast is seen outlining the huge trichobezoar.</td></tr>
</tbody></table>
<div>
<br /></div>
iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.com0tag:blogger.com,1999:blog-6578035841982602934.post-24305941351142811782018-06-06T10:48:00.000+08:002018-06-06T10:48:40.692+08:00Ascites – Xray, CT Scan, Ultrasound Examination<br />
<h4>
Clinical Characteristics of Ascites</h4>
<div>
<ul>
<li>Intra-abdominal free fluid that may be classified as:</li>
<li>Exudate: greater than 30g/dl of protein; causes include peritoneal TB, pancreatitis, Meig’s syndrome and carcinomatosis.</li>
<li>Transudate: less than 30g/dl of protein; causes include hypoalbuminaemia, congestive cardiac failure, chronic renal failure, Budd-Chiari Syndrome and cirrhosis.</li>
</ul>
</div>
<h4>
Radiological Features and Examinations<br />Xray examination of Ascites</h4>
<div>
<ul>
<li>The initial signs relate to the dependent accumulation of free fluid in the pelvis and may be subtle and overlooked.</li>
<li>Later signs are medial displacement of both the lateral border of the liver and ascending and descending colon, bulging flanks, centralised bowel loops and a generalised greying of the abdominal film.</li>
</ul>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjVyETd_L09YPM4HFqTIXkFlHyTRn-AlA1xeQyIykfg-2D8CRFroFdx9Xd4al5h9FLcNXrhLIBSsuXg6tRNKDFYqhMW23sPNHxZ62ioneqQj6GQ0dTflvR8UNyQhFpTGVHTrXZJClLbBAhd/s1600/Ascite+xray.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="" border="0" data-original-height="493" data-original-width="407" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjVyETd_L09YPM4HFqTIXkFlHyTRn-AlA1xeQyIykfg-2D8CRFroFdx9Xd4al5h9FLcNXrhLIBSsuXg6tRNKDFYqhMW23sPNHxZ62ioneqQj6GQ0dTflvR8UNyQhFpTGVHTrXZJClLbBAhd/s320/Ascite+xray.JPG" title="ascites" width="264" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Generalized greying of the abdominal film in AP abdominal xray <br />with several centralized bowel loops.</td></tr>
</tbody></table>
</div>
<h4>
Ultrasound Examination</h4>
<div>
This is the examination of choice to confirm the presence of ascites, without the use of ionizing radiation.</div>
<div>
Ultrasound may provide additional information about the ascite such as loculation or the presents of debris within the fluid.</div>
<div>
In addition, ultrasound allows the sitting of diagnostic taps or therapeutic drains.</div>
<div>
Evidence as to the aetiology of the ascites can also be gained, such as the presence of cirrhosis.</div>
<div>
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjqHUXFMjwDafGi4GYx6ST0GXokY3gaCQLaeV-Lvt_AsTy6bvdg4Yg-OsP9k7_E9FzfGrNgiPMy_jsznvbDO6VoQpY2JjW0wIhVgrQ06e7i2HmA7xaWrPo8_HBREs5tUU6zBDJe5h_nURWk/s1600/Ascite+ultrasound.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="" border="0" data-original-height="332" data-original-width="415" height="256" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjqHUXFMjwDafGi4GYx6ST0GXokY3gaCQLaeV-Lvt_AsTy6bvdg4Yg-OsP9k7_E9FzfGrNgiPMy_jsznvbDO6VoQpY2JjW0wIhVgrQ06e7i2HmA7xaWrPo8_HBREs5tUU6zBDJe5h_nURWk/s320/Ascite+ultrasound.JPG" title="ascites" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Abdominal Ultrasound showing large volume of ascites (asterisk).</td></tr>
</tbody></table>
<div>
<br /></div>
<h4>
CT Scan of Ascites</h4>
<div>
The radiation dose prevents this as an investigation to confirm the presence of ascites, but CT scan often use to confirm the presence and extend of ascites when performed for another reason.</div>
<div>
The cause may also be identified, such as evidence of pancreatitis.</div>
<div>
It is less sensitive than ultrasound in assessing for loculation or debris within the ascetic fluid.</div>
<div>
<br /></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjsT_EB1hgukEGzdCLDQONW8Mx8tpmBLBZimZ1ZmIk-JDNc5Pk2cHIx7A6gXC2eOxP5As6-ZJpJyZ2XYXKpX3L2QqpY2jQ2NclhBkTGu9kGEjG9-2awSa_KoNHUga8DK1WQn2iQo7ht83xq/s1600/Ascites+ct+scan.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="" border="0" data-original-height="424" data-original-width="544" height="249" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjsT_EB1hgukEGzdCLDQONW8Mx8tpmBLBZimZ1ZmIk-JDNc5Pk2cHIx7A6gXC2eOxP5As6-ZJpJyZ2XYXKpX3L2QqpY2jQ2NclhBkTGu9kGEjG9-2awSa_KoNHUga8DK1WQn2iQo7ht83xq/s320/Ascites+ct+scan.JPG" title="ascites" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Axial slice of the abdomen CT: Large volume of ascites (asterisk) <br />and a small left basal pleural effusion in CT images (arrow).</td></tr>
</tbody></table>
<div>
<br /></div>
iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.com0tag:blogger.com,1999:blog-6578035841982602934.post-56078496215025303192018-06-06T10:09:00.000+08:002018-06-06T10:09:48.667+08:00Appendicitis - Xray, Ultrasound and CT scan <h4>
Clinical Characteristics</h4>
<ul>
<li>A common cause of an acute appendicitis with a peak incidence in the 2nd and 3rd decades.</li>
<li>The aetiology is probably related to the luminal obstruction, often by lymphoid hyperplasia or a foecolith.</li>
<li>Typically presents with RIF pain, nausea, vomiting, fever and evidence of inflammation such as raised WBC and CRP.</li>
<li>However 1/3 may have an atypical presentation.</li>
<li>Complication include localised perforation, abscess formation and generalised peritonitis. Rarely an obstructed appendix becomes distended by abnormal accumulation of mucus, forming an appendix mucocoele.</li>
</ul>
<div>
<br /></div>
<div>
Radiological Features</div>
<div>
<br /></div>
<h4>
Xray Examination of Appendicitis</h4>
<div>
<ul>
<li>In xray examination it is neither sensitive nor specific but can provide clues on a radiograph.</li>
<li>The presence of a calcified appendicolith in the right lower quadrant, combined with abdominal pain, has a high positive predictive value for acute appendicitis.</li>
<li>Other signs are less specific and include caecal wall thickening, small bowel ileus and decreased small bowel gas in the RIF.</li>
<li>Free peritoneal fluid can lead to loss of the psoas outline, loss of the fat planes around the bladder and loss of definition the inferior liver outline.</li>
</ul>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj2RCB4Tm7hMy8EuoXPG20PHzssViWQHArBSrqoP71VW-d3ZajYQWyuZShY9fsRr_HVUKv_Q824pKBMAFlRX4tw6Fg12KD5sIrcLPd0G_iB-FlkwMjqmGNw8UFXO4gJlOcpoaAxqAUAYzth/s1600/plain+abdominal+with+appendicitis.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="" border="0" data-original-height="609" data-original-width="401" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj2RCB4Tm7hMy8EuoXPG20PHzssViWQHArBSrqoP71VW-d3ZajYQWyuZShY9fsRr_HVUKv_Q824pKBMAFlRX4tw6Fg12KD5sIrcLPd0G_iB-FlkwMjqmGNw8UFXO4gJlOcpoaAxqAUAYzth/s320/plain+abdominal+with+appendicitis.JPG" title="appendicitis" width="210" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Plain Abdominal Xray Appendicolith</td></tr>
</tbody></table>
<div>
<br /></div>
</div>
<div>
<div class="MsoNormal">
A coronal CT reformat on picture below demonstrate the presence of a RIF
appendicolith (arrows). The CT demonstrate free fluid within abdomen and pelvis
and several dilated loops of small bowel, secondary to ruptured appendicitis
with an associated ileus.<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
</div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjjNqHLHBTCoQzw8uCoEzagUkh6Jf8P6mqiNLXavkGMleHt0rrhMmob3qus_AD79YYnBBGDYTaoODEjqXcMaqJh9oeRa05EhDf3UgPpR03xy-8hRtPTzIj52K30CIcwvEWXQMhbbhHek-Ct/s1600/Appendicitis+CT+Scan.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="" border="0" data-original-height="607" data-original-width="403" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjjNqHLHBTCoQzw8uCoEzagUkh6Jf8P6mqiNLXavkGMleHt0rrhMmob3qus_AD79YYnBBGDYTaoODEjqXcMaqJh9oeRa05EhDf3UgPpR03xy-8hRtPTzIj52K30CIcwvEWXQMhbbhHek-Ct/s320/Appendicitis+CT+Scan.JPG" title="appendicitis" width="212" /></a></div>
<div>
<br /></div>
<h4>
Ultrasound Scan of the Appedicitis</h4>
<div>
Ultrasound of the appendix is the initial imaging of choice if there is a diagnostic uncertainty.</div>
<div>
It can identify other causes of RIF pain such as ovarian torsion and mesenteric adenitis.</div>
<h4>
Ultrasound findings that suggest appendicitis include:</h4>
<div>
<ul>
<li>Visualization of a blind ending, non peristaltic, non compressible appendix.</li>
<li>A diameter of greater than 6mm.</li>
<li>Presence of an appendicolith, and distention of lumen.</li>
<li>Peri-appendiceal free fluid.</li>
<li>NB a negative ultrasound does not exlude appendicitis; if there is a high degree of clinical suspicion this should not preclude further imaging or laparoscopy. </li>
</ul>
</div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEidofFbFNN7w68vw8SjyAZ9vu_pw8IwRGIj74B0LsSuF-LWp_RpWwmfCxOqd6y_bpbRJMby0ddDAAhWdqEoHnklIs2cY0Np82yrPoLUdMXJ1tqJK9MdSrPmsJ2KA3CHg0dSXeXqHQfigsor/s1600/raptured+appendicitis.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="" border="0" data-original-height="685" data-original-width="541" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEidofFbFNN7w68vw8SjyAZ9vu_pw8IwRGIj74B0LsSuF-LWp_RpWwmfCxOqd6y_bpbRJMby0ddDAAhWdqEoHnklIs2cY0Np82yrPoLUdMXJ1tqJK9MdSrPmsJ2KA3CHg0dSXeXqHQfigsor/s320/raptured+appendicitis.JPG" title="appendicitis" width="252" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Raptured appendicitis on arrows. Note the presence of an ill defined mottled gas pattern within the RIF, with an air-fluid level, caused by the raptured appendix. </td></tr>
</tbody></table>
<div>
<br /></div>
<h4>
Contrast Enhanced CT scan</h4>
<div>
Contrast enhances CT is increasingly being used. However, it is not a first line investigation owing to the radiation dose incurred by the patient.</div>
<div>
Tends to be used where there is diagnostic delimma such as with an atypical presentation.</div>
<div>
<br /></div>
<div>
Findings include in CT Images:</div>
<div>
<ul>
<li>A thickened appendix plus an appendicolith</li>
<li>Inflammatory stranding in the adjacent fat.</li>
<li>An inflammatory appendix mass.</li>
<li>A local collection</li>
<li>Local lymphadenopathy.</li>
</ul>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiM_ub7XLNi9FAGe9MFTFtbODjvMRRh_d6iOXz3ilbPBY3dKddRxj6BrgtjY0JQhMrM3Pqtn0K5k10gXbtBnE7INzeLz_LTILxFYZvzhgyjRfRuxpSI8evp3vKDEhd5bB7US7zJ9Bv4Hjkq/s1600/ct+appendix.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="" border="0" data-original-height="376" data-original-width="540" height="222" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiM_ub7XLNi9FAGe9MFTFtbODjvMRRh_d6iOXz3ilbPBY3dKddRxj6BrgtjY0JQhMrM3Pqtn0K5k10gXbtBnE7INzeLz_LTILxFYZvzhgyjRfRuxpSI8evp3vKDEhd5bB7US7zJ9Bv4Hjkq/s320/ct+appendix.JPG" title="appendicitis" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Appendicitis. Dilated tubular appendix containing an appendicolith (arrow).</td></tr>
</tbody></table>
<div>
<br /></div>
</div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhvd-88hLQ0myi2S1CIaJIlxaOFAEspx-2SvqVVlDIIO8UoKTfgXxGWIpxOfQPAMylMf-BpxykiU9TdZ12_wKGKm6-K1DV6vLsZ0rbJLOqtAQdJsxscK_2t4l92AYCPl_0wl9bpkv3q2dgi/s1600/ct+appendicitis.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img alt="" border="0" data-original-height="330" data-original-width="544" height="194" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhvd-88hLQ0myi2S1CIaJIlxaOFAEspx-2SvqVVlDIIO8UoKTfgXxGWIpxOfQPAMylMf-BpxykiU9TdZ12_wKGKm6-K1DV6vLsZ0rbJLOqtAQdJsxscK_2t4l92AYCPl_0wl9bpkv3q2dgi/s320/ct+appendicitis.JPG" title="appendicitis" width="320" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Thickened tubular appendix, with inflammatory stranding seen at its tip (arrow).</td></tr>
</tbody></table>
<div>
<br /></div>
iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.com0tag:blogger.com,1999:blog-6578035841982602934.post-42464175367312303122018-06-05T22:20:00.001+08:002020-12-25T22:05:28.994+08:00Lateral Projection – Lateromedial (Suspected Fracture)<h3>
Recumbent or Lateral Recumbent</h3>
<div>
<ul>
<li>When a known or suspected fracture exist, position the patient in the recumbent or lateral recumbent position, place the image receptor close to the axilla, and center the humerus to the image receptor’s midline.</li>
<li>Unless contraindicated, flex the elbow, turn the thumb surface of the hand up, and rest the humerus on a suitable support.</li>
<li>Adjust the position of the body to place the lateral surface of the humerus perpendicular to the central ray.</li>
<li>Shield gonads</li>
<li>Respiration: suspended</li>
</ul>
<div class="separator" style="clear: both; text-align: center;"><br /></div>
<div>
<br /></div>
</div>
<h4>
Central Ray:</h4>
<h4>
Recumbent Position</h4>
<div>
The central ray on recumbent positionis horizontal and perpendicular to the midportion of the humerus and the center of the image receptor.</div>
<div>
<br /></div>
<h4>
Lateral Recumbent Position</h4>
<div>
The central ray on lateral recumbent position is directed to the center of the image receptor, which exposes only the distal humerus.</div>
<div>
<br /></div>
<h4>
Stucture shown:</h4>
<div>
The lateral projection demonstrates the distal humerus.</div>
<div>
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjUL8dY4MiFVkyo1Mx9xP5OPLV3dNQaSHY7C31_ZYFNO_YCf7YGGqxXPFKbZ5xM3MnAoHlPpvThkLkuY9KbmEuIMISudfd4sJ2IFBSODabK7A2fEhPjSbRE9ILXh1cP4zBHX0I_pCUCxjAv/s1600/radiograph+humerus.JPG" style="margin-left: 1em; margin-right: 1em;"><img alt="" border="0" data-original-height="780" data-original-width="736" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjUL8dY4MiFVkyo1Mx9xP5OPLV3dNQaSHY7C31_ZYFNO_YCf7YGGqxXPFKbZ5xM3MnAoHlPpvThkLkuY9KbmEuIMISudfd4sJ2IFBSODabK7A2fEhPjSbRE9ILXh1cP4zBHX0I_pCUCxjAv/s320/radiograph+humerus.JPG" title="radiograph humerus" width="301" /></a></div>
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<h4>
Evaluation Criteria:<br />The following should be clearly demonstrated:</h4>
<div>
<ul>
<li>Distal Humerus</li>
<li>Superimposed epicondyles</li>
</ul>
</div>
iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.com0tag:blogger.com,1999:blog-6578035841982602934.post-92045686157492640122018-05-22T11:29:00.003+08:002020-12-25T22:06:31.866+08:00Radiography of Humerus with the patient in lying position (Trauma) AP Lateral Projection<h3>
AP Projection - Recumbent</h3>
The image receptor size should be long enough to include the entire humerus.<br />
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<div>
Image receptor: Lenghtwise 18 X 43 cm</div>
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<h4>
Patient Position:</h4>
With the patient in supine position, adjust the image receptor to include the entire length of the humerus.</div>
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<h4>
Part Position:</h4>
<ul>
<li>Place the upper margin of the image receptor approximately 1.5 inches above the humeral head.</li>
<li>Elevate the opposite shoulder on a sandbag to place the affected arm in contact with the image receptor or elevate the arm and image receptor on sandbags.</li>
<li>Unless contraindicated, supinate the hand and adjust the limb to place the epicondyles parallel with the plane of the image receptor.</li>
</ul>
</div>
<div>
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<div>
<h4>
Shield gonads</h4>
Respiration: suspended</div>
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<h4>
Central Ray:</h4>
Perpendicular to the mid portion of the humerus and the center of the image receptor.</div>
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<br /></div>
<h3>
Lateral Projection - Lateromedial Recumbent</h3>
<h4>
Patient Position:</h4>
<div>
Place the patient in the supine position with the humerus centered to the image receptor, or use a bucky tray.</div>
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<h4>
Part Position:</h4>
<div>
<ul>
<li>Adjust the top of the image receptor to be approximately 1.5 inches above the level of the head of the humerus.</li>
<li>Unless contraindicated by the possible fracture, abduct the arm somewhat and center the image receptor under it.</li>
<li>Rotate the forearm medially to place the epicondyles perpendicular to the plane of the image receptor, and rest the posterior aspect of the hand against the patient’s side. This movement turns the epicondyles in the lateral position without flexing the elbow. (the elbow maybe flexed slightly for comfort)</li>
<li>Adjust the position of the image receptor to include the entire length of the humerus.</li>
</ul>
</div>
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<h3>
Lateral Projection – Lateromedial</h3>
<h4>
Recumbent or Lateral Recumbent Position</h4>
<div>
<ul>
<li>When a known or suspected fracture exists, position the patient in the recumbent of lateral recumbent position, place the image receptor close to axilla and center the humerus to the image receptor’s midline.</li>
<li>Unless contraindicated, flex the elbow, turn the thumb surface of the hand up, and rest the humerus on a suitable support.</li>
<li>Adjust the position of the body to place the lateral surface of the humerus perpendicular to the central ray.</li>
<li>Shield gonads</li>
<li>Respiration: suspend</li>
</ul>
</div>
<div>
<br /></div>
<h4>
Central ray Recumbent Position:</h4>
<div>
The central ray is horizontal and perpendicular to the midportion of the humerus and the center of the image receptor.</div>
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<br /></div>
<h4>
Central ray Lateral Recumbent:</h4>
<div>
Directed to the center of the image receptor, which exposes only the distal humerus.</div>
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<h4>
Structure shown:</h4>
<div>
The lateral projection demonstrate the distal humerus.</div>
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<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi8sJwHIaruVqSrrwSLuApPCJT_sscR51Gt5C-P1todN-Aj6POx4XBmvyyRetQNN3662VIUKi0egiVSKm1fqbYrAZxF0YCleNJFWhOuA9-mxfwmC-PmkBYyXevNyoYxHDpGnbMJGvNEsGlh/s1600/radiograph+humerus.JPG" style="margin-left: auto; margin-right: auto;"><img alt="radiograph" border="0" data-original-height="792" data-original-width="753" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi8sJwHIaruVqSrrwSLuApPCJT_sscR51Gt5C-P1todN-Aj6POx4XBmvyyRetQNN3662VIUKi0egiVSKm1fqbYrAZxF0YCleNJFWhOuA9-mxfwmC-PmkBYyXevNyoYxHDpGnbMJGvNEsGlh/s320/radiograph+humerus.JPG" title="radiograph" width="304" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">a. healing fracture b. comminuted fracture</td></tr>
</tbody></table>
<div>
<br /></div>
<h4>
Evaluation Criteria:</h4>
<div>
The following should be clearly clearly demonstrated:</div>
<div>
<ul>
<li>Distal humerus</li>
<li>Superimposed epicondyles</li>
</ul>
</div>
iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.com0tag:blogger.com,1999:blog-6578035841982602934.post-5591973056678531332018-05-21T15:58:00.001+08:002020-12-25T22:06:42.344+08:00Lateral Projection Humerus – Lateromedial (Upright)<h4>
Lateral Projection – Lateromedial (Upright)</h4>
<div>
Image receptor: 18 x 43 cm or 35 x 43 cm<div>
<br /></div>
<div>
<h4>
Patient Position:</h4>
<div>
<div style="text-align: justify;">
Place the patient in a seated upright or standing position facing the xray tube. The body position, whether oblique or facing toward or away from the image receptor, is not critical as long as a true projection of the lateral arm is obtained.</div>
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<div class="separator" style="clear: both; text-align: center;"><br /></div>
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<h4>
Part Position:</h4>
<div>
<ul>
<li>Place the top margin of the image receptor approximately 1.5 inches above the level of the head of the humerus.</li>
<li>Unless contraindicated by possible fracture, internally rotate the arm, flex the elbow approximately 90 degrees and place the patient’s anterior hand on the hip. This will place the humerus in lateral position. A coronal plane passing through the epicondyles should be perpendicular with the image receptor plane.</li>
<li>Shield gonads.</li>
<li>Respiration: suspended</li>
</ul>
<div>
<div>
<br /></div>
<div>
<h4>
Central ray:</h4>
<div>
Perpendicular to the midportion of the humerus and the center of the IR.<div>
<br /></div>
<div>
<h4>
Structure shown:</h4>
<div>
The lateral projection demonstrate the entire length of the humerus. A lateral image is confirmed by superimposed epicondyles.<div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBrovMwlSQz8xgfTnF_7ALfyWGx_yBT7eXJBFZOMKK_atOxzbHMzYkaNEPQ74gWU0b9_efdfp1cH_euoDUEkDq407IsAYbNG8_Mi5XqZa0Ujsw6lW_ylbHwBIFmfxfOuWRRHBxhamjSyvG/s1600/humerus+radiograph.JPG" style="margin-left: 1em; margin-right: 1em;"><img alt="" border="0" data-original-height="696" data-original-width="304" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgBrovMwlSQz8xgfTnF_7ALfyWGx_yBT7eXJBFZOMKK_atOxzbHMzYkaNEPQ74gWU0b9_efdfp1cH_euoDUEkDq407IsAYbNG8_Mi5XqZa0Ujsw6lW_ylbHwBIFmfxfOuWRRHBxhamjSyvG/s320/humerus+radiograph.JPG" title="radiograph" width="139" /></a></div>
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<div>
<h4>
Evaluation Criteria:</h4>
<div>
The following should be clearly demonstrated:<div>
<ul>
<li>Elbow and shoulder joints</li>
<li>Superimposed epicondyles</li>
<li>Lesser tubercle in profile</li>
<li>Greater tubercle superimposed over the humeral head</li>
<li>Beam divergence possibly partially closing the elbow joint.</li>
<li>No great variation in radiographic densities of the proximal and distal humerus.</li>
</ul>
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<div>
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iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.com0tag:blogger.com,1999:blog-6578035841982602934.post-2524700603086015072018-05-19T22:34:00.000+08:002018-06-05T22:21:11.454+08:00Humerus or Arm Anatomy and Positioning<h4>
Humerus or Arm</h4>
<div>
<div style="text-align: justify;">
The arm has one bone called the humerus, which consists of a body and two articular ends. The proximal part of the humerus articulates with the shoulder girdle. The distal humerus is broad and flattened and presents numerous processes and depressions.</div>
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<br /></div>
<div>
<h4>
Humeral Condyle, Trochlea and Capitulum</h4>
<div style="text-align: justify;">
The distal end of the humerus is called the humeral condyle and includes two smooth elevations for articulation with the bones of the forearm. The trochlea on the medial side and the capitulum on the lateral side. The medial and lateral epicondyle are superior to the condyle and easily palpated.</div>
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<div>
<br /></div>
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<h4>
Coronoid Fossa</h4>
<div>
<div style="text-align: justify;">
On the anterior surface superior to the trochlea, a shallow depression called the coronoid fossa receives the coronoid process when the elbow is flexed. The relatively small radial fossa, which receives the radial head when the elbow is flexed, is located lateral to the coronoid fossa and proximal to the capitulum.</div>
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<br /></div>
<div>
<h4>
Olecranon Fossa</h4>
<div>
<div style="text-align: justify;">
The olecranon fossa is a deep depression found immediately behind the coronoid fossa on the posterior surface and accommodates the olecranon process when the elbow is extended.</div>
<div>
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<div class="separator" style="clear: both; text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhBITBnuNmYvKOgBwhgYsqh75G32U3ll70xP_y259__yfHpLE9tpCQNS4kncjx0NaqlSYXgcy-kPVOz-DNHysCcySTV2URuJ5i8CVeSkXDqOpNKV6kkY5Pl9xARdx7EedqkZ3pivahS9BLw/s1600/Humerus.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img alt="" border="0" data-original-height="513" data-original-width="571" height="287" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhBITBnuNmYvKOgBwhgYsqh75G32U3ll70xP_y259__yfHpLE9tpCQNS4kncjx0NaqlSYXgcy-kPVOz-DNHysCcySTV2URuJ5i8CVeSkXDqOpNKV6kkY5Pl9xARdx7EedqkZ3pivahS9BLw/s320/Humerus.JPG" title="humerus anatomy" width="320" /></a></div>
<br /></div>
<div>
<h4>
Head, Neck and Body</h4>
<div style="text-align: justify;">
The proximal end of the humerus contains the head, which is large, smooth and rounded and lies in an oblique plane on the superomedial side. Just below the head, lying in the same oblique plane, is the narrow, constricted anatomic neck. The constriction of the body just below the tubercles is called the surgical neck, which is the site of many fracture.</div>
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<div>
<br /></div>
<div>
<h4>
Lesser Tubercle</h4>
<div>
<div style="text-align: justify;">
The lesser tubercle is situated on the anterior surface of the bone immediately below the anatomic neck. The tendon of the subscapularis muscle inserts at the lesser tubercle.</div>
<div>
<br /></div>
<div>
<h4>
Greater Tubercle</h4>
<div style="text-align: justify;">
The greater tubercle is located on the lateral surface of the bone just below the anatomic neck and is separated from the lesser tubercle by a deep depression called the intertubercular groove.</div>
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<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<h4>
Humerus or Arm Positioning</h4>
</div>
<div style="text-align: justify;">
<ul>
<li><a href="http://www.radtechonduty.com/2012/01/ap-projection-humerus.html" target="_blank">AP Projection - Humerus</a></li>
<li><a href="http://www.radtechonduty.com/2018/05/lateral-projection-humerus-lateromedial.html" target="_blank">Lateral Projection - Upright</a></li>
<li><a href="http://www.radtechonduty.com/2018/05/radiography-of-humerus-with-patient-in.html" target="_blank">Humerus Positioning with Patient in Trauma</a></li>
<li><a href="http://www.radtechonduty.com/2017/06/lateral-projection-trauma-humerus.html" target="_blank">Lateral Projection - Trauma Patient Cross table</a></li>
<li><a href="http://www.radtechonduty.com/2012/02/transthoracic-lateral-projection.html" target="_blank">Transthoracic Lateral Projection - Trauma</a></li>
<li><a href="http://www.radtechonduty.com/2017/06/x-ray-rotational-lateral-humerus.html" target="_blank">Rotational Lateral Projection</a></li>
<li><a href="http://www.radtechonduty.com/2012/02/humerus-x-ray-trauma.html" target="_blank">Horizontal Beam Lateral Projection</a></li>
<li><a href="http://www.radtechonduty.com/2018/06/lateral-projection-lateromedial.html" target="_blank">Lateral Recumbent Position - Trauma</a></li>
</ul>
</div>
iyah limhttp://www.blogger.com/profile/02089117056983795368noreply@blogger.com0