SUBMENTOVERTEX (SMV) PROJECTION : ZYGOMATIC ARCHES

Monday, August 18, 2014

X-ray of ZYGOMATIC ARCHES - SUBMENTOVERTEX (SMV) PROJECTION

Pathology Demonstrated:

Fractures of the zygomatic arch and neoplastic or inflammation processes are shown.

Technical Factors:

SMV - Patient Erect

Image receptor size - 18 x 24 cm ( 8 x 10 inches), crosswise
60 to 70 kV range (soft tissue technique)
Small focal spot
Automatic Electronic Control (AEC) not recommended
mAs 6

Patient Position:

Be sure to remove all metallic or plastic objects from patients head and neck.
This projection maybe taken with the patient erect or supine.
The erect position maybe easier for the patient.

Part Position:

SMV - Patient Supine

Raise chin, Hyperextend neck until Intra Orbital Meatal Line (IOML) is parallel to image receptor. (see note)
Rest head on vertex of skull
Align Mid-sagital Plane to midline of the grid or the table or upright Bucky surface, avoiding all tilt and / or rotation.

Central Ray:

Align central ray (CR) perpendicular to image receptor (IR) see notes.
Center Image Receptor (IR) to CR, with plane of image receptor parallel to IOML.
Minimum SID is 40 inches (100 cm)

Collimation:

Collimate to outer margins of zygoma.

Respiration:

Suspend respiration during exposure.

Notes:
If patient is unable to extend neck adequately, angle CR perpendicular to IOML. If equipment allows, the image receptor (IR) should be angled to maintain the CR / IR perpendicular relationship.
This projection is very uncomfortable for the patients; complete the projection as quickly as possible.

Radiographic Criteria:

Structure Shown:

Zygomatic arches are demonstrated laterally from each mandibular ramus.

Position:

Correct IOML / CR relationship, as indicated by superimposition of mandibular symphisis on frontal bone. No patient rotation, as indicated by zygomatic arches visualized symmetrically.