What Cr angle is required for AP axial projection for the temporomandibular joints with the IOML perpendicular to the image receptor?

Taking TMJ Temporomandibular joints axial projection if patient has possible fracture do not attempt to open mouth. Fractures and abnormal relationship/ range of motion between condyle and temporomadibular fossa. Image receptor used 18 x 24 cm or 8 x 10 inches, put in crosswise. Moving or stationary grid. 70 to 80 kV range, mAs 16, and Small focal spot.

AP AXIAL TMJ (Closed Mouth Position)

if AEC is used, density is reduced to 20% - 30%. Remove all objects from head and neck like metallic and plastics, Patient position when taking TMJ joint is ERECT or SUPINE. Posterior part of of the skull is rested on table or bucky. Orbitomeatal Line (OML) is perpendicular to image receptor or bucky, To make IOML perpendicular to CR angle central ray by 7°. MSP of patient is in midline to avoid head rotation and tilt. Central ray is 35° caudad from OML or 42° from IOML. Central Ray is directed to 1 inch anterior level of temporomandibular joint or 2inches to EAM. Image receptor is in the center of Central Ray. SID 40 inches. Collimate on region of interest. Suspended during exposure. When patient conditions allows, these projections are taken open and close mouth for comparison on somes departments protocol and to best demonstrate temporomadibular fossae and joints increase cnetral ray angulation by 7°. Structure must be shown on these projection are Condyloid processes of mandible a

AP Axial Projection (Closed Mouth)

nd temporomandibular joint and fossae. Correct Positioning: Condyloid process is shown symmetrical, lateral to the cervical spine, clear visualization of condyle and TM fossae relationship. Condyloid process of the mandible and the TMJ and fossa are in collimated field. and TMJ must be in center.
Contrast and density are sufficient to visualize condyloid process and temporomadibular fossa.
Sharp bony margins indicate no motion.

The Towne view is an angled anteroposterior radiograph of the skull and visualizes the petrous part of the pyramids, the dorsum sellae and the posterior clinoid processes, which are visible in the shadow of the foramen magnum.

This projection is used to evaluate for medial and lateral displacements of skull fractures, in addition to neoplastic changes and Paget disease.

nuchal ridge is placed against the image detector
the infraorbitomeatal line perpendicular to the image receptor

anteroposterior axial projection
centering point
- the beam travels 30° caudad to the orbitomeatal line
collimation
- superior to include skin margins
- inferior to include base of skull
- lateral to the skin margins
orientation
detector size
exposure
SID
grid

dorsum sella overlies the foramen magnum
petrous ridges are symmetrical

if the dorsum sella projects above the foramen magnum it requires an increase in angle
if the anterior arch of C1 is laying in the foramen magnum, less angle is required

occipital bone and posterior fossa space better evaluated than with a non angulated AP view, which would have more skull base and facial bone overlap
better than a conventional AP view for evaluating an occipital plagiocephaly involving the lambdoid suture
may be a useful additional view for evaluating skull fractures 1

1. Shaffer MA, Doris PE. Increasing the diagnostic yield of portable skull films. Ann Emerg Med. 1982;11 (6): 303-6. Pubmed citation

The axiolateral temporomandibular joint (TMJ) view allows for visualization of the articular tubercle, mandibular condyle and fossa of the temporomandibular joint (TMJ).

This projection is useful in identifying structural changes and displaced fractures, assessing excursion and joint spaces in the trauma setting, and evaluating the presence of joint noises, trismus and occlusal alterations 1.

the patient is seated upright with the side of interest closest to the detector.
the head is placed in a true lateral position
oblique the body to assist in patient positioning and reduce the object to image receptor distance
depending on the projection (open or closed mouth) instruct the patient to open their mouth side and keep it there or keep it shut

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left and right lateral and open and closed mouth
centering point
- central ray 25-30º caudad, centered 5 cm superior and 1 cm anterior to the external auditory meatus
collimation
- no more than 10 x 10 cm with temporomandibular joint of interest in the middle of the image
orientation
detector size
exposure
SID
grid

the temporomandibular joint closest to the image receptor should be clearly demonstrated without the superimposition of the opposite temporomandibular joint.
the joint is central on the radiograph

a radiolucent support such as a sponge can be used to help maintain the head position
in patients that cannot stand unsupported, this projection can be performed prone to increase patient stability

1. Ferreira LA, Grossmann E, Januzzi E, Paula MVQd, Carvalho ACP. Diagnosis of temporomandibular joint disorders: indication of imaging exams. Brazilian Journal of Otorhinolaryngology. 2016;82:341-52.