Cervical Spine - AP
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Radiographic Positioning
Adult | Other related pages of interest |
Name of projection | Cervical Spine - AP |
Area Covered | The cervical vertebrae from C3 down to approximately T2 |
Pathology shown | Some pathologies of the cervical vertebrae C3 through to C7 |
Radiographic Anatomy | Cervical Spine Radiographic Anatomy |
IR Size & Orientation | 18 x 24 cm Portrait |
Film / Screen Combination | Regular (CR and DR as recommended by manufacturer) |
Bucky / Grid | Moving or Stationary Grid |
Filter | No |
Exposure | 65 kVp 16 mAs |
FFD / SID | 100 cm |
Central Ray | Directed to the level of C4, which is approximately the level of the angle of the mandible 15 degrees cephalad. (to match the lordotic curve of the cervical spine, to penetrate the intervertebral disc spaces) |
Collimation | Centre: C4, collimate to the 18 x 24cm film size Shutter A: Open so that the light of the collimated field just includes the top of the ear. The light will appear to bend around due to the central ray being angled cephalad Shutter B: Open to include the soft tissue of the neck laterally |
Markers | Lateral Marker orientation AP |
Shielding | Gonadal (check your department's policy guidelines) |
Respiration | Suspended respiration |
Positioning |
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Critique | Positioning
Area Covered
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Special Notes | Determining the direction of rotation Using spinous process alignment: When the spinous processes are not seen in the midline of the vertebral bodies this usually indicates rotation of that part of the cervical spine. As the head is rotated in a particular direction, the spinous process tip will move in the opposite direction. For example, if the spinous process tip is closer to the left vertebral body edge, then the patient's neck is rotated so they are looking towards the right side. Using pedicle alignment: In an AP view the pedicles are seen laterally in the area between the transverse process and the vertebral body. With correct positioning the pedicles should be equidistant from the vertebral body edges. Example: If the right pedicle is more towards the midline of the vertebral body (it is rolled under/behind the vertebral body), indicating the patient is rotated so they are looking towards the right side. Demonstrating intervertebral disc spaces Successful demonstration of the intervertebral disc spaces is largely dependent on correct central ray angulation. Generally, the central ray is approximately 15 degrees up (cephalad). Consider varying this angle when:
If the mandible is not superimposed over the base of skull, first determine which structure is the base of skull. Locating the mastoid tips will assist with this. If the mandible/chin is more inferior/lower, then raise the chin half the distance of the difference seen on the image. If the mandible/chin is more superior/higher than the base of skull margin, then lower the chin half the distance of the difference seen on the image |