cervical spine oblique x ray positioning

Centering the CR to the iliac crest level will demonstrate both the lumbar spine and sacrum if a 14 x 17 inch (35 x 43 cm) cassette is used. Central Ray (CR): Carefully palpate the superior portion of iliac crest (this corresponds to the L4-L5 intervertebral disc space) and direct the CR at this level, perpendicular to the cassette.Center the midsagittal plane of the patient’s body to the midline of the grid/table, with the shoulders and hips lying in the same horizontal plane. Place the patient’s hands on the upper chest.The upright position is also useful for demonstrating the natural weight-bearing status of the spine.

If the patient is having excruciating back pain and is unable to assume a recumbent position, an AP or PA projection can be performed in an upright position.

This better delineates the vertebral bodies and opens intervertebral disk spaces. Flexion of the knees and hips straightens the spine, reduces the lumbar curvature (lordosis), and brings their back closer to the table and their vertebral column more parallel to the IR.

The patient is positioned supine on the radiographic table, with the hips and knees flexed and the head on a pillow so that their back is in firm contact with the table.

Positioning for the AP projection of the lumbar-lumbosacral spine

Surface to image distance (SID) of 48 inches (122 cm) is recommended to reduce distortion.

75- 80 kVp range, some department protocols require use of a higher kVp (85-92) with reduction of mAs.Image receptor (IR): 14 x 17 inch (35 x 43 cm) for the lumbosacral spine, 11 x 14 inch (30 x 35 cm) for the lumbar spine only.A disadvantage of the PA projection for a patient with a large abdomen is the increased object to image distance (OID) of the lumbar vertebra, which results in radiographic distortion. An additional advantage is lower radiation dose for females (25%-30% less for a PA projection compared with AP projection).

Cervical spine oblique x ray positioning