Purpose
Observation of spondylolysis (Scottie dog sign), and the interphalangeal joint on the side near the cassette.
Prior confirmation
Confirm how radiograph will be taken (AP standing or PA standing or supine).
Remove any obstacles.
Positioning
Erect :
Standing position with the lower limbs shoulder-width apart in the AP or PA direction and in the RAO or LAO direction.
Oblique position of 30°-40°. (A line connecting the medial 5 cm of the anterior superior iliac spine on the side away from the cassette and the lumbar spinous process is perpendicular to the cassette.)
Align the trunk center with the central axis of the cassette.
The cassette should be a half-slice size, and the center height should be aligned with the iliac crest (Jacoby’s line).
Supine :
Oblique position with one side elevated from the supine position, either in the RAO or LAO direction.
The oblique position should be 30° to 40°. (A line connecting the medial 5 cm of the superior anterior iliac spine and the lumbar spinous process on the side away from the cassette is perpendicular to the cassette.)
Align the trunk center with the cassette central axis.
Bend both knees to reduce the kyphosis of the lumbar spine.
Use a cassette of a 10×12, 14×17 size, and align the center of the cassette with the third lumbar vertebra (two transverse fingers headward from the Jacoby line).
CR, distance, field size
CR :
Erect : Incidence should be perpendicular to a point 5 cm medial to the anterior superior iliac spine on the side away from the cassette at the level of the iliac crest (Jacoby line, L4).
Supine : Perpendicular incidence at a point 2 lateral fingers head-side from the Jacoby line, and 5 cm medial to the anterior superior iliac spine on the side away from the cassette.
Distance : 100-150cm
Field size :
Erect : The irradiation field should be centered on the Jacoby lines, extend to 14 x 17 inches in size, and extend to both greater trochanter.
Supine : The irradiation field is extended to the size of a cassette. The center should be 2 lateral finger widths from the jacoby lines, head side. The left and right sides should be limited to 10 finger widths.
Exposure condition
75kV / 32mAs
Grid ( + )
Suspend respiration on expiration.
Image, check-point
Abnormal (Radiopaedia)
Erect : L4 should be centered and the upper margin should be the 12th thoracic vertebra and the lower margin should include the hip joint.
Supine : L3 should be centered and the upper margin should include the 12th thoracic vertebra and the lower margin should include the superior sacrum.
The scottie dog sign should be observable.
The intervertebral joint should project to the center of the vertebral body. The more angled, the more the intervertebral joints are projected toward the spinous process.
The spinal column should be projected to the center of the image.
There should be no blurring due to body movement.
Videos
Related materials
Six lumbar type vertebrae
