ARRT - American Registry of Radiologic Technologists Spine and Pelvis Procedures Questions and Answers

Question 1

A patient is positioned for an AP axial projection of the sacrum. Which of the following describes the correct central ray (CR) orientation and centering point?

Accepted Answer

15 degrees cephalad, centered 2 inches superior to the pubic symphysis

Answer

For the AP axial projection of the sacrum, a 15-degree cephalic (upward) angle is required to project the pubic symphysis inferior to the sacrum, thus elongating the sacrum and opening the sacral foramina. The central ray should be directed to a point approximately 2 inches superior to the pubic symphysis.

Question 2

A radiograph of a lateral lumbar spine shows that the L5-S1 intervertebral joint space is not open. The patient was positioned with the midcoronal plane parallel to the image receptor. Which of the following modifications is MOST appropriate for a coned-down 'spot' view?

Accepted Answer

Angle the CR 5-8 degrees caudad

Answer

When the L5-S1 joint space is not open on a true lateral lumbar spine image, it is often because the spine is not parallel to the image receptor due to the natural curve and pelvic tilt. A caudal (downward) angulation of 5-8 degrees (typically 5 for males, 8 for females) is necessary to align the central ray with the intervertebral joint space, effectively 'opening' it on the image.

Question 3

To properly visualize the right sacroiliac (SI) joint with minimal superimposition, which of the following positions should be performed?

Accepted Answer

AP projection, left posterior oblique (LPO)

Answer

For AP oblique projections of the SI joints, the joint of interest is the one that is elevated, or farthest from the image receptor. Therefore, to visualize the right SI joint, the patient should be placed in a left posterior oblique (LPO) position with a body rotation of approximately 25-30 degrees.

Question 4

A trauma patient requires an evaluation for a suspected pelvic ring fracture. The physician orders an AP axial 'outlet' projection (Taylor method). How should the technologist direct the central ray for a male patient?

Accepted Answer

20-35 degrees cephalad, centered 2 inches distal to the superior border of the pubic symphysis

Answer

The AP axial 'outlet' projection, or Taylor method, is designed to demonstrate the pubic and ischial rami without foreshortening. This is achieved by directing the central ray with a cephalic (upward) angle. For male patients, the angle is typically 20-35 degrees cephalad, centered to a point 2 inches distal to the superior border of the pubic symphysis.

Question 5

A scoliosis series including AP right and left bending projections (Ferguson method) is ordered. What is the primary purpose of performing these bending views?

Accepted Answer

To differentiate between structural and functional scoliosis

Answer

The Ferguson method, which involves AP projections with lateral bending, is specifically used to distinguish between structural and functional scoliosis. A structural curve is fixed and will show minimal correction on the bending films. A functional curve is compensatory and will straighten or reduce significantly when the patient bends toward the convex side of the curve.

ARRT - American Registry of Radiologic Technologists Practice Test

ARRT - American Registry of Radiologic Technologists Practice Test

ARRT - American Registry of Radiologic Technologists Spine and Pelvis Procedures Questions and Answers