American Society of Radiologic Technologist (ASRT) Practice Exam

The ________ position BEST demonstrates the right sacroiliac joint.

1. LPO

2. RPO

3. LAO

4. right lateral

The correct answer is: LPO

The left posterior oblique (LPO) position is the best choice for demonstrating the right sacroiliac joint due to the specific angles it creates between the x-ray beam and the anatomy being imaged. In the LPO position, the patient is positioned at approximately a 45-degree angle, with the left side of the pelvis down. This orientation allows the x-ray beam to project the right sacroiliac joint in an unobstructed manner, minimizing the overlying structures and providing a clearer view of the joint's morphology. When utilizing the LPO position, the right sacroiliac joint becomes more parallel to the image receptor, which enhances the visibility of its details. Moreover, this positioning reduces superimposition from the lumbar vertebrae and other structures that may obscure the joint in other positions. In contrast to the LPO position, other positions such as the RPO or right lateral do not provide the same optimal angles to demonstrate the right sacroiliac joint effectively. The RPO position focuses more on the left sacroiliac joint, while the right lateral view does not adequately visualize the joint since it results in superimposition from surrounding structures. Similarly, the LAO position is geared towards visualizing the