CAMRT Radiography Practice Exam

In an AP pelvis view, if the right obturator foramen is open, what position is the patient likely in?

1. Supine position

2. LPO position

3. RPO position

4. Prone position

The correct answer is: RPO position

In an AP pelvis view, when the right obturator foramen appears open, it typically indicates that the patient's right side is rotated posteriorly. This positioning allows for a clearer visualization of the right obturator foramen because it minimizes the overlap of the pelvic structures. In this case, the right posterior oblique (RPO) position is usually adopted, as it helps in achieving the required angulation and orientation needed to properly see the anatomical details. When the patient is in an RPO position, the right side of the pelvis is turned backward relative to the x-ray beam, resulting in the right obturator foramen being more open or appearing less foreshortened than it would in other positions. This contrasts with other positions like supine (where the pelvis is flat and symmetrical) or the left posterior oblique (LPO), where the left obturator foramen would appear more open. The prone position would also not lead to an open appearance of the right obturator foramen, as it would obscure that view entirely. Thus, the positioning greatly influences the visual representation of the pelvic anatomy in radiography.