CAMRT Radiography Practice Exam

What projection can be used as an acceptable substitute for the AP projection of the thumb in an elderly patient unable to assume the required position?

1. PA projection

2. Oblique projection

3. Lateral projection

4. Subluxated position

The correct answer is: PA projection

In the scenario where an elderly patient is unable to assume the position necessary for the anteroposterior (AP) projection of the thumb, utilizing the posteroanterior (PA) projection serves as an acceptable substitute. The PA projection involves having the patient place their thumb flat on the image receptor, with the finger extended, which allows for clear visualization of the thumb's anatomy while minimizing distortion. This method is particularly advantageous for older patients who may have limited mobility or pain when attempting to position their thumb in the standard AP way. Despite the slight shift in how the structure is visualized, a PA projection still provides sufficient detail for diagnostic purposes, primarily because of the robustness of the anatomy of the thumb, which remains well-represented even in this alternative orientation. Other projections may not provide the same level of diagnostic clarity or may require more complicated positioning that might not be feasible for the patient. Thus, the PA projection is preferred in these situations for its practicality and reliability in diagnosis.