CAMRT Radiography Practice Exam

What is the purpose of the CR angle on the lateral projection of the knee?

1. To reduce exposure time

2. To prevent magnification of the medial femoral condyle

3. To improve patient comfort

4. To enhance contrast in imaging

The correct answer is: To prevent magnification of the medial femoral condyle

The purpose of the CR angle on the lateral projection of the knee is primarily to prevent magnification of the medial femoral condyle. When positioning for a lateral knee projection, the central ray (CR) is angled appropriately to ensure the correct anatomical representation of the knee joint. Angling the CR helps to align the femoral condyles, which minimizes distortion and magnification of the structures involved. This technique is crucial for accurate measurements and evaluation of the knee joint, particularly for assessing joint spaces and the presence of abnormalities. Other options, while relevant in different contexts, do not specifically pertain to the fundamental reason for angling the CR in this scenario. Reducing exposure time, improving patient comfort, and enhancing contrast may have their importance in imaging practices, but they are not the primary purposes for the specific CR angling technique used in the lateral knee projection. The emphasis on minimizing magnification directly relates to producing a true representation of the knee anatomy for diagnostic purposes.