What is the appropriate collimation for an AP knee?

The appropriate collimation for an AP (anterior-posterior) knee is to set the superior and inferior margins approximately 1 inch from the film. This method of collimation helps ensure that the x-ray field is focused on the knee joint itself, capturing the necessary anatomical details while reducing unnecessary exposure to surrounding tissues. By limiting the x-ray beam to just above and below the knee, it enhances image quality and provides clearer visualization of the joint, which is crucial for accurate diagnosis.

This approach balances encompassing the joint adequately while minimizing excess radiation exposure. Proper collimation is essential in radiographic practices to adhere to safety protocols and ensure optimal diagnostic results.