What is the appropriate collimation size for an AP KNEE X-ray?

The appropriate collimation size for an anteroposterior (AP) knee X-ray is typically 10" x 12". This size is chosen because it adequately encompasses the anatomy of the knee while minimizing exposure to surrounding tissues. Proper collimation helps to reduce radiation dose to the patient and enhances image quality by limiting scatter radiation.

In an AP knee view, the primary area of interest is the knee joint itself, including the femur just above the joint and the tibia below it. The 10" x 12" collimation provides sufficient field coverage while focusing on the knee area specifically. Additionally, this collimation is a standard practice in radiography for knee imaging, making it a familiar size for technologists to use, maintaining consistency in procedure and outcomes.