What describes the correct image receptor (IR) placement for a lateral projection of the distal femur?

The correct choice states that the bottom of the image receptor should be positioned 2 inches distal to the patellar apex for a lateral projection of the distal femur. This placement is crucial for ensuring that the entire area of interest, which includes the distal femur, is captured in the image. Proper positioning of the IR allows for accurate visualization of the femoral condyles, joints, and surrounding anatomy.

In lateral projections, it’s essential to include the area of the joint above and below the region of interest; hence, positioning the IR 2 inches below the patellar apex ensures that both the distal femur and the knee joint are adequately represented in the image. This technique is particularly important to provide a comprehensive view that aids in diagnosing any potential fractures or pathological conditions in the distal femur and knee area.