What is the focal film distance (FFD) for an AP Semiaxial Clavicle projection?

The focal film distance (FFD), also known as the source-to-image distance (SID), is crucial for obtaining high-quality radiographs, as it influences the magnification and sharpness of the image. For an anteroposterior (AP) semiaxial projection of the clavicle, the appropriate FFD is typically set at 38 inches. This specific distance is chosen to achieve an optimal balance between image clarity and geometric distortion, especially for the angled positioning required in this projection.

Using a 38-inch distance helps to minimize tissue overlap and provide a clearer depiction of the clavicle in conjunction with the surrounding anatomy. This is particularly important in the semiaxial projection, where the clavicle is often projected at an angle to avoid superimposition with adjacent structures. In contrast, the other distances listed may not yield the same level of detail and clarity necessary for accurate diagnosis of clavicular conditions. Utilizing the correct FFD is vital in aligning the radiographic technique with the anatomical structures being examined.