What is the recommended source-to-image distance (SID) for tangential sesamoid radiographs?

The recommended source-to-image distance (SID) for tangential sesamoid radiographs is typically 40 inches. This distance is favored because it provides a good balance between image quality and the need to visualize the sesamoid bones clearly.

Using a 40-inch SID helps to minimize the magnification of the sesamoids, which are relatively small structures located beneath the first metatarsophalangeal joint. At this distance, the radiographic technique allows for optimal detail and minimizes distortion, which is especially important for accurately assessing these small bones and any related pathologies.

In radiography, longer distances, like 60 or 72 inches, are generally employed for chest or other imaging that requires less magnification and more depth, but for the purpose of capturing detailed images of small bones like sesamoids, the shorter 40-inch distance is more effective. A shorter distance, such as 30 inches, could potentially increase magnification too much, affecting the clarity and accuracy of the image. Therefore, 40 inches is the ideal choice for achieving high-quality tangential images of sesamoids.