Which combination of object-to-image distance (OID) and source-to-image distance (SID) provides the best spatial resolution?

To achieve the best spatial resolution in imaging, the relationship between object-to-image distance (OID) and source-to-image distance (SID) is critical. Spatial resolution improves with increased SID because it reduces magnification and the effects of geometric unsharpness. A larger SID results in a narrower beam of radiation hitting the imaging receptor, leading to a sharper image.

A smaller OID is also beneficial for spatial resolution, as it minimizes the distance between the object being imaged and the receptor. This reduction in OID decreases the potential for magnification and distortion, further enhancing image sharpness.

In the correct answer, having a 1 inch OID, which is quite small, combined with a 72 inches SID, which is relatively long, strikes an optimal balance. This combination allows for excellent spatial resolution because it maximizes the distance from the source to the image receptor while maintaining a close proximity of the object to the receptor. The small OID minimizes magnification and mitigates unsharpness, enhancing the details captured in the image.

Thus, the combination of a 1 inch OID and a 72 inches SID results in the best spatial resolution among the provided options, allowing for the clearest and most defined images to be produced.