Which focal spot size (FSS) would produce the highest spatial resolution?

The focal spot size (FSS) is a critical factor in determining spatial resolution in radiographic imaging. Smaller focal spot sizes result in finer detail being captured in images, which directly translates to improved spatial resolution.

In this context, a focal spot size of 0.3 mm produces the highest spatial resolution because it allows for better definition of edges and small structures in the image. When the focal spot size is reduced, the x-ray beam is more focused, minimizing the degree of geometric unsharpness.

As a result, the smaller the focal spot size, the more sharply defined the imagery, enabling better visualization of anatomical details. Therefore, out of the given choices, a focal spot size of 0.3 mm is the optimal choice for achieving the highest spatial resolution in imaging.

In terms of the other options, larger focal spot sizes like 0.6 mm, 1.0 mm, and 2.0 mm would lead to increased geometric unsharpness and thus lower spatial resolution.