To achieve the sharpest radiographic image, what should be true about the radiographic source?

To achieve the sharpest radiographic image, it is essential for the radiographic source to be small. A smaller source size reduces the geometric penumbra, which is the blurred edge around the images caused by the divergence of the X-ray beams. When the source is small, the X-rays emanate more uniformly, allowing for a finer resolution and clearer details in the resulting image.

A small source size minimizes the extent to which the X-rays spread out as they travel toward the film or imaging receptor. This leads to sharper images, which is particularly important when examining details within welds, joints, and other critical areas. Thus, a small source enhances the clarity and definition of the radiographic image.