What is the term given to the area of unsharpness surrounding the image of an object on a radiographic image?

The term that describes the area of unsharpness surrounding the image of an object on a radiographic image is known as penumbra. In radiography, penumbra occurs due to the finite size of the x-ray source, which leads to a gradual transition from the sharp image of the object to the unsharp areas at the edges. This effect is particularly important in imaging techniques as it can influence the clarity and detail of the resulting image. Understanding penumbra is crucial for radiologic technologists, as they need to minimize this unsharpness to obtain high-quality diagnostic images.

Shadowing refers to the complete lack of detail where the x-ray beam is blocked, while blurring generally indicates a loss of sharpness due to motion during the imaging process, and geometric distortion pertains to the misrepresentation of the shape or size of the object due to the angle of imaging. Each of these terms describes different phenomena but does not specifically address the unsharpness surrounding the object image in the context of radiographic imaging.