What is xray penumbra?

Answer 1

Penumbra is lack of sharpness of the film. It is a fuzzy, unclear area that surrounds a radiographic image and is affected by focal spot size(smaller the better), film composition(larger the size of crystals less sharp the image), and movement during the exposure.

Answer 2

X-ray penumbra refers to the blurred or shadowy edges that can be seen around the edges of structures on an X-ray image. It is caused by the divergence of the X-ray beam, which can lead to a loss of image sharpness and detail at the periphery of the image. Techniques such as collimation and beam restriction help to minimize the effects of penumbra in X-ray imaging.