How does geometric penumbra (penumbra due to source size) vary with source-to-surface distance (SSD)?
Radiation Physics
No
U
A
See figure (GP = geometric penumbra). The penumbra is the distance between the rays arising from the center of the source and the rays arising from the edges of the source. As one moves farther from the collimators (i.e. increasing the SSD), that distance becomes larger, thereby increasing the geometric penumbra.
Heads up! You can use keyboard for test navigation: press → for Next,
← for Previous, M for Mark/Unmark, P for Pause,
R for Review, A,B,C,... or 1,2,3,... to select answer.
