What is the effect of collimation on image contrast?

Collimation is a technique used in radiography to limit the area of the X-ray beam, reducing exposure to surrounding tissue and minimizing the amount of scatter radiation that can affect the image. When collimation is applied, it enhances image contrast because it ensures that only the relevant anatomy is illuminated on the detector, while reducing the amount of scattered photons that can degrade the image quality.

By limiting the beam to the area of interest, collimation helps in maintaining a clearer distinction between different tissue densities. The reduced scatter means there is less background noise that can obscure the details, thus resulting in a sharper, more defined image. Higher contrast images make it easier for radiologists to identify pathologies or variations in tissue density.

Therefore, when collateral factors like scatter reduction and a more focused X-ray beam are considered, it's clear that collimation improves contrast in the resulting radiographic image.