American Registry of Radiologic Technologists (ARRT) Practice Exam

When tissue thickness increases, the interaction of the x-ray beam with the tissue also changes, which directly affects contrast. As tissue thickness increases, the x-rays are more likely to be absorbed rather than transmitted, resulting in less penetration of the x-ray beam. This results in a reduction of the range of x-ray intensities that reach the detector, which decreases the contrast in the resulting image.

In radiography, higher contrast images are achieved when there is a greater difference in the amount of radiation absorbed by different tissues. Thicker tissue will absorb more x-rays, leading to less differentiation between various densities on the film or detector. Therefore, as tissue thickness increases, the overall result is a decrease in contrast. This relationship is important for radiologic technologists to understand, as it influences image quality and diagnostic capabilities.