Process in which an X-ray beam is reduced in intensity by passing through material; combination of absorption and scattering processes results in reduction of the beam intensity?

• A. Attenuation
• B. Absorption
• C. Artifact
• D. ALARA

Answer: (A)

Attenuation is the process by which the X-ray beam loses intensity as it passes through matter. This reduction comes from two main interactions: absorption, where photons are removed from the beam by transferring energy to the atoms (often through the photoelectric effect), and scattering, where photons are redirected out of the original path (Compton scattering) or otherwise deflected. The combination of these events decreases the number of photons that reach the detector, which is what shapes the radiographic image. The extent of attenuation depends on tissue thickness, density, and atomic number, as well as the beam’s energy. In contrast, ALARA refers to keeping dose low, and artifacts are image misrepresentations, so they aren’t describing the physical process reducing beam intensity.