Computed Tomography Technologist Practice Exam

Beam-hardening artifacts are characterized by dark streaks and areas of decreased density within a CT image. This phenomenon occurs when x-ray beams pass through dense materials, such as bone, which causes lower energy photons to be absorbed more than higher energy photons. As a result, the effective energy of the x-ray beam increases as it penetrates these dense structures, leading to an image with darker areas and streaks where the beam has been hardened.

Understanding this artifact helps technicians recognize its appearance to differentiate it from other artifacts, such as motion artifacts, which result from patient movement during the scan and typically cause blurriness rather than specific dark streaks. Partial volume artifacts arise when different tissues with varying densities are averaged together within a single voxel, and edge enhancement artifacts pertain to the artificial increase in contrast at the edges of structures, which is not characterized by the specific pattern of dark streaks and decreased density. Thus, the identification of beam-hardening artifacts is crucial for accurate interpretation of CT images.