Computed Tomography Technologist Practice Exam

Out-of-field artifacts in computed tomography are primarily caused by anatomy that extends outside of the selected scan field of view (SFOV). When a patient's body part or anatomical structure is not included within the SFOV, the system may inadvertently produce incorrect image data. This may manifest as anomalies in the image, such as streaks or unwanted shadows, because the CT scanner is unable to accurately account for the external anatomy during the image reconstruction process.

In this scenario, the SFOV is crucial because it defines the area captured during scanning. If important structures are missed or fall outside this designated area, the resulting images may lead to misinterpretations or incomplete evaluations. Understanding this is essential for ensuring that the entire region of interest is adequately imaged, thus minimizing the potential for out-of-field artifacts.

The other choices address different aspects of CT technology but do not directly relate to the specific cause of out-of-field artifacts. Imperfect detector elements might lead to image quality issues, but these are not inherently related to the fields of view. Excessive radiation exposure and low gantry rotation speed concern operational parameters but do not contribute to artifacts from anatomy being outside of the scanning field.