CAMRT Radiography Practice Exam

What does the term "pitch" refer to in CT?

1. The angle of the x-ray beam

2. The distance between consecutive slices

3. The relationship between patient couch movement and x-ray beam collimation

4. The duration of the scan

The correct answer is: The relationship between patient couch movement and x-ray beam collimation

The term "pitch" in the context of computed tomography (CT) refers to the relationship between the movement of the patient couch during a scan and the width of the x-ray beam as it collides with the detectors. It is a crucial factor in understanding the efficiency and quality of the imaging process. Specifically, pitch is defined as the ratio of the distance the couch moves during a single rotation of the x-ray tube to the width of the x-ray beam or the detector array. In practical terms, a higher pitch indicates that the couch moves further compared to the width of the beam, which can increase the speed of the scan but may also affect image quality. In contrast, the angle of the x-ray beam, the distance between consecutive slices, and the duration of the scan, while important in their own right, do not capture the specific concept of pitch as it relates directly to the interaction between patient movement and x-ray beam coverage. Therefore, the definition centered on the relationship provides the accurate context for understanding pitch in CT imaging.