CAMRT Radiography Practice Exam

What is the equation used to calculate Pitch?

1. Pitch = Slice thickness / Couch movement

2. Pitch = Couch movement every 360-degrees / Slice thickness

3. Pitch = Total exposure time / Slice thickness

4. Pitch = Couch movement / Total number of slices

The correct answer is: Pitch = Couch movement every 360-degrees / Slice thickness

The equation used to calculate Pitch in computed tomography (CT) is derived from the relationship between the distance the patient table moves during a complete rotation of the x-ray tube and the slice thickness being used for imaging. The formula states that Pitch equals the couch movement for each complete rotation of the x-ray tube divided by the slice thickness. This relationship is crucial because it describes how the scanner moves in relation to the slices being produced. A higher pitch value indicates that the table is moving faster relative to the width of the slices, which can affect the quality of the images obtained and the radiation dose to the patient. In essence, understanding this relationship helps radiographers optimize scanning parameters for effective imaging while considering patient safety. In contrast, the other options do not accurately represent the relationship required to define pitch. For example, while slice thickness is involved in other calculations related to imaging parameters, only the movement of the couch (or patient table) relative to the slice thickness during a complete rotation directly determines the pitch.