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

In helical CT, "pitch" specifically refers to the ratio of the distance the table moves in one complete rotation of the x-ray tube to the width of the x-ray beam. This measurement is crucial as it influences image quality, radiation dose, and scan time. A higher pitch indicates a greater distance traveled by the table relative to the beam width, which can allow for faster scans but may result in lower image quality due to gaps in data acquisition. Conversely, a lower pitch can provide improved image quality by ensuring more complete data collection but at the cost of longer scan times and potentially higher radiation doses. Understanding pitch is essential for optimizing CT protocols for both diagnostic effectiveness and patient safety.