How often should CT number constancy for tissue, air, and bone-like materials be checked?

The practice of checking CT number constancy at regular intervals is essential in maintaining the accuracy and consistency of CT imaging. CT number constancy ensures that the Hounsfield units (HU) assigned to various tissues, air, and bone-like materials remain stable over time, which is critical for diagnostic precision and treatment planning, especially in fields like radiation therapy.

Regular intervals allow for systematic monitoring of the imaging system's performance, helping to identify any drift or variations that could affect measurements and subsequent clinical decisions. This could encompass factors like changes in calibration, equipment wear, or environmental influences that may alter the imaging characteristics of the materials being analyzed.

Frequency of monitoring can be guided by institutional protocols and may also be influenced by the manufacturer’s recommendations, but the key is that it must not occur as infrequently as once a month or only during initial setup. Conducting these checks at appropriate intervals strikes a balanced approach between ensuring high-quality imaging and operational efficiency, ultimately supporting patient safety and treatment accuracy.