Clinical CT performance evaluation
This chapter focuses on CT performance evaluations from the perspective of the clinical medical physicist. A clinical physicist may need to evaluate a CT system under several different circumstances such as acceptance testing, annual testing, post-service testing, and accreditation testing. Each of these has a slightly different purpose, and the physicist should ensure that the scope of a specific evaluation is appropriate for the situation and regulatory environment. In this chapter we describe a set of procedures that should be considered when designing such an evaluation. Typically, a thorough evaluation will assess the following: System safety and operation, system geometry, radiation output, and image quality. The safety and operational inspection focuses on radiation safety, quality control measures, and display monitor operation. System geometry testing ensures that the table, lasers, gantry, and collimation are all operating as intended. Radiation output is evaluated based on measurements of beam quality, a validation of computed tomography dose index (CTDI) accuracy, and characterization of tube current modulation. Finally, it is essential to evaluate the image quality of a system, including both traditional metrics (i.e., CT number accuracy and uniformity) and more advanced methods (i.e., noise power spectrum analysis and task-based metrics). These components collectively aid in ensuring the scanner is capable of safe high-quality imaging.
