A protocol-based evaluation of medical image digitizers.

Medical film digitizers play an important transitory role as digital-to-analogue bridges in radiology. Their use requires performance evaluation to assure medical image quality. A complete quality control protocol is presented, based on a set of test objects adaptable to the specification of various digitizers. The protocol includes parameters such as uniformity, input-output response, noise, geometric distortion, spatial resolution, low contrast discrimination, film slippage and light leakage, as well as associated measurement methods. The applicability of the protocol is demonstrated with two types of medical film digitizers; a charge-coupled device (CCD) digitizer and a laser digitizer. The potential value of the protocol is also discussed.