The goal of tissue characterization via quantitative computed tomography can only be accomplished with careful control of certain parameters. A quality assurance program is described which includes daily measurement of certain essential elements e.g. Hounsfield conversion, linearity, noise and resolution. Secondary measurements of collimation, bed movement, dose, and sensitivity profiles are performed on a monthly basis. Daily measurements are accomplished in less than 15 minutes while monthly checks take less than 1.5 hr thus minimizing conflict with a busy clinical routine. Examples of rapid recording methods and measurement techniques are included. © 1982 SPIE.