In conclusion, the minimum requirements²³ (after instrument acceptance or initial testing) for a satisfactory quality control program for each data acquisition system in nuclear medicine are: a. quality control tests should be performed routinely and should take no more than 15 min; b. protocols for each counting instrument and imaging system should be defined for the routine tests described in this paper. Test procedures may be adopted from the literature; c. the resulting data (numerical data and images) should be carefully scrutinized, compared with information (reference data) obtained initially under similar conditions, and used to decide whether to proceed with clinical studies (see scheme 1); d. all test images should be properly labeled and retained for immediate reference, preferably in the form of a logbook; e. a review of these data should be made on a weekly basis to detect long-term deterioration. A review image recording and its quality control is included in theAppendix.