Abstract
We have reviewed quality control testing of dose calibrators and have analyzed the potential for error. The uncertainty in half-lives of reference sources can lead to inaccurate assessment of the accuracy and constancy in dose calibrator performance. Molybdenum-99 contamination of 99mTc used as a reference source can appear as a nonlinear response of the dose calibrator. The useful life of a reference source and the tolerable amount of 99Mo contamination are examined.