This part of IEC 61948@ which is a technical report@ describes test methods of instruments that count and measure the energy of photons emitted by RADIONUCLIDES in vivo and in vitro without the option of imaging. This includes@ for example@ well counters and organ probes. Geiger-Mueller counters and dose calibrators are not within the scope of this document. As part of QUALITY CONTROL this report is defining ROUTINE TESTS to be performed by the user of gamma radiation counting systems to maintain proper operation conditions. The results of these ROUTINE TESTS are compared to the REFERENCE DATA determined during or after the ACCEPTANCE TEST.