A system of radioactivity measuring instruments designed for quantifying the amount of radiation in a radiopharmaceutical dose or other test samples inserted into a shielded chamber or well for measurement. The system's instruments radiation level measurements in units of Curie and/or Becquerel are used to quantify the radioactivity in diagnostic or therapeutic radiopharmaceuticals prior to and after patient administration. This will be used to measure radiation levels of in vitro diagnostic test samples, e.g., those required for Schilling tests, Cr-51 or I-125 blood volume.