Measurements of radiation doses in diagnostic applications of sup(99m)Tc

The goal of the investigation was the direct measurement of radiation doses on the patients and the comparison with calculated values. Sup(99m)Tc as one of the most frequently used radioisotopes in medicine was chosen for this examinations. Dose measurements were performed with TLD dosimeters on a Remcal phantom in relevant organs and compared with doses on the surface of the phantom. The contribution of different organs to surface dose at different locations was examined. A set of representative areas was chosen for each organ and calibration factors were established. On the patients the measurements were made on corresponding areas of body surface. For consideration of anatomical variations, organ position and activity distributions were controlled by measurements with collimated scintillation detectors and with a gamma camera. The results show that the actual dose can be determined in the individual case by a small number of surface dose measurements. The measured doses are evaluated and compared with the values calculated according to current methods. Sources of errors as geometrical factors or 'cross-talk' of various organs to dose meters are discussed