Mass Internal Exposure Monitoring of Population in Russia After the Chernobyl Accident

Abstract

The organisation and carrying out of mass monitoring of radionuclide activity in the inhabitants of Russian regions contaminated with radionuclides after the Chernobyl accident are here reviewed. Methods to calibrate 131I in the thyroid and 134-137Cs in the whole body are presented. Dependence of calibration factors for monitoring of 131I in thyroid, and 134Cs and 137Cs in a whole body on age, body mass and size are presented. The shielding of the background radiation by a human body influences significantly the measurement result. It depends on the chosen measurement geometry, the energy range applied, the spectrum of background radiation, mass and dimensions of the measured person. 131I content in the thyroid should be calculated from the measurement results taking into account the contribution of radiation from radionuclides distributed in the body. Neglect of this factor could result in an overestimation of 131I content in the thyroid up to a factor of 2 to 4.