Investigation of certain factors affecting measurement of radioactivity in man

The present study deals with internal radiation dosimetry using whole body (WBC) technique or personal air sampler (PAS). Radiation workers are exposed to sources of ionizing radiation such as Cs - 137, I - 131, and other. For internal dosimetry the following items such as subject background radiation, metabolic of the gastrointestinal tract (GIT), respiratory tract and iodine model, elimination rate constant, concept of effective half life, dose calculation and dose limit are described. For ingestation internal dosimetry the inshass whole body counter and new york University (NYU) medical center, whole body counter, USA were used. For inhalation internal dosimetry personal air sampler are used. The efficiency study of Nal (TI) detector of whole body counter using pressed wood phantom at different depths indicates that efficiency decreases with increment of the depth due to increases the self absorption of the pressed wood phantom. The counting geometry study indicates that the efficiency of Nal (TI) detector with chair geometry is higher than the efficiency with a meter arc geometry. The resolution of 8 X 4 NaI (TI) for inshass and New york university detectors in energy range of 661 - 2614 KeV was varied in range 8. 1 - 10 % and 4. 7 .8. % respectively which accepted with the published data. The resolution of 8 X 4 NaI(TI) detector is better than resolution of phoswich detectors (Cs - NaI) but the efficiency for phoswich detector is better is than that for NaI(TI) detector. The percentage error in the regions of Annihilation, K - 40 and TI - 208 of a complete spectrum of a background was 1:1:2.1 which means there is stability in the system. The change in peak position as a function of time for annihilation.3-21 tabs.,3-24 figs., 51 refs