Influence of radionuclide distributions in human bodies on whole-body counting

Takahashi, Masa ; Kinase, Sakae   ; Kramer, R.*; Yoshitomi, Hiroshi   

Calibrations of whole-body counters are usually performed using anthropomorphic physical phantoms that have uniformly distributed radioactive sources in those phantoms. The purpose of this work is to study the influence of radionuclide distributions on counting efficiencies of a whole-body counter using Monte Carlo simulation method and a voxel phantom. Realistic distributions of the radionuclides were determined with biokinetic models that are used for internal exposure dosimetry. It was found that the evaluated counting efficiencies for the realistic distributions in the voxel phantom are different from those for uniformed distributions. For Co, the difference was close to -30%. We conclude that the calibrations of the whole-body counter considering the biokinetic models, using the Monte Carlo simulation and voxel phantoms, are important for more reliable measurements.