Conversion from tooth enamel dose to organ doses for electron spin resonance dosimetry

Conversion from tooth enamel dose to organ doses was analyzed to establish a method of retrospective individual dose assessment against external photon exposure by electron spin resonance (ESR) dosimetry. Dose to tooth enamel was obtained by Monte Carlo calculations using a modified MIRD-type phantom with a teeth part. The calculated tooth enamel doses were verified by measurements with thermo-luminescence dosimeters inserted in a physical head phantom. Energy and angular dependences of tooth enamel dose were compared with those of other organ doses. Additional Monte Carlo calculations were performed to study the effect of human model on the tooth enamel dose with a voxel-type phantom, which was based on computed tomography images of the physical phantom. The data derived with the modified MIRD-type phantom were applied to convert from tooth enamel dose to organ doses against external photon exposure in a hypothesized field, where scattered radiation was taken into account. The results indicated that energy distribution of photons incident to a human body is required to evaluate precisely an individual dose based on ESR dosimetry for teeth. (author)