MCNPX internal dosimetry studies based on the NORMAN-05 voxel model

Anthropomorphic computational models coupled with radiation transport codes are valuable tools in radiation protection dosimetry. In particular, they are very reliable for the estimate of the energy absorbed by different organs due to an incorporated radionuclide. MIRD-based stylised analytical models are widely accepted as standards but the recent generation of voxel phantoms, developed on real anatomical data derived from tomographic images, can represent a valid alternative for radiation protection and dosimetry purposes. Specific absorbed fraction evaluation and patient-specific dose estimate in nuclear medicine and radiotherapy could be considered as the optimal area for their implementation and use. On the other hand, the accuracy of organ and body structure representation guarantees an improved dose evaluation system also for radiation protection purposes in the workplace in case of accidental internal contamination. In the present work the voxel model NORMAN-05, a modified version of NORMAN (HPA, UK) model, has been employed with the Monte Carlo code MCNPX. Some preliminary investigations were carried out to evaluate the absorbed fractions for a series of source-target organ couples in case of gamma emitters and the organ absorbed doses in case of 90Sr incorporation. The paper summarises the main preliminary outcomes of such studies.