MONTE CARLO BETA DOSE CALCULATION AT CELLULAR LEVEL FOR INTERNALLY DEPOSITED RADIONUCLIDES

Standard macroscopic methods to assess the dose in nuclear medicine are limited in the case of inhomogeneous radionuclide distributions, especially with emitters. In a few applications, like radioimmunotherapy, the mean dose to an organ is not suitable to explain clinical observations and the knowledge of dose at the cellular level is necessary. Though, we have written a software (CLUSTER3D) which is able to build a biologically representative spheres cluster model. The corresponding mathematical description has been implemented in our EGS4-PRESTA usercode, called DOSE3D, using the combinatorial geometry package MORSE-CG in order to calculate the deposited dose in various compartments. We present here principles of this dosimetric method, and rst results obtained on thyroid models. They highlight the need of cellular models to take into account actual radionuclides distributions in tissues. The e xibility of developed softwares make them useful tools to study the energy deposition at various cellular levels. That could complete standard methods in most cases.