Abstract ID: 151 Monte Carlo MCNP calculation of absorbed dose for 90Y

Abstract

After the introduction of new therapeutic methods the nuclear medicine has experienced a renaissance. Strong beta emiteres, like 90Y, 177Lu and 188Re labeled on peptide (DOTATOC, DOTATATE) [1] , [2] are used for treatment of neuroendocrine tumours (NET). However, this therapy is renotoxic and there is a limit for kidney exposure. For this therapy dosimetric studies are very important. Absorbed dose due to 90Y was calculated using MCNP [3] and ORNL human phantom. Tumour was simulated as a sphere with the diameter of 3 cm in the centre fo abdomen. Tumour, kidney and liver are treated as a sources of beta radiation. To estimate the number of beta particles emitted in each organ, it is necessary to develop biokinetic model which describes behavior of radionuclide 90Y in human body. Transfer parameters of biokinetic model were determined based on activity of 90Y measured in urine and blood of patients. For the calculations, a spectrum of electrons emitted by 90Y is needed. Particle energy was sampled according to yields using random method incorporated in MCNP software. In order to simulate emission of whole spectrum of β - radiation, large number of histories was created (about 108) to ensure uncertainty lower than few percent. The results of MCNP calculations were obtained MeV/g per particle. This work shows that the largest dose in tumour, which is the main target of this therapy.