Internal dosimetry for alpha emitters radiopharmaceuticals in biological tissue studied with the FLUKA code

MAURO VALENTE

MONTEVIDEO

Congreso; X - LATIN AMERICAN SYMPOSIUM OF NUCLEAR PHYSICS AND APPLICATIONS; 2013

COM LATINOAMERICANA DE FISICA - JEFFERSON LAB USA - UNIV. REPUBLICA URUGUAY

Clinical practices for neoplasic disease diagnose and treatment are based on the incor-poration of α, β and γ radiotracers and radiopharmaceuticals, which might be associatedwith potential damage. Thus, being necessary accurate dosimetry strategies. In vivoabsorbed dose appears as an ideal solution. However, its implementation in clinics doesnot attain enough reliability. On the other hand, different approaches were proposed forinternal dosimetry calculations. Some specific analytical methodologies were developedby the Committee on Medical Internal Radiation Dose (MIRD) to assess organ-level dosevalues in nuclear medicine [1]. Improvements in informatics achieve better computationperformance, but Monte Carlo approaches for patient-specific dosimetry are sometimeshigh time-consuming limitating its use in routine clinical practices.Analytical approaches introduce kernel convolution techniques aimed to patient-specificdosimetry. Although scattering effects are not accurately handled, these methods are ca-pable of fast dosimetry computation based on photon Energy Deposition Kernel (EDK)and particle Dose Point Kernel (DPK) assessed for radionuclides in order to perform fur-ther dosimetry calculations. EDK and DPK are obtained according to specific sourceemission. It was considered a point source isotropically emitting within an homogeneousmedium, so that radiation transport is accounted as uniformly distributed over concentricspherical regions by shell tally.Dedicated Monte Carlo simulations were performed by a subroutine adapted from theFLUKA cose [2, 3]. In-water EDK were evaluated at different photon energies and sometypical γ-emitters radiopharmaceuticals; whereas DPK were obtained for both α- andβ- emitters. Additionally, EDK and DPK were calculated for several biological tissues.Obtained results agree with energy loss from stopping power calculated by Bethe-Barkas-Bloch theory in the continuous slowing down approximation[1] W. Snyder et al. MIRD Pamphlet Number 12 Society of Nuclear Medicine, (1977)[2] A. Ferrari et al.FLUKA: a multi-particle transport code CERN-2005-10, INFN/TC05/11, SLAC-R-773 (2005)[3] G. Battistoni et al.The FLUKA code: Description and benchmarking Proceedings ofthe Hadronic Shower Simulation Workshop Fermilab 6-8 Sept AIP Conference Proceeding896, 31-49, (2007)