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Calculation of electron and isotopes dose point kernels with fluka Monte Carlo code for dosimetry in nuclear medicine therapy
Author(s) -
Botta F.,
Mairani A.,
Battistoni G.,
Cremonesi M.,
Di Dia A.,
Fassò A.,
Ferrari A.,
Ferrari M.,
Paganelli G.,
Pedroli G.,
Valente M.
Publication year - 2011
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3586038
Subject(s) - monte carlo method , dosimetry , physics , electron , computational physics , nuclear physics , radionuclide therapy , nuclear medicine , medical physics , medicine , mathematics , statistics
Purpose: The calculation of patient‐specific dose distribution can be achieved by Monte Carlo simulations or by analytical methods. In this study, fluka Monte Carlo code has been considered for use in nuclear medicine dosimetry. Up to now, fluka has mainly been dedicated to other fields, namely high energy physics, radiation protection, and hadrontherapy. When first employing a Monte Carlo code for nuclear medicine dosimetry, its results concerning electron transport at energies typical of nuclear medicine applications need to be verified. This is commonly achieved by means of calculation of a representative parameter and comparison with reference data. Dose point kernel (DPK), quantifying the energy deposition all around a point isotropic source, is often the one. Methods: fluka DPKs have been calculated in both water and compact bone for monoenergetic electrons (10–3 MeV) and for beta emitting isotopes commonly used for therapy ( 89 Sr, 90 Y, 131 I, 153 Sm, 177 Lu, 186 Re, and 188 Re). Point isotropic sources have been simulated at the center of a water (bone) sphere, and deposed energy has been tallied in concentric shells. fluka outcomes have been compared to penelope v.2008 results, calculated in this study as well. Moreover, in case of monoenergetic electrons in water, comparison with the data from the literature ( etran , geant 4 , mcnpx ) has been done. Maximum percentage differences within 0.8· R CSDA and 0.9· R CSDA for monoenergetic electrons ( R CSDA being the continuous slowing down approximation range) and within 0.8·X 90 and 0.9·X 90 for isotopes (X 90 being the radius of the sphere in which 90% of the emitted energy is absorbed) have been computed, together with the average percentage difference within 0.9· R CSDA and 0.9·X 90 for electrons and isotopes, respectively. Results: Concerning monoenergetic electrons, within 0.8· R CSDA (where 90%–97% of the particle energy is deposed), fluka and penelope agree mostly within 7%, except for 10 and 20 keV electrons (12% in water, 8.3% in bone). The discrepancies between fluka and the other codes are of the same order of magnitude than those observed when comparing the other codes among them, which can be referred to the different simulation algorithms. When considering the beta spectra, discrepancies notably reduce: within 0.9·X 90 , fluka and penelope differ for less than 1% in water and less than 2% in bone with any of the isotopes here considered. Complete data of fluka DPK s are given as Supplementary Material as a tool to perform dosimetry by analytical point kernel convolution. Conclusions: fluka provides reliable results when transporting electrons in the low energy range, proving to be an adequate tool for nuclear medicine dosimetry.