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 medicinedosimetry. 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 medicinedosimetry, 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:flukaDPKs have been calculated in both water and compact bone for monoenergetic electrons (10–3 MeV) and for beta emitting isotopes commonly used for therapy (89Sr, 90Y, 131I, 153Sm, 177Lu, 186Re, and 188Re). 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, geant4, 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·X90 and 0.9·X90 for isotopes (X90 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·X90 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·X90, 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 flukaDPKs 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 medicinedosimetry.
II. MATERIALS AND METHODS
II.A. penelope code
II.B. fluka code
II.C. Dose point kernel calculation
II.C.3. Water vs Soft Tissue comparison
II.C.4. Comparison of DPK profiles
III.A. Convergence study and simulation speed
III.B. Monoenergetic electrons
III.D. Water vs soft tissue comparison
IV.A. Monoenergetic electrons
IV.C. Water vs tissue simulations
IV.D. Final considerations
Data & Media loading...
Article metrics loading...
Full text loading...