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Influence of photon energy spectra from brachytherapy sources on Monte Carlo simulations of kerma and dose rates in water and air
Author(s) -
Rivard Mark J.,
Granero Domingo,
PerezCalatayud Jose,
Ballester Facundo
Publication year - 2010
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 - 10.1118/1.3298008
Subject(s) - kerma , monte carlo method , photon , dosimetry , brachytherapy , physics , computational physics , spectral line , photon energy , medical physics , nuclear medicine , optics , medicine , radiology , statistics , mathematics , radiation therapy , astronomy
Purpose: For a given radionuclide, there are several photon spectrum choices available to dosimetry investigators for simulating the radiation emissions from brachytherapy sources. This study examines the dosimetric influence of selecting the spectra for I192 r ,I125, andP103 d on the final estimations of kerma and dose. Methods: For I192 r ,I125, andP103 d , the authors considered from two to five published spectra. Spherical sources approximating common brachytherapy sources were assessed. Kerma and dose results from GEANT4 , MCNP5 , and PENELOPE‐2008 were compared for water and air. The dosimetric influence ofI192 r ,I125, andP103 d spectral choice was determined. Results: For the spectra considered, there were no statistically significant differences between kerma or dose results based on Monte Carlo code choice when using the same spectrum. Water‐kerma differences of about 2%, 2%, and 0.7% were observed due to spectrum choice for I192 r ,I125, andP103 d , respectively (independent of radial distance), when accounting for photon yield per Bq. Similar differences were observed for air‐kerma rate. However, their ratio (as used in the dose‐rate constant) did not significantly change when the various photon spectra were selected because the differences compensated each other when dividing dose rate by air‐kerma strength. Conclusions: Given the standardization of radionuclide data available from the National Nuclear Data Center (NNDC) and the rigorous infrastructure for performing and maintaining the data set evaluations, NNDC spectra are suggested for brachytherapy simulations in medical physics applications.