%0 Journal Article
%T Evaluation of interpolation methods for TG-43 dosimetric parameters based on comparison with Monte Carlo data for high-energy brachytherapy sources
%A Ma Carmen Pujades-Claumarchirant
%A Domingo Granero
%A Jose Perez-Calatayud
%A Facundo Ballester
%J Journal of Contemporary Brachytherapy
%D 2010
%I Termedia Publishing House
%X Purpose: The aim of this work was to determine dose distributions for high-energy brachytherapy sources at spatial locations not included in the radial dose function gL(r) and 2D anisotropy function F(r,¦È) table entries for radial distancer and polar angle ¦È. The objectives of this study are as follows: 1) to evaluate interpolation methods in order to accurately derive gL(r) and F(r,¦È) from the reported data; 2) to determine the minimum number of entries in gL(r) and F(r,¦È) that allow reproduction of dose distributions with sufficient accuracy.Material and methods: Four high-energy photon-emitting brachytherapy sources were studied: 60Co model Co0.A86, 137Cs model CSM-3, 192Ir model Ir2.A85-2, and 169Yb hypothetical model. The mesh used for r was: 0.25, 0.5, 0.75, 1, 1.5, 2¨C8 (integer steps) and 10 cm. Four different angular steps were evaluated for F(r,¦È): 1¡ã, 2¡ã, 5¡ã and 10¡ã. Linear-linear and logarithmic-linear interpolation was evaluated for gL(r). Linear-linear interpolation was used to obtain F(r,¦È) with resolution of 0.05 cm and 1¡ã. Results were compared with values obtained from the Monte Carlo (MC) calculations for thefour sources with the same grid.Results: Linear interpolation of gL(r) provided differences ¡Ü 0.5% compared to MC for all four sources. Bilinear interpolation of F(r,¦È) using 1¡ã and 2¡ã angular steps resulted in agreement ¡Ü 0.5% with MC for 60Co, 192Ir, and 169Yb, while 137Cs agreement was ¡Ü 1.5% for ¦È < 15¡ã.Conclusions: The radial mesh studied was adequate for interpolating gL(r) for high-energy brachytherapy sources, and was similar to commonly found examples in the published literature. For F(r,¦È) close to the source longitudinalaxis, polar angle step sizes of 1¡ã-2¡ã were sufficient to provide 2% accuracy for all sources.
%K brachytherapy
%K dosimetry
%K TG-43
%K interpolation
%K radial dose function
%K 2D anisotropy function
%U http://www.termedia.pl/Physics-Contributions-Evaluation-of-interpolation-methods-for-TG-43-dosimetric-parameters-based-on-comparison-with-Monte-Carlo-data-for-high-energy-brachytherapy-sources,54,14478,1,1.html