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Monte Carlo calculation of dosimetry parameters for the IR08‐ P 103 d brachytherapy source
Author(s) -
Saidi Pooneh,
Sadeghi Mahdi,
Shirazi Alireza,
Tenreiro Claudio
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 - 10.1118/1.3416922
Subject(s) - monte carlo method , brachytherapy , dosimetry , nuclear medicine , computational physics , photon , radiation treatment planning , materials science , ionization chamber , physics , medical physics , optics , mathematics , medicine , radiation therapy , statistics , radiology , ion , quantum mechanics , ionization
Purpose For the treatment of some cancerous tumors using brachytherapy methods and low‐energy photon sources, such asI125andP103 d , the American Association of Physicists in Medicine Task Group No. 43U1 report recommends that the dosimetric parameters of a new brachytherapy source must be determined in two experimental and Monte Carlo theoretical methods before using each new source clinically. This study presents the results of Monte Carlo calculations of the dosimetric parameters for IR08‐ P103 d brachytherapy source design. IR08‐ P103 d seed has been manufactured at the Agricultural, Medical and Industrial Research School . Methods Version 5 of the ( MCNP ) Monte Carlo radiation transport code was used to calculate the dosimetry parameters around the source. Three geometric models of the seed, based on different locations of beads inside the titanium capsule, were simulated. The seed contains five resin beads of 0.6 mm diameter havingP103 d uniformly absorbed in the bead volume, which were contained within a cylindrical titanium capsule having 0.8 mm outside diameter and 4.8 mm length. Results The Monte Carlo calculated dose rate constant Λ of the IR08‐ P103 d seed was found to be 0.695 ± 0.021cGyU − 1h − 1. Also in this study, the geometry function G ( r , θ ) , line and point‐source radial dose functionsg L ( r )andg P ( r ) , and the anisotropy function F ( r , θ ) , have been calculated at distances from 0.25 to 7 cm. The results of these calculations have been compared with measured values for an actual IR08‐ P103 d seed. Conclusions There are no statistical significant dosimetric differences among the three seed orientations in this study (i.e., ideal, vertical, and diagonal). However, the observed differences between the calculated and measured values could be explained by the measurement uncertainty and the configuration of the resin beads within the capsule and capsule orientation.