open access

Vol 16, No 1 (2011)
Published online: 2011-01-01
Submitted: 2010-08-16
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Monte Carlo dose calculation of GZP6 Co stepping source based on a matrix shift technique

Mohammad Taghi Toossi, Malihe Abdollahi, Mahdi Ghorbani
DOI: 10.1016/j.rpor.2010.11.005
·
Rep Pract Oncol Radiother 2011;16(1):10-13.

open access

Vol 16, No 1 (2011)
Published online: 2011-01-01
Submitted: 2010-08-16

Abstract

Background

As a routine method for stepping source simulation, a Monte Carlo program is run according to the number of steps and then the summation of dose from each run is taken to obtain total dose distribution. This method is time consuming.

Aim

As an alternative method, a matrix shift based technique was applied to simulate a stepping source for brachytherapy.

Materials and methods

The stepping source of GZP6 brachytherapy unit was simulated. In a matrix shift method, it is assumed that a radiation source is stationary and instead the data matrix is shifted based on the number of steps. In this study, by running MCNPX program for one point and calculation of the dose matrix using the matrix shift method, the isodose curves for the esophageal cancer tumor lengths of 4 and 6[[ce:hsp sp="0.25"/]]cm were obtained and compared with the isodose curves obtained by running MCNPX programs in each step position separately (15 and 23 steps for esophageal cancer tumor lengths of 4 and 6[[ce:hsp sp="0.25"/]]cm, respectively).

Results

The difference between the two dose matrixes for the stepping and matrix shift methods based on the average dose differences are 3.85[[ce:hsp sp="0.25"/]]×[[ce:hsp sp="0.25"/]]10−4[[ce:hsp sp="0.25"/]]Gy and 5.19[[ce:hsp sp="0.25"/]]×[[ce:hsp sp="0.25"/]]10−4[[ce:hsp sp="0.25"/]]Gy for treatment length of 4[[ce:hsp sp="0.25"/]]cm and 6[[ce:hsp sp="0.25"/]]cm, respectively. Dose differences are insignificant and these two methods are equally valid.

Conclusions

The matrix shift method presented in this study can be used for calculation of dose distribution for a brachytherapy stepping source as a quicker tool compared to other routine Monte Carlo based methods.

Abstract

Background

As a routine method for stepping source simulation, a Monte Carlo program is run according to the number of steps and then the summation of dose from each run is taken to obtain total dose distribution. This method is time consuming.

Aim

As an alternative method, a matrix shift based technique was applied to simulate a stepping source for brachytherapy.

Materials and methods

The stepping source of GZP6 brachytherapy unit was simulated. In a matrix shift method, it is assumed that a radiation source is stationary and instead the data matrix is shifted based on the number of steps. In this study, by running MCNPX program for one point and calculation of the dose matrix using the matrix shift method, the isodose curves for the esophageal cancer tumor lengths of 4 and 6[[ce:hsp sp="0.25"/]]cm were obtained and compared with the isodose curves obtained by running MCNPX programs in each step position separately (15 and 23 steps for esophageal cancer tumor lengths of 4 and 6[[ce:hsp sp="0.25"/]]cm, respectively).

Results

The difference between the two dose matrixes for the stepping and matrix shift methods based on the average dose differences are 3.85[[ce:hsp sp="0.25"/]]×[[ce:hsp sp="0.25"/]]10−4[[ce:hsp sp="0.25"/]]Gy and 5.19[[ce:hsp sp="0.25"/]]×[[ce:hsp sp="0.25"/]]10−4[[ce:hsp sp="0.25"/]]Gy for treatment length of 4[[ce:hsp sp="0.25"/]]cm and 6[[ce:hsp sp="0.25"/]]cm, respectively. Dose differences are insignificant and these two methods are equally valid.

Conclusions

The matrix shift method presented in this study can be used for calculation of dose distribution for a brachytherapy stepping source as a quicker tool compared to other routine Monte Carlo based methods.

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Keywords

Brachytherapy; Co-60; Stepping source; Monte Carlo simulation; Matrix shift based technique

About this article
Title

Monte Carlo dose calculation of GZP6 Co stepping source based on a matrix shift technique

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 16, No 1 (2011)

Pages

10-13

Published online

2011-01-01

DOI

10.1016/j.rpor.2010.11.005

Bibliographic record

Rep Pract Oncol Radiother 2011;16(1):10-13.

Keywords

Brachytherapy
Co-60
Stepping source
Monte Carlo simulation
Matrix shift based technique

Authors

Mohammad Taghi Toossi
Malihe Abdollahi
Mahdi Ghorbani

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