open access

Vol 18, No 2 (2013)
Original research articles
Published online: 2013-03-01
Submitted: 2012-04-30
Get Citation

A Monte Carlo study on dose distribution validation of GZP6 Co stepping source

Mohammad Taghi Bahreyni Toossi, Maliheh Abdollahi, Mahdi Ghorbani
DOI: 10.1016/j.rpor.2012.10.004
·
Rep Pract Oncol Radiother 2013;18(2):112-116.

open access

Vol 18, No 2 (2013)
Original research articles
Published online: 2013-03-01
Submitted: 2012-04-30

Abstract

Aim

Stepping source in brachytherapy systems is used to treat a target lesion longer than the effective treatment length of the source. Cancerous lesions in the cervix, esophagus and rectum are examples of such a target lesion.

Background

In this study, the stepping source of a GZP6 afterloading intracavitary brachytherapy unit was simulated using Monte Carlo (MC) simulation and the results were used for the validation of the GZP6 treatment planning system (TPS).

Materials and methods

The stepping source was simulated using MCNPX Monte Carlo code. Dose distributions in the longitudinal plane were obtained by using a matrix shift method for esophageal tumor lengths of 8 and 10[[ce:hsp sp="0.25"/]]cm. A mesh tally has been employed for the absorbed dose calculation in a cylindrical water phantom. A total of 5[[ce:hsp sp="0.25"/]]×[[ce:hsp sp="0.25"/]]108 photon histories were scored and the MC statistical error obtained was at the range of 0.008–3.5%, an average of 0.2%.

Results

The acquired MC and TPS isodose curves were compared and it was shown that the dose distributions in the longitudinal plane were relatively coincidental. In the transverse direction, a maximum dose difference of 7% and 5% was observed for tumor lengths of 8 and 10[[ce:hsp sp="0.25"/]]cm, respectively.

Conclusion

Considering that the certified source activity is given with ±10% uncertainty, the obtained difference is reasonable. It can be concluded that the accuracy of the dose distributions produced by GZP6 TPS for the stepping source is acceptable for its clinical applications.

Abstract

Aim

Stepping source in brachytherapy systems is used to treat a target lesion longer than the effective treatment length of the source. Cancerous lesions in the cervix, esophagus and rectum are examples of such a target lesion.

Background

In this study, the stepping source of a GZP6 afterloading intracavitary brachytherapy unit was simulated using Monte Carlo (MC) simulation and the results were used for the validation of the GZP6 treatment planning system (TPS).

Materials and methods

The stepping source was simulated using MCNPX Monte Carlo code. Dose distributions in the longitudinal plane were obtained by using a matrix shift method for esophageal tumor lengths of 8 and 10[[ce:hsp sp="0.25"/]]cm. A mesh tally has been employed for the absorbed dose calculation in a cylindrical water phantom. A total of 5[[ce:hsp sp="0.25"/]]×[[ce:hsp sp="0.25"/]]108 photon histories were scored and the MC statistical error obtained was at the range of 0.008–3.5%, an average of 0.2%.

Results

The acquired MC and TPS isodose curves were compared and it was shown that the dose distributions in the longitudinal plane were relatively coincidental. In the transverse direction, a maximum dose difference of 7% and 5% was observed for tumor lengths of 8 and 10[[ce:hsp sp="0.25"/]]cm, respectively.

Conclusion

Considering that the certified source activity is given with ±10% uncertainty, the obtained difference is reasonable. It can be concluded that the accuracy of the dose distributions produced by GZP6 TPS for the stepping source is acceptable for its clinical applications.

Get Citation

Keywords

High dose rate; GZP6 brachytherapy system; Stepping source; Monte Carlo

About this article
Title

A Monte Carlo study on dose distribution validation of GZP6 Co stepping source

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 18, No 2 (2013)

Pages

112-116

Published online

2013-03-01

DOI

10.1016/j.rpor.2012.10.004

Bibliographic record

Rep Pract Oncol Radiother 2013;18(2):112-116.

Keywords

High dose rate
GZP6 brachytherapy system
Stepping source
Monte Carlo

Authors

Mohammad Taghi Bahreyni Toossi
Maliheh Abdollahi
Mahdi Ghorbani

Important: This website uses cookies. More >>

The cookies allow us to identify your computer and find out details about your last visit. They remembering whether you've visited the site before, so that you remain logged in - or to help us work out how many new website visitors we get each month. Most internet browsers accept cookies automatically, but you can change the settings of your browser to erase cookies or prevent automatic acceptance if you prefer.

By "Via Medica sp. z o.o." sp.k., ul. Świętokrzyska 73, 80–180 Gdańsk, Poland
tel.:+48 58 320 94 94, fax:+48 58 320 94 60, e-mail: journals@viamedica.pl