Influence of metal of the applicator on the dose distribution during brachytherapy

Chin-Hui Wu; An-Cheng Shiau; Yi-Jen Liao; Hsin-Yu Lin; Yen-Wan Hsueh Liu; Shih-Ming Hsu

doi:10.1371/journal.pone.0104831

Influence of metal of the applicator on the dose distribution during brachytherapy

PLoS One. 2014 Aug 18;9(8):e104831. doi: 10.1371/journal.pone.0104831. eCollection 2014.

Authors

Chin-Hui Wu¹, An-Cheng Shiau², Yi-Jen Liao³, Hsin-Yu Lin⁴, Yen-Wan Hsueh Liu¹, Shih-Ming Hsu⁵

Affiliations

¹ Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu, Taiwan, ROC.
² Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan, ROC; Department of Radiation Oncology, Koo Foundation Sun Yat-Sen Cancer Center, Taipei, Taiwan, ROC.
³ School of Medical Laboratory Science and Biotechnology, Taipei Medical University, Taipei, Taiwan, ROC.
⁴ Department of Radiation Oncology, Saint Mary's Hospital Luodong, Yilan, Taiwan, ROC.
⁵ Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan, ROC; Biophotonics and Molecular Imaging Research Center, National Yang-Ming University, Taipei, Taiwan, ROC.

Abstract

This study explores how the metal materials of the applicator influence the dose distribution when performing brachytherapy for cervical cancer. A pinpoint ionization chamber, Monte Carlo code MCNPX, and treatment planning system are used to evaluate the dose distribution for a single Ir-192 source positioned in the tandem and ovoid. For dose distribution in water with the presence of the tandem, differences among measurement, MCNPX calculation and treatment planning system results are <5%. For dose distribution in water with the presence of the ovoid, the MCNPX result agrees with the measurement. But the doses calculated from treatment planning system are overestimated by up to a factor of 4. This is due to the shielding effect of the metal materials in the applicator not being considered in the treatment planning system. This result suggests that the treatment planning system should take into account corrections for the metal materials of the applicator in order to improve the accuracy of the radiation dose delivered.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Brachytherapy / instrumentation*
Humans
Phantoms, Imaging
Radiometry
Stainless Steel

Substances

Stainless Steel

Grants and funding

This work was supported by Grant No. NSC100-2314-B-039-044 from National Science Council of Taiwan. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.