title: HDR Brachytherapy Dose Distribution is Influenced by the Metal Material of the Applicator.
abstract: Applicators containing metal have been widely used in recent years when applying brachytherapy to patients with cervical cancer. However, the high dose rate (HDR) treatment-planning system (TPS) that is currently used in brachytherapy still assumes that the treatment environment constitutes a homogeneous water medium and does not include a dose correction for the metal material of the applicator. The primary purpose of this study was to evaluate the HDR (192)Ir dose distribution in cervical cancer patients when performing brachytherapy using a metal-containing applicator. Thermoluminescent dosimeter (TLD) measurements and Monte Carlo N-Particle eXtended (MCNPX) code were used to explore the doses to the rectum and bladder when using a Henschke applicator containing metal during brachytherapy. When the applicator was assumed to be present, the absolute dose difference between the TLD measurement and MCNPX simulation values was within approximately 5%. A comparison of the MCNPX simulation and TPS calculation values revealed that the TPS overestimated the International Commission of Radiation Units and Measurement (ICRU) rectum and bladder reference doses by 57.78% and 49.59%, respectively. We therefore suggest that the TPS should be modified to account for the shielding effects of the applicator to ensure the accuracy of the delivered doses.
authors.affiliation: Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu, Taiwan, ROC.
authors.forename: Chin-Hui
authors.initials: CH
authors.lastname: Wu
authors.affiliation: School of Medical Laboratory Science and Biotechnology, Taipei Medical University, Taipei, Taiwan, ROC.
authors.forename: Yi-Jen
authors.initials: YJ
authors.lastname: Liao
authors.affiliation: Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan, ROC.|Medical Physics Research Center, Institute for Radiological Research, Chang Gung University. Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan, ROC.
authors.forename: An-Cheng
authors.initials: AC
authors.lastname: Shiau
authors.affiliation: Department of Radiation Oncology, Saint Mary's Hospital Luodong, Yilan, Taiwan, ROC.
authors.forename: Hsin-Yu
authors.initials: HY
authors.lastname: Lin
authors.affiliation: Institute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu, Taiwan, ROC.
authors.forename: Yen-Wan
authors.initials: YW
authors.lastname: Hsueh Liu
authors.affiliation: 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.
authors.forename: Shih-Ming
authors.initials: SM
authors.lastname: Hsu
mesh_terms: D001918:Brachytherapy / Q000379:methods*; D003198:Computer Simulation; D006801:Humans; D008670:Metals; D009010:Monte Carlo Method; D011874:Radiometry; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D012007:Rectum; D001743:Urinary Bladder
chemical_list: D008670:Metals