Determination of dosimetric parameters for shielded 153Gd source in prostate cancer brachytherapy

  • Benyamin khajetash Medical Physics Department, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
  • Mahdi Ghorbani Medical Physics Department, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
  • Najmeh Ghatei Radiotherapy Department, Namazi Hospital, Shiraz, Iran
  • Mohammad Mehrpouyan Department of Radiology and Radiotherapy, Faculty of Medicine, Sabzevar University of Medical Sciences, Sabzevar, Iran
  • Ali S. Meigooni Comprehensive Cancer Centers of Nevada, Las Vegas, Nevada, USA
  • Ramin Shahraini Department of Radiology and Radiotherapy, Faculty of Medicine, Sabzevar University of Medical Sciences, Sabzevar, Iran

Abstract

Aims: Interstitial rotating shield brachytherapy (I-RSBT) is a recently developed method for treatment of prostate cancer. In the present study TG-43 dosimetric parameters of a 153Gd source are obtained for use in I-RSBT. Materials and methods: A 153Gd source located inside a needle including a Pt shield and an aluminum window was simulated using MCNPX Monte Carlo code. Dosimetric parameters of this source model, including air kerma strength, dose rate constant, radial dose function and 2D anisotropy function, with and without the shields were calculated according to the TG-43 report. Results: The air kerma strength was found to be 6.71 U for the non-shielded source with 1 GBq activity. This value was found to be 0.04 U and 6.19 U for the Pt shield and Al window cases, respectively. Dose rate constant for the non-shielded source was found to be 1.20 cGy/hU. However, for a shielded source with Pt and aluminum window, dose rate constants were found to be 0.07 cGy/hU and 0.96 cGy/hU, on the shielded and window sides, respectively. The values of radial dose function and anisotropy function were tabulated for these sources. Additionally, isodose curves were drawn for sources with and without shield, in order to evaluate the effect of shield on dose distribution. Conclusion: Existence of the Pt shield may greatly reduce the dose to organs at risk and normal tissues which are located toward the shielded side. The calculated air kerma strength, dose rate constant, radial dose function and 2D anisotropy function data for the 153Gd source for the non-shielded and the shielded sources can be used in the treatment planning system (TPS).
Published
2017-02-28
How to Cite
khajetash, B., Ghorbani, M., Ghatei, N., Mehrpouyan, M., S. Meigooni, A., & Shahraini, R. (2017). Determination of dosimetric parameters for shielded 153Gd source in prostate cancer brachytherapy. Radiology and Oncology, 51(1). Retrieved from https://radioloncol.com/index.php/ro/article/view/2637
Section
Medical Physics