title: A Monte Carlo study on dose distribution evaluation of Flexisource (192)Ir brachytherapy source.
abstract: OBJECTIVE
  The aim of this study is to evaluate the dose distribution of the Flexisource (192)Ir source.
  
  
  BACKGROUND
  Dosimetric evaluation of brachytherapy sources is recommended by task group number 43 (TG. 43) of American Association of Physicists in Medicine (AAPM).
  
  
  METHODS
  MCNPX code was used to simulate Flexisource (192)Ir source. Dose rate constant and radial dose function were obtained for water and soft tissue phantoms and compared with previous data on this source. Furthermore, dose rate along the transverse axis was obtained by simulation of the Flexisource and a point source and the obtained data were compared with those from Flexiplan treatment planning system (TPS).
  
  
  RESULTS
  The values of dose rate constant obtained for water and soft tissue phantoms were equal to 1.108 and 1.106, respectively. The values of the radial dose function are listed in the form of tabulated data. The values of dose rate (cGy/s) obtained are shown in the form of tabulated data and figures. The maximum difference between TPS and Monte Carlo (MC) dose rate values was 11% in a water phantom at 6.0 cm from the source.
  
  
  CONCLUSIONS
  Based on dosimetric parameter comparisons with values previously published, the accuracy of our simulation of Flexisource (192)Ir was verified. The results of dose rate constant and radial dose function in water and soft tissue phantoms were the same for Flexisource and point sources. For Flexisource (192)Ir source, the results of TPS calculations in a water phantom were in agreement with the simulations within the calculation uncertainties. Furthermore, the results from the TPS calculation for Flexisource and MC calculation for a point source were practically equal within the calculation uncertainties.
authors.affiliation: Medical Physics and Medical Engineering Department, Faculty of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran.
authors.forename: Majid
authors.initials: M
authors.lastname: Alizadeh
authors.affiliation: Medical Physics Department, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Mahdi
authors.initials: M
authors.lastname: Ghorbani
authors.affiliation: Medical Physics and Medical Engineering Department, Faculty of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran.
authors.forename: Abbas
authors.initials: A
authors.lastname: Haghparast
authors.affiliation: Brachytherapy Department, Atiyeh Hospital, Tehran, Iran.
authors.forename: Naser
authors.initials: N
authors.lastname: Zare
authors.affiliation: Department of Basic Medical Sciences, Neyshabur University of Medical Sciences, Neyshabur, Iran.
authors.forename: Toktam
authors.initials: T
authors.lastname: Ahmadi Moghaddas
keywords: 192Ir source; Flexiplan treatment planning system; Flexisource; HDR brachytherapy; Monte Carlo