title: Conformal fields in prostate radiotherapy: a comparison between measurement, calculation and simulation.
abstract: OBJECTIVE
  The objective of this study is to evaluate the accuracy of a treatment planning system (TPS) for calculating the dose distribution parameters in conformal fields (CF). Dosimetric parameters of CF's were compared between measurement, Monte Carlo simulation (MCNP4C) and TPS calculation.
  
  
  METHODS
  Field analyzer water phantom was used for obtaining percentage depth dose (PDD) curves and beam profiles (BP) of different conformal fields. MCNP4C was used to model conformal fields dose specification factors and head of linear accelerator varian model 2100C/D.
  
  
  RESULTS
  Results showed that the distance to agreement (DTA) and dose difference (DD) of our findings were well within the acceptance criteria of 3 mm and 3%, respectively.
  
  
  CONCLUSIONS
  According to this study it can be revealed that TPS using equivalent tissue air ratio calculation method is still convenient for dose prediction in non small conformal fields normally used in prostate radiotherapy. It was also showed that, since there is a close correlation with Monte Carlo simulation, measurements and TPS, Monte Carlo can be further confirmed for implementation and calculation dose distribution in non standard and complex conformal irradiation field for treatment planning systems.
authors.affiliation: Department of Medical Physics, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Seied R
authors.initials: SR
authors.lastname: Mahdavi
authors.forename: Hamed
authors.initials: H
authors.lastname: Rezaeejam
authors.forename: Alireza
authors.initials: A
authors.lastname: Shirazi
authors.forename: Mohammad
authors.initials: M
authors.lastname: Hosntalab
authors.forename: Ahmad
authors.initials: A
authors.lastname: Mostaar
authors.forename: Mohsen
authors.initials: M
authors.lastname: Motamedi
mesh_terms: D003198:Computer Simulation; D006801:Humans; D008297:Male; D009010:Monte Carlo Method; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011874:Radiometry; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D020266:Radiotherapy, Conformal; D015203:Reproducibility of Results