title: Fast and accurate Monte Carlo modeling of a kilovoltage X-ray therapy unit using a photon-source approximation for treatment planning in complex media.
abstract: To accurately recompute dose distributions in chest-wall radiotherapy with 120 kVp kilovoltage X-rays, an MCNP4C Monte Carlo model is presented using a fast method that obviates the need to fully model the tube components. To validate the model, half-value layer (HVL), percentage depth doses (PDDs) and beam profiles were measured. Dose measurements were performed for a more complex situation using thermoluminescence dosimeters (TLDs) placed within a Rando phantom. The measured and computed first and second HVLs were 3.8, 10.3 mm Al and 3.8, 10.6 mm Al, respectively. The differences between measured and calculated PDDs and beam profiles in water were within 2 mm/2% for all data points. In the Rando phantom, differences for majority of data points were within 2%. The proposed model offered an approximately 9500-fold reduced run time compared to the conventional full simulation. The acceptable agreement, based on international criteria, between the simulations and the measurements validates the accuracy of the model for its use in treatment planning and radiobiological modeling studies of superficial therapies including chest-wall irradiation using kilovoltage beam.
authors.affiliation: Department of Medical Radiation, School of Mechanical Engineering, Shiraz University, Shiraz, Iran.
authors.forename: B
authors.initials: B
authors.lastname: Zeinali-Rafsanjani
authors.affiliation: Department of Radiotherapy and Oncology, Shiraz University of Medical Sciences, Shiraz, Iran ; Radiology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: M A
authors.initials: MA
authors.lastname: Mosleh-Shirazi
authors.affiliation: Department of Medical Radiation, School of Mechanical Engineering, Shiraz University, Shiraz, Iran ; Radiation Research Center, School of Mechanical Engineering, Shiraz University, Shiraz, Iran.
authors.forename: R
authors.initials: R
authors.lastname: Faghihi
authors.affiliation: Department of Radiotherapy and Oncology, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: S
authors.initials: S
authors.lastname: Karbasi
authors.affiliation: Department of Radiotherapy and Oncology, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: A
authors.initials: A
authors.lastname: Mosalaei
keywords: Fast Monte Carlo; kilovoltage therapy; modeling of external therapy; treatment planning