title: Monte Carlo simulation of stereotactic microbeam radiation therapy: evaluation of the usage of a linear accelerator as the x-ray source.
abstract: The usage of linear accelerator-generated x-rays for the stereotactic microbeam radiation therapy technique was evaluated in this study. Dose distributions were calculated with the Monte Carlo code MCNPX. Unidirectional single beams and beam arrays were simulated in a cylindrical water phantom to observe the effects of x-ray energies and irradiation geometry on dose distributions. Beam arrays were formed with square pencil beams. Two orthogonally interlaced beam arrays were simulated in a detailed head phantom and dose distributions were compared with ones which had been calculated for a bidirectional interlaced microbeam therapy (BIMRT) technique that uses synchrotron-generated x-rays. A parallel pattern of the beams was preserved through the phantom; however an unsegmented dose region could not be formed at the target. Five orthogonally interlaced beam array pairs (ten beam arrays) were simulated in a mathematical head phantom and the unsegmented dose region was formed. However, the dose fall-off distance is longer than the one that had been calculated for the BIMRT technique. Besides, the peak-to-dose ratios between the phantom's outer surface and the target region are lower. Therefore, the advantages of the MRT technique may not be preserved with the usage of a linac as the x-ray source.
authors.affiliation: Department of Nuclear Engineering, Hacettepe University, Ankara, Turkey. gurdal.gokeri@taek.gov.tr
authors.forename: Gurdal
authors.initials: G
authors.lastname: Gokeri
authors.forename: Cemil
authors.initials: C
authors.lastname: Kocar
authors.forename: Mehmet
authors.initials: M
authors.lastname: Tombakoglu
authors.forename: Yigit
authors.initials: Y
authors.lastname: Cecen
mesh_terms: D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D009010:Monte Carlo Method; D010315:Particle Accelerators / Q000295:instrumentation*; D011874:Radiometry / Q000379:methods*; D016634:Radiosurgery / Q000295:instrumentation*; D011879:Radiotherapy Dosage; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014965:X-Rays