title: Investigations of different kilovoltage X-ray energy for three-dimensional converging stereotactic radiotherapy system: Monte Carlo simulations with CT data.
abstract: We are investigating three-dimensional converging stereotactic radiotherapy (3DCSRT) with suitable medium-energy x rays as treatment for small lung tumors with better dose homogeneity at the target. A computed tomography (CT) system dedicated for non-coplanar converging radiotherapy was simulated with BEAMnrc (EGS4) Monte-Carlo code for x-ray energy of 147.5, 200, 300, and 500 kilovoltage (kVp). The system was validated by comparing calculated and measured percentage of depth dose in a water phantom for the energy of 120 and 147.5 kVp. A thorax phantom and CT data from lung tumors (<20 cm3) were used to compare dose homogeneities of kVp energies with MV energies of 4, 6, and 10 MV. Three non-coplanar arcs (0 degrees and +/-25 degrees ) around the center of the target were employed. The Monte Carlo dose data format was converted to the XiO RTP format to compare dose homogeneity, differential, and integral dose volume histograms of kVp and MV energies. In terms of dose homogeneity and DVHs, dose distributions at the target of all kVp energies with the thorax phantom were better than MV energies, with mean dose absorption at the ribs (human data) of 100%, 85%, 50%, 30% for 147.5, 200, 300, and 500 kVp, respectively. Considering dose distributions and reduction of the enhanced dose absorption at the ribs, a minimum of 500 kVp is suitable for the lung kVp 3DCSRT system.
authors.affiliation: Department of Radiology, Keio University, Tokyo, Japan and CREST, Japan Science and Technology Agency, Tokyo, Japan.
authors.forename: Hossain M
authors.initials: HM
authors.lastname: Deloar
authors.forename: Etsuo
authors.initials: E
authors.lastname: Kunieda
authors.forename: Takatsugu
authors.initials: T
authors.lastname: Kawase
authors.forename: Takanori
authors.initials: T
authors.lastname: Tsunoo
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Saitoh
authors.forename: Masahiro
authors.initials: M
authors.lastname: Ozaki
authors.forename: Kimiaki
authors.initials: K
authors.lastname: Saito
authors.forename: Shunji
authors.initials: S
authors.lastname: Takagi
authors.forename: Osamu
authors.initials: O
authors.lastname: Sato
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Fujisaki
authors.forename: Atsushi
authors.initials: A
authors.lastname: Myojoyama
authors.forename: Graham
authors.initials: G
authors.lastname: Sorell
mesh_terms: D003198:Computer Simulation; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging / Q000473:pathology; D008962:Models, Theoretical; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D013902:Radiography, Thoracic / Q000295:instrumentation / Q000379:methods; D011874:Radiometry / Q000379:methods*; D011878:Radiotherapy / Q000295:instrumentation* / Q000379:methods*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D013238:Stereotaxic Techniques; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014867:Water / Q000737:chemistry; D014965:X-Rays
chemical_list: D014867:Water