title: Monte Carlo simulation of portal dosimetry on a rectilinear voxel geometry: a variable gantry angle solution.
abstract: A software solution has been developed to carry out Monte Carlo simulations of portal dosimetry using the BEAMnrc/DOSXYZnrc code at oblique gantry angles. The solution is based on an integrated phantom, whereby the effect of incident beam obliquity was included using geometric transformations. Geometric transformations are accurate within +/- 1 mm and +/- 1 degrees with respect to exact values calculated using trigonometry. An application in portal image prediction of an inhomogeneous phantom demonstrated good agreement with measured data, where the root-mean-square of the difference was under 2% within the field. Thus, we achieved a dose model framework capable of handling arbitrary gantry angles, voxel-by-voxel phantom description and realistic particle transport throughout the geometry.
authors.affiliation: Department of Medical Physics, Velindre Hospital, Cardiff CF14 2TL, UK. mary.chin@physics.org
authors.forename: P W
authors.initials: PW
authors.lastname: Chin
authors.forename: E
authors.initials: E
authors.lastname: Spezi
authors.forename: D G
authors.initials: DG
authors.lastname: Lewis
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D008954:Models, Biological; D015233:Models, Statistical; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000295:instrumentation* / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity