title: Monte Carlo model of the scanning beam digital x-ray (SBDX) source.
abstract: The scanning-beam digital x-ray (SBDX) system has been developed for fluoroscopic imaging using an inverse x-ray imaging geometry. The SBDX system consists of a large-area x-ray source with a multihole collimator and a small detector. The goal of this study was to build a Monte Carlo (MC) model of the SBDX source as a useful tool for optimization of the SBDX imaging system in terms of its hardware components and imaging parameters. The MC model of the source was built in the EGSnrc/BEAMnrc code and validated using the DOSXYZnrc code and Gafchromic film measurements for 80, 100, and 120 kV x-ray source voltages. The MC simulated depth dose curves agreed with measurements to within 5%, and beam profiles at three selected depths generally agreed within 5%. Exposure rates and half-value layers for three voltages were also calculated from the MC simulations. Patient skin-dose per unit detector-dose was quantified as a function of patient size for all three x-ray source voltages. The skin-dose to detector-dose ratio ranged from 5-10 for a 20 cm thick patient to 1 × 10(3)-1 × 10(5) for a 50 cm patient for the 120 and 80 kV beams, respectively. Simulations of imaging dose for a prostate patient using common imaging parameters revealed that skin-dose per frame was as low as 0.2 mGy.
authors.affiliation: Department of Radiation Oncology, Stanford University, Stanford, CA 94305-5847, USA. bazalova@stanford.edu
authors.forename: M
authors.initials: M
authors.lastname: Bazalova
authors.forename: M D
authors.initials: MD
authors.lastname: Weil
authors.forename: B
authors.initials: B
authors.lastname: Wilfley
authors.forename: E E
authors.initials: EE
authors.lastname: Graves
mesh_terms: D006801:Humans; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D011856:Radiographic Image Enhancement / Q000379:methods*; D061089:Radiotherapy, Image-Guided