title: Monte Carlo simulation of a prototypical patient dosimetry system for fluoroscopic procedures.
abstract: The purpose of this study is to investigate feasibility of a novel real-time dosimetry method for fluoroscopically guided interventions utilizing thin-film detector arrays in several potential locations with respect to the patient and x-ray equipment. We employed Monte Carlo (MC) simulation to establish the fluoroscopic beam model to determine dosimetric quantities directly from measured doses in thin-film detector arrays at three positions: A-attached to the x-ray source, B-on the couch under the patient and C-attached to the fluoroscopic imager. Next, we developed a calibration method to determine skin dose at the entry of the beam ([Formula: see text]) as well as the dose distribution along each ray of the beam in a water-equivalent patient model. We utilized the concept of water-equivalent thickness to determine the dose inside the patient based on doses measured outside of the patient by the thin-film detector array layers: (a) A, (b) B, or (c) B and C. In the process of calibration we determined a correction factor that characterizes the material-specific response of the detector, backscatter factor and attenuation factor for slab water phantoms of various thicknesses. Application of this method to an anthropomorphic phantom showed accuracy of about 1% for [Formula: see text] and up to about 10% for integral dose along the beam path when compared to a direct simulation of dose by MC.
authors.affiliation: Department of Radiation Oncology, Brigham and Women's Hospital, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02115, USA. Department of Physics and Applied Physics, Medical Physics Program, University of Massachusetts Lowell, Lowell, MA 01854, USA. Department of Radiation Oncology, University Medical Center Mannheim, Heidelberg University, Germany.
authors.forename: Lukas
authors.initials: L
authors.lastname: Goertz
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Tsiamas
authors.forename: Andrew
authors.initials: A
authors.lastname: Karellas
authors.forename: Erno
authors.initials: E
authors.lastname: Sajo
authors.forename: Piotr
authors.initials: P
authors.lastname: Zygmanski
mesh_terms: D005373:Film Dosimetry / Q000379:methods*; D005471:Fluoroscopy / Q000379:methods; D006801:Humans; D009010:Monte Carlo Method; D019047:Phantoms, Imaging