PMID: 8587942Nov 1, 1995Paper

Portal dose measurement in radiotherapy using an electronic portal imaging device (EPID)

Physics in Medicine and Biology
B J HeijmenH Huizenga

Abstract

Physical characteristics of a commercially available electronic portal imaging device (EPID), relevant to dosimetric applications in high-energy photon beams, have been investigated. The EPID basically consists of a fluorescent screen, mirrors and a CCD camera. Image acquisition for portal dose measurement has been performed with a special procedure, written in the command language that comes with the system. The observed day-to-day variation in local EPID responses, i.e. measured grey scale value (EPID signal) per unit of delivered portal dose, is 0.4% (1 SD); day-to-day variation in relative EPID responses (e.g. normalized to the on-axis response) are within 0.2% (1 SD). Measured grey scale values are linearly proportional to transmitted portal doses with a proportionality constant which is independent of the thickness of a flat, water-equivalent absorber in the beam, but which does significantly depend on the size of the applied x-ray beam. It is shown that the observed increased in EPID response with increasing field size is mainly due to contributions to the EPID signals from scattered light: visible photons produced by the x-ray beam in a point of the fluorescent screen not only generate a grey scale value in the correspo...Continue Reading

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Citations

Jul 1, 2008·Radiological Physics and Technology·Kunihiko TateokaMasato Hareyama
Mar 3, 1999·Radiotherapy and Oncology : Journal of the European Society for Therapeutic Radiology and Oncology·M KroonwijkB J Heijmen
Jun 2, 1998·International Journal of Radiation Oncology, Biology, Physics·R BoellaardB J Mijnheer
Feb 25, 1999·International Journal of Radiation Oncology, Biology, Physics·M Essers, B J Mijnheer
Dec 29, 1999·International Journal of Radiation Oncology, Biology, Physics·K L PasmaB J Heijmen
Mar 4, 2000·International Journal of Radiation Oncology, Biology, Physics·E M DonovanJ R Yarnold
Sep 30, 2000·Medical Physics·B M McCurdy, S Pistorius
Jan 10, 2004·Medical Physics·B WarkentinB G Fallone
Mar 6, 2004·Medical Physics·S M J J G NijstenI A D Bruinvis
Aug 13, 2004·Medical Physics·Jeffrey V SiebersRadhe Mohan
May 8, 1998·Medical Physics·S N BoonE Grusell
Sep 29, 1999·Medical Physics·Y El-MohriJ H Siewerdsen
Apr 11, 2000·Medical Physics·L SpiesT Bortfeld
Jan 1, 2006·Biomedical Imaging and Intervention Journal·Ky Cheung
May 16, 2006·Medical Physics·E M FrankenB J M Heijmen
Dec 13, 2006·Medical Physics·Angelo PiermatteiNuma Cellini
Apr 19, 2007·Medical Physics·Luca GrimaldiAngelo Piermattei
Mar 15, 2006·Medical Physics·Markus WendlingBen J Mijnheer
Jan 26, 2010·Medical Physics·Helen GustafssonPeter B Greer
Aug 11, 2006·Medical Physics·Wouter J C van ElmptAndré W H Minken
Jun 20, 2008·Medical Physics·Angelo PiermatteiLuigi Azario
Aug 2, 2006·Medical Physics·Josephine ChenJean Pouliot
Nov 4, 2005·Medical Physics·W J C van ElmptA W H Minken

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