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DOI http://dx.doi.org/10.1016/S0360-3016(97)85831-2
Title Utilization of an electronic portal imaging device for measurement of dynamic wedge data
Creator/Author Elder, Eric S. ; Miner, Marc S. ; Butker, Elizabeth K. ; Sutton, Danny S. ; Davis, Lawrence W
Publication Date1996 Sep 01
OSTI IdentifierOSTI ID: 20392082
Other Number(s)ISSN 0360-3016; IOBPD3 ; TRN: US03R2480067715
Resource TypeJournal Article
Resource RelationInternational Journal of Radiation Oncology, Biology and Physics ; VOL. 36 ; ISSUE: 1 ; 38. annual meeting of the American Society for Therapeutic Radiology and Oncology (ASTRO), Los Angeles, CA (United States), 27-30 Oct 1996 ; PII: S0360301697858312; Copyright (c) 1996 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: Argentina; PBD: Sep 1996
Subject62 RADIOLOGY AND NUCLEAR MEDICINE ; ACCELERATORS; COLLIMATORS; COMPUTER CALCULATIONS; DOSIMETRY; PHOTON BEAMS; RADIOTHERAPY
Description/Abstract Purpose/Objective: Due to the motion of the collimator during dynamic wedge treatments, the conventional method of collecting comprehensive wedge data with a water tank and a scanning ionization chamber is obsolete. It is the objective of this work to demonstrate the use of an electronic portal imaging device (EPID) and software to accomplish this task. Materials and Methods: A Varian Clinac[reg] 2300 C/D, equipped with a PortalVision{sup TM} EPID and Dosimetry Research Mode experimental software, was used to produce the radiation field. The Dosimetry Research Mode experimental software allows for a band of 10 of 256 high voltage electrodes to be continuously read and averaged by the 256 electrometer electrodes. The file that is produced contains data relating to the integrated ionization at each of the 256 points, essentially the cross plane beam profile. Software was developed using Microsoft C{sup++} to reformat the data for import into a Microsoft Excel spreadsheet allowing for easy mathematical manipulation and graphical display. Beam profiles were measured by the EPID with a 100 cm TSD for various field sizes. Each field size was measured open, steel wedged, and dynamically wedged. Scanning ionization chamber measurements performed in a water tank were compared to the open and steel wedged fields. Ionization chamber measurements taken in a water tank were compared with the dynamically wedged measurements. For the EPID measurements the depth was varied using Gammex RMI Solid Water{sup TM} placed directly above the EPID sensitive volume. Bolus material was placed between the Solid Water{sup TM} and the EPID to avoid an air gap. Results: Comparison of EPID measurements with those from an ion chamber in a water tank showed a discrepancy of{approx}5%. Scans were successfully obtained for open, steel wedged and dynamically wedged beams. Software has been developed to allow for easy graphical display of beam profiles. Conclusions: Measurement of dynamic wedge data proves to be easily performed using an EPID with the above equipment and software.
Country of PublicationUnited States
LanguageEnglish
Formatpage(s) 404
System Entry Date2003 Nov 24

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