PMID: 9547177Apr 18, 1998Paper

Monitor chamber backscatter for intensity modulated radiation therapy using multileaf collimators

Physics in Medicine and Biology
A R Hounsell

Abstract

Backscattered radiation into the machine monitor chamber can affect the machine output variation, with changes in field size and shape. For intensity modulated radiation therapy (IMRT) where many field, which may have small dimensions, are summed to give an intensity modulated field, the magnitude of backscatter will be different due to both the backscattering surface area changing, and the delivered monitor units being larger than for the equivalent static field. The effect of backscatter variation with field size for a Philips SL15 accelerator has been investigated at 8 MV for static and IMRT fields both in the standard clinical operating condition where an anti-backscatter plate is fitted, and also for a case where the anti-backscatter plate has been removed. The results show that in the absence of the anti-backscatter plate the variation in output between a 4 cm by 4 cm field and a 40 cm by 40 cm field size due to backscattered radiation was 5% for static fields. The anti-backscatter plate reduced this variation to less than 1%. When the accelerator operated in IMRT mode, with the backscatter plate in place, changes in the output due to additional backscattered radiation were less than 0.3%. With the backscatter plate remov...Continue Reading

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Citations

Oct 31, 2009·Australasian Physical & Engineering Sciences in Medicine·T KairnA L Fielding
Mar 20, 2008·Physica Medica : PM : an International Journal Devoted to the Applications of Physics to Medicine and Biology : Official Journal of the Italian Association of Biomedical Physics (AIFB)·Maha A Ali, Ismail Emam
Nov 4, 2009·Applied Radiation and Isotopes : Including Data, Instrumentation and Methods for Use in Agriculture, Industry and Medicine·Maíra T YoshizumiLinda V E Caldas
Dec 10, 2009·Medical Physics·Timothy C ZhuUNKNOWN AAPM Therapy Physics Committee Task Group 74
Feb 2, 2013·Technology in Cancer Research & Treatment·Murugan AppasamyRamasubramanian Velayudham
Dec 5, 2003·Physics in Medicine and Biology·Frank Verhaegen, Jan Seuntjens
Apr 28, 2001·Physics in Medicine and Biology·J DengC M Ma
Apr 17, 2003·Physics in Medicine and Biology·C M MaA L Boyer
Dec 10, 1999·Physics in Medicine and Biology·A Ahnesjö, M M Aspradakis
Mar 11, 1999·Physics in Medicine and Biology·A R Hounsell, J M Wilkinson
May 5, 2000·Physics in Medicine and Biology·J F SutcliffeK W Croft
Mar 1, 2007·Physics in Medicine and Biology·Darío Esteban SanzFlavio Enrico Nelli

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