PMID: 11339752May 8, 2001Paper

Analytical scatter kernels for portal imaging at 6 MV

Medical Physics
L Spies, T Bortfeld

Abstract

X-ray photon scatter kernels for 6 MV electronic portal imaging are investigated using an analytical and a semi-analytical model. The models are tested on homogeneous phantoms for a range of uniform circular fields and scatterer-to-detector air gaps relevant for clinical use. It is found that a fully analytical model based on an exact treatment of photons undergoing a single Compton scatter event and an approximate treatment of second and higher order scatter events, assuming a multiple-scatter source at the center of the scatter volume, is accurate within 1% (i.e., the residual scatter signal is less than 1% of the primary signal) for field sizes up to 100 cm2 and air gaps over 30 cm, but shows significant discrepancies for larger field sizes. Monte Carlo results are presented showing that the effective multiple-scatter source is located toward the exit surface of the scatterer, rather than at its center. A second model is therefore investigated where second and higher-order scattering is instead modeled by fitting an analytical function describing a nonstationary isotropic point-scatter source to Monte Carlo generated data. This second model is shown to be accurate to within 1% for air gaps down to 20 cm, for field sizes up t...Continue Reading

References

Oct 1, 1976·Radiology·E P MuntzD J Klein
May 1, 1985·Medical Physics·J A Sorenson, J Floch
Aug 1, 1997·Radiotherapy and Oncology : Journal of the European Society for Therapeutic Radiology and Oncology·R BoellaardB Mijnheer
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Apr 11, 2000·Medical Physics·L SpiesT Bortfeld
May 5, 2000·Physics in Medicine and Biology·K J RuchalaT R Mackie
Mar 30, 2001·Physics in Medicine and Biology·L SpiesT Bortfeld

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Citations

Mar 15, 2006·Medical Physics·Markus WendlingBen J Mijnheer
Nov 4, 2005·Medical Physics·W J C van ElmptA W H Minken
Jan 12, 2012·Strahlentherapie und Onkologie : Organ der Deutschen Röntgengesellschaft ... [et al]·H K LooeK C Willborn
May 3, 2011·Zeitschrift für medizinische Physik·Ndimofor ChoforBjörn Poppe
Oct 5, 2010·Zeitschrift für medizinische Physik·Hui Khee LooeBjörn Poppe
Aug 19, 2008·Radiotherapy and Oncology : Journal of the European Society for Therapeutic Radiology and Oncology·Wouter van ElmptBen Mijnheer
Jun 26, 2010·Physics in Medicine and Biology·Ndimofor ChoforBjörn Poppe
Feb 14, 2013·Physics in Medicine and Biology·A Teymurazyan, G Pang

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