PMID: 9167168May 1, 1997Paper

Geometric analysis of light-field position of a multileaf collimator with curved ends

Medical Physics
A L Boyer, S Li

Abstract

The purpose of this work was to analyze the difference between the light-field edge and the radiation field edge produced by multileaf collimator (MLC) leaves that are constructed with rounded ends. A formula was derived using three-dimensional geometry predicting the location of the ideal point-source light-field edge relative to the geometric projection of the tip of the rounded leaf end. The theoretical edge of the radiation field for a point source was also calculated along the projection of a chord whose length was one Half-Value Thickness (HVT). Analytic solutions were found for the radiation-field edge and the transmission penumbra. The displacement of the light-field edge relative to the projection of the leaf tip varied from 0 mm for the leaf tip projected onto the central axis to approximately 3.2 mm for the leaf tip projected to 20 cm off the central axis. The light-field edge was always displaced into the unblocked area. The location of the projection of the 1 HVT chord was displaced from the light-field edge by a small and essentially constant distance (approximately 0.3 mm) for all field sizes. The transmission penumbra (80%-20%) was about 1.2 mm for all leaf positions. The calibration of the leaf position must ac...Continue Reading

References

Sep 1, 1992·Medical Physics·A L BoyerC J Huntzinger
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Citations

Dec 18, 2001·International Journal of Cancer. Journal International Du Cancer·C W ChengT Steinberg
Jul 11, 2001·Medical Dosimetry : Official Journal of the American Association of Medical Dosimetrists·M R ArnfieldR Mohan
Jun 11, 2003·American Journal of Clinical Oncology·C-W ChengM Uematsu
Oct 6, 2007·Nihon Hoshasen Gijutsu Gakkai zasshi·Kaoru OnoMasanori Miyazawa
Oct 9, 2009·Medical Physics·Eric E KleinUNKNOWN Task Group 142, American Association of Physicists in Medicine
Oct 17, 1998·Medical Physics·I J DasT E Schultheiss
Sep 13, 2000·Medical Physics·Y ChenC M Ma
Aug 31, 2002·Medical Physics·J H KilloranL Chin
Oct 4, 2002·Physics in Medicine and Biology·Jeffrey V SiebersRadhe Mohan
Oct 9, 2004·Physics in Medicine and Biology·P TangboonduangjitA Rosenfeld
Oct 19, 2006·Physics in Medicine and Biology·Philip VialClive Baldock
Oct 24, 2007·Physics in Medicine and Biology·N HardcastleM J Williams
Jan 21, 2006·Physics in Medicine and Biology·James C L ChowRunqing Jiang
Feb 10, 2006·Physics in Medicine and Biology·M J Williams, P Metcalfe
Nov 28, 2015·Physics in Medicine and Biology·Juan Diego AzconaJavier Burguete
Sep 30, 2015·Physics in Medicine and Biology·Zhen TianXun Jia
Dec 9, 2016·Journal of Applied Clinical Medical Physics·Benjamin J ZwanChristopher Lee
Jul 18, 2002·Physics in Medicine and Biology·M Saiful HuqJames M Galvin
Feb 19, 2002·Physics in Medicine and Biology·E Spezi, D G Lewis
Dec 25, 2015·Journal of Applied Clinical Medical Physics·Shifeng ChenWarren D D'Souza
Dec 9, 2016·Journal of Applied Clinical Medical Physics·Lori A YoungJuergen Meyer
Dec 15, 2020·Medical Physics·Victor Gabriel Leandro AlvesJeffrey Vincent Siebers

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