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Determination of field size‐dependent wedge factors from a few selected measurements

Some modern treatment‐planning systems (TPSs) provide for input of wedge factor (WF) tables covering the entire range of square and elongated fields available on the LINAC. Depending on the field size increment chosen and the number of available wedge orientations, one may have to take more than 100...

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Autores principales: Popple, Richard A., Brezovich, Ivan A., Duan, Jun, Shen, Sui, Pareek, Prem N., Ye, Sung‐Joon
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2005
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5723504/
https://www.ncbi.nlm.nih.gov/pubmed/15770196
http://dx.doi.org/10.1120/jacmp.v6i1.2063
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author Popple, Richard A.
Brezovich, Ivan A.
Duan, Jun
Shen, Sui
Pareek, Prem N.
Ye, Sung‐Joon
author_facet Popple, Richard A.
Brezovich, Ivan A.
Duan, Jun
Shen, Sui
Pareek, Prem N.
Ye, Sung‐Joon
author_sort Popple, Richard A.
collection PubMed
description Some modern treatment‐planning systems (TPSs) provide for input of wedge factor (WF) tables covering the entire range of square and elongated fields available on the LINAC. Depending on the field size increment chosen and the number of available wedge orientations, one may have to take more than 100 measurements per wedge and photon energy to commission the TPS. To expedite TPS commissioning while maintaining high accuracy, we demonstrate a simple method that requires only a few measurements per wedge, from which the remaining wedge factors can be found through linear interpolation based on field area. For the externally mounted wedges of two common LINACs, we have shown that WFs are proportional to field area and are nearly independent of field elongation and wedge orientation. Wedge factors computed from five to seven measurements comprised of square fields and a single, large rectangular field agreed with direct measurements throughout the entire range of achievable field dimensions within 0.6% at 6 MV and within 1% at 15 MV. Making the same set of measurements and using the equivalent square method to find WFs at other field sizes leads to errors up to 2%. Measuring the WF for a [Formula: see text] field and applying the same value to all field sizes can lead to errors of up to 10% at both 6 MV and 15 MV. PACS numbers: 87.53.Bn, 87.53.Mr
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spelling pubmed-57235042018-04-02 Determination of field size‐dependent wedge factors from a few selected measurements Popple, Richard A. Brezovich, Ivan A. Duan, Jun Shen, Sui Pareek, Prem N. Ye, Sung‐Joon J Appl Clin Med Phys Radiation Oncology Physics Some modern treatment‐planning systems (TPSs) provide for input of wedge factor (WF) tables covering the entire range of square and elongated fields available on the LINAC. Depending on the field size increment chosen and the number of available wedge orientations, one may have to take more than 100 measurements per wedge and photon energy to commission the TPS. To expedite TPS commissioning while maintaining high accuracy, we demonstrate a simple method that requires only a few measurements per wedge, from which the remaining wedge factors can be found through linear interpolation based on field area. For the externally mounted wedges of two common LINACs, we have shown that WFs are proportional to field area and are nearly independent of field elongation and wedge orientation. Wedge factors computed from five to seven measurements comprised of square fields and a single, large rectangular field agreed with direct measurements throughout the entire range of achievable field dimensions within 0.6% at 6 MV and within 1% at 15 MV. Making the same set of measurements and using the equivalent square method to find WFs at other field sizes leads to errors up to 2%. Measuring the WF for a [Formula: see text] field and applying the same value to all field sizes can lead to errors of up to 10% at both 6 MV and 15 MV. PACS numbers: 87.53.Bn, 87.53.Mr John Wiley and Sons Inc. 2005-03-17 /pmc/articles/PMC5723504/ /pubmed/15770196 http://dx.doi.org/10.1120/jacmp.v6i1.2063 Text en © 2005 The Authors. This is an open access article under the terms of the Creative Commons Attribution (http://creativecommons.org/licenses/by/3.0/) License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Radiation Oncology Physics
Popple, Richard A.
Brezovich, Ivan A.
Duan, Jun
Shen, Sui
Pareek, Prem N.
Ye, Sung‐Joon
Determination of field size‐dependent wedge factors from a few selected measurements
title Determination of field size‐dependent wedge factors from a few selected measurements
title_full Determination of field size‐dependent wedge factors from a few selected measurements
title_fullStr Determination of field size‐dependent wedge factors from a few selected measurements
title_full_unstemmed Determination of field size‐dependent wedge factors from a few selected measurements
title_short Determination of field size‐dependent wedge factors from a few selected measurements
title_sort determination of field size‐dependent wedge factors from a few selected measurements
topic Radiation Oncology Physics
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5723504/
https://www.ncbi.nlm.nih.gov/pubmed/15770196
http://dx.doi.org/10.1120/jacmp.v6i1.2063
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