Practical implementation of compensators in breast radiotherapy
Identifieur interne : 004B21 ( Istex/Corpus ); précédent : 004B20; suivant : 004B22Practical implementation of compensators in breast radiotherapy
Auteurs : Philip M. Evans ; Ellen M. Donovan ; Natalie Fenton ; Vibeke N. Hansen ; Ian Moore ; Michael Partridge ; Stephanie Reise ; Bridget Suter ; J. Richard N. Symonds-Tayler ; John R. YarnoldSource :
- Radiotherapy and Oncology [ 0167-8140 ] ; 1999.
English descriptors
Abstract
Background and purpose: A method of using electronic portal imaging to design compensators for tangential breast irradiation has been developed. We describe how this has been implemented. Materials and methods: The compensator design method generates wedged and unwedged beam weights, in conjunction with templates for multiple lead-sheet compensators and pseudo-CT outlines. The latter describe the breast and lung profiles in a set of transverse slices. The layers of the compensator and pseudo-CT outlines are transferred to a treatment planning system for verification. The accuracy of the planning system for the high transmission blocks used to describe the compensators has been verified using a plotting tank system. Dose volume histogram data and transaxial and sagittal plan slices have been compared for both standard and compensated treatments for a sample set of five patients. Results: The planning system predicted the dose at depths of 1.5 and 5 cm to within 2% for the compensators tested. The biggest source of discrepancy was a consequence of the planning system requiring blocks to have integer percentage transmission. For all patients studied, the compensated treatment resulted in a significant reduction in the percentage volume outside the 95–105% dose, with an average reduction of 10.2%. The percentage volume outside the 95–107% dose was also reduced by typically 3.4%. The implementation was found to yield a convenient automatic method of designing compensators using electronic portal imaging and verifying the results using a planning system. Conclusions: These results indicate that this method of implementation can be used in practice. The dosimetric accuracy of the treatment planning system is limited by the requirement that blocks should be of integer transmission, but this effect is small.
Url:
DOI: 10.1016/S0167-8140(98)00126-1
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ISTEX:9FCB893C27D9B341D94CED4B9799F6BF7C60C968Le document en format XML
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Donovan</name><affiliation><mods:affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</mods:affiliation></affiliation></author><author><name sortKey="Fenton, Natalie" sort="Fenton, Natalie" uniqKey="Fenton N" first="Natalie" last="Fenton">Natalie Fenton</name><affiliation><mods:affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</mods:affiliation></affiliation></author><author><name sortKey="Hansen, Vibeke N" sort="Hansen, Vibeke N" uniqKey="Hansen V" first="Vibeke N." last="Hansen">Vibeke N. Hansen</name><affiliation><mods:affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</mods:affiliation></affiliation></author><author><name sortKey="Moore, Ian" sort="Moore, Ian" uniqKey="Moore I" first="Ian" last="Moore">Ian Moore</name><affiliation><mods:affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</mods:affiliation></affiliation></author><author><name sortKey="Partridge, Michael" sort="Partridge, Michael" uniqKey="Partridge M" first="Michael" last="Partridge">Michael Partridge</name><affiliation><mods:affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</mods:affiliation></affiliation></author><author><name sortKey="Reise, Stephanie" sort="Reise, Stephanie" uniqKey="Reise S" first="Stephanie" last="Reise">Stephanie Reise</name><affiliation><mods:affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</mods:affiliation></affiliation></author><author><name sortKey="Suter, Bridget" sort="Suter, Bridget" uniqKey="Suter B" first="Bridget" last="Suter">Bridget Suter</name><affiliation><mods:affiliation>Department of Radiotherapy, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</mods:affiliation></affiliation></author><author><name sortKey="Symonds Tayler, J Richard N" sort="Symonds Tayler, J Richard N" uniqKey="Symonds Tayler J" first="J. 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Evans</name><affiliation><mods:affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</mods:affiliation></affiliation></author><author><name sortKey="Donovan, Ellen M" sort="Donovan, Ellen M" uniqKey="Donovan E" first="Ellen M." last="Donovan">Ellen M. Donovan</name><affiliation><mods:affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</mods:affiliation></affiliation></author><author><name sortKey="Fenton, Natalie" sort="Fenton, Natalie" uniqKey="Fenton N" first="Natalie" last="Fenton">Natalie Fenton</name><affiliation><mods:affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</mods:affiliation></affiliation></author><author><name sortKey="Hansen, Vibeke N" sort="Hansen, Vibeke N" uniqKey="Hansen V" first="Vibeke N." last="Hansen">Vibeke N. Hansen</name><affiliation><mods:affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</mods:affiliation></affiliation></author><author><name sortKey="Moore, Ian" sort="Moore, Ian" uniqKey="Moore I" first="Ian" last="Moore">Ian Moore</name><affiliation><mods:affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</mods:affiliation></affiliation></author><author><name sortKey="Partridge, Michael" sort="Partridge, Michael" uniqKey="Partridge M" first="Michael" last="Partridge">Michael Partridge</name><affiliation><mods:affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</mods:affiliation></affiliation></author><author><name sortKey="Reise, Stephanie" sort="Reise, Stephanie" uniqKey="Reise S" first="Stephanie" last="Reise">Stephanie Reise</name><affiliation><mods:affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</mods:affiliation></affiliation></author><author><name sortKey="Suter, Bridget" sort="Suter, Bridget" uniqKey="Suter B" first="Bridget" last="Suter">Bridget Suter</name><affiliation><mods:affiliation>Department of Radiotherapy, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</mods:affiliation></affiliation></author><author><name sortKey="Symonds Tayler, J Richard N" sort="Symonds Tayler, J Richard N" uniqKey="Symonds Tayler J" first="J. Richard N." last="Symonds-Tayler">J. Richard N. Symonds-Tayler</name><affiliation><mods:affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</mods:affiliation></affiliation></author><author><name sortKey="Yarnold, John R" sort="Yarnold, John R" uniqKey="Yarnold J" first="John R." last="Yarnold">John R. Yarnold</name><affiliation><mods:affiliation>Department of Radiotherapy, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</mods:affiliation></affiliation></author></analytic><monogr></monogr><series><title level="j">Radiotherapy and Oncology</title><title level="j" type="abbrev">RADION</title><idno type="ISSN">0167-8140</idno><imprint><publisher>ELSEVIER</publisher><date type="published" when="1999">1999</date><biblScope unit="volume">49</biblScope><biblScope unit="issue">3</biblScope><biblScope unit="page" from="255">255</biblScope><biblScope unit="page" to="265">265</biblScope></imprint><idno type="ISSN">0167-8140</idno></series></biblStruct></sourceDesc><seriesStmt><idno type="ISSN">0167-8140</idno></seriesStmt></fileDesc><profileDesc><textClass><keywords scheme="KwdEn" xml:lang="en"><term>Breast cancer</term><term>Electronic portal imaging</term><term>Intensity modulated beams</term><term>Radiotherapy</term></keywords></textClass><langUsage><language ident="en">en</language></langUsage></profileDesc></teiHeader><front><div type="abstract" xml:lang="en">Background and purpose: A method of using electronic portal imaging to design compensators for tangential breast irradiation has been developed. We describe how this has been implemented. Materials and methods: The compensator design method generates wedged and unwedged beam weights, in conjunction with templates for multiple lead-sheet compensators and pseudo-CT outlines. The latter describe the breast and lung profiles in a set of transverse slices. The layers of the compensator and pseudo-CT outlines are transferred to a treatment planning system for verification. The accuracy of the planning system for the high transmission blocks used to describe the compensators has been verified using a plotting tank system. Dose volume histogram data and transaxial and sagittal plan slices have been compared for both standard and compensated treatments for a sample set of five patients. Results: The planning system predicted the dose at depths of 1.5 and 5 cm to within 2% for the compensators tested. The biggest source of discrepancy was a consequence of the planning system requiring blocks to have integer percentage transmission. For all patients studied, the compensated treatment resulted in a significant reduction in the percentage volume outside the 95–105% dose, with an average reduction of 10.2%. The percentage volume outside the 95–107% dose was also reduced by typically 3.4%. The implementation was found to yield a convenient automatic method of designing compensators using electronic portal imaging and verifying the results using a planning system. Conclusions: These results indicate that this method of implementation can be used in practice. The dosimetric accuracy of the treatment planning system is limited by the requirement that blocks should be of integer transmission, but this effect is small.</div></front></TEI><istex><corpusName>elsevier</corpusName><keywords><teeft><json:string>compensator</json:string><json:string>compensators</json:string><json:string>radiotherapy</json:string><json:string>unwedged</json:string><json:string>standard plan</json:string><json:string>phys</json:string><json:string>eld</json:string><json:string>attenuation</json:string><json:string>planning system</json:string><json:string>oncology</json:string><json:string>oncol</json:string><json:string>isocentre</json:string><json:string>radiother</json:string><json:string>tangential</json:string><json:string>medial</json:string><json:string>biol</json:string><json:string>treatment planning system</json:string><json:string>nipple</json:string><json:string>sagittal</json:string><json:string>dose distribution</json:string><json:string>unwedged beams</json:string><json:string>radiological thickness</json:string><json:string>tangential breast irradiation</json:string><json:string>chest wall</json:string><json:string>effective attenuation</json:string><json:string>lateral beams</json:string><json:string>electronic portal imaging</json:string><json:string>lateral</json:string><json:string>breast cancer</json:string><json:string>unwedged data</json:string><json:string>score grid</json:string><json:string>imaging</json:string><json:string>treatment position</json:string><json:string>electronic portal imaging device</json:string><json:string>cancer research</json:string><json:string>central slice</json:string><json:string>compensator layers</json:string><json:string>average reduction</json:string><json:string>standard treatment</json:string><json:string>standard outline</json:string><json:string>portal imaging</json:string><json:string>original plan</json:string><json:string>royal marsden</json:string><json:string>radiation therapy</json:string><json:string>unwedged value</json:string><json:string>high transmission blocks</json:string><json:string>target volume</json:string><json:string>dose range</json:string><json:string>portal</json:string><json:string>dose</json:string><json:string>wedge</json:string><json:string>breast</json:string><json:string>unwedged beam weights</json:string><json:string>manual outline</json:string><json:string>thickness values</json:string><json:string>beam weights</json:string><json:string>plan normalization</json:string><json:string>quality assurance</json:string><json:string>dose heterogeneity</json:string><json:string>elsevier science ireland</json:string><json:string>compensator designs</json:string><json:string>wedge parameters</json:string><json:string>dosimetric accuracy</json:string><json:string>percentage volume</json:string><json:string>biggest source</json:string><json:string>solid line</json:string><json:string>colosseum compensator</json:string><json:string>wedge direction</json:string><json:string>dose values</json:string><json:string>experimental measurements</json:string><json:string>breast treatments</json:string><json:string>standard technique</json:string><json:string>portal image</json:string><json:string>breast volume</json:string><json:string>small increase</json:string><json:string>sagittal slice</json:string><json:string>breast radiotherapy</json:string><json:string>previous paper</json:string><json:string>physical model</json:string><json:string>average dose</json:string><json:string>relative weights</json:string><json:string>standard beams</json:string><json:string>more uniform</json:string><json:string>intact breast</json:string><json:string>patient movement</json:string><json:string>original model</json:string><json:string>xref yref</json:string><json:string>compensator design method</json:string><json:string>unwedged beam</json:string><json:string>wedge angle</json:string><json:string>neighbouring points</json:string><json:string>design compensators</json:string><json:string>compensator design software</json:string><json:string>downs road</json:string><json:string>electronic portal images</json:string><json:string>premenopausal women</json:string><json:string>centre</json:string></teeft></keywords><author><json:item><name>Philip M. Evans</name><affiliations><json:string>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</json:string></affiliations></json:item><json:item><name>Ellen M. Donovan</name><affiliations><json:string>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</json:string></affiliations></json:item><json:item><name>Natalie Fenton</name><affiliations><json:string>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</json:string></affiliations></json:item><json:item><name>Vibeke N. Hansen</name><affiliations><json:string>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</json:string></affiliations></json:item><json:item><name>Ian Moore</name><affiliations><json:string>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</json:string></affiliations></json:item><json:item><name>Michael Partridge</name><affiliations><json:string>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</json:string></affiliations></json:item><json:item><name>Stephanie Reise</name><affiliations><json:string>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</json:string></affiliations></json:item><json:item><name>Bridget Suter</name><affiliations><json:string>Department of Radiotherapy, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</json:string></affiliations></json:item><json:item><name>J.Richard N. Symonds-Tayler</name><affiliations><json:string>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</json:string></affiliations></json:item><json:item><name>John R. Yarnold</name><affiliations><json:string>Department of Radiotherapy, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</json:string></affiliations></json:item></author><subject><json:item><lang><json:string>eng</json:string></lang><value>Radiotherapy</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>Breast cancer</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>Intensity modulated beams</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>Electronic portal imaging</value></json:item></subject><language><json:string>eng</json:string></language><originalGenre><json:string>Full-length article</json:string></originalGenre><abstract>Background and purpose: A method of using electronic portal imaging to design compensators for tangential breast irradiation has been developed. We describe how this has been implemented. Materials and methods: The compensator design method generates wedged and unwedged beam weights, in conjunction with templates for multiple lead-sheet compensators and pseudo-CT outlines. The latter describe the breast and lung profiles in a set of transverse slices. The layers of the compensator and pseudo-CT outlines are transferred to a treatment planning system for verification. The accuracy of the planning system for the high transmission blocks used to describe the compensators has been verified using a plotting tank system. Dose volume histogram data and transaxial and sagittal plan slices have been compared for both standard and compensated treatments for a sample set of five patients. Results: The planning system predicted the dose at depths of 1.5 and 5 cm to within 2% for the compensators tested. The biggest source of discrepancy was a consequence of the planning system requiring blocks to have integer percentage transmission. For all patients studied, the compensated treatment resulted in a significant reduction in the percentage volume outside the 95–105% dose, with an average reduction of 10.2%. The percentage volume outside the 95–107% dose was also reduced by typically 3.4%. The implementation was found to yield a convenient automatic method of designing compensators using electronic portal imaging and verifying the results using a planning system. Conclusions: These results indicate that this method of implementation can be used in practice. The dosimetric accuracy of the treatment planning system is limited by the requirement that blocks should be of integer transmission, but this effect is small.</abstract><qualityIndicators><score>8</score><pdfVersion>1.2</pdfVersion><pdfPageSize>612 x 792 pts (letter)</pdfPageSize><refBibsNative>true</refBibsNative><keywordCount>4</keywordCount><abstractCharCount>1830</abstractCharCount><pdfWordCount>6297</pdfWordCount><pdfCharCount>36479</pdfCharCount><pdfPageCount>11</pdfPageCount><abstractWordCount>275</abstractWordCount></qualityIndicators><title>Practical implementation of compensators in breast radiotherapy</title><pii><json:string>S0167-8140(98)00126-1</json:string></pii><genre><json:string>research-article</json:string></genre><host><title>Radiotherapy and Oncology</title><language><json:string>unknown</json:string></language><publicationDate>1998</publicationDate><issn><json:string>0167-8140</json:string></issn><pii><json:string>S0167-8140(00)X0047-3</json:string></pii><volume>49</volume><issue>3</issue><pages><first>255</first><last>265</last></pages><genre><json:string>journal</json:string></genre></host><categories><wos><json:string>science</json:string><json:string>radiology, nuclear medicine & medical imaging</json:string><json:string>oncology</json:string></wos><scienceMetrix><json:string>health sciences</json:string><json:string>clinical medicine</json:string><json:string>oncology & carcinogenesis</json:string></scienceMetrix><inist><json:string>sciences appliquees, technologies et medecines</json:string><json:string>sciences biologiques et medicales</json:string><json:string>sciences medicales</json:string></inist></categories><publicationDate>1999</publicationDate><copyrightDate>1999</copyrightDate><doi><json:string>10.1016/S0167-8140(98)00126-1</json:string></doi><id>9FCB893C27D9B341D94CED4B9799F6BF7C60C968</id><score>1</score><fulltext><json:item><extension>pdf</extension><original>true</original><mimetype>application/pdf</mimetype><uri>https://api.istex.fr/document/9FCB893C27D9B341D94CED4B9799F6BF7C60C968/fulltext/pdf</uri></json:item><json:item><extension>zip</extension><original>false</original><mimetype>application/zip</mimetype><uri>https://api.istex.fr/document/9FCB893C27D9B341D94CED4B9799F6BF7C60C968/fulltext/zip</uri></json:item><istex:fulltextTEI uri="https://api.istex.fr/document/9FCB893C27D9B341D94CED4B9799F6BF7C60C968/fulltext/tei"><teiHeader><fileDesc><titleStmt><title level="a" type="main" xml:lang="en">Practical implementation of compensators in breast radiotherapy</title></titleStmt><publicationStmt><authority>ISTEX</authority><publisher>ELSEVIER</publisher><availability><p>©1999 Elsevier Science Ireland Ltd</p></availability><date>1999</date></publicationStmt><notesStmt><note type="content">Fig. 1: Compensator for left lateral irradiation. The thick lines are the sagittal breast outline and the sagittal lung edge. The thinner lines are the compensator layers. The numbers indicate the number of compensation layers.</note><note type="content">Fig. 2: Results from plotting tank measurements and Target II calculations for staircase compensator. (a) Profiles across the staircase. (b) The calculated value subtracted from the measured value (dashed line). The solid line labelled 0–5 shows the systematic rounding error in each layer of the compensator as a function of position.</note><note type="content">Fig. 3: Profiles across the colosseum compensator from measurements and Target II calculations. The thickness of the compensator in terms of the number of lead sheets is also shown. Data are shown for 1.5 and 5 cm depth.</note><note type="content">Fig. 4: Differences between Target II calculations and measurements for colosseum compensator in the direction of the wedge at a depth of 5 cm. A positive value indicates that the measurement is higher than the calculation and vice versa. (a) The results for the unwedged data. (b) The wedged data. (c) A weighted combination of the wedged and unwedged data in the ratio of 1:3.</note><note type="content">Fig. 5: Transaxial plans for the manually taken central outline. (a) Standard plan. (b) Compensated plan. The relative weights of the medial and lateral beams are taken from the standard plan. The wedged percentages for the standard beams are taken from the standard plan, whereas those for compensated beams are determined using the method presented in Section 2.3.</note><note type="content">Fig. 6: Sagittal plans for the EPID-generated outlines. (a) Standard plan. (b) Compensated plan. The relative weights of the medial and lateral beams are set equal. The wedged percentages for the standard beams are taken from the standard plan, whereas those for compensated beams are determined using the method presented in Section 2.3. The dashed line indicates the lung boundary.</note><note type="content">Fig. 7: Example dose volume histograms for wedged and compensated plans.</note><note type="content">Fig. 8: Flow diagram showing the stages in the compensator design process. IMB denotes intensity modulated beam. Boxes shown in bold indicate a part of the process that differs from the original model.</note><note type="content">Fig. 9: Illustration of the method used to determine edges of blocks. The 4×4 array of 1s and 0s is a binary map indicating whether an image pixel is inside (1) or outside (0) the lead sheet. The score grid is constructed between these points (circles with values between 0 and 15). The thick line joining score grid values of 4, 11, 13 etc. is the block edge.</note><note type="content">Table 1: Dose volume statistics for five patientsa</note></notesStmt><sourceDesc><biblStruct type="inbook"><analytic><title level="a" type="main" xml:lang="en">Practical implementation of compensators in breast radiotherapy</title><author xml:id="author-0000"><persName><forename type="first">Philip M.</forename><surname>Evans</surname></persName><note type="correspondence"><p>Corresponding author</p></note><affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</affiliation></author><author xml:id="author-0001"><persName><forename type="first">Ellen M.</forename><surname>Donovan</surname></persName><affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</affiliation></author><author xml:id="author-0002"><persName><forename type="first">Natalie</forename><surname>Fenton</surname></persName><affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</affiliation></author><author xml:id="author-0003"><persName><forename type="first">Vibeke N.</forename><surname>Hansen</surname></persName><affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</affiliation></author><author xml:id="author-0004"><persName><forename type="first">Ian</forename><surname>Moore</surname></persName><affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</affiliation></author><author xml:id="author-0005"><persName><forename type="first">Michael</forename><surname>Partridge</surname></persName><affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</affiliation></author><author xml:id="author-0006"><persName><forename type="first">Stephanie</forename><surname>Reise</surname></persName><affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</affiliation></author><author xml:id="author-0007"><persName><forename type="first">Bridget</forename><surname>Suter</surname></persName><affiliation>Department of Radiotherapy, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</affiliation></author><author xml:id="author-0008"><persName><forename type="first">J.Richard N.</forename><surname>Symonds-Tayler</surname></persName><affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</affiliation></author><author xml:id="author-0009"><persName><forename type="first">John R.</forename><surname>Yarnold</surname></persName><affiliation>Department of Radiotherapy, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</affiliation></author><idno type="istex">9FCB893C27D9B341D94CED4B9799F6BF7C60C968</idno><idno type="DOI">10.1016/S0167-8140(98)00126-1</idno><idno type="PII">S0167-8140(98)00126-1</idno></analytic><monogr><title level="j">Radiotherapy and Oncology</title><title level="j" type="abbrev">RADION</title><idno type="pISSN">0167-8140</idno><idno type="PII">S0167-8140(00)X0047-3</idno><imprint><publisher>ELSEVIER</publisher><date type="published" when="1999"></date><biblScope unit="volume">49</biblScope><biblScope unit="issue">3</biblScope><biblScope unit="page" from="255">255</biblScope><biblScope unit="page" to="265">265</biblScope></imprint></monogr></biblStruct></sourceDesc></fileDesc><profileDesc><creation><date>1999</date></creation><langUsage><language ident="en">en</language></langUsage><abstract xml:lang="en"><p>Background and purpose: A method of using electronic portal imaging to design compensators for tangential breast irradiation has been developed. We describe how this has been implemented. Materials and methods: The compensator design method generates wedged and unwedged beam weights, in conjunction with templates for multiple lead-sheet compensators and pseudo-CT outlines. The latter describe the breast and lung profiles in a set of transverse slices. The layers of the compensator and pseudo-CT outlines are transferred to a treatment planning system for verification. The accuracy of the planning system for the high transmission blocks used to describe the compensators has been verified using a plotting tank system. Dose volume histogram data and transaxial and sagittal plan slices have been compared for both standard and compensated treatments for a sample set of five patients. Results: The planning system predicted the dose at depths of 1.5 and 5 cm to within 2% for the compensators tested. The biggest source of discrepancy was a consequence of the planning system requiring blocks to have integer percentage transmission. For all patients studied, the compensated treatment resulted in a significant reduction in the percentage volume outside the 95–105% dose, with an average reduction of 10.2%. The percentage volume outside the 95–107% dose was also reduced by typically 3.4%. The implementation was found to yield a convenient automatic method of designing compensators using electronic portal imaging and verifying the results using a planning system. Conclusions: These results indicate that this method of implementation can be used in practice. The dosimetric accuracy of the treatment planning system is limited by the requirement that blocks should be of integer transmission, but this effect is small.</p></abstract><textClass xml:lang="en"><keywords scheme="keyword"><list><head>Keywords</head><item><term>Radiotherapy</term></item><item><term>Breast cancer</term></item><item><term>Intensity modulated beams</term></item><item><term>Electronic portal imaging</term></item></list></keywords></textClass></profileDesc><revisionDesc><change when="1998-09-16">Modified</change><change when="1999">Published</change></revisionDesc></teiHeader></istex:fulltextTEI><json:item><extension>txt</extension><original>false</original><mimetype>text/plain</mimetype><uri>https://api.istex.fr/document/9FCB893C27D9B341D94CED4B9799F6BF7C60C968/fulltext/txt</uri></json:item></fulltext><metadata><istex:metadataXml wicri:clean="Elsevier, elements deleted: ce:floats; body; tail"><istex:xmlDeclaration>version="1.0" encoding="utf-8"</istex:xmlDeclaration><istex:docType PUBLIC="-//ES//DTD journal article DTD version 4.5.2//EN//XML" URI="art452.dtd" name="istex:docType"><istex:entity SYSTEM="gr1" NDATA="IMAGE" name="gr1"></istex:entity><istex:entity SYSTEM="gr2" NDATA="IMAGE" name="gr2"></istex:entity><istex:entity SYSTEM="gr3" NDATA="IMAGE" name="gr3"></istex:entity><istex:entity SYSTEM="gr4" NDATA="IMAGE" name="gr4"></istex:entity><istex:entity SYSTEM="gr5" NDATA="IMAGE" name="gr5"></istex:entity><istex:entity SYSTEM="gr6" NDATA="IMAGE" name="gr6"></istex:entity><istex:entity SYSTEM="gr7" NDATA="IMAGE" name="gr7"></istex:entity><istex:entity SYSTEM="gr8" NDATA="IMAGE" name="gr8"></istex:entity><istex:entity SYSTEM="gr9" NDATA="IMAGE" name="gr9"></istex:entity></istex:docType><istex:document><converted-article version="4.5.2" docsubtype="fla" xml:lang="en"><item-info><jid>RADION</jid><aid>2252</aid><ce:pii>S0167-8140(98)00126-1</ce:pii><ce:doi>10.1016/S0167-8140(98)00126-1</ce:doi><ce:copyright type="full-transfer" year="1999">Elsevier Science Ireland Ltd</ce:copyright></item-info><head><ce:title>Practical implementation of compensators in breast radiotherapy</ce:title><ce:author-group><ce:author><ce:given-name>Philip M.</ce:given-name><ce:surname>Evans</ce:surname><ce:cross-ref refid="AFF1"><ce:sup>a</ce:sup></ce:cross-ref><ce:cross-ref refid="CORR1">*</ce:cross-ref></ce:author><ce:author><ce:given-name>Ellen M.</ce:given-name><ce:surname>Donovan</ce:surname><ce:cross-ref refid="AFF1"><ce:sup>a</ce:sup></ce:cross-ref></ce:author><ce:author><ce:given-name>Natalie</ce:given-name><ce:surname>Fenton</ce:surname><ce:cross-ref refid="AFF1"><ce:sup>a</ce:sup></ce:cross-ref></ce:author><ce:author><ce:given-name>Vibeke N.</ce:given-name><ce:surname>Hansen</ce:surname><ce:cross-ref refid="AFF1"><ce:sup>a</ce:sup></ce:cross-ref></ce:author><ce:author><ce:given-name>Ian</ce:given-name><ce:surname>Moore</ce:surname><ce:cross-ref refid="AFF1"><ce:sup>a</ce:sup></ce:cross-ref></ce:author><ce:author><ce:given-name>Michael</ce:given-name><ce:surname>Partridge</ce:surname><ce:cross-ref refid="AFF1"><ce:sup>a</ce:sup></ce:cross-ref></ce:author><ce:author><ce:given-name>Stephanie</ce:given-name><ce:surname>Reise</ce:surname><ce:cross-ref refid="AFF1"><ce:sup>a</ce:sup></ce:cross-ref></ce:author><ce:author><ce:given-name>Bridget</ce:given-name><ce:surname>Suter</ce:surname><ce:cross-ref refid="AFF2"><ce:sup>b</ce:sup></ce:cross-ref></ce:author><ce:author><ce:given-name>J.Richard N.</ce:given-name><ce:surname>Symonds-Tayler</ce:surname><ce:cross-ref refid="AFF1"><ce:sup>a</ce:sup></ce:cross-ref></ce:author><ce:author><ce:given-name>John R.</ce:given-name><ce:surname>Yarnold</ce:surname><ce:cross-ref refid="AFF2"><ce:sup>b</ce:sup></ce:cross-ref></ce:author><ce:affiliation id="AFF1"><ce:label>a</ce:label><ce:textfn>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</ce:textfn></ce:affiliation><ce:affiliation id="AFF2"><ce:label>b</ce:label><ce:textfn>Department of Radiotherapy, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</ce:textfn></ce:affiliation><ce:correspondence id="CORR1"><ce:label>*</ce:label><ce:text>Corresponding author</ce:text></ce:correspondence></ce:author-group><ce:date-received day="8" month="6" year="1998"></ce:date-received><ce:date-revised day="16" month="9" year="1998"></ce:date-revised><ce:date-accepted day="5" month="10" year="1998"></ce:date-accepted><ce:abstract><ce:section-title>Abstract</ce:section-title><ce:abstract-sec><ce:simple-para><ce:italic>Background and purpose</ce:italic>: A method of using electronic portal imaging to design compensators for tangential breast irradiation has been developed. We describe how this has been implemented.</ce:simple-para><ce:simple-para><ce:italic>Materials and methods</ce:italic>: The compensator design method generates wedged and unwedged beam weights, in conjunction with templates for multiple lead-sheet compensators and pseudo-CT outlines. The latter describe the breast and lung profiles in a set of transverse slices. The layers of the compensator and pseudo-CT outlines are transferred to a treatment planning system for verification. The accuracy of the planning system for the high transmission blocks used to describe the compensators has been verified using a plotting tank system. Dose volume histogram data and transaxial and sagittal plan slices have been compared for both standard and compensated treatments for a sample set of five patients.</ce:simple-para><ce:simple-para><ce:italic>Results</ce:italic>: The planning system predicted the dose at depths of 1.5 and 5 cm to within 2% for the compensators tested. The biggest source of discrepancy was a consequence of the planning system requiring blocks to have integer percentage transmission. For all patients studied, the compensated treatment resulted in a significant reduction in the percentage volume outside the 95–105% dose, with an average reduction of 10.2%. The percentage volume outside the 95–107% dose was also reduced by typically 3.4%. The implementation was found to yield a convenient automatic method of designing compensators using electronic portal imaging and verifying the results using a planning system.</ce:simple-para><ce:simple-para><ce:italic>Conclusions</ce:italic>: These results indicate that this method of implementation can be used in practice. The dosimetric accuracy of the treatment planning system is limited by the requirement that blocks should be of integer transmission, but this effect is small.</ce:simple-para></ce:abstract-sec></ce:abstract><ce:keywords class="keyword"><ce:section-title>Keywords</ce:section-title><ce:keyword><ce:text>Radiotherapy</ce:text></ce:keyword><ce:keyword><ce:text>Breast cancer</ce:text></ce:keyword><ce:keyword><ce:text>Intensity modulated beams</ce:text></ce:keyword><ce:keyword><ce:text>Electronic portal imaging</ce:text></ce:keyword></ce:keywords></head></converted-article></istex:document></istex:metadataXml><mods version="3.6"><titleInfo lang="en"><title>Practical implementation of compensators in breast radiotherapy</title></titleInfo><titleInfo type="alternative" lang="en" contentType="CDATA"><title>Practical implementation of compensators in breast radiotherapy</title></titleInfo><name type="personal"><namePart type="given">Philip M.</namePart><namePart type="family">Evans</namePart><affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</affiliation><description>Corresponding author</description><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">Ellen M.</namePart><namePart type="family">Donovan</namePart><affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">Natalie</namePart><namePart type="family">Fenton</namePart><affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">Vibeke N.</namePart><namePart type="family">Hansen</namePart><affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">Ian</namePart><namePart type="family">Moore</namePart><affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">Michael</namePart><namePart type="family">Partridge</namePart><affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">Stephanie</namePart><namePart type="family">Reise</namePart><affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">Bridget</namePart><namePart type="family">Suter</namePart><affiliation>Department of Radiotherapy, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">J.Richard N.</namePart><namePart type="family">Symonds-Tayler</namePart><affiliation>Joint Department of Physics, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">John R.</namePart><namePart type="family">Yarnold</namePart><affiliation>Department of Radiotherapy, Institute of Cancer Research and Royal Marsden NHS Trust, Downs Road, Sutton, Surrey, SM2 5PT, UK</affiliation><role><roleTerm type="text">author</roleTerm></role></name><typeOfResource>text</typeOfResource><genre type="research-article" displayLabel="Full-length article"></genre><originInfo><publisher>ELSEVIER</publisher><dateIssued encoding="w3cdtf">1999</dateIssued><dateModified encoding="w3cdtf">1998-09-16</dateModified><copyrightDate encoding="w3cdtf">1999</copyrightDate></originInfo><language><languageTerm type="code" authority="iso639-2b">eng</languageTerm><languageTerm type="code" authority="rfc3066">en</languageTerm></language><physicalDescription><internetMediaType>text/html</internetMediaType></physicalDescription><abstract lang="en">Background and purpose: A method of using electronic portal imaging to design compensators for tangential breast irradiation has been developed. We describe how this has been implemented. Materials and methods: The compensator design method generates wedged and unwedged beam weights, in conjunction with templates for multiple lead-sheet compensators and pseudo-CT outlines. The latter describe the breast and lung profiles in a set of transverse slices. The layers of the compensator and pseudo-CT outlines are transferred to a treatment planning system for verification. The accuracy of the planning system for the high transmission blocks used to describe the compensators has been verified using a plotting tank system. Dose volume histogram data and transaxial and sagittal plan slices have been compared for both standard and compensated treatments for a sample set of five patients. Results: The planning system predicted the dose at depths of 1.5 and 5 cm to within 2% for the compensators tested. The biggest source of discrepancy was a consequence of the planning system requiring blocks to have integer percentage transmission. For all patients studied, the compensated treatment resulted in a significant reduction in the percentage volume outside the 95–105% dose, with an average reduction of 10.2%. The percentage volume outside the 95–107% dose was also reduced by typically 3.4%. The implementation was found to yield a convenient automatic method of designing compensators using electronic portal imaging and verifying the results using a planning system. Conclusions: These results indicate that this method of implementation can be used in practice. The dosimetric accuracy of the treatment planning system is limited by the requirement that blocks should be of integer transmission, but this effect is small.</abstract><note type="content">Fig. 1: Compensator for left lateral irradiation. The thick lines are the sagittal breast outline and the sagittal lung edge. The thinner lines are the compensator layers. The numbers indicate the number of compensation layers.</note><note type="content">Fig. 2: Results from plotting tank measurements and Target II calculations for staircase compensator. (a) Profiles across the staircase. (b) The calculated value subtracted from the measured value (dashed line). The solid line labelled 0–5 shows the systematic rounding error in each layer of the compensator as a function of position.</note><note type="content">Fig. 3: Profiles across the colosseum compensator from measurements and Target II calculations. The thickness of the compensator in terms of the number of lead sheets is also shown. Data are shown for 1.5 and 5 cm depth.</note><note type="content">Fig. 4: Differences between Target II calculations and measurements for colosseum compensator in the direction of the wedge at a depth of 5 cm. A positive value indicates that the measurement is higher than the calculation and vice versa. (a) The results for the unwedged data. (b) The wedged data. (c) A weighted combination of the wedged and unwedged data in the ratio of 1:3.</note><note type="content">Fig. 5: Transaxial plans for the manually taken central outline. (a) Standard plan. (b) Compensated plan. The relative weights of the medial and lateral beams are taken from the standard plan. The wedged percentages for the standard beams are taken from the standard plan, whereas those for compensated beams are determined using the method presented in Section 2.3.</note><note type="content">Fig. 6: Sagittal plans for the EPID-generated outlines. (a) Standard plan. (b) Compensated plan. The relative weights of the medial and lateral beams are set equal. The wedged percentages for the standard beams are taken from the standard plan, whereas those for compensated beams are determined using the method presented in Section 2.3. The dashed line indicates the lung boundary.</note><note type="content">Fig. 7: Example dose volume histograms for wedged and compensated plans.</note><note type="content">Fig. 8: Flow diagram showing the stages in the compensator design process. IMB denotes intensity modulated beam. Boxes shown in bold indicate a part of the process that differs from the original model.</note><note type="content">Fig. 9: Illustration of the method used to determine edges of blocks. The 4×4 array of 1s and 0s is a binary map indicating whether an image pixel is inside (1) or outside (0) the lead sheet. The score grid is constructed between these points (circles with values between 0 and 15). The thick line joining score grid values of 4, 11, 13 etc. is the block edge.</note><note type="content">Table 1: Dose volume statistics for five patientsa</note><subject lang="en"><genre>Keywords</genre><topic>Radiotherapy</topic><topic>Breast cancer</topic><topic>Intensity modulated beams</topic><topic>Electronic portal imaging</topic></subject><relatedItem type="host"><titleInfo><title>Radiotherapy and Oncology</title></titleInfo><titleInfo type="abbreviated"><title>RADION</title></titleInfo><genre type="journal">journal</genre><originInfo><dateIssued encoding="w3cdtf">19981201</dateIssued></originInfo><identifier type="ISSN">0167-8140</identifier><identifier type="PII">S0167-8140(00)X0047-3</identifier><part><date>19981201</date><detail type="volume"><number>49</number><caption>vol.</caption></detail><detail type="issue"><number>3</number><caption>no.</caption></detail><extent unit="issue pages"><start>205</start><end>356</end></extent><extent unit="pages"><start>255</start><end>265</end></extent></part></relatedItem><identifier type="istex">9FCB893C27D9B341D94CED4B9799F6BF7C60C968</identifier><identifier type="DOI">10.1016/S0167-8140(98)00126-1</identifier><identifier type="PII">S0167-8140(98)00126-1</identifier><accessCondition type="use and reproduction" contentType="copyright">©1999 Elsevier Science Ireland Ltd</accessCondition><recordInfo><recordContentSource>ELSEVIER</recordContentSource><recordOrigin>Elsevier Science Ireland Ltd, ©1999</recordOrigin></recordInfo></mods></metadata><serie></serie></istex></record>Pour manipuler ce document sous Unix (Dilib)
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