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A novel and clinically useful dynamic conformal arc (DCA)‐based VMAT planning technique for lung SBRT
PURPOSE: Volumetric modulated arc therapy (VMAT) is gaining popularity for stereotactic treatment of lung lesions for medically inoperable patients. Due to multiple beamlets in delivery of highly modulated VMAT plans, there are dose delivery uncertainties associated with small‐field dosimetry error...
Autores principales: | , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
John Wiley and Sons Inc.
2020
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7386176/ https://www.ncbi.nlm.nih.gov/pubmed/32306530 http://dx.doi.org/10.1002/acm2.12878 |
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author | Pokhrel, Damodar Visak, Justin Sanford, Lana |
author_facet | Pokhrel, Damodar Visak, Justin Sanford, Lana |
author_sort | Pokhrel, Damodar |
collection | PubMed |
description | PURPOSE: Volumetric modulated arc therapy (VMAT) is gaining popularity for stereotactic treatment of lung lesions for medically inoperable patients. Due to multiple beamlets in delivery of highly modulated VMAT plans, there are dose delivery uncertainties associated with small‐field dosimetry error and interplay effects with small lesions. We describe and compare a clinically useful dynamic conformal arc (DCA)‐based VMAT (d‐VMAT) technique for lung SBRT using flattening filter free (FFF) beams to minimize these effects. MATERIALS AND METHODS: Ten solitary early‐stage I‐II non‐small‐cell lung cancer (NSCLC) patients were treated with a single dose of 30 Gy using 3–6 non‐coplanar VMAT arcs (clinical VMAT) with 6X‐FFF beams in our clinic. These clinically treated plans were re‐optimized using a novel d‐VMAT planning technique. For comparison, d‐VMAT plans were recalculated using DCA with user‐controlled field aperture shape before VMAT optimization. Identical beam geometry, dose calculation algorithm, grid size, and planning objectives were used. The clinical VMAT and d‐VMAT plans were compared via RTOG‐0915 protocol compliances for conformity, gradient indices, and dose to organs at risk (OAR). Additionally, treatment delivery efficiency and accuracy were recorded. RESULTS: All plans met RTOG‐0915 requirements. Comparing with clinical VMAT, d‐VMAT plans gave similar target coverage with better target conformity, tighter radiosurgical dose distribution with lower gradient indices, and dose to OAR. Lower total number of monitor units and small beam modulation factor reduced beam‐on time by 1.75 min (P < 0.001), on average (maximum up to 2.52 min). Beam delivery accuracy was improved by 2%, on average (P < 0.05) and maximum up to 6% in some cases for d‐VMAT plans. CONCLUSION: This simple d‐VMAT technique provided excellent plan quality, reduced intermediate dose‐spillage, and dose to OAR while providing faster treatment delivery by significantly reducing beam‐on time. This novel treatment planning approach will improve patient compliance along with potentially reducing intrafraction motion error. Moreover, with less MLC modulation through the target, d‐VMAT could potentially minimize small‐field dosimetry errors and MLC interplay effects. If available, d‐VMAT planning approach is recommended for future clinical lung SBRT plan optimization. |
format | Online Article Text |
id | pubmed-7386176 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2020 |
publisher | John Wiley and Sons Inc. |
record_format | MEDLINE/PubMed |
spelling | pubmed-73861762020-07-30 A novel and clinically useful dynamic conformal arc (DCA)‐based VMAT planning technique for lung SBRT Pokhrel, Damodar Visak, Justin Sanford, Lana J Appl Clin Med Phys Radiation Oncology Physics PURPOSE: Volumetric modulated arc therapy (VMAT) is gaining popularity for stereotactic treatment of lung lesions for medically inoperable patients. Due to multiple beamlets in delivery of highly modulated VMAT plans, there are dose delivery uncertainties associated with small‐field dosimetry error and interplay effects with small lesions. We describe and compare a clinically useful dynamic conformal arc (DCA)‐based VMAT (d‐VMAT) technique for lung SBRT using flattening filter free (FFF) beams to minimize these effects. MATERIALS AND METHODS: Ten solitary early‐stage I‐II non‐small‐cell lung cancer (NSCLC) patients were treated with a single dose of 30 Gy using 3–6 non‐coplanar VMAT arcs (clinical VMAT) with 6X‐FFF beams in our clinic. These clinically treated plans were re‐optimized using a novel d‐VMAT planning technique. For comparison, d‐VMAT plans were recalculated using DCA with user‐controlled field aperture shape before VMAT optimization. Identical beam geometry, dose calculation algorithm, grid size, and planning objectives were used. The clinical VMAT and d‐VMAT plans were compared via RTOG‐0915 protocol compliances for conformity, gradient indices, and dose to organs at risk (OAR). Additionally, treatment delivery efficiency and accuracy were recorded. RESULTS: All plans met RTOG‐0915 requirements. Comparing with clinical VMAT, d‐VMAT plans gave similar target coverage with better target conformity, tighter radiosurgical dose distribution with lower gradient indices, and dose to OAR. Lower total number of monitor units and small beam modulation factor reduced beam‐on time by 1.75 min (P < 0.001), on average (maximum up to 2.52 min). Beam delivery accuracy was improved by 2%, on average (P < 0.05) and maximum up to 6% in some cases for d‐VMAT plans. CONCLUSION: This simple d‐VMAT technique provided excellent plan quality, reduced intermediate dose‐spillage, and dose to OAR while providing faster treatment delivery by significantly reducing beam‐on time. This novel treatment planning approach will improve patient compliance along with potentially reducing intrafraction motion error. Moreover, with less MLC modulation through the target, d‐VMAT could potentially minimize small‐field dosimetry errors and MLC interplay effects. If available, d‐VMAT planning approach is recommended for future clinical lung SBRT plan optimization. John Wiley and Sons Inc. 2020-04-19 /pmc/articles/PMC7386176/ /pubmed/32306530 http://dx.doi.org/10.1002/acm2.12878 Text en © 2020 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine. This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. |
spellingShingle | Radiation Oncology Physics Pokhrel, Damodar Visak, Justin Sanford, Lana A novel and clinically useful dynamic conformal arc (DCA)‐based VMAT planning technique for lung SBRT |
title | A novel and clinically useful dynamic conformal arc (DCA)‐based VMAT planning technique for lung SBRT |
title_full | A novel and clinically useful dynamic conformal arc (DCA)‐based VMAT planning technique for lung SBRT |
title_fullStr | A novel and clinically useful dynamic conformal arc (DCA)‐based VMAT planning technique for lung SBRT |
title_full_unstemmed | A novel and clinically useful dynamic conformal arc (DCA)‐based VMAT planning technique for lung SBRT |
title_short | A novel and clinically useful dynamic conformal arc (DCA)‐based VMAT planning technique for lung SBRT |
title_sort | novel and clinically useful dynamic conformal arc (dca)‐based vmat planning technique for lung sbrt |
topic | Radiation Oncology Physics |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7386176/ https://www.ncbi.nlm.nih.gov/pubmed/32306530 http://dx.doi.org/10.1002/acm2.12878 |
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