Dosimetric Comparison of RapidArc Dynamic, VMAT, and IMRT in Left-sided Chest Radiotherapy: Focusing on Cardiac Substructure Sparing and NTCP

Dosimetric Comparison of RapidArc Dynamic, VMAT, and IMRT in Left-sided Chest Radiotherapy: Focusing on Cardiac Substructure Sparing and NTCP | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Dosimetric Comparison of RapidArc Dynamic, VMAT, and IMRT in Left-sided Chest Radiotherapy: Focusing on Cardiac Substructure Sparing and NTCP Yutong Zhao, Xinqiang Zhang#, Xiaoshen Wang, Zejun Jiang, Jinzhi Wang, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9014808/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version Abstract Background Left-sided breast cancer radiotherapy poses a challenge in balancing target coverage with the sparing of critical cardiac substructures. A novel hybrid technique - RapidArc Dynamic (RAD) - integrated continuous arc delivery of volumetric modulated arc therapy (VMAT) with fixed-beam modulation of intensity modulated radiotherapy (IMRT) through strategic gantry pauses and dynamic collimator rotation. Purpose This study aims to evaluate the dosimetric performance of RAD, benchmarking it against IMRT and VMAT, with a specific focus on cardiac substructure sparing and normal tissue complication probability (NTCP). Methods Twenty patients with left-sided breast cancer treated with post-mastectomy adjuvant radiotherapy were retrospectively enrolled. For each patient, three plans (RAD, IMRT, and VMAT) were generated with a prescription of 50 Gy in 25 fractions. RAD plans utilized a “balanced” optimization strategy combining static ports and dynamic arcs with strategic gantry pauses to enhance modulation. Dosimetric metrics were analyzed for the planning target volume (PTV) and organs at risk (OARs). NTCP values were calculated using the Lyman-Kutcher-Burman (LKB) model for multiple endpoints. Results RAD demonstrated significantly lower dose metrics for the heart, left lung, and spinal cord compared to both IMRT and VMAT (P < 0.05). Specifically, RAD achieved superior sparing of the left anterior descending coronary artery (LAD) and left ventricle (LV), reducing mean and maximum doses significantly compared to competing modalities. While VMAT provided better conformity than IMRT, it resulted in a higher low-dose bath to the contralateral breast. Radiobiological modelling demonstrated that RAD successfully mitigated this issue, delivering significantly lower contralateral doses than VMAT. RAD yielded significantly lower predicted NTCPs for cardiac perfusion defects, LA major adverse cardiac events, and pulmonary pneumonitis compared to IMRT and VMAT. Conclusion RAD offers a feasible and effective alternative for left-sided chest radiotherapy, providing an optimal balance between high dose conformity and superior organ sparing. Breast Cancer RapidArc Dynamic Cardiac substructures NTCP Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 08 May, 2026 Reviews received at journal 05 May, 2026 Reviews received at journal 16 Apr, 2026 Reviewers agreed at journal 16 Apr, 2026 Reviewers agreed at journal 16 Apr, 2026 Reviewers agreed at journal 15 Apr, 2026 Reviewers invited by journal 13 Apr, 2026 Editor assigned by journal 13 Mar, 2026 Submission checks completed at journal 13 Mar, 2026 First submitted to journal 12 Mar, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9014808","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":624305441,"identity":"16efaeb1-c3e8-4b31-9e41-a27d7154f43a","order_by":0,"name":"Yutong Zhao","email":"","orcid":"","institution":"Shandong Cancer Hospital and Institute, Shandong First Medical University, Shandong Academy of Medical Science","correspondingAuthor":false,"prefix":"","firstName":"Yutong","middleName":"","lastName":"Zhao","suffix":""},{"id":624305442,"identity":"f796f4f0-f5c0-4c4f-b9fe-472d65d43182","order_by":1,"name":"Xinqiang Zhang#","email":"","orcid":"","institution":"Shandong Cancer Hospital and Institute, Shandong First Medical University, Shandong Academy of Medical Science","correspondingAuthor":false,"prefix":"","firstName":"Xinqiang","middleName":"","lastName":"Zhang#","suffix":""},{"id":624305443,"identity":"cd85f3ad-69c3-4845-ae26-ff2f6261f681","order_by":2,"name":"Xiaoshen Wang","email":"","orcid":"","institution":"Varian Medical System","correspondingAuthor":false,"prefix":"","firstName":"Xiaoshen","middleName":"","lastName":"Wang","suffix":""},{"id":624305444,"identity":"2e4a6f38-8c52-44e1-b0b9-76aa316e2536","order_by":3,"name":"Zejun Jiang","email":"","orcid":"","institution":"Shandong Cancer Hospital and Institute, Shandong First Medical University, Shandong Academy of Medical Science","correspondingAuthor":false,"prefix":"","firstName":"Zejun","middleName":"","lastName":"Jiang","suffix":""},{"id":624305445,"identity":"fa23ae43-8d64-40fa-a87a-d4e37bcf0d34","order_by":4,"name":"Jinzhi 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02:09:01","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9014808/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9014808/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":107390759,"identity":"ddbf6606-bdc9-471a-a140-f4071c416294","added_by":"auto","created_at":"2026-04-21 05:10:31","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":579412,"visible":true,"origin":"","legend":"","description":"","filename":"ManuscriptEurJMed.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9014808/v1_covered_c3c3e5f9-a23f-4297-b73a-01e6d05c5265.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Dosimetric Comparison of RapidArc Dynamic, VMAT, and IMRT in Left-sided Chest Radiotherapy: Focusing on Cardiac Substructure Sparing and NTCP","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"european-journal-of-medical-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ejmr","sideBox":"Learn more about [European Journal of Medical Research](http://eurjmedres.biomedcentral.com)","snPcode":"40001","submissionUrl":"https://submission.nature.com/new-submission/40001/3","title":"European Journal of Medical Research","twitterHandle":"@BioMedCentral","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Breast Cancer, RapidArc Dynamic, Cardiac substructures, NTCP","lastPublishedDoi":"10.21203/rs.3.rs-9014808/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9014808/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eLeft-sided breast cancer radiotherapy poses a challenge in balancing target coverage with the sparing of critical cardiac substructures. A novel hybrid technique - RapidArc Dynamic (RAD) - integrated continuous arc delivery of volumetric modulated arc therapy (VMAT) with fixed-beam modulation of intensity modulated radiotherapy (IMRT) through strategic gantry pauses and dynamic collimator rotation.\u003c/p\u003e\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003eThis study aims to evaluate the dosimetric performance of RAD, benchmarking it against IMRT and VMAT, with a specific focus on cardiac substructure sparing and normal tissue complication probability (NTCP).\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eTwenty patients with left-sided breast cancer treated with post-mastectomy adjuvant radiotherapy were retrospectively enrolled. For each patient, three plans (RAD, IMRT, and VMAT) were generated with a prescription of 50 Gy in 25 fractions. RAD plans utilized a \u0026ldquo;balanced\u0026rdquo; optimization strategy combining static ports and dynamic arcs with strategic gantry pauses to enhance modulation. Dosimetric metrics were analyzed for the planning target volume (PTV) and organs at risk (OARs). NTCP values were calculated using the Lyman-Kutcher-Burman (LKB) model for multiple endpoints.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eRAD demonstrated significantly lower dose metrics for the heart, left lung, and spinal cord compared to both IMRT and VMAT (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Specifically, RAD achieved superior sparing of the left anterior descending coronary artery (LAD) and left ventricle (LV), reducing mean and maximum doses significantly compared to competing modalities. While VMAT provided better conformity than IMRT, it resulted in a higher low-dose bath to the contralateral breast. Radiobiological modelling demonstrated that RAD successfully mitigated this issue, delivering significantly lower contralateral doses than VMAT. RAD yielded significantly lower predicted NTCPs for cardiac perfusion defects, LA major adverse cardiac events, and pulmonary pneumonitis compared to IMRT and VMAT.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eRAD offers a feasible and effective alternative for left-sided chest radiotherapy, providing an optimal balance between high dose conformity and superior organ sparing.\u003c/p\u003e","manuscriptTitle":"Dosimetric Comparison of RapidArc Dynamic, VMAT, and IMRT in Left-sided Chest Radiotherapy: Focusing on Cardiac Substructure Sparing and NTCP","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-21 05:09:03","doi":"10.21203/rs.3.rs-9014808/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-05-08T12:56:35+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-05T06:27:43+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-16T12:19:37+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"104273252936532519903238100200494491468","date":"2026-04-16T11:41:46+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"260909729791579715594458235946034272829","date":"2026-04-16T06:54:11+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"114983292557662367067856965408781496605","date":"2026-04-15T05:05:43+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-04-13T18:30:56+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-13T11:45:52+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-13T05:19:24+00:00","index":"","fulltext":""},{"type":"submitted","content":"European Journal of Medical Research","date":"2026-03-12T06:09:01+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"european-journal-of-medical-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ejmr","sideBox":"Learn more about [European Journal of Medical Research](http://eurjmedres.biomedcentral.com)","snPcode":"40001","submissionUrl":"https://submission.nature.com/new-submission/40001/3","title":"European Journal of Medical Research","twitterHandle":"@BioMedCentral","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"b2f59de8-a9e9-4b9c-a70c-5f8771e47c25","owner":[],"postedDate":"April 21st, 2026","published":true,"recentEditorialEvents":[{"type":"editorInvitedReview","content":"","date":"2026-05-08T12:56:35+00:00","index":38,"fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-05T06:27:43+00:00","index":35,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-04-21T05:09:03+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-21 05:09:03","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9014808","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9014808","identity":"rs-9014808","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}