Analytical framework for LET- and oxygen-dependent transport of hydroxyl radicals under irradiation

Analytical framework for LET- and oxygen-dependent transport of hydroxyl radicals under irradiation | 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 Article Analytical framework for LET- and oxygen-dependent transport of hydroxyl radicals under irradiation Ladan Rezaee This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8714254/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 The biological effectiveness of ionizing radiation depends not only on absorbed dose but also on radiation quality and microenvironmental factors, particularly linear energy transfer (LET) and oxygenation. Although Monte Carlo track-structure simulations can describe radiation–matter interactions in detail, such complexity often obscures the individual roles played by governing parameters. We present here a closed-form, analytical transport–reaction model of the indirect chemical stage of radiation action. The model introduces an LET-dependent source term for hydroxyl radical production based on experimentally and computationally established G-value trends and combines it with an analytical transport equation formulated using a directional Boltzmann-P₁ approximation. Macroscopic reaction rates incorporate the presence of oxygen and background scavengers, leading to an explicit, steady-state expression for hydroxyl radical density independent of biological response functions. The model systematically replicates suppression of indirect chemical activity with increasing LET and predicts the natural emergence of smoothly varying radiochemical regimes corresponding to production-limited, scavenging-limited, and track-structure-dominated behavior. These regimes emerge from first-principles considerations rather than imposed thresholds. The framework is not designed to predict biological damage or clinical outcomes but provides a physically transparent and analytically tractable description of the chemical stage of radiation action, one suitable for incorporation into multiscale models of heterogeneous irradiation. Biological sciences/Biophysics Physical sciences/Chemistry Physical sciences/Mathematics and computing Physical sciences/Physics Hydroxyl radicals DNA damage transport modeling adaptive radiotherapy Full Text Additional Declarations No competing interests reported. Supplementary Files SupplementaryFile.pdf Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 15 Mar, 2026 Reviews received at journal 14 Mar, 2026 Reviews received at journal 13 Mar, 2026 Reviewers agreed at journal 01 Mar, 2026 Reviewers agreed at journal 20 Feb, 2026 Reviewers invited by journal 20 Feb, 2026 Editor invited by journal 02 Feb, 2026 Editor assigned by journal 30 Jan, 2026 Submission checks completed at journal 30 Jan, 2026 First submitted to journal 27 Jan, 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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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-8714254","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":595619195,"identity":"5d085415-e0cf-452d-bc8b-d1b3c76ee785","order_by":0,"name":"Ladan Rezaee","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA6UlEQVRIiWNgGAWjYBACPgYGAwTvA4ydgEcLG7IWxhkka2HmIcZhbOyHN34uYLgnJ99++OBjmwK7xAb2ww8YHu7Bo4UnrVh6BkOxMWNPWrJxjkFyYgNPmgFDwjN8DssxkOZhSEhsZsgxk84xYE5sYMgB+uUAHi38b4x/A7XUt/G///7bwqA+sYH/DQEtEkDDgVoSeCRy2JgZDA4nNkgQskXiWZk1j0GC4QyJZ8aSPQbHjdsknhkcwKeFnz95822eigR5+f7khx9+/KmW7edPfvjwBx4tEICUAEAxxUBQwygYBaNgFIwC/AAAECFEl1ObfXkAAAAASUVORK5CYII=","orcid":"","institution":"Islamic Azad University","correspondingAuthor":true,"prefix":"","firstName":"Ladan","middleName":"","lastName":"Rezaee","suffix":""}],"badges":[],"createdAt":"2026-01-27 20:54:22","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8714254/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8714254/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":103313592,"identity":"a580b7f9-fb37-4ec9-90c1-00675ab930f1","added_by":"auto","created_at":"2026-02-24 10:28:04","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":754584,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8714254/v1_covered_a59c66f2-2440-424a-9e53-4ddbd0add84b.pdf"},{"id":103313589,"identity":"784e84a1-21e7-4c78-bc24-92f05bb69203","added_by":"auto","created_at":"2026-02-24 10:27:59","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":322969,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryFile.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8714254/v1/2cc13e16af434d617aeb9cbf.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Analytical framework for LET- and oxygen-dependent transport of hydroxyl radicals under irradiation","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":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Hydroxyl radicals, DNA damage, transport modeling, adaptive radiotherapy","lastPublishedDoi":"10.21203/rs.3.rs-8714254/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8714254/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe biological effectiveness of ionizing radiation depends not only on absorbed dose but also on radiation quality and microenvironmental factors, particularly linear energy transfer (LET) and oxygenation. Although Monte Carlo track-structure simulations can describe radiation\u0026ndash;matter interactions in detail, such complexity often obscures the individual roles played by governing parameters. We present here a closed-form, analytical transport\u0026ndash;reaction model of the indirect chemical stage of radiation action. The model introduces an LET-dependent source term for hydroxyl radical production based on experimentally and computationally established G-value trends and combines it with an analytical transport equation formulated using a directional Boltzmann-P₁ approximation. Macroscopic reaction rates incorporate the presence of oxygen and background scavengers, leading to an explicit, steady-state expression for hydroxyl radical density independent of biological response functions. 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