Spatial distribution of light-melanosome interaction dependent on irradiation fluence and spot size for short-pulsed laser skin treatment: A phantom study

Spatial distribution of light-melanosome interaction dependent on irradiation fluence and spot size for short-pulsed laser skin treatment: A phantom study | 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 Spatial distribution of light-melanosome interaction dependent on irradiation fluence and spot size for short-pulsed laser skin treatment: A phantom study Gakuto Takeda, Yu Shimojo, Toshiyuki Ozawa, Takahiro Nishimura This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5848430/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 30 May, 2025 Read the published version in Lasers in Medical Science → Version 1 posted 11 You are reading this latest preprint version Abstract Purpose: Short-pulsed lasers provide safe and efficacious treatment of pigmented lesions by setting irradiation parameters based on immediate whitening resulting from vacuolization. However, visual observation of this phenomenon as an irradiation endpoint is subjective and makes it difficult to assess the depth to which the light response is induced inside the skin. To quantitatively understand the dependence of the light response on irradiation parameters, this study analyzes the spatial distribution of light-melanosome interaction based on the fluence distribution in an optical phantom. Methods: Nanosecond laser irradiation was applied to an optical phantom with a uniform distribution of melanosomes with varying irradiation fluence and spot size. The observed spatial distribution of the light-melanosome response was compared with the fluence distribution in the phantom calculated from numerical simulations. Results: The resulting relationship between irradiation parameters and optical response showed that cavitation increased rapidly at an in-phantom fluence of 1.37 J/cm$^2$ and reached a saturated state at the threshold fluence for melanosome disruption. Additionally, increasing the spot size promoted cavitation at greater depths as well as increasing irradiation fluence, highlighting the need to consider both irradiation fluence and spot size for treatment depth control. Conclusion: The experimental results suggest the potential for quantitative control of optical responses in laser treatment of pigmented lesions. Further validation by experiments on samples with spatial distribution of cutaneous melanosomes is required. Short-pulsed laser pigmented lesion melanosome phantom Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 30 May, 2025 Read the published version in Lasers in Medical Science → Version 1 posted Editorial decision: Revision requested 26 Feb, 2025 Reviews received at journal 21 Feb, 2025 Reviews received at journal 16 Feb, 2025 Reviewers agreed at journal 14 Feb, 2025 Reviewers agreed at journal 08 Feb, 2025 Reviewers agreed at journal 08 Feb, 2025 Reviewers agreed at journal 07 Feb, 2025 Reviewers invited by journal 07 Feb, 2025 Editor assigned by journal 07 Feb, 2025 Submission checks completed at journal 23 Jan, 2025 First submitted to journal 17 Jan, 2025 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. 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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-5848430","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":406209014,"identity":"da02eea5-cd0c-4817-ab48-ef87872104fb","order_by":0,"name":"Gakuto Takeda","email":"data:image/png;base64,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","orcid":"","institution":"Osaka University","correspondingAuthor":true,"prefix":"","firstName":"Gakuto","middleName":"","lastName":"Takeda","suffix":""},{"id":406209015,"identity":"2ab359cb-3172-4742-ad62-e9a50617f140","order_by":1,"name":"Yu Shimojo","email":"","orcid":"","institution":"Osaka Metropolitan University","correspondingAuthor":false,"prefix":"","firstName":"Yu","middleName":"","lastName":"Shimojo","suffix":""},{"id":406209016,"identity":"6cd220e4-35da-443c-a583-e04b83ea76d9","order_by":2,"name":"Toshiyuki Ozawa","email":"","orcid":"","institution":"Osaka Metropolitan University","correspondingAuthor":false,"prefix":"","firstName":"Toshiyuki","middleName":"","lastName":"Ozawa","suffix":""},{"id":406209017,"identity":"30b4f18b-072e-4eb4-aa76-0569cbb274d6","order_by":3,"name":"Takahiro Nishimura","email":"","orcid":"","institution":"Osaka University","correspondingAuthor":false,"prefix":"","firstName":"Takahiro","middleName":"","lastName":"Nishimura","suffix":""}],"badges":[],"createdAt":"2025-01-17 10:38:33","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5848430/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5848430/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10103-025-04430-x","type":"published","date":"2025-05-30T15:57:13+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":83783117,"identity":"c7993955-e55e-4e11-963e-e8b08dd809ef","added_by":"auto","created_at":"2025-06-02 16:10:56","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3051824,"visible":true,"origin":"","legend":"","description":"","filename":"paperreview.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5848430/v1_covered_774a4f35-4744-46ed-a27e-cc8fba1b67b8.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Spatial distribution of light-melanosome interaction dependent on irradiation fluence and spot size for short-pulsed laser skin treatment: A phantom study","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"lasers-in-medical-science","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"lims","sideBox":"Learn more about [Lasers in Medical Science](https://link.springer.com/journal/10103)","snPcode":"10103","submissionUrl":"https://submission.springernature.com/new-submission/10103/3","title":"Lasers in Medical Science","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Short-pulsed laser, pigmented lesion, melanosome, phantom","lastPublishedDoi":"10.21203/rs.3.rs-5848430/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5848430/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003ePurpose: \u003c/strong\u003eShort-pulsed lasers provide safe and efficacious treatment of pigmented lesions by setting irradiation parameters based on immediate whitening resulting from vacuolization. However, visual observation of this phenomenon as an irradiation endpoint is subjective and makes it difficult to assess the depth to which the light response is induced inside the skin. To quantitatively understand the dependence of the light response on irradiation parameters, this study analyzes the spatial distribution of light-melanosome interaction based on the fluence distribution in an optical phantom.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods: \u003c/strong\u003eNanosecond laser irradiation was applied to an optical phantom with a uniform distribution of melanosomes with varying irradiation fluence and spot size. The observed spatial distribution of the light-melanosome response was compared with the fluence distribution in the phantom calculated from numerical simulations.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults: \u003c/strong\u003eThe resulting relationship between irradiation parameters and optical response showed that cavitation increased rapidly at an in-phantom fluence of 1.37 J/cm$^2$ and reached a saturated state at the threshold fluence for melanosome disruption. Additionally, increasing the spot size promoted cavitation at greater depths as well as increasing irradiation fluence, highlighting the need to consider both irradiation fluence and spot size for treatment depth control.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion: \u003c/strong\u003eThe experimental results suggest the potential for quantitative control of optical responses in laser treatment of pigmented lesions. 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