{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,2]],"date-time":"2026-04-02T18:07:18Z","timestamp":1775153238801,"version":"3.50.1"},"reference-count":42,"publisher":"Public Library of Science (PLoS)","issue":"4","license":[{"start":{"date-parts":[[2026,4,2]],"date-time":"2026-04-02T00:00:00Z","timestamp":1775088000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/"}],"funder":[{"DOI":"10.13039\/100011541","name":"Division of Cancer Epidemiology and Genetics, National Cancer Institute","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100011541","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS One"],"abstract":"<jats:p>Approximately one-third of US adults have tattoos, yet the dosimetric impact of intradermal tattoo pigments during radiation therapy remains uncharacterized. Commercial tattoo inks contain unregulated metallic impurities including chromium, lead, and nickel, raising concerns about dose perturbations in tattooed skin. This work quantifies radiation dose perturbations induced by high-atomic-number (Z) tattoo pigments under clinically relevant radiotherapy conditions. Monte Carlo simulations (TOPAS) modeled layered skin phantoms with a 0.3-mm intradermal tattoo layer embedded at 1.25\u20131.55\u2009mm depth. Three commercial inks were evaluated: carbon-based (black) and metal-containing (Fe-rich brown, Al-containing orange) at pigment loadings of 5\u2013100 vol% within the tattoo layer, to establish upper-bound effects. Electron (6, 18 MeV) and photon (6, 18 MV) beams were simulated with standard clinical geometry (1\u2009\u00d7\u20091 cm\u00b2 field, SSD\u2009=\u2009100\u2009cm). Photon irradiation produced pronounced, depth-localized dose enhancement, with peak dose enhancement factor (DEF) reaching 2.5 for brown ink at 18 MV, a 62% mean increase relative to non-tattooed skin driven by high-Z\u2013mediated secondary electron production. Electron beams exhibited energy-dependent behavior: 6 MeV produced modest enhancement (peak DEF\u2009~\u20091.07), while 18 MeV unexpectedly generated dose deficits (DEF\u2009&lt;\u20091.0) due to enhanced lateral scattering. Critically, all perturbations remained depth-confined without lateral propagation, preserving spatial dose uniformity across tattooed and non-tattooed regions. Tattoo pigments containing toxic metals create substantial localized dose enhancements under photon irradiation but minimal perturbations under electron therapy. These modality-dependent effects represent a previously unrecognized source of dose uncertainty in radiotherapy and warrant consideration in treatment planning for the growing population of tattooed patients.<\/jats:p>","DOI":"10.1371\/journal.pone.0346501","type":"journal-article","created":{"date-parts":[[2026,4,2]],"date-time":"2026-04-02T17:37:53Z","timestamp":1775151473000},"page":"e0346501","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":0,"title":["An overlooked source of skin dose perturbation: Commercial tattoo inks in radiotherapy"],"prefix":"10.1371","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8978-7342","authenticated-orcid":true,"given":"Hongjun","family":"Park","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Beechui","family":"Koo","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jungwook","family":"Shin","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Byoung Hyuck","family":"Kim","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7209-4104","authenticated-orcid":true,"given":"James J.","family":"Sohn","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"340","published-online":{"date-parts":[[2026,4,2]]},"reference":[{"key":"pone.0346501.ref001","unstructured":"Schaeffer K, Dinesh S. 32% of Americans have a tattoo, including 22% who have more than one. Pew Research Center; 2023. 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Commission Regulation (EU) 2020\/2081. Brussels. 2020. https:\/\/www.legislation.gov.uk\/eur\/2020\/2081"},{"issue":"9","key":"pone.0346501.ref008","doi-asserted-by":"crossref","first-page":"3906","DOI":"10.1021\/acs.analchem.3c05687","article-title":"What\u2019s in My Ink: An Analysis of Commercial Tattoo Ink on the US Market","volume":"96","author":"K Moseman","year":"2024","journal-title":"Anal Chem"},{"issue":"21","key":"pone.0346501.ref009","doi-asserted-by":"crossref","first-page":"5329","DOI":"10.1039\/D4AN00793J","article-title":"Analysis of blue and green REACH compliant tattoo inks","volume":"149","author":"K Moseman","year":"2024","journal-title":"Analyst"},{"key":"pone.0346501.ref010","first-page":"248","article-title":"Regulation of tattoo ink production and the tattoo business in the US","volume":"48","author":"IM Haugh","year":"2015","journal-title":"Curr Probl Dermatol"},{"key":"pone.0346501.ref011","unstructured":"U.S. Food and Drug Administration. Tattoos & permanent makeup: fact sheet. https:\/\/www.fda.gov\/cosmetics\/cosmetic-products\/tattoos-permanent-makeup-fact-sheet. 2024. Accessed 2025 October 29."},{"key":"pone.0346501.ref012","unstructured":"U.S. Food and Drug Administration. FDA issues final guidance on tattoo inks. https:\/\/www.fda.gov\/cosmetics\/cosmetics-news-events\/fda-issues-final-guidance-tattoo-inks. 2024. Accessed 2025 October 29."},{"issue":"2","key":"pone.0346501.ref013","doi-asserted-by":"crossref","first-page":"180","DOI":"10.1002\/jmri.10049","article-title":"Magnetic resonance imaging and permanent cosmetics (tattoos): survey of complications and adverse events","volume":"15","author":"WD Tope","year":"2002","journal-title":"J Magn Reson Imaging"},{"issue":"2","key":"pone.0346501.ref014","doi-asserted-by":"crossref","first-page":"278","DOI":"10.1111\/srt.12426","article-title":"MR scanning, tattoo inks, and risk of thermal burn: An experimental study of iron oxide and organic pigments","volume":"24","author":"KK Alsing","year":"2017","journal-title":"Skin Research and Technology"},{"issue":"8","key":"pone.0346501.ref015","doi-asserted-by":"crossref","DOI":"10.1371\/journal.pone.0220030","article-title":"Glamour, expression, and consequences of tattoos in radiation treatment","volume":"14","author":"PE Galavis","year":"2019","journal-title":"PLoS 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