{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,12]],"date-time":"2026-10-12T07:45:46Z","timestamp":1791791146063,"version":"4.3.4"},"reference-count":21,"publisher":"IOP Publishing","issue":"19","license":[{"start":{"date-parts":[[2026,10,12]],"date-time":"2026-10-12T00:00:00Z","timestamp":1791763200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/publishingsupport.iopscience.iop.org\/iop-standard\/v1"},{"start":{"date-parts":[[2026,10,12]],"date-time":"2026-10-12T00:00:00Z","timestamp":1791763200000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/iopscience.iop.org\/info\/page\/text-and-data-mining"},{"start":{"date-parts":[[2026,10,12]],"date-time":"2026-10-12T00:00:00Z","timestamp":1791763200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/publishingsupport.iopscience.iop.org\/questions\/alternative-author-rights-policies\/"},{"start":{"date-parts":[[2026,10,12]],"date-time":"2026-10-12T00:00:00Z","timestamp":1791763200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/publishingsupport.iopscience.iop.org\/questions\/alternative-author-rights-policies\/"}],"content-domain":{"domain":["iopscience.iop.org"],"crossmark-restriction":false},"short-container-title":["Phys. Med. Biol."],"published-print":{"date-parts":[[2026,10,14]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>\n                    <jats:italic>Objective<\/jats:italic>\n                    . To investigate whether converging electron beams using quadrupole electromagnets can mitigate fluence loss and bremsstrahlung contamination in small irradiation fields.\n                    <jats:italic>Approach<\/jats:italic>\n                    . A three-stage quadrupole electromagnet system was installed beneath a linear accelerator head to converge 6, 9, 12, and 15 MeV electron beams. Dose distributions, dose rate, and bremsstrahlung contamination were evaluated for 2 cm and 1 cm fields. The 2 cm convergent field was compared with a 2 cm tubular applicator, whereas the 1 cm convergent field was evaluated at 5.1 and 10 cm air gaps. Monte Carlo simulations at 6 and 9 MeV assessed detector volume-averaging effects and the origins of bremsstrahlung photons.\n                    <jats:italic>Main results<\/jats:italic>\n                    . The dose rate of the 2 cm convergent field was 1.05\u20132.53 times higher than that of the 2 cm tubular applicator, while bremsstrahlung contamination was reduced by 0.40\u20131.79 percentage points. The 1 cm convergent field achieved a therapeutic field width \u2a7d1 cm and penumbra \u2a7d0.85 cm at all energies. At a 5.1 cm air gap, the dose rate was comparable to that of a 3 cm tubular applicator at 9 MeV and exceeded that of a 10 \u00d7 10 cm\n                    <jats:sup>2<\/jats:sup>\n                    applicator at 12 and 15 MeV. Bremsstrahlung contamination was 1.08%, 0.87%, 1.04%, and 1.32% at 6, 9, 12, and 15 MeV, respectively, and remained lower than that of the 2 cm tubular applicator at all energies. At a 10 cm air gap, output decreased and dose profiles broadened. Bremsstrahlung contamination increased to 2.56%, 1.70%, 1.72%, and 2.11%, respectively, but remained lower than that of the 2 cm tubular applicator at 12 MeV and above.\n                    <jats:italic>Significance<\/jats:italic>\n                    . Converging electron beams can mitigate fluence loss while reducing bremsstrahlung contamination in small fields. This externally mounted system provides proof of concept for high-spatial-resolution electron beam delivery and future electromagnetic spot-scanning applications.\n                  <\/jats:p>","DOI":"10.1088\/1361-6560\/aeaf41","type":"journal-article","created":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T22:54:01Z","timestamp":1790895241000},"page":"195036","update-policy":"https:\/\/doi.org\/10.1088\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["A convergent electron beam approach for small-field irradiation with reduced bremsstrahlung"],"prefix":"10.1088","volume":"71","author":[{"ORCID":"https:\/\/orcid.org\/0009-0006-4244-0815","authenticated-orcid":true,"given":"Y","family":"Hayashi","sequence":"first","affiliation":[{"name":"Graduate School of Human Health Sciences, Tokyo Metropolitan University"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"},{"role":"visualization","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4360-9663","authenticated-orcid":true,"given":"A","family":"Myojoyama","sequence":"additional","affiliation":[{"name":"Graduate School of Human Health Sciences, Tokyo Metropolitan University"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"funding-acquisition","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"supervision","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]}],"member":"266","published-online":{"date-parts":[[2026,10,12]]},"reference":[{"key":"pmbaeaf41bib1","doi-asserted-by":"publisher","first-page":"403","DOI":"10.3109\/02841868709113708","type":"journal-article","article-title":"Design principles and clinical possibilities with a new generation of radiation therapy equipment: a review","volume":"26","author":"Brahme","year":"1987","journal-title":"Acta Oncol."},{"key":"pmbaeaf41bib2","doi-asserted-by":"publisher","first-page":"359","DOI":"10.1016\/j.meddos.2024.05.001","type":"journal-article","article-title":"Defining the role of intensity modulation in electron conformal therapy for the treatment of head and neck cancer","volume":"49","author":"Cabrera","year":"2024","journal-title":"Med. 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All rights, including for text and data mining, AI training, and similar technologies, are reserved.","name":"copyright_information","label":"Copyright Information"},{"value":"2026-03-12","name":"date_received","label":"Date Received","group":{"name":"publication_dates","label":"Publication dates"}},{"value":"2026-10-01","name":"date_accepted","label":"Date Accepted","group":{"name":"publication_dates","label":"Publication dates"}},{"value":"2026-10-12","name":"date_epub","label":"Online publication date","group":{"name":"publication_dates","label":"Publication dates"}}]}}