{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,30]],"date-time":"2026-06-30T06:44:59Z","timestamp":1782801899613,"version":"3.54.5"},"reference-count":24,"publisher":"IOP Publishing","issue":"13","license":[{"start":{"date-parts":[[2026,6,30]],"date-time":"2026-06-30T00:00:00Z","timestamp":1782777600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/publishingsupport.iopscience.iop.org\/iop-standard\/v1"},{"start":{"date-parts":[[2026,6,30]],"date-time":"2026-06-30T00:00:00Z","timestamp":1782777600000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/iopscience.iop.org\/info\/page\/text-and-data-mining"}],"funder":[{"DOI":"10.13039\/501100001691","name":"Japan Society for the Promotion of Science","doi-asserted-by":"crossref","award":["22K07695"],"award-info":[{"award-number":["22K07695"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"crossref"}]},{"name":"Duke-NUS Oncology Academic Program Goh Foundation Proton Research Programme","award":["08\/FY2025\/EX(SL)\/ 000364"],"award-info":[{"award-number":["08\/FY2025\/EX(SL)\/ 000364"]}]}],"content-domain":{"domain":["iopscience.iop.org"],"crossmark-restriction":false},"short-container-title":["Phys. Med. Biol."],"published-print":{"date-parts":[[2026,7,14]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>\n                    <jats:italic>Objective.<\/jats:italic>\n                    Real-time gated proton therapy (RGPT) enables precise irradiation of moving targets and is an important motion-management technique in proton therapy. Uninterrupted continuous delivery (UCD) avoids frequent gating interruptions, which improves proton beam extraction stability and treatment efficiency in synchrotron-based systems. However, because fluoroscopic x-rays remain on during proton irradiation in UCD, scattered fluoroscopic x-rays may be detected by the dose monitor (DM) and mistakenly counted as proton monitor units (MUs), potentially causing beam aborts. This study aimed to quantify scattered fluoroscopic x-rays detected by the DM during RGPT and evaluate their impact on beam delivery during simultaneous fluoroscopy and proton irradiation.\n                    <jats:italic>Methods.<\/jats:italic>\n                    Scattered fluoroscopic x-ray signals detected by the DM were measured using an RGPT system. Phantom experiments evaluated scattered x-ray dose rates using plastic water\u00ae (PW) and anthropomorphic phantoms while varying phantom thickness, fluoroscopic parameters, and range-shifter conditions. Beam-abort simulations were conducted under UCD conditions for both phantom and clinical liver treatment plans. Abort probability was assessed as a function of proton MU per spot, scattered x-ray MU per frame, and fluoroscopy frames per second.\n                    <jats:italic>Results.<\/jats:italic>\n                    DM signals from scattered fluoroscopic x-rays increased with tube voltage, tube current, field size, and phantom thickness, and were higher without a range shifter (RS). The maximum dose rate was 0.0211 MU\/frame at 125 kV, 80 mA, 200 \u00d7 200 mm\n                    <jats:sup>2<\/jats:sup>\n                    , and PW-30 cm without a RS, representing an 11.7-fold increase compared to the in-air conditions. The results obtained from the anthropomorphic phantom experiments further validated the findings observed in the PW phantom study. Beam-abort simulations showed abort proportions below 2% for monoenergetic fields and below 3% for clinical liver plans across all tested conditions.\n                    <jats:italic>Significance.<\/jats:italic>\n                    With the DM positioned closer to the x-ray tube, scattered fluoroscopic x-ray contamination increased with phantom thickness, differing from prior reports. Optimization of proton dose rate, imaging parameters, and system geometry can minimize beam interruptions, supporting the clinical feasibility of UCD.\n                  <\/jats:p>","DOI":"10.1088\/1361-6560\/ae7954","type":"journal-article","created":{"date-parts":[[2026,6,5]],"date-time":"2026-06-05T22:56:26Z","timestamp":1780700186000},"page":"135003","update-policy":"https:\/\/doi.org\/10.1088\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Impact of x-ray contamination in the dose monitor on beam abortion during uninterrupted continuous delivery in proton therapy"],"prefix":"10.1088","volume":"71","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2827-5407","authenticated-orcid":true,"given":"Masashi","family":"Yagi","sequence":"first","affiliation":[{"name":"National Cancer Centre Singapore"},{"name":"The University of Osaka Graduate School of Medicine"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kah Seng","family":"Lew","sequence":"additional","affiliation":[{"name":"National Cancer Centre Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Clifford Ghee Ann","family":"Chua","sequence":"additional","affiliation":[{"name":"National Cancer Centre Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wei Yang Calvin","family":"Koh","sequence":"additional","affiliation":[{"name":"National Cancer Centre Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1824-2724","authenticated-orcid":true,"given":"Kang Hao","family":"Lee","sequence":"additional","affiliation":[{"name":"National Cancer Centre Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"James Cheow Lei","family":"Lee","sequence":"additional","affiliation":[{"name":"National Cancer Centre Singapore"},{"name":"School of Physical and Mathematical Science, Nanyang Technological University"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7961-2119","authenticated-orcid":true,"given":"Sung Yong","family":"Park","sequence":"additional","affiliation":[{"name":"National Cancer Centre Singapore"},{"name":"Duke-NUS Medical School"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7878-4544","authenticated-orcid":true,"given":"Hong Qi","family":"Tan","sequence":"additional","affiliation":[{"name":"National Cancer Centre Singapore"},{"name":"School of Physical and Mathematical Science, Nanyang Technological University"},{"name":"Duke-NUS Medical School"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"266","published-online":{"date-parts":[[2026,6,30]]},"reference":[{"key":"pmbae7954bib1","doi-asserted-by":"publisher","DOI":"10.1002\/mp.18050","type":"journal-article","article-title":"Quality assurance of the inter-spot beam delivery of a dose driven continuous scanning proton therapy system","volume":"52","author":"Chua","year":"2025a","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":"2026-02-01","name":"date_received","label":"Date Received","group":{"name":"publication_dates","label":"Publication dates"}},{"value":"2026-06-05","name":"date_accepted","label":"Date Accepted","group":{"name":"publication_dates","label":"Publication dates"}},{"value":"2026-06-30","name":"date_epub","label":"Online publication date","group":{"name":"publication_dates","label":"Publication dates"}}]}}