{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T14:23:47Z","timestamp":1787927027492,"version":"build-2784847793"},"reference-count":27,"publisher":"IOP Publishing","issue":"3","license":[{"start":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T00:00:00Z","timestamp":1787875200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/publishingsupport.iopscience.iop.org\/iop-standard\/v1"},{"start":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T00:00:00Z","timestamp":1787875200000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/iopscience.iop.org\/info\/page\/text-and-data-mining"},{"start":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T00:00:00Z","timestamp":1787875200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/publishingsupport.iopscience.iop.org\/questions\/alternative-author-rights-policies\/"},{"start":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T00:00:00Z","timestamp":1787875200000},"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":["J. Radiol. Prot."],"published-print":{"date-parts":[[2026,9,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>\n                    Monte Carlo simulation of secondary neutron and photon dosimetry\n                    <jats:bold>\u2014<\/jats:bold>\n                    specifically the ambient dose equivalent H*(10)\n                    <jats:bold>\u2014<\/jats:bold>\n                    is central to radiation protection in pencil-beam scanning (PBS) proton therapy. We report particle and heavy ion transport code system (PHITS) version 3.35 calculations of H*(10) for proton beams from 70 to 250MeV incident on a water phantom representative of the Ion Beam Applications Blue Phantom, scored at 11 emission angles at 80 cm using International Commission on Radiological Protection Publication 74 fluence-to-dose conversion coefficients. Results are normalised to peak absorbed dose, yielding the quantity H*(10)\/D [nSv Gy\n                    <jats:sup>\u22121<\/jats:sup>\n                    ] relevant to facility shielding and patient out-of-field dose estimation. The distal Bragg-peak range R80 was benchmarked against independent Geant4\/Gate calculations, agreeing within \u22120.56% to \u22123.61% and meeting the \u00b13% clinical criterion for energies\u2a7e 100MeV. Enabling the low-energy neutron event-generator mode changed secondary-neutron yields by less than 0.2%, indicating that default settings are adequate for these radiation-protection estimates. The H*(10)\/D angular distribution showed a forward maximum near 40\u00b0 and a backward maximum at 180\u00b0; the forward-to-lateral ratio H*(40\u00b0)\/H*(90\u00b0) rose from 1.1 at 70 MeV to 2.5 at 250MeV\n                    <jats:bold>\u2014<\/jats:bold>\n                    the forward peak becoming the global maximum above 150 MeV\n                    <jats:bold>\u2014<\/jats:bold>\n                    while neutrons exceeded photons at 90\u00b0 by factors of 22.9\n                    <jats:bold>\u2013<\/jats:bold>\n                    56.2. A representative PBS nozzle model was added to quantify the effect of beam-line components; the simulated forward energy dependence and neutron spectral composition agree with published pencil-beam-scanning measurements, while absolute magnitudes remain lower owing to the single-pencil bare-phantom geometry. For a 150 MeV spread-out Bragg peak, H*(10)\/D was 4.8\n                    <jats:bold>\u2013<\/jats:bold>\n                    6.2\u00d7 higher than the monoenergetic beam, reflecting the larger number of protons required per unit dose. The dose-normalised dataset provides a systematic, practical reference for PHITS users in proton therapy radiation protection.\n                  <\/jats:p>","DOI":"10.1088\/1361-6498\/ae9aa5","type":"journal-article","created":{"date-parts":[[2026,8,17]],"date-time":"2026-08-17T22:47:57Z","timestamp":1787006877000},"page":"031528","update-policy":"https:\/\/doi.org\/10.1088\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Angular distributions of secondary neutron and photon ambient dose equivalent in proton therapy: a systematic PHITS 3.35 study at 70\u2013250 MeV"],"prefix":"10.1088","volume":"46","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7787-9258","authenticated-orcid":true,"given":"Thi Yen Hong","family":"Huynh","sequence":"first","affiliation":[{"name":"University of Science"},{"name":"University of Science"},{"name":"Vietnam National University"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9952-1118","authenticated-orcid":true,"given":"Huu Ngan Thy","family":"Truong","sequence":"additional","affiliation":[{"name":"University of Science"},{"name":"University of Science"},{"name":"Vietnam National University"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hong Hai","family":"Vo","sequence":"additional","affiliation":[{"name":"University of Science"},{"name":"Vietnam National University"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hoa Lang","family":"Trinh","sequence":"additional","affiliation":[{"name":"University of Science"},{"name":"Vietnam National University"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"266","published-online":{"date-parts":[[2026,8,28]]},"reference":[{"key":"jrpae9aa5bib1","author":"Paganetti","year":"2018","edition":"2nd edn","type":"book"},{"key":"jrpae9aa5bib2","article-title":"Particle therapy facilities in clinical operation (available at: www.ptcog.site)","author":"Particle Therapy Co-Operative Group (PTCOG)","year":"2024","type":"web-resource"},{"key":"jrpae9aa5bib3","doi-asserted-by":"publisher","first-page":"185","DOI":"10.1088\/0031-9155\/44\/1\/014","type":"journal-article","article-title":"Intensity modulation methods for proton radiotherapy","volume":"44","author":"Lomax","year":"1999","journal-title":"Phys. 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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":"2026-06-14","name":"date_received","label":"Date Received","group":{"name":"publication_dates","label":"Publication dates"}},{"value":"2026-08-17","name":"date_accepted","label":"Date Accepted","group":{"name":"publication_dates","label":"Publication dates"}},{"value":"2026-08-28","name":"date_epub","label":"Online publication date","group":{"name":"publication_dates","label":"Publication dates"}}]}}