{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,29]],"date-time":"2026-07-29T12:20:11Z","timestamp":1785327611898,"version":"3.55.0"},"reference-count":28,"publisher":"Wiley","issue":"6","license":[{"start":{"date-parts":[[2025,3,19]],"date-time":"2025-03-19T00:00:00Z","timestamp":1742342400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["aapm.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["J Applied Clin Med Phys"],"published-print":{"date-parts":[[2025,6]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Background<\/jats:title><jats:p>The dose\u2010averaged linear energy transfer (LET<jats:sub>D<\/jats:sub>) in proton therapy (PT) has in pre\u2010clinical studies been linked to the relative biological effectiveness (RBE) of protons. Until recently, the most common PT delivery method in prostate cancer has been double\u2010scattered PT, with LET<jats:sub>D<\/jats:sub> only available through dedicated Monte Carlo (MC) simulations. However, as most studies of the relationship between LET<jats:sub>D<\/jats:sub> and RBE in double scattered PT have been focused on the head and neck region, existing MC implementations have not been capable of calculating LET<jats:sub>D<\/jats:sub> for the longer field ranges used, for example, in the pelvic region.<\/jats:p><\/jats:sec><jats:sec><jats:title>Purpose<\/jats:title><jats:p>The initial aim of this study was to implement a MC code allowing for LET<jats:sub>D<\/jats:sub> calculations in double\u2010scattered PT of prostate cancer. Additionally, we explored LET<jats:sub>D<\/jats:sub> profiles and LET<jats:sub>D<\/jats:sub> as a function of field configuration, by performing MC calculations for a large prostate cancer cohort treated with double\u2010scattered PT.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>The components of a passive scattered clinical treatment nozzle used for delivery of extended field ranges, with two associated modulation wheels, were implemented into an existing FLUKA MC framework for LET<jats:sub>D<\/jats:sub> calculations. The code was validated to spread out Bragg peak (SOBP) measurements conducted using the treatment nozzle with 11 different range and modulation width configurations. After validation, LET<jats:sub>D<\/jats:sub> distributions were calculated on the planning computed tomographies of 582 prostate cancer patients treated with two\u2010field double\u2010scattered PT. All patients had symmetric field configurations with respect to the sagittal plane, with one pair of posterior oblique, lateral opposing, or anterior oblique fields. Dose and LET<jats:sub>D<\/jats:sub> volume parameters and the mean LET<jats:sub>D<\/jats:sub> ratio between the bladder and rectum were compared across the three groups.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>The range differences were below 1\u00a0mm for all SOBP scenarios used for calibration. For 9 of 11 SOBP scenarios, the modulation width differences were below 2\u00a0mm. For the patient simulations, the mean gamma pass rates (3\u00a0mm\/3%) were at least 98% in the PTV, bladder, and rectum. Comparing anterior to posterior field configurations, the mean LET<jats:sub>D<\/jats:sub> in the bladder increased within both the 10 and 70\u00a0Gy iso\u2010dose regions, and conversely, the mean LET<jats:sub>D<\/jats:sub> decreased for the rectum. There was a marked difference in the mean bladder\u2010to\u2010rectum LET<jats:sub>D<\/jats:sub> ratios between anterior oblique, lateral opposing and posterior oblique field configurations.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>A MC code allowing for accurate calculations of dose and LET<jats:sub>D<\/jats:sub> in double\u2010scattered PT of prostate cancer was implemented and validated. The LET<jats:sub>D<\/jats:sub> distributions in the rectum and bladder showed a systematic dependence on the field configuration.<\/jats:p><\/jats:sec>","DOI":"10.1002\/acm2.70032","type":"journal-article","created":{"date-parts":[[2025,3,19]],"date-time":"2025-03-19T06:41:10Z","timestamp":1742366470000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Modelling of a double\u2010scattering proton therapy nozzle using the FLUKA Monte Carlo code and analysis of linear energy transfer in patients treated for prostate cancer"],"prefix":"10.1002","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0009-0000-5382-6592","authenticated-orcid":false,"given":"Rasmus","family":"Klitgaard","sequence":"first","affiliation":[{"name":"Danish Centre for Particle Therapy Aarhus University  Aarhus N Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lars Fredrik","family":"Fj\u00e6ra","sequence":"additional","affiliation":[{"name":"Department of Medical Physics Oslo University Hospital  Oslo Norway"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Camilla Hanquist","family":"Stokkev\u00e5g","sequence":"additional","affiliation":[{"name":"Department of Physics and Technology University of Bergen  Bergen Norway"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Perry","family":"Johnson","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology College of Medicine University of Florida Health  Jacksonville Florida USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mark","family":"Artz","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology College of Medicine University of Florida Health  Jacksonville Florida USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nancy Price","family":"Mendenhall","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology College of Medicine University of Florida Health  Jacksonville Florida USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Curtis","family":"Bryant","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology College of Medicine University of Florida Health  Jacksonville Florida USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ludvig Paul","family":"Muren","sequence":"additional","affiliation":[{"name":"Danish Centre for Particle Therapy Aarhus University  Aarhus N Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2025,3,19]]},"reference":[{"key":"e_1_2_9_2_1","unstructured":"Protons vs. Photons for High\u2010risk Prostate Cancer. 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