{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,25]],"date-time":"2026-09-25T05:00:40Z","timestamp":1790312440775,"version":"4.1.0"},"reference-count":20,"publisher":"Oxford University Press (OUP)","license":[{"start":{"date-parts":[[2026,9,25]],"date-time":"2026-09-25T00:00:00Z","timestamp":1790294400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>High geometric precision is essential in proton beam therapy (PBT) for pancreatic cancer. This study evaluated inter-fraction positional accuracy during image-guided PBT using radiopaque surrogates and assessed endoscopic ultrasound\u2013guided fiducial marker placement (EUS-FP). Patients with pancreatic cancer treated with PBT between 2020 and 2024 were retrospectively reviewed. The positional accuracy cohort included 58 patients with a radiopaque surrogate (fiducial marker group, n\u2009=\u200946; biliary stent group, n\u2009=\u200912). Major positional deviation was defined as a couch displacement \u22655\u00a0mm after bony alignment. Factors associated with major positional deviation were analyzed using generalized estimating equations. Oncologic outcomes were analyzed in patients with unresectable locally advanced (UR-LA) pancreatic cancer receiving concurrent chemoradiotherapy (n\u2009=\u200927). EUS-FP was technically successful in 45\/46 patients (98%), with mild adverse events in 13%. Major positional deviation occurred in 18.5%, 30.9% and 11.2% of setups in the left\u2013right, cranio-caudal and antero-posterior directions, respectively. Tumor location and disease status were independently associated with major positional deviation, whereas surrogate type was not. Pancreatic head tumors showed a higher risk than tail tumors, while UR-LA cases demonstrated greater positional stability. Overall survival from diagnosis did not differ significantly between surrogate groups; the median follow-up was 14.9\u00a0months. These findings indicate that positional deviation during PBT is primarily driven by tumor-related characteristics rather than the type of radiopaque surrogate used for image guidance. Although biliary stents may serve as radiopaque surrogates in selected cases, EUS-FP is a safe and reproducible technique enabling image-guided PBT.<\/jats:p>","DOI":"10.1093\/jrr\/rrag082","type":"journal-article","created":{"date-parts":[[2026,8,24]],"date-time":"2026-08-24T11:23:11Z","timestamp":1787570591000},"source":"Crossref","is-referenced-by-count":0,"title":["Endoscopic ultrasound\u2013guided fiducial marker placement for image-guided proton beam therapy in pancreatic cancer: implications for positional accuracy and position management"],"prefix":"10.1093","author":[{"given":"Kazunori","family":"Takeuchi","sequence":"first","affiliation":[{"name":"Department of Gastroenterology and Hepatology, Nagoya University Graduate School of Medicine , 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550 ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5814-3555","authenticated-orcid":false,"given":"Takuya","family":"Ishikawa","sequence":"additional","affiliation":[{"name":"Department of Gastroenterology and Hepatology, Nagoya University Graduate School of Medicine , 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550 ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2497-7740","authenticated-orcid":false,"given":"Kentaro","family":"Yamao","sequence":"additional","affiliation":[{"name":"Department of Gastroenterology and Hepatology, Nagoya University Graduate School of Medicine , 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550 ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4363-3161","authenticated-orcid":false,"given":"Yasuyuki","family":"Mizutani","sequence":"additional","affiliation":[{"name":"Department of Gastroenterology and Hepatology, Nagoya University Graduate School of Medicine , 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550 ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5491-6012","authenticated-orcid":false,"given":"Tadashi","family":"Iida","sequence":"additional","affiliation":[{"name":"Department of Endoscopy, Nagoya University Hospital , 65 Tsurumai-cho, Showa-ku, Nagoya 466-8560 ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1658-7304","authenticated-orcid":false,"given":"Yoshihisa","family":"Takada","sequence":"additional","affiliation":[{"name":"Department of Gastroenterology and Hepatology, Nagoya University Graduate School of Medicine , 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550 ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Masashi","family":"Tomida","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology, Narita Memorial Proton Center , 78 Shirakawa-cho, Toyohashi, Aichi 441-8021 ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3179-753X","authenticated-orcid":false,"given":"Takeshi","family":"Yanagi","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology, Narita Memorial Proton Center , 78 Shirakawa-cho, Toyohashi, Aichi 441-8021 ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuta","family":"Shibamoto","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology, Narita Memorial Proton Center , 78 Shirakawa-cho, Toyohashi, Aichi 441-8021 ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0003-6621-7114","authenticated-orcid":false,"given":"Takahiro","family":"Toyama","sequence":"additional","affiliation":[{"name":"Department of Gastroenterology, Narita Memorial Hospital , 134 Haneihonmachi, Toyohashi, Aichi 441-8029 ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2849-7779","authenticated-orcid":false,"given":"Kenji","family":"Yamao","sequence":"additional","affiliation":[{"name":"Department of Gastroenterology, Narita Memorial Hospital , 134 Haneihonmachi, Toyohashi, Aichi 441-8029 ,","place":["Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Makoto","family":"Narita","sequence":"additional","affiliation":[{"name":"Department of Gastroenterology, Narita Memorial Hospital , 134 Haneihonmachi, Toyohashi, Aichi 441-8029 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