{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,20]],"date-time":"2026-08-20T15:03:29Z","timestamp":1787238209460,"version":"build-2736575974"},"reference-count":34,"publisher":"IOP Publishing","issue":"3","license":[{"start":{"date-parts":[[2026,2,4]],"date-time":"2026-02-04T00:00:00Z","timestamp":1770163200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,2,4]],"date-time":"2026-02-04T00:00:00Z","timestamp":1770163200000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/iopscience.iop.org\/info\/page\/text-and-data-mining"}],"funder":[{"name":"Duke-NUS Oncology Academic Program Goh Foundation Proton Research Programme","award":["08\/FY2023\/EX(SL)\/163-A218(b)"],"award-info":[{"award-number":["08\/FY2023\/EX(SL)\/163-A218(b)"]}]},{"name":"Clinical & Systems Innovation Support \u2013 Innovation Seed Grant","award":["08\/FY2022\/P2\/02-A68"],"award-info":[{"award-number":["08\/FY2022\/P2\/02-A68"]}]}],"content-domain":{"domain":["iopscience.iop.org"],"crossmark-restriction":false},"short-container-title":["Phys. Med. Biol."],"published-print":{"date-parts":[[2026,2,14]]},"abstract":"Abstract<\/jats:title>\n \n Objective.<\/jats:italic>\n Adaptive radiotherapy aimed to account for inter- and intra-fractional anatomical changes to improve target coverage and spare normal tissues. Commercial softwares could quantify anatomical and setup differences between planning computed tomography (pCT) and image-guidance cone-beam computed tomography (CBCT) using density gamma passing rate (dGPR). This study evaluated the utility of dGPR as an automated, site-specific trigger for offline adaptive workflows, using statistical process control (SPC) to define tolerance thresholds and correlating dGPR with setup errors, planning target volume (PTV) coverage, and longitudinal stability.\n Approach.<\/jats:italic>\n 240 patients across six anatomical sites were retrospectively analysed. First-fraction CBCTs were compared to pCTs using MobiusCB to compute dGPR. SPC analysis was performed to establish site-specific tolerance limits. Rigid phantom studies were conducted to quantify dGPR sensitivity to setup errors. Correlation between dGPR and PTV\n V<\/jats:italic>\n 100%<\/jats:sub>\n was assessed in patients with repeat CTs, and longitudinal stability of dGPR across fractions was evaluated.\n Main results.<\/jats:italic>\n SPC-derived lower action limits (\n \n \n \n <\/jats:tex-math>\n \n \n \n \n A<\/mml:mi>\n \n l<\/mml:mtext>\n <\/mml:mrow>\n <\/mml:msub>\n <\/mml:mrow>\n <\/mml:mrow>\n <\/mml:math>\n <\/jats:inline-formula>\n ) ranged from 97.3% (brain) to 82.2% (breast), reflecting site-specific anatomical variability and imaging protocols. Phantom studies verified dGPR sensitivity due to rigid shifts, with head dGPR decreasing to as low as 83.5% at 8 mm translation, while pelvis dGPR remained above 93.2% for the same shift, reflecting greater tolerance due to its larger volume. In head-and-neck patients, dGPR correlated moderately with changes in PTV\n V<\/jats:italic>\n 100%<\/jats:sub>\n (\n r<\/jats:italic>\n = 0.56), with no coverage losses >10% observed when dGPR exceeded 90%. Longitudinal analysis showed stable dGPR for most sites, but gradual declines in head-and-neck patients, with some values falling below SPC-derived threshold of 94.3% towards the end of treatment.\n Significance.<\/jats:italic>\n dGPR offered a practical, automated, and site-specific metric for detecting anatomical changes and setup errors during radiotherapy. SPC-derived thresholds provided robust action levels tailored to each site, and MobiusCB enabled automated alerts when thresholds were exceeded, reducing reliance on subjective image inspection.\n <\/jats:p>","DOI":"10.1088\/1361-6560\/ae3c55","type":"journal-article","created":{"date-parts":[[2026,1,22]],"date-time":"2026-01-22T22:53:03Z","timestamp":1769122383000},"page":"035008","update-policy":"https:\/\/doi.org\/10.1088\/crossmark-policy","source":"Crossref","is-referenced-by-count":1,"title":["Statistical process control of CBCT density gamma analysis as a clinical trigger for offline adaptive radiotherapy"],"prefix":"10.1088","volume":"71","author":[{"ORCID":"https:\/\/orcid.org\/0009-0004-0061-5889","authenticated-orcid":true,"given":"Ping Lin","family":"Yeap","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Melvin Ming Long","family":"Chew","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1564-2087","authenticated-orcid":true,"given":"Yun Ming","family":"Wong","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0005-5350-9630","authenticated-orcid":true,"given":"Geoffvinc","family":"Ng","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1824-2724","authenticated-orcid":true,"given":"Kang Hao","family":"Lee","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Clifford Ghee Ann","family":"Chua","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Calvin Wei Yang","family":"Koh","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"James Cheow Lei","family":"Lee","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7878-4544","authenticated-orcid":true,"given":"Hong Qi","family":"Tan","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"266","published-online":{"date-parts":[[2026,2,4]]},"reference":[{"key":"pmbae3c55bib1","doi-asserted-by":"publisher","first-page":"691","DOI":"10.1109\/TRPMS.2025.3533749","type":"journal-article","article-title":"Synthetic CT image generation from CBCT: a systematic review","volume":"9","author":"Altalib","year":"2025","journal-title":"IEEE Trans. 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