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This retrospective study evaluated a\u00a0density-override optimization technique to mitigate dosimetric uncertainties caused by bowel air changes.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Materials and methods<\/jats:title>\n                    <jats:p>Planning CT and cone-beam CT data from 8\u00a0patients with locally advanced pancreatic cancer undergoing stereotactic ablative radiotherapy were analyzed. Treatment simulations used a\u00a0dose of 55.2\u00a0GyE in 12\u00a0fractions with a\u00a0four-field setup (anterior, lateral, posterior, posterior oblique). Four density-override patterns were compared: pattern\u00a00 (no override), pattern\u00a01 (replacing bowel gas with water), pattern\u00a02 (replacing the entire bowel with mean bowel HU), and pattern\u00a03 (replacing bowel gas with mean bowel HU). Dose evaluations included fraction-wise and accumulated dose analyses, focusing on target coverage, homogeneity index, and organs at risk doses.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Pattern\u00a02 achieved the largest clinical tumor volume coverage and the fewest fractions with\u202f&gt;\u20095% coverage loss for the anterior beam, followed by pattern\u00a03. However, pattern\u00a02 demonstrated poorer homogeneity for the lateral beam compared to patterns\u00a01 and\u00a03 and a\u00a0higher gastrointestinal (GI) dose for the anterior beam.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>This study evaluated the importance of density overrides to address bowel air variations. For patients where a\u00a0more uniform dose is desirable or whose tumor is adjacent to the GI tract, a\u00a0pattern\u00a03 density-override should be considered.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1007\/s00066-025-02450-8","type":"journal-article","created":{"date-parts":[[2025,8,21]],"date-time":"2025-08-21T07:26:19Z","timestamp":1755761179000},"page":"84-94","update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Carbon ion radiotherapy optimization techniques for pancreatic cancer: accounting for the effect of bowel gas variation"],"prefix":"10.1007","volume":"202","author":[{"given":"Chaebeom","family":"Sheen","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sunghyun","family":"Lee","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Bitbyeol","family":"Kim","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jaeman","family":"Son","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kyungsu","family":"Kim","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5046-4418","authenticated-orcid":false,"given":"Hyeongmin","family":"Jin","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"297","published-online":{"date-parts":[[2025,8,21]]},"reference":[{"issue":"9","key":"2450_CR1","doi-asserted-by":"publisher","first-page":"851","DOI":"10.1001\/jama.2021.13027","volume":"326","author":"W Park","year":"2021","unstructured":"Park\u00a0W, Chawla\u00a0A, O\u2019Reilly\u00a0EM (2021) Pancreatic cancer: a\u00a0review. 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