{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,31]],"date-time":"2026-03-31T01:25:24Z","timestamp":1774920324677,"version":"3.50.1"},"reference-count":17,"publisher":"Korean Society for Therapeutic Radiology and Oncology","issue":"1","license":[{"start":{"date-parts":[[2026,3,26]],"date-time":"2026-03-26T00:00:00Z","timestamp":1774483200000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/3.0\/"}],"content-domain":{"domain":["e-roj.org"],"crossmark-restriction":true},"short-container-title":["Radiat Oncol J"],"published-print":{"date-parts":[[2026,3,31]]},"abstract":"<jats:p>Purpose: This study aimed to develop and validate a 10-point, threshold-based variation score (VS) that integrates magnetic resonance imaging (MRI)\u2013derived spacer morphology and assesses its association with rectal dose after low-dose-rate (LDR) prostate brachytherapy.Materials and Methods: We retrospectively studied 149 men treated with iodine-125 LDR brachytherapy and polyethylene-glycol spacers (August 2022\u2013April 2023). Using day 30 fused computed tomography\u2013MRI, the VS assigned one point each for total volume &gt;5 mL; hemisphere volumes (apex, base, left, and right) &gt;5 mL; midgland thickness &gt;5 mm; and thickness &gt;5 mm 1-cm toward apex, base, left, and right. Univariable linear regression tested VS versus change in rectal D1cc (maximum dose to 1 mL). Bonferroni-adjusted Fisher's exact tests evaluated component differences across prespecified VS thresholds (\u22656, \u22658, and 10).Results: Median rectal D1cc decreased from 92.4% pre-spacer to 53.4% of prescription at day 30. Each one-point higher VS was associated with 5.4 Gy lower D1cc (95% confidence interval, 3.4 to 7.4; p &lt; 0.001, R\u00b2 = 0.166). Threshold analyses identified key contributors: midgland separation distinguished VS &lt;6 from 6\u20137 (adequacy 57%\u2192100%; adjusted p = 0.026); uniform directional thickness, especially apical, distinguished 6\u20137 from 8\u20139 (22%\u219291%; adjusted p &lt; 0.001); apical volume &gt;5 mL was required for VS = 10 (19%\u2192100%; adjusted p &lt; 0.001).Conclusion: VS is a simple, objective metric linking spacer morphology with rectal dose reduction. Threshold-oriented targets, midgland separation for VS \u2265 6, uniform thickness for VS \u2265 8, and robust apical volume for VS = 10, may guide technical optimization and quality assurance in prostate LDR brachytherapy.<\/jats:p>","DOI":"10.3857\/roj.2025.00619","type":"journal-article","created":{"date-parts":[[2026,3,25]],"date-time":"2026-03-25T22:56:16Z","timestamp":1774479376000},"page":"69-78","update-policy":"https:\/\/doi.org\/10.3857\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Morphological variation in rectal hydrogel spacer one month after insertion during low-dose-rate brachytherapy for prostate adenocarcinoma"],"prefix":"10.3857","volume":"44","author":[{"given":"Hyeok","family":"Choi","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Seo Jin","family":"Lee","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yeonok","family":"Park","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Wooshik","family":"Kim","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ho","family":"Lee","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jaeho","family":"Cho","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"2224","reference":[{"key":"ref1","doi-asserted-by":"publisher","DOI":"10.1111\/j.1464-410x.2011.10827.x"},{"key":"ref2","doi-asserted-by":"publisher","DOI":"10.1016\/j.ijrobp.2015.04.030"},{"key":"ref3","doi-asserted-by":"publisher","DOI":"10.1016\/j.ijrobp.2016.12.024"},{"key":"ref4","doi-asserted-by":"publisher","DOI":"10.5114\/jcb.2021.112110"},{"key":"ref5","doi-asserted-by":"publisher","DOI":"10.1186\/s13256-021-02864-9"},{"key":"ref6","doi-asserted-by":"publisher","DOI":"10.1016\/j.prro.2021.09.015"},{"key":"ref7","doi-asserted-by":"publisher","DOI":"10.14338\/ijpt-18-00041.1"},{"key":"ref8","doi-asserted-by":"publisher","DOI":"10.1186\/s13014-018-1135-6"},{"key":"ref9","doi-asserted-by":"publisher","DOI":"10.1016\/j.prro.2016.10.004"},{"key":"ref10","doi-asserted-by":"publisher","DOI":"10.1016\/j.adro.2023.101396"},{"key":"ref11","doi-asserted-by":"publisher","DOI":"10.1016\/j.ctro.2021.05.003"},{"key":"ref12","doi-asserted-by":"publisher","DOI":"10.1007\/s11604-023-01506-y"},{"key":"ref13","doi-asserted-by":"publisher","DOI":"10.1016\/j.prro.2023.05.013"},{"key":"ref14","doi-asserted-by":"publisher","DOI":"10.3389\/fonc.2024.1386058"},{"key":"ref15","doi-asserted-by":"publisher","DOI":"10.1016\/j.prro.2023.08.009"},{"key":"ref16","doi-asserted-by":"publisher","DOI":"10.1016\/j.ijrobp.2024.07.2145"},{"key":"ref17","first-page":"105","volume-title":"Quantitative evaluation of volume change of perirectal hydrogel spacer by Dixon-based water-only images","author":"Hama","year":"2022"}],"container-title":["Radiation Oncology Journal"],"original-title":[],"language":"en","link":[{"URL":"http:\/\/e-roj.org\/upload\/pdf\/roj-2025-00619.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"http:\/\/e-roj.org\/journal\/view.php?doi=10.3857\/roj.2025.00619","content-type":"unspecified","content-version":"vor","intended-application":"text-mining"},{"URL":"http:\/\/e-roj.org\/upload\/pdf\/roj-2025-00619.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,3,31]],"date-time":"2026-03-31T00:21:04Z","timestamp":1774916464000},"score":1,"resource":{"primary":{"URL":"http:\/\/e-roj.org\/journal\/view.php?doi=10.3857\/roj.2025.00619"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,3,31]]},"references-count":17,"journal-issue":{"issue":"1","published-print":{"date-parts":[[2026,3]]}},"URL":"https:\/\/doi.org\/10.3857\/roj.2025.00619","relation":{},"ISSN":["2234-1900","2234-3156"],"issn-type":[{"value":"2234-1900","type":"print"},{"value":"2234-3156","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,3,31]]},"assertion":[{"value":"2025-09-18","order":0,"name":"received","label":"Received","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-01-26","order":1,"name":"accepted","label":"Accepted","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-03-26","order":2,"name":"published","label":"Published online","group":{"name":"publication_history","label":"Publication History"}},{"value":"2026-03-31","order":3,"name":"published","label":"Print publication","group":{"name":"publication_history","label":"Publication History"}}]}}