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Using three fiducial markers in the prostate for image fusion, the displacement between the catheter and the guide-wire in the prostatic urethra was calculated. In 155 consecutive patients treated between 2011 and 2017, 5531 slices of RT-CT were evaluated.<\/jats:p>\n<\/jats:sec><jats:sec>\n<jats:title>Results<\/jats:title>\n<jats:p>Assuming that \u22653.0\u2009mm of difference between the catheter and the guide-wire position was a significant displacement, the urethra with the catheter was displaced significantly from the urethra with the guide-wire alone in &gt;\u200920% of the RT-CT slices in 23.2% (36\/155) of the patients. The number of patients who showed \u22653.0\u2009mm anterior displacement with the catheter in \u226520% RT-CT slices was significantly larger at the superior segment (38\/155) than at the middle (14\/155) and inferior segments (18\/155) of the prostatic urethra (<jats:italic>p<\/jats:italic>\u2009&lt;\u20090.0167).<\/jats:p>\n<\/jats:sec><jats:sec>\n<jats:title>Conclusions<\/jats:title>\n<jats:p>The urethral position with a Foley catheter is different from the urethral position with a thin and soft guide-wire in a significant proportion of the patients. This should be taken into account for the PRV of the urethra to ensure precise radiotherapy such as in urethra-sparing radiotherapy.<\/jats:p>\n<\/jats:sec>","DOI":"10.1186\/s13014-019-1424-8","type":"journal-article","created":{"date-parts":[[2019,12,12]],"date-time":"2019-12-12T17:05:02Z","timestamp":1576170302000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":20,"title":["The urethral position may shift due to urethral catheter placement in the treatment planning for prostate radiation therapy"],"prefix":"10.1186","volume":"14","author":[{"given":"Yasuhiro","family":"Dekura","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8272-7603","authenticated-orcid":false,"given":"Kentaro","family":"Nishioka","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Takayuki","family":"Hashimoto","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Naoki","family":"Miyamoto","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ryusuke","family":"Suzuki","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Takaaki","family":"Yoshimura","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ryuji","family":"Matsumoto","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Takahiro","family":"Osawa","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Takashige","family":"Abe","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yoichi M.","family":"Ito","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nobuo","family":"Shinohara","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hiroki","family":"Shirato","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shinichi","family":"Shimizu","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2019,12,12]]},"reference":[{"key":"1424_CR1","doi-asserted-by":"publisher","first-page":"2345","DOI":"10.1016\/j.ejca.2015.07.019","volume":"51","author":"RF Wolff","year":"2015","unstructured":"Wolff RF, Ryder S, Bossi A, Briganti A, Crook J, Henry A, et al. 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