{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,13]],"date-time":"2026-03-13T12:32:44Z","timestamp":1773405164173,"version":"3.50.1"},"reference-count":22,"publisher":"Wiley","issue":"1","license":[{"start":{"date-parts":[[2008,1,28]],"date-time":"2008-01-28T00:00:00Z","timestamp":1201478400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J Applied Clin Med Phys"],"published-print":{"date-parts":[[2008,12]]},"abstract":"<jats:p>To analyze the magnitude of setup errors corrected by helical tomotherapy megavoltage computed tomography (MVCT) on a daily or weekly basis and the impact of those corrections on the delivered dose to the tumor and organs at risk (OARs), we retrospectively analyzed the setup errors for 6 nasal cavity and 4 nasopharyngeal cancer patients treated with helical tomotherapy for 25 \u2013 33 fractions. Each patient had MVCT\u2010guided repositioning for all fractions of treatment. The new dose\u2013volume histograms (DVHs) and equivalent uniform doses (EUDs) for the planning target volume (PTV) and OARs were calculated for hypothetical situations in which no imaging guidance (IG) or once\u2010weekly imaging guidance (WIG) took place. The mean total setup error for treatment without daily IG was <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/acm20036-math-0001.png\" xlink:title=\"urn:x-wiley:15269914:acm20036:equation:acm20036-math-0001\"\/> mm, which could be reduced to <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/acm20036-math-0002.png\" xlink:title=\"urn:x-wiley:15269914:acm20036:equation:acm20036-math-0002\"\/> mm if WIG were to be performed. The geometric uncertainties from the absence of IG resulted in a reduction of mean PTV EUD by <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/acm20036-math-0003.png\" xlink:title=\"urn:x-wiley:15269914:acm20036:equation:acm20036-math-0003\"\/>, which could be reduced to <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/acm20036-math-0004.png\" xlink:title=\"urn:x-wiley:15269914:acm20036:equation:acm20036-math-0004\"\/> with WIG. The EUDs of the OARs increased to <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/acm20036-math-0005.png\" xlink:title=\"urn:x-wiley:15269914:acm20036:equation:acm20036-math-0005\"\/> Gy or <jats:inline-graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" xlink:href=\"graphic\/acm20036-math-0006.png\" xlink:title=\"urn:x-wiley:15269914:acm20036:equation:acm20036-math-0006\"\/> Gy without and with WIG respectively. Without daily IG, the mean uncertainty in patient position has a relatively small effect on the mean dosimetry for PTV and OARs, and the use of WIG can further reduce those effects by approximately half. On the other hand, because of the large variance, with low probability, substantial deviation from the original planned dosimetry may occur without IG. Therefore, daily MVCT is preferred as an important safety measure in the delivery of intensity\u2010modulated radiation therapy.<\/jats:p><jats:p>PACS number: 87.53.Dq<\/jats:p>","DOI":"10.1120\/jacmp.v9i1.2686","type":"journal-article","created":{"date-parts":[[2008,4,30]],"date-time":"2008-04-30T18:49:52Z","timestamp":1209581392000},"page":"36-46","source":"Crossref","is-referenced-by-count":17,"title":["Is daily computed tomography image guidance necessary for nasal cavity and nasopharyngeal radiotherapy? An investigation based on helical tomotherapy"],"prefix":"10.1002","volume":"9","author":[{"given":"Ke","family":"Sheng","sequence":"first","affiliation":[{"name":"Department of Radiation Oncology University of Virginia  Charlottesville Virginia U.S.A."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jennifer","family":"Chow","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology University of Virginia  Charlottesville Virginia U.S.A."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Grant","family":"Hunter","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology University of Virginia  Charlottesville Virginia U.S.A."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"James","family":"Larner","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology University of Virginia  Charlottesville Virginia U.S.A."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Paul","family":"Read","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology University of Virginia  Charlottesville Virginia U.S.A."}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2008,1,28]]},"reference":[{"key":"e_1_2_6_2_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0360-3016(02)02724-4"},{"key":"e_1_2_6_3_1","doi-asserted-by":"publisher","DOI":"10.1259\/bjr.73.869.10884741"},{"key":"e_1_2_6_4_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0360-3016(99)00247-3"},{"key":"e_1_2_6_5_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0360-3016(00)00585-X"},{"key":"e_1_2_6_6_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0360-3016(00)01389-4"},{"key":"e_1_2_6_7_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0360-3016(00)00702-1"},{"key":"e_1_2_6_8_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0167-8140(00)00280-2"},{"key":"e_1_2_6_9_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0167-8140(00)00260-7"},{"key":"e_1_2_6_10_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ijrobp.2004.07.696"},{"key":"e_1_2_6_11_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0360-3016(01)01740-0"},{"key":"e_1_2_6_12_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0360-3016(97)00229-0"},{"key":"e_1_2_6_13_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0360-3016(01)02805-X"},{"key":"e_1_2_6_14_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031-9155\/47\/19\/302"},{"key":"e_1_2_6_15_1","doi-asserted-by":"publisher","DOI":"10.1088\/0031-9155\/50\/15\/003"},{"key":"e_1_2_6_16_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.ijrobp.2006.02.038"},{"key":"e_1_2_6_17_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.radonc.2007.01.008"},{"key":"e_1_2_6_18_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0167-8140(00)00192-4"},{"key":"e_1_2_6_19_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.599023"},{"key":"e_1_2_6_20_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.598063"},{"key":"e_1_2_6_21_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0360-3016(01)02585-8"},{"key":"e_1_2_6_22_1","doi-asserted-by":"publisher","DOI":"10.1118\/1.2349698"},{"key":"e_1_2_6_23_1","first-page":"265","volume-title":"A pyramid approach to sub\u2010pixel image fusion based on mutual information. 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