{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,9]],"date-time":"2026-03-09T05:30:40Z","timestamp":1773034240740,"version":"3.50.1"},"reference-count":23,"publisher":"Oxford University Press (OUP)","issue":"6","license":[{"start":{"date-parts":[[2025,10,16]],"date-time":"2025-10-16T00:00:00Z","timestamp":1760572800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2025,11,25]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>This study evaluates current practices and challenges associated with computed tomography number-to-mass density (CT\u2013MD) conversion tables in helical tomotherapy across Japan and explores directions for standardization and quality improvement amid the increasing adoption of adaptive radiotherapy (ART). A nationwide web-based survey was conducted across 34 institutions utilizing the Radixact system. Data were collected on CT acquisition protocols, calibration phantoms, density plugs, reconstruction algorithms, table registration timing and quality assurance (QA) frequency. Registered CT\u2013MD tables were categorized by CT modality: Simulation CT (SimCT), ClearRT and CTrue. ClearRT tables were analyzed by phantom setup (full vs half), and CTrue tables by reconstruction method [filtered back projection (FPB) vs iterative reconstruction (IR)]. Inter-institutional variations in CT numbers and the number of data points were assessed. SimCT tables exhibited the widest variation in the number of data points (median\u2009=\u200910) and high-density CT numbers. ClearRT tables (median\u2009=\u20098) showed variations of up to 300 Hounsfield units (HU) in cortical bone; the half-phantom setup reduced inter-institutional variability. CTrue tables (median\u2009=\u20098) demonstrated high consistency, with negligible differences between IR and FPB. All plug CT numbers of CTrue remained within the tolerance defined by the American Association of Physicists in Medicine Task Group 148. However, CT numbers for air plugs varied by ~\u00b130 HU, indicating inconsistent handling of air reference values. Additionally, 43% of institutions did not perform routine QA. Standardizing phantom geometry, air CT number handling and QA protocols\u2014particularly using half-phantom calibration\u2014may improve CT\u2013MD table consistency and dose accuracy in ART.<\/jats:p>","DOI":"10.1093\/jrr\/rraf063","type":"journal-article","created":{"date-parts":[[2025,9,15]],"date-time":"2025-09-15T11:27:25Z","timestamp":1757935645000},"page":"606-616","source":"Crossref","is-referenced-by-count":1,"title":["Inter-institutional variability in CT-to-mass-density conversion tables for helical tomotherapy: a national survey in Japan"],"prefix":"10.1093","volume":"66","author":[{"ORCID":"https:\/\/orcid.org\/0009-0001-4471-0237","authenticated-orcid":false,"given":"Shogo","family":"Tsunemine","sequence":"first","affiliation":[{"name":"Department of Radiation and Proton Office, Shizuoka Cancer Center , 1007 Shimonagakubo, Nagaizumi-cho, Sunto-gun, Shizuoka 411-8777 ,","place":["Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5459-9846","authenticated-orcid":false,"given":"Shuichi","family":"Ozawa","sequence":"additional","affiliation":[{"name":"Hiroshima High-Precision Radiotherapy Cancer Center , 3-2-2 Futabanosato, Higashi-ku, Hiroshima 732-0057 ,","place":["Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ryosei","family":"Nakada","sequence":"additional","affiliation":[{"name":"Department of Radiation and Proton Office, Shizuoka Cancer Center , 1007 Shimonagakubo, Nagaizumi-cho, Sunto-gun, Shizuoka 411-8777 ,","place":["Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yasuo","family":"Shiota","sequence":"additional","affiliation":[{"name":"Division of Medical Physics, Iwata City Hospital , 512-3 Okubo, Iwata, Shizuoka 438-0002 ,","place":["Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Satoshi","family":"Kito","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology, Department of Radiology, Metropolitan Cancer and Infectious Disease Center Komagome Hospital , Tokyo, 3-18-22 Honkomagome, Bunkyo-ku, Tokyo 113-8677 ,","place":["Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6633-0964","authenticated-orcid":false,"given":"Hidetoshi","family":"Shimizu","sequence":"additional","affiliation":[{"name":"Division of Medical Physics, School of Medical Sciences, Fujita Health University , 1-98 Dengakugakubo, Kutsukake-cho, Toyoake, Aichi 470-1192 ,","place":["Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Takashi","family":"Hashido","sequence":"additional","affiliation":[{"name":"Department of Medical Physics and Engineering, Division of Health Sciences, The University of Osaka Graduate School of Medicine , 2-15 Yamadaoka, Suita, Osaka 565-0871 ,","place":["Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Takehiro","family":"Shiinoki","sequence":"additional","affiliation":[{"name":"Department of Radiation Oncology, Yamaguchi University Graduate School of Medicine ,","place":["1-1-1 Minami-Kogushi, Ube, Yamaguchi 755-0046, Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yuto","family":"Kitagawa","sequence":"additional","affiliation":[{"name":"Department of Radiology, Nagoya City University Hospital , 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8602 ,","place":["Japan"]}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hiroshi","family":"Fukuma","sequence":"additional","affiliation":[{"name":"Department of Radiology, Nagoya City University Hospital , 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8602 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