title: A new shielding calculation method for X-ray computed tomography regarding scattered radiation.
abstract: The goal of this study is to develop a more appropriate shielding calculation method for computed tomography (CT) in comparison with the Japanese conventional (JC) method and the National Council on Radiation Protection and Measurements (NCRP)-dose length product (DLP) method. Scattered dose distributions were measured in a CT room with 18 scanners (16 scanners in the case of the JC method) for one week during routine clinical use. The radiation doses were calculated for the same period using the JC and NCRP-DLP methods. The mean (NCRP-DLP-calculated dose)/(measured dose) ratios in each direction ranged from 1.7 ± 0.6 to 55 ± 24 (mean ± standard deviation). The NCRP-DLP method underestimated the dose at 3.4% in fewer shielding directions without the gantry and a subject, and the minimum (NCRP-DLP-calculated dose)/(measured dose) ratio was 0.6. The reduction factors were 0.036 ± 0.014 and 0.24 ± 0.061 for the gantry and couch directions, respectively. The (JC-calculated dose)/(measured dose) ratios ranged from 11 ± 8.7 to 404 ± 340. The air kerma scatter factor κ is expected to be twice as high as that calculated with the NCRP-DLP method and the reduction factors are expected to be 0.1 and 0.4 for the gantry and couch directions, respectively. We, therefore, propose a more appropriate method, the Japanese-DLP method, which resolves the issues of possible underestimation of the scattered radiation and overestimation of the reduction factors in the gantry and couch directions.
authors.affiliation: Department of Radiological Technology, Japan Organization of Occupational Health and Safety Yokohama Rosai Hospital, 3211, Kozukue, Kohoku, Yokohama, Kanagawa, 222-0036, Japan. hiwatanabe-jsnmt@umin.ac.jp.|Graduate School of Health Science, Suzuka University of Medical Science, 1001-1, Kishioka, Suzuka, Mie, 510-0293, Japan. hiwatanabe-jsnmt@umin.ac.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Watanabe
authors.affiliation: Department of Radiology, Kanazawa University Hospital, 13-1, Takaramachi, Kanazawa, Ishikawa, 920-8641, Japan.
authors.forename: Kimiya
authors.initials: K
authors.lastname: Noto
authors.affiliation: Department of Radiology, The Jikei University Kashiwa Hospital, 163-1 Kashiwashita, Kashiwa, Chiba, 277-8567, Japan.
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Shohji
authors.affiliation: Department of Imaging Center, St. Marianna University School of Medicine Hospital, 2-16-1, Sugao, Miyame, Kawasaki, Kanagawa, 216-8511, Japan.
authors.forename: Yasuyoshi
authors.initials: Y
authors.lastname: Ogawa
authors.affiliation: Medical Quantum Science, Department of Health Sciences, Faculty of Medical Sciences, Graduate School of Medical Sciences, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Toshioh
authors.initials: T
authors.lastname: Fujibuchi
authors.affiliation: Department of Environmental Health, National Institute of Public Health, 2-3-6, Minami, Wako, Saitama, 351-0197, Japan.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Yamaguchi
authors.affiliation: Department of Radiological Technology, Teikyo University School of Medicine, University Hospital, Mizonokuchi, 3-8-3, Mizonokuchi, Takatsu-ku, Kawasaki City, Kanagawa, 213-8507, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Hiraki
authors.affiliation: Department of Radiology Service, Shiga University of Medical Science Hospital, Setatsukinowa-chou, Ootsu, Shiga, 520-2192, Japan.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Kida
authors.affiliation: Department of Radiology, Nippon Medical School Tama Nagayama Hospital, 1-7-1, Nagayama, Tama, Tokyo, 206-8512, Japan.
authors.forename: Kazutoshi
authors.initials: K
authors.lastname: Sasanuma
authors.affiliation: Department of Medical Technology, Tokai University of Medical Science Hospital, 143, Shimokasuya, Isehara, Kanagawa, 259-1143, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Katsunuma
authors.affiliation: Diagnostic Imaging, Kawasaki Municipal Tama Hospital, 1-30-37, Syukugawara, Tama-ku, Kawasaki, Kanagawa, 214-8525, Japan.
authors.forename: Takurou
authors.initials: T
authors.lastname: Nakano
authors.affiliation: Department of Nuclear Medicine and Tracer Kinetics, Osaka University Graduate School of Medicine, 2-2, Yamadaoka, Suita, Osaka, 565-0871, Japan.
authors.forename: Genki
authors.initials: G
authors.lastname: Horitsugi
authors.affiliation: Department of Radiology, Kindai University Faculty of Medicine, 377-2, Ohno-Higashi, Osaka-Sayama, Osaka, 589-8511, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Hosono
mesh_terms: D011829:Radiation Dosage; D011835:Radiation Protection; D012542:Scattering, Radiation; D014057:Tomography, X-Ray Computed
keywords: Air kerma scatter factor; Computed tomography; Dose length product; Shielding calculation method; Workload