title: Comparison of dosimetric properties among four commercial multi-detector computed tomography scanners.
abstract: This study compared dosimetric properties among four commercial multi-detector CT (MDCT) scanners. The X-ray beam characteristics were obtained from photon intensity attenuation curves of aluminum and off-center ratio (OCR) profiles in air, which were measured with four commercial MDCT scanners. The absorbed dose for MDCT scanners was evaluated with Farmer ionization chamber measurements at the center and four peripheral points in the body- and head-type cylindrical water phantoms. Measured collected charge was converted to absorbed dose using a60Co absorbed dose-to-water calibration factor and Monte Carlo (MC)-calculated correction factors. Four MDCT scanners were modeled to correspond with measured X-ray beam characteristics using GMctdospp (IMPS, Germany) software. Al half-value layers (Al-HVLs) with a body-bowtie filter determined from measured Al-attenuation curves ranged 7.2‒9.1mm at 120kVp and 6.1‒8.0mm at 100kVp. MC-calculated Al-HVLs and OCRs in air were in acceptable agreement within 0.5mm and 5% of measured values, respectively. The percentage difference between nominal and actual beam width was greater with decreasing collimation width. The absorbed doses for MDCT scanners at 120kVp ranged 5.1‒7.1mGy and 10.8‒17.5mGy per 100mAs at the center in the body- and head-type water phantoms, respectively. Measured doses at four peripheral points were within 5% agreement of MC-calculated values. The absorbed dose at the center in both water phantoms increased with decreasing Al-HVL for the same charge on the focus. In this study the X-ray beam characteristics and the absorbed dose were measured and compared with calculated values for four MDCT scanners.
authors.affiliation: Department of Health Sciences, Faculty of Life Sciences, Kumamoto University, 4-24-1 Kuhonji, Kumamoto, Japan. Electronic address: t_oono@kumamoto-u.ac.jp.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ohno
authors.affiliation: Department of Health Sciences, Faculty of Life Sciences, Kumamoto University, 4-24-1 Kuhonji, Kumamoto, Japan.
authors.forename: Fujio
authors.initials: F
authors.lastname: Araki
authors.affiliation: Graduate School of Health Sciences, Kumamoto University, 4-24-1 Kuhonji, Kumamoto, Japan.
authors.forename: Ryota
authors.initials: R
authors.lastname: Onizuka
authors.affiliation: Kumamoto University Hospital, 1-1-1 Honjo, Kumamoto, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hatemura
authors.affiliation: Kumamoto University Hospital, 1-1-1 Honjo, Kumamoto, Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Shimonobou
authors.affiliation: Saiseikai Kumamoto Hospital, 5-3-1 Chikami, Kumamoto, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Sakamoto
authors.affiliation: Saiseikai Kumamoto Hospital, 5-3-1 Chikami, Kumamoto, Japan.
authors.forename: Shuichiro
authors.initials: S
authors.lastname: Okumura
authors.affiliation: National Hospital Organization Kyusyu Medical Center, 1-8-1 Jigyohama, Fukuoka, Japan.
authors.forename: Daichi
authors.initials: D
authors.lastname: Ideguchi
authors.affiliation: Kumamoto Chuo Hospital, 1-5-1 Tainoshima, Kumamoto, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Honda
authors.affiliation: Kumamoto Chuo Hospital, 1-5-1 Tainoshima, Kumamoto, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Kawata
mesh_terms: D000465:Algorithms; D002138:Calibration; D003037:Cobalt Radioisotopes; D003198:Computer Simulation; D008962:Models, Theoretical; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D011874:Radiometry; D015898:Tomography Scanners, X-Ray Computed; D014057:Tomography, X-Ray Computed / Q000295:instrumentation*; D014867:Water; D014965:X-Rays
chemical_list: D003037:Cobalt Radioisotopes; D014867:Water
keywords: Absorbed dose; Ionization chamber measurement; Monte Carlo technique; Multi-detector CT