title: Numerical Analysis of Organ Doses Delivered During Computed Tomography Examinations Using Japanese Adult Phantoms with the WAZA-ARI Dosimetry System.
abstract: A dosimetry system for computed tomography (CT) examinations, named WAZA-ARI, is being developed to accurately assess radiation doses to patients in Japan. For dose calculations in WAZA-ARI, organ doses were numerically analyzed using average adult Japanese male (JM) and female (JF) phantoms with the Particle and Heavy Ion Transport code System (PHITS). Experimental studies clarified the photon energy distribution of emitted photons and dose profiles on the table for some multi-detector row CT (MDCT) devices. Numerical analyses using a source model in PHITS could specifically take into account emissions of x rays from the tube to the table with attenuation of photons through a beam-shaping filter for each MDCT device based on the experiment results. The source model was validated by measuring the CT dose index (CTDI). Numerical analyses with PHITS revealed a concordance of organ doses with body sizes of the JM and JF phantoms. The organ doses in the JM phantoms were compared with data obtained using previously developed systems. In addition, the dose calculations in WAZA-ARI were verified with previously reported results by realistic NUBAS phantoms and radiation dose measurement using a physical Japanese model (THRA1 phantom). The results imply that numerical analyses using the Japanese phantoms and specified source models can give reasonable estimates of dose for MDCT devices for typical Japanese adults.
authors.affiliation: *Japan Atomic Energy Agency, †Tokyo Healthcare University, ‡Tokai University Oiso Hospital, §Tokai University Hospital, **Shin-Beppu Hospital, ††Oita University of Nursing and Health Sciences.
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Takahashi
authors.forename: Kaoru
authors.initials: K
authors.lastname: Sato
authors.forename: Akira
authors.initials: A
authors.lastname: Endo
authors.forename: Koji
authors.initials: K
authors.lastname: Ono
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Ban
authors.forename: Takayuki
authors.initials: T
authors.lastname: Hasegawa
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Katsunuma
authors.forename: Takayasu
authors.initials: T
authors.lastname: Yoshitake
authors.forename: Michiaki
authors.initials: M
authors.lastname: Kai
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D061330:Multidetector Computed Tomography; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011874:Radiometry