title: Operator Dose Measurements and Image Quality Assessment in Computed Tomography Fluoroscopy Using Bismuth Sheet.
abstract: The purpose of this study was to assess the dose reduction and the image quality using bismuth sheets during the computed tomography fluoroscopy (CTF).
  
  
  
  The bismuth sheets of 1-mm thick were put on the upper mylar ring to reduce the frontal X-ray. The dose rates of an operator were measured using a torso phantom in the patient position during the CTF. The torso phantom was set on the gantry rotation center (center) and the lower position from the center (off-center). The image quality of the CTF image was assessed using an original phantom that mimics the normal liver parenchyma and the low attenuation lesions. The image contrast and contrast-to-noise ratio (CNR) were compared with and without the bismuth sheets.
  
  
  
  The bismuth sheets reduced the dose rate of the operator, regardless of whether the torso phantom was set at the center or the off-center. The reduction rate of exposure at the center and the off-center were 42.3% and 34.5%, respectively. There were no significant differences in the image contrast and the CNR, although the bismuth sheets increased the CT values of the liver parenchyma and the low attenuation lesions.
  
  
  
  The bismuth sheets were effective for the reduction of exposure to the operator without degrading the image quality of CTF images.
authors.affiliation: Department of Diagnostic Radiology, Shizuoka Cancer Center.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Takiguchi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Urikura
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Yoshida
authors.forename: Kenichi
authors.initials: K
authors.lastname: Hirosawa
authors.forename: Takahiro
authors.initials: T
authors.lastname: Ito
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Nakaya
mesh_terms: D001729:Bismuth; D005471:Fluoroscopy / Q000379:methods*; D006801:Humans; D016273:Occupational Exposure / Q000517:prevention & control*; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011835:Radiation Protection / Q000295:instrumentation* / Q000379:methods; D014057:Tomography, X-Ray Computed
chemical_list: D001729:Bismuth