title: Indirect computed tomography venography with a low-tube-voltage technique: reduction in the radiation and contrast material dose--a prospective randomized study.
abstract: OBJECTIVE
  The objective of the study was to investigate the effects of low-tube-voltage computed tomography (CT) venography on qualitative and quantitative image parameters and the radiation dose.
  
  
  METHODS
  Eighty-eight studies on 84 patients underwent pelvic and lower-extremity CT venography under protocol A (standard 120 kV with 150 mL of contrast material, n = 44) or protocol B (80 kV with 100 mL of contrast material, n = 44) on a 64-detector CT scanner. We compared the dose length product in the 2 protocols. Two blinded observers measured CT attenuation in the veins, the image noise, contrast-to-noise ratio, and figure of merit.
  
  
  RESULTS
  The mean dose length product was significantly lower under protocol B than A (603.2 [SD, 67.2] vs 1131.7 [SD, 67.0] mGy × cm) (P < 0.01). Mean CT attenuation of the veins was significantly greater with protocol B (125.3 [SD, 16.2] vs 106.1 [SD, 16.0] Hounsfield units) (P < 0.01), and the mean image noise was also significantly higher under protocol B (6.6 [SD, 0.8] vs 4.9 [SD, 0.7] Hounsfield units) (P < 0.01). There was no difference in contrast-to-noise ratio (P = 0.46). Figure of merit was significantly higher under protocol B (P < 0.01).
  
  
  CONCLUSIONS
  Computed tomography venography with a low-tube-voltage technique allows reducing the radiation dose and the amount of contrast material without image quality degradation.
authors.affiliation: Department of Diagnostic Radiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan. seisei0430@nifty.com
authors.forename: Seitaro
authors.initials: S
authors.lastname: Oda
authors.forename: Daisuke
authors.initials: D
authors.lastname: Utsunomiya
authors.forename: Kazuo
authors.initials: K
authors.lastname: Awai
authors.forename: Hiroko
authors.initials: H
authors.lastname: Takaoka
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nakaura
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Katahira
authors.forename: Syoji
authors.initials: S
authors.lastname: Morishita
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Namimoto
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yamashita
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D007479:Iopamidol / Q000008:administration & dosage*; D007866:Leg / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D010690:Phlebography / Q000295:instrumentation*; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed / Q000295:instrumentation / Q000379:methods*; D020246:Venous Thrombosis / Q000000981:diagnostic imaging*
chemical_list: D003287:Contrast Media; D007479:Iopamidol