title: Reduction in dose from CT examinations of liver lesions with a new postprocessing filter: a ROC phantom study.
abstract: BACKGROUND
  It is desirable to lower the dose from computed tomography (CT) examinations as much as possible without reducing diagnostic performance. Mathematical postprocessing filters are one tool to achieve dose reduction.
  
  
  OBJECTIVE
  To evaluate the possibilities of reducing CT doses from liver examinations using a new postprocessing filter.
  
  
  METHODS
  An anthropomorphic upper-abdomen phantom was used in receiver operating characteristic (ROC) studies of the detectability of liver lesions. A standard abdominal CT protocol was used. Only mA settings were changed; all other scan parameters were constant. The postprocessing filter used was SharpView CT, which provides context-controlled restoration of digital images using adaptive filters. Six readers were given a set of 10 images obtained at five different dose levels, each image with 32 predefined areas to be evaluated on a five-point scale. In total, 1920 areas were evaluated. At each dose level, the readers evaluated five images without enhancement and five images based on postprocessing filters. All images were randomized with respect to dose level.
  
  
  RESULTS
  The postprocessing filter improved the diagnostic performance significantly compared to the unenhanced images at all dose levels. Radiation dose for abdominal CT examinations of liver lesions in the range 2-7 mm was reduced by 30% using postprocessing filters, while diagnostic performance of the examination was maintained or even improved.
  
  
  CONCLUSIONS
  This study indicates great potential for lowering doses for CT examinations of liver lesions using the new postprocessing filter. The software must be fully tested clinically to reliably assess the benefits of this filtration.
authors: Department of Diagnostic Physics, Division of Radiology, Ullevål University Hospital, Oslo, Norway. neti@uus.no
authors: A C Traegde
authors: AC
authors: Martinsen
authors: H Kjernlie
authors: HK
authors: Saether
authors: D R
authors: DR
authors: Olsen
authors: P
authors: P
authors: Skaane
authors: H M
authors: HM
authors: Olerud
mesh_terms: D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging*; D015588:Observer Variation; D019047:Phantoms, Imaging; D012372:ROC Curve; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000295:instrumentation* / Q000379:methods; D011860:Radiography, Abdominal / Q000295:instrumentation / Q000379:methods; D014057:Tomography, X-Ray Computed / Q000295:instrumentation* / Q000379:methods