title: Application of adaptive non-linear 2D and 3D postprocessing filters for reduced dose abdominal CT.
abstract: BACKGROUND
  Abdominal computed tomography (CT) is a frequently performed imaging procedure, resulting in considerable radiation doses to the patient population. Postprocessing filters are one of several dose reduction measures that might help to reduce radiation doses without loss of image quality.
  
  
  OBJECTIVE
  To assess and compare the effect of two- and three-dimensional (2D, 3D) non-linear adaptive filters on reduced dose abdominal CT images.
  
  
  METHODS
  Two baseline abdominal CT image series with a volume computer tomography dose index (CTDI (vol)) of 12 mGy and 6 mGy were acquired for 12 patients. Reduced dose images were postprocessed with 2D and 3D filters. Six radiologists performed blinded randomized, side-by-side image quality assessments. Objective noise was measured. Data were analyzed using visual grading regression and mixed linear models.
  
  
  RESULTS
  All image quality criteria were rated as superior for 3D filtered images compared to reduced dose baseline and 2D filtered images (P < 0.01). Standard dose images had better image quality than reduced dose 3D filtered images (P < 0.01), but similar image noise. For patients with body mass index (BMI) < 30 kg/m(2) however, 3D filtered images were rated significantly better than normal dose images for two image criteria (P < 0.05), while no significant difference was found for the remaining three image criteria (P > 0.05). There were no significant variations of objective noise between standard dose and 2D or 3D filtered images.
  
  
  CONCLUSIONS
  The quality of 3D filtered reduced dose abdominal CT images is superior compared to reduced dose unfiltered and 2D filtered images. For patients with BMI < 30 kg/m(2), 3D filtered images are comparable to standard dose images.
authors.affiliation: Department of Radiology, Drammen Hospital, Drammen and Buskerud University College, Norway. lars.borgen@vestreviken.no
authors.forename: Lars
authors.initials: L
authors.lastname: Borgen
authors.forename: Mannudeep K
authors.initials: MK
authors.lastname: Kalra
authors.forename: Frode
authors.initials: F
authors.lastname: Laerum
authors.forename: Isabelle W
authors.initials: IW
authors.lastname: Hachette
authors.forename: Carina H
authors.initials: CH
authors.lastname: Fredriksson
authors.forename: Michael
authors.initials: M
authors.lastname: Sandborg
authors.forename: Orjan
authors.initials: O
authors.lastname: Smedby
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001822:Body Burden; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011446:Prospective Studies; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D011860:Radiography, Abdominal / Q000379:methods*; D016037:Single-Blind Method; D014057:Tomography, X-Ray Computed / Q000379:methods*