title: Adaptive iterative dose reduction algorithm in CT: effect on image quality compared with filtered back projection in body phantoms of different sizes.
abstract: OBJECTIVE
  To evaluate the impact of the adaptive iterative dose reduction (AIDR) three-dimensional (3D) algorithm in CT on noise reduction and the image quality compared to the filtered back projection (FBP) algorithm and to compare the effectiveness of AIDR 3D on noise reduction according to the body habitus using phantoms with different sizes.
  
  
  METHODS
  Three different-sized phantoms with diameters of 24 cm, 30 cm, and 40 cm were built up using the American College of Radiology CT accreditation phantom and layers of pork belly fat. Each phantom was scanned eight times using different mAs. Images were reconstructed using the FBP and three different strengths of the AIDR 3D. The image noise, the contrast-to-noise ratio (CNR) and the signal-to-noise ratio (SNR) of the phantom were assessed. Two radiologists assessed the image quality of the 4 image sets in consensus. The effectiveness of AIDR 3D on noise reduction compared with FBP were also compared according to the phantom sizes.
  
  
  RESULTS
  Adaptive iterative dose reduction 3D significantly reduced the image noise compared with FBP and enhanced the SNR and CNR (p < 0.05) with improved image quality (p < 0.05). When a stronger reconstruction algorithm was used, greater increase of SNR and CNR as well as noise reduction was achieved (p < 0.05). The noise reduction effect of AIDR 3D was significantly greater in the 40-cm phantom than in the 24-cm or 30-cm phantoms (p < 0.05).
  
  
  CONCLUSIONS
  The AIDR 3D algorithm is effective to reduce the image noise as well as to improve the image-quality parameters compared by FBP algorithm, and its effectiveness may increase as the phantom size increases.
authors.affiliation: College of Medicine, Seoul National University, Seoul 110-744, Korea.
authors.forename: Milim
authors.initials: M
authors.lastname: Kim
authors.affiliation: Department of Radiology, Seoul National University Hospital, Seoul 110-744, Korea. ; Research Institute of Radiation Medicine, Seoul National University College of Medicine, Seoul 110-744, Korea.
authors.forename: Jeong Min
authors.initials: JM
authors.lastname: Lee
authors.affiliation: Department of Radiology, Seoul National University Hospital, Seoul 110-744, Korea.
authors.forename: Jeong Hee
authors.initials: JH
authors.lastname: Yoon
authors.affiliation: College of Medicine, Seoul National University, Seoul 110-744, Korea.
authors.forename: Hyoshin
authors.initials: H
authors.lastname: Son
authors.affiliation: Department of Radiology, Seoul National University Hospital, Seoul 110-744, Korea.
authors.forename: Jin Woo
authors.initials: JW
authors.lastname: Choi
authors.affiliation: Department of Radiology, Seoul National University Hospital, Seoul 110-744, Korea. ; Research Institute of Radiation Medicine, Seoul National University College of Medicine, Seoul 110-744, Korea.
authors.forename: Joon Koo
authors.initials: JK
authors.lastname: Han
authors.affiliation: Department of Radiology, Seoul National University Hospital, Seoul 110-744, Korea. ; Research Institute of Radiation Medicine, Seoul National University College of Medicine, Seoul 110-744, Korea.
authors.forename: Byung Ihn
authors.initials: BI
authors.lastname: Choi
mesh_terms: D000465:Algorithms; D000818:Animals; D049628:Body Size; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D019047:Phantoms, Imaging / Q000592:standards; D011829:Radiation Dosage; D059629:Signal-To-Noise Ratio; D050507:Subcutaneous Fat, Abdominal / Q000000981:diagnostic imaging*; D013552:Swine; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Adaptive iterative dose reduction; Body sizes; CT, phantom study