title: Reducing the radiation dose for computed tomography colonography using model-based iterative reconstruction.
abstract: OBJECTIVE
  To determine whether radiation doses during computed tomography (CT) colonography (CTC) can be further reduced while maintaining image quality using model-based iterative reconstruction (MBIR).
  
  
  METHODS
  Twenty patients underwent CTC at a standard dose in supine and prone positions and at a reduced dose in the supine position. All other scan parameters (except noise index) were held constant. Acquisitions were reconstructed using 3 algorithms: filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), and MBIR. Noise was assessed quantitatively by comparing the SD in Hounsfield units at 5 standard locations. Qualitative assessment was made by 2 experienced radiologists blinded to technique who subjectively scored image quality, noise, and sharpness (from 0 to 4).
  
  
  RESULTS
  The standard-dose and reduced-dose CT dose index/dose-length product were 6.7/328 and 2.7 mGy/129 mGy-cm, respectively (60% reduction). Measured mean noise level increased from the standard to the reduced dose (FBP, from 58.6 to 97.2; ASIR from 35.8 to 60.6; and MBIR from 16.6 to 21.9). MBIR had significantly less noise than ASIR on 2-dimensional images at both standard and reduced doses (P < .01).
  
  
  CONCLUSIONS
  Radiation dose in CTC using MBIR can be reduced by 60% while maintaining image quality and reducing image noise.
authors.affiliation: Department of Radiology, Mayo Clinic, 13400 E Shea Blvd, Scottsdale, AZ, 85259, USA.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Millerd
authors.forename: Robert G
authors.initials: RG
authors.lastname: Paden
authors.forename: Jeffrey T
authors.initials: JT
authors.lastname: Lund
authors.forename: Amy K
authors.initials: AK
authors.lastname: Hara
authors.forename: Wendy L
authors.initials: WL
authors.lastname: Stiles
authors.forename: Miao
authors.initials: M
authors.lastname: He
authors.forename: Qing
authors.initials: Q
authors.lastname: Wu
authors.forename: C Daniel
authors.initials: CD
authors.lastname: Johnson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003110:Colonic Neoplasms / Q000000981:diagnostic imaging*; D023881:Colonography, Computed Tomographic / Q000379:methods*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D011829:Radiation Dosage