title: Radiation dose reduction with chest computed tomography using adaptive statistical iterative reconstruction technique: initial experience.
abstract: OBJECTIVE
  To assess radiation dose reduction and image quality for weight-based chest computed tomographic (CT) examination results reconstructed using adaptive statistical iterative reconstruction (ASIR) technique.
  
  
  METHODS
  With local ethical committee approval, weight-adjusted chest CT examinations were performed using ASIR in 98 patients and filtered backprojection (FBP) in 54 weight-matched patients on a 64-slice multidetector CT. Patients were categorized into 3 groups: 60 kg or less (n = 32), 61 to 90 kg (n = 77), and 91 kg or more (n = 43) for weight-based adjustment of noise indices for automatic exposure control (Auto mA; GE Healthcare, Waukesha, Wis). Remaining scan parameters were held constant at 0.984:1 pitch, 120 kilovolts (peak), 40-mm table feed per rotation, and 2.5-mm section thickness. Patients' weight, scanning parameters, and CT dose index volume were recorded. Effective doses (EDs) were estimated. Image noise was measured in the descending thoracic aorta at the level of the carina. Data were analyzed using analysis of variance.
  
  
  RESULTS
  Compared with FBP, ASIR was associated with an overall mean (SD) decrease of 27.6% in ED (ASIR, 8.8 [2.3] mSv; FBP, 12.2 [2.1] mSv; P < 0.0001). With the use of ASIR, the ED values were 6.5 (1.8) mSv (28.8% decrease), 7.3 (1.6) mSv (27.3% decrease), and 12.8 (2.3) mSv (26.8% decrease) for the weight groups of 60 kg or less, 61 to 90 kg, and 91 kg or more, respectively, compared with 9.2 (2.3) mSv, 10.0 (2.0) mSv, and 17.4 (2.1) mSv with FBP (P < 0.0001). Despite dose reduction, there was less noise with ASIR (12.6 [2.9] mSv) than with FBP (16.6 [6.2] mSv; P < 0.0001).
  
  
  CONCLUSIONS
  Adaptive statistical iterative reconstruction helps reduce chest CT radiation dose and improve image quality compared with the conventionally used FBP image reconstruction.
authors.affiliation: Division of Thoracic Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA.
authors.forename: Priyanka
authors.initials: P
authors.lastname: Prakash
authors.forename: Mannudeep K
authors.initials: MK
authors.lastname: Kalra
authors.forename: Subba R
authors.initials: SR
authors.lastname: Digumarthy
authors.forename: Jiang
authors.initials: J
authors.lastname: Hsieh
authors.forename: Homer
authors.initials: H
authors.lastname: Pien
authors.forename: Sarabjeet
authors.initials: S
authors.lastname: Singh
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Gilman
authors.forename: Jo-Anne O
authors.initials: JA
authors.lastname: Shepard
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011829:Radiation Dosage; D013902:Radiography, Thoracic / Q000379:methods*; D012189:Retrospective Studies; D017678:Sex Distribution; D014057:Tomography, X-Ray Computed / Q000379:methods*