title: Adaptive statistical iterative reconstruction reduces patient radiation dose in neuroradiology CT studies.
abstract: BACKGROUND
  Adaptive statistical iterative reconstruction (ASIR) can decrease image noise, thereby generating CT images of comparable diagnostic quality with less radiation. The purpose of this study is to quantify the effect of systematic use of ASIR versus filtered back projection (FBP) for neuroradiology CT protocols on patients' radiation dose and image quality.
  
  
  METHODS
  We evaluated the effect of ASIR on six types of neuroradiologic CT studies: adult and pediatric unenhanced head CT, adult cervical spine CT, adult cervical and intracranial CT angiography, adult soft tissue neck CT with contrast, and adult lumbar spine CT. For each type of CT study, two groups of 100 consecutive studies were retrospectively reviewed: 100 studies performed with FBP and 100 studies performed with ASIR/FBP blending factor of 40 %/60 % with appropriate noise indices. The weighted volume CT dose index (CTDIvol), dose-length product (DLP) and noise were recorded. Each study was also reviewed for image quality by two reviewers. Continuous and categorical variables were compared by t test and free permutation test, respectively.
  
  
  RESULTS
  For adult unenhanced brain CT, CT cervical myelography, cervical and intracranial CT angiography and lumbar spine CT both CTDIvol and DLP were lowered by up to 10.9 % (p < 0.001), 17.9 % (p = 0.005), 20.9 % (p < 0.001), and 21.7 % (p = 0.001), respectively, by using ASIR compared with FBP alone. Image quality and noise were similar for both FBP and ASIR.
  
  
  CONCLUSIONS
  We recommend routine use of iterative reconstruction for neuroradiology CT examinations because this approach affords a significant dose reduction while preserving image quality.
authors.affiliation: Department of Radiology and Medical Imaging, Division of Neuroradiology, University of Virginia, PO Box 800170, Charlottesville, VA, 22908-0170, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Komlosi
authors.forename: Yanrong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Carlos
authors.initials: C
authors.lastname: Leiva-Salinas
authors.forename: David
authors.initials: D
authors.lastname: Ornan
authors.forename: James T
authors.initials: JT
authors.lastname: Patrie
authors.forename: Wenjun
authors.initials: W
authors.lastname: Xin
authors.forename: Deborah
authors.initials: D
authors.lastname: Grady
authors.forename: Max
authors.initials: M
authors.lastname: Wintermark
mesh_terms: D000465:Algorithms; D001927:Brain Diseases / Q000000981:diagnostic imaging*; D003627:Data Interpretation, Statistical; D005246:Feedback; D005260:Female; D006801:Humans; D008297:Male; D009485:Neuroradiography / Q000379:methods; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods*; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013118:Spinal Cord Diseases / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*