title: Pediatric CT dose reduction for suspected appendicitis: a practice quality improvement project using artificial Gaussian noise--part 1, computer simulations.
abstract: OBJECTIVE
  The purpose of this study was to develop a departmental practice quality improvement project to systematically reduce CT doses for the evaluation of suspected pediatric appendicitis by introducing computer-generated gaussian noise.
  
  
  METHODS
  Two hundred MDCT abdominopelvic examinations of patients younger than 20 years performed with girth-based scanning parameters for suspected appendicitis were reviewed. Two judges selected 45 examinations in which the diagnosis of appendicitis was excluded (14, appendix not visualized; 31, normal appendix visualized). Gaussian noise was introduced into axial image series, creating five additional series acquired at 25-76% of the original dose. Two readers reviewed 270 image series for appendix visualization (4-point Likert scale and arrow localization). Volume CT dose index (CTDIvol) and size-specific dose estimate (SSDE) were calculated by use of patient girth. Confidence ratings and localization accuracy were analyzed with mixed models and nonparametric bootstrap analysis at a 0.05 significance level.
  
  
  RESULTS
  The mean baseline SSDE for the 45 patients was 16 mGy (95% CI, 12-20 mGy), and the corresponding CTDIvol was 10 mGy (95% CI, 4-16 mGy). Changes in correct appendix localization frequencies were minor. There was no substantial trend with decreasing simulated dose level (p = 0.46). Confidence ratings decreased with increasing dose reduction (p = 0.007). The average decreases were -0.27 for the 25% simulated dose (p = 0.01), -0.17 for 33% (p = 0.03), and -0.03 for 43% (p = 0.65).
  
  
  CONCLUSIONS
  Pediatric abdominal MDCT can be performed with 43% of the original dose (SSDE, 7 mGy; CTDIvol, 4.3 mGy) without substantially affecting visualization of a normal appendix.
authors.affiliation: 1 Department of Radiology, Boston Children's Hospital, 300 Longwood Ave, Boston, MA 02115.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Callahan
authors.forename: Patricia L
authors.initials: PL
authors.lastname: Kleinman
authors.forename: Keith J
authors.initials: KJ
authors.lastname: Strauss
authors.forename: Andriy
authors.initials: A
authors.lastname: Bandos
authors.forename: George A
authors.initials: GA
authors.lastname: Taylor
authors.forename: Andy
authors.initials: A
authors.lastname: Tsai
authors.forename: Paul K
authors.initials: PK
authors.lastname: Kleinman
mesh_terms: D065638:Absorption, Radiation; D000293:Adolescent; D001064:Appendicitis / Q000000981:diagnostic imaging*; D002648:Child; D002675:Child, Preschool; D003198:Computer Simulation; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008954:Models, Biological; D015233:Models, Statistical; D016011:Normal Distribution; D058996:Quality Improvement; 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; D059629:Signal-To-Noise Ratio; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult
keywords: CT; appendicitis; pediatrics; radiation dose reduction; size-specific dose estimate