title: Radiation dose reduction in paediatric cranial CT.
abstract: BACKGROUND
  There is no consensus about the optimal milliamperage-second (mAs) settings for computed tomography (CT). Most operators follow the recommended settings of the manufacturers, but these may not be the most appropriate settings.
  
  
  OBJECTIVE
  To determine whether a lower radiation dose technique could be used in CT of the paediatric brain without jeopardising the diagnostic accuracy of the images.
  
  
  METHODS
  A randomised prospective trial. A group of 53 children underwent CT using manufacturer's default levels of 200 or 250 mAs; 47 underwent scanning at 125 or 150 mAs. Anatomical details and the confidence level in reaching a diagnosis were evaluated by two radiologists in a double-blinded manner using a 4-point scoring system.
  
  
  RESULTS
  For both readers there was no statistically significant difference in the confidence level for reaching a diagnosis between the two groups. The 95 % confidence intervals and P values were -0.9-1.1 and 0.13 (reader 1) and -1.29-1.37 and 0.70 (reader 2), respectively. Reliability tests showed the results were consistent.
  
  
  CONCLUSIONS
  The recommended level may not be the optimum setting. Dose reduction of 40 % is possible on our system in paediatric brain CT without affecting the diagnostic quality of the images.
authors.affiliation: Department of Diagnostic Radiology, Tuen Mun Hospital, Tsing Chung Koon Road, Tuen Mun, New Territories, Hong Kong, China.
authors.forename: C Y
authors.initials: CY
authors.lastname: Chan
authors.forename: Y C
authors.initials: YC
authors.lastname: Wong
authors.forename: L F
authors.initials: LF
authors.lastname: Chau
authors.forename: S K
authors.initials: SK
authors.lastname: Yu
authors.forename: P C
authors.initials: PC
authors.lastname: Lau
mesh_terms: D001921:Brain / Q000000981:diagnostic imaging*; D002648:Child; D002675:Child, Preschool; D004311:Double-Blind Method; D006801:Humans; D007223:Infant; D015588:Observer Variation; D019047:Phantoms, Imaging; D011446:Prospective Studies; D011829:Radiation Dosage; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed