title: Estimated Patient Dose Indexes in Adult and Pediatric MDCT: Comparison of Automatic Tube Voltage Selection With Fixed Tube Current, Fixed Tube Voltage, and Weight-Based Protocols.
abstract: OBJECTIVE
  The purposes of this study were to determine the differences in estimated volumetric CT dose index (CTDIvol) obtained from the topogram before abdominal and pelvic MDCT in adult and pediatric patients using a scan type-based algorithm for selecting kilovoltage (CARE kV) and a fixed and a weight-based Quality Reference mAs for selecting tube (gmAs) current-exposure time product, in comparison with standard protocols, and to determine the bias and variability of estimated CTDIvol vis-à-vis actual CTDIvol using the standard protocols.
  
  
  METHODS
  During a 14-month period, 312 adult and pediatric patients referred for abdominal and pelvic MDCT were included in the study. For all patients, the estimated CTDIvol based on the topogram was recorded: protocol A, CARE kV on and 210 gmAs; protocol B, CARE kV on and 1 gmAs times patient weight (in pounds); and protocol C (standard protocol), CARE kV off, 120 kVp, and 1 gmAs times patient weight (in pounds). For the pediatric patients, estimated CTDIvol for the standard protocol D was calculated with 120 kVp and 150 gmAs. All patients were scanned with the standard protocols, and the actual CTDIvol was recorded. Linear regression models compared the CTDIvol of the three protocols in adults and the fourth for children. The estimated and actual CTDIvol were compared using a t test.
  
  
  RESULTS
  Protocol B yielded the lowest estimated CTDIvol (mean, 13.2 mGy for adults and 3.5 mGy for pediatric patients). The estimated CTDIvol overestimated the actual CTDIvol by, on average, 1.07 mGy for adults and 0.3 mGy for children.
  
  
  CONCLUSIONS
  CARE kV appears to reduce estimated CTDIvol vis-à-vis standard protocols only when a weight-based gmAs is used. Prescan estimated CTDIvol calculations appear to generally overestimate actual CTDIvol.
authors: 1 Imaging Institute, Cleveland Clinic, 9500 Euclid Ave, L10, Cleveland, OH 44195.
authors: Mark E
authors: ME
authors: Baker
authors: 1 Imaging Institute, Cleveland Clinic, 9500 Euclid Ave, L10, Cleveland, OH 44195.
authors: Wadih
authors: W
authors: Karim
authors: 2 Department of Quantitative Health Sciences, Cleveland Clinic, Cleveland, OH.
authors: Jennifer A
authors: JA
authors: Bullen
authors: 3 Siemens Healthcare, Malvern, PA.
authors: Andrew N
authors: AN
authors: Primak
authors: 1 Imaging Institute, Cleveland Clinic, 9500 Euclid Ave, L10, Cleveland, OH 44195.
authors: Frank F
authors: FF
authors: Dong
authors: 1 Imaging Institute, Cleveland Clinic, 9500 Euclid Ave, L10, Cleveland, OH 44195.
authors: Brian R
authors: BR
authors: Herts
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D061330:Multidetector Computed Tomography / Q000295:instrumentation*; D011829:Radiation Dosage; D011860:Radiography, Abdominal
keywords: CT; automated tube voltage selection; dose reduction