title: Evaluation of the effect of computed tomography scan protocols and freeform fabrication methods on bone biomodel accuracy.
abstract: OBJECTIVE
  To assess the effect of computed tomography (CT) scan protocols (radiation amounts) and fabrication methods on biomodel accuracy and variability.
  
  
  METHODS
  Cadaveric femur of a Basset Hound.
  
  
  METHODS
  Retroreconstructions (n = 158) were performed of 16 original scans and were visually inspected to select 17 scans to be used for biomodel fabrication. Biomodels of the 17 scans were made in triplicate by use of 3 freeform fabrication processes (stereolithography, fused deposition modeling, and 3-D printing) for 153 models. The biomodels and original bone were measured by use of a coordinate measurement machine.
  
  
  RESULTS
  Differences among fabrication methods accounted for 2% to 29% of the total observed variation in inaccuracy and differences among method-specific radiation configurations accounted for 4% to 44%. Biomodels underestimated bone length and width and femoral head diameter and overestimated cortical thickness. There was no evidence of a linear association between thresholding adjustments and biomodel accuracy. Higher measured radiation dose led to a decrease in absolute relative error for biomodel diameter and for 4 of 8 cortical thickness measurements.
  
  
  CONCLUSIONS
  The outside dimensions of biomodels have a clinically acceptable accuracy. The cortical thickness of biomodels may overestimate cortical thickness. Variability among biomodels was caused by model fabrication reproducibility and, to a lesser extent, by the radiation settings of the CT scan and differences among fabrication methods.
authors: Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA.
authors: Kathryn L
authors: KL
authors: Fitzwater
authors: Denis J
authors: DJ
authors: Marcellin-Little
authors: Ola L A
authors: OL
authors: Harrysson
authors: Jason A
authors: JA
authors: Osborne
authors: E Christine
authors: EC
authors: Poindexter
mesh_terms: D000818:Animals; D001837:Body Weights and Measures / Q000662:veterinary; D017076:Computer-Aided Design / Q000295:instrumentation; D004285:Dogs; D005260:Female; D005269:Femur / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008953:Models, Anatomic; D014057:Tomography, X-Ray Computed / Q000379:methods*