title: Computed tomography can improve the selection of fragment simulating projectiles from which to test future body armor materials.
abstract: BACKGROUND
  Ballistic protective materials used in body armor are tested with fragment simulating projectiles (FSPs). The type of FSP used has historically been made by choosing fragments representative of those produced by controlled explosions, which may not be representative of those fragments actually injuring soldiers.
  
  
  METHODS
  75 cylindrical FSPs of three different sizes were fired into six euthanized pigs, imaged using computed tomography (CT) and the wound tracks dissected. Skin entry wound locations, as determined by surface-shaded CT, were compared to clinical photographs. FSP dimensions and depth of penetration derived from CT were compared to surgical dissection using a Mann-Whitney U test.
  
  
  RESULTS
  Skin entry wound locations derived from CT were identical to that seen clinically. FSP dimensions were consistently 15% to 19% larger than the true measurements, reflecting the magnifying effect associated with metallic artifact. No statistical difference (p = 0.26) was found between depth of penetration measured radiologically compared to dissection when a projectile did not hit bone but there was a statistical difference when bone was hit (p < 0.05).
  
  
  CONCLUSIONS
  CT has the potential to accurately ascertain values required to improve the selection of representative FSPs from which future ballistic protective materials are tested.
authors.affiliation: Academic Department of Military Surgery and Trauma, Royal Centre for Defence Medicine, Birmingham Research Park, Birmingham, United Kingdom.
authors.forename: John
authors.initials: J
authors.lastname: Breeze
authors.forename: Joanna
authors.initials: J
authors.lastname: Leason
authors.forename: Iain
authors.initials: I
authors.lastname: Gibb
authors.forename: Nicholas C
authors.initials: NC
authors.lastname: Hunt
authors.forename: Alan
authors.initials: A
authors.lastname: Hepper
authors.forename: Jon
authors.initials: J
authors.lastname: Clasper
mesh_terms: D000818:Animals; D044709:Forensic Ballistics / Q000379:methods*; D008954:Models, Biological; D013552:Swine; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014948:Wounds, Gunshot / Q000000981:diagnostic imaging*; D014950:Wounds, Penetrating / Q000000981:diagnostic imaging