1. Pilot : CT scans for determining the caliber of a bullet
Zeno Geradts / Jo Puts / Bert Ottevanger / Netherlands Forensic Insitute
Guido Zonneveld (VU University Hospital Amsterdam

2. Opening
Bullet size and shape determination in a living human body can be done with X-Rays
Nowadays often CT-scans are received by our laboratory

3. CT-scans

4. Opening Reasons for leaving the bullet in the human body :
medical reasons
patient does not want the bullet to be recovered

5. Pilot with the VU-hospital
How can the CT-scan be used for determining the caliber of a bullet ?
Is it possible to determine the kind of metal
Experiments with bullets in gelatin

6. CT scan

7. CT scan

8. CT-scanner Siemens Somatom 4

9. Benefits
3D-image of a bullet
can measure exactly on scan

10. Problems
Streak Artifacts
Beam Hardening Effect
Scatter

11. Streak Artifacts
Streak artifacts are caused by reconstruction : low CT-numbers

12. Beam Hardening
Beam hardening occurs in polychromatic X-ray beams due to photons of lower energy being preferentially attenuated.

13. Scatter Photons which interact with the bullet when it is scanned
Influence is limited

14. Streak Artifacts Solution : Scan with a higher window of CT-numbers
CT-numbers normally <-1000,3000>
Modify settings to <-10000,30000>

15. Houndsfield Units

16. .22 LR

17. .38 round

18. .38 wadcutter

19. Ball

20. Determination of caliber
Based on size (error 0,5 mm)
Based on shape

21. Fragmentation / deformation

22. Metal determination

23. Deformation

24. Measurement

25. Conclusions Measurement : more research on protocol
Ethics : radiation which is not necessary for medical treatment ?
Shape and caliber can be determined
Metals might be determined
Future : flesh and bone structures