A novel approach to bullet trajectory analysis using computed tomography data

The field of terminal ballistics deals with the science used to explain the interaction between a given projectile and its ultimate target. An understanding of wound ballistics, a specialisation within this field that deals with the penetration of living tissues is highly important in forensic science, particularly in the investigation of shootings. The modern approach to wound ballistics is tending towards the use of tissue stimulants and radiography to help understand and thus explain what is happening as projectiles pass through certain tissues. Gelatin and soap are the tissue simulants that have been used for more than half a century to help explain wound ballistic phenomena such as the permanent and temporary cavities respectively. It should be noted that neither of them are ideal, but they still represent the most useful materials at our disposal for such investigations, particularly as they give reproducible results and overcome the ethical issues associated with using live animal tissue. By using computed tomography (CT) scanning with suitable parameters, a permanent representation of the aforementioned phenomena following shooting can be captured before the materials are able to ‘spoil’, thus losing the structure created by the projectile. This is of particular use with gelatin, as its components (gelatin powder and water) leave it accessible to biological degradation or melting within small time scales after use. Further, an increase in the number of software packages available in recent times for the manipulation of CT scan data has led to enhanced capabilities for analysis. In this work, some of the potential directions that a combination of simulant studies, CT scanning and appropriate software can ultimately take through trial scenarios are demonstrated.