J Breeze1, N Hunt, I Gibb, G James, A Hepper, J Clasper. 1. Academic Department of Military Surgery and Trauma, Royal Centre for Defence Medicine, United Kingdom. jbreeze@dstl.gov.uk
Abstract
INTRODUCTION: Ballistic gelatin is well validated in its ability to simulate the retardation of bullets into homogenous muscle. However the relationship is less clear for fragmentation projectiles and non-homogenous tissues as would truly be found in a human. METHOD: 0.16 g, 1.10 g and 2.84 g NATO standardised cylindrical Fragment Simulating Projectiles (FSPs) were fired at a range of velocities (112-1652 m s(-1)) into four body areas (thigh, abdomen, thorax or neck) of six pig cadavers as well as 20% gelatin. Cadavers were imaged by Computed Tomography (CT) scanning and FSP Depth of Penetration (DoP) ascertained through radiology followed by dissection by a forensic pathologist. RESULTS: 106/149 (71%) FSPs were retained in tissues enabling DoP measurements and 43/149 (29%) exited the subjects. There was significantly less retardation of FSPs in the thorax and abdomen compared to gelatin but no difference in retardation in leg and neck tissue compared to gelatin. Although the gradient appeared identical for the 2.84 g FSP as well, there were insufficient FSPs retained in the neck and leg for meaningful analysis to be undertaken. DISCUSSION: Porcine leg and neck muscle was demonstrated to be comparable to 20% ballistic gelatin in terms of retardation, validating the use of projectile penetration algorithms derived from this tissue simulant. The effect of pig skin was significant for the 0.16 g FSP, especially at lower velocities, and we would therefore suggest that specific algorithms for any future numerical injury models be based directly from animal data or validated skin simulants for this smaller sized FSP. Reproducing the retardation effects of FSPs in the thorax and abdomen using tissue simulants alone will be problematic due to the anatomical complexity as well as multiple tissue-air interfaces and we would recommend further research in this area. Crown
INTRODUCTION: Ballistic gelatin is well validated in its ability to simulate the retardation of bullets into homogenous muscle. However the relationship is less clear for fragmentation projectiles and non-homogenous tissues as would truly be found in a human. METHOD: 0.16 g, 1.10 g and 2.84 g NATO standardised cylindrical Fragment Simulating Projectiles (FSPs) were fired at a range of velocities (112-1652 m s(-1)) into four body areas (thigh, abdomen, thorax or neck) of six pig cadavers as well as 20% gelatin. Cadavers were imaged by Computed Tomography (CT) scanning and FSP Depth of Penetration (DoP) ascertained through radiology followed by dissection by a forensic pathologist. RESULTS: 106/149 (71%) FSPs were retained in tissues enabling DoP measurements and 43/149 (29%) exited the subjects. There was significantly less retardation of FSPs in the thorax and abdomen compared to gelatin but no difference in retardation in leg and neck tissue compared to gelatin. Although the gradient appeared identical for the 2.84 g FSP as well, there were insufficient FSPs retained in the neck and leg for meaningful analysis to be undertaken. DISCUSSION: Porcine leg and neck muscle was demonstrated to be comparable to 20% ballistic gelatin in terms of retardation, validating the use of projectile penetration algorithms derived from this tissue simulant. The effect of pig skin was significant for the 0.16 g FSP, especially at lower velocities, and we would therefore suggest that specific algorithms for any future numerical injury models be based directly from animal data or validated skin simulants for this smaller sized FSP. Reproducing the retardation effects of FSPs in the thorax and abdomen using tissue simulants alone will be problematic due to the anatomical complexity as well as multiple tissue-air interfaces and we would recommend further research in this area. Crown