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Visualization and material-based differentiation of lodged projectiles by extended CT scale and the dual-energy index


Gascho, Dominic; Zoelch, Niklaus; Deininger-Czermak, Eva; Tappero, Carlo; Buehlmann, Alexander; Wyss, Philipp; Thali, Michael J; Schaerli, Sarah (2020). Visualization and material-based differentiation of lodged projectiles by extended CT scale and the dual-energy index. Journal of Forensic and Legal Medicine, 70:101919.

Abstract

Computed tomography (CT) scans of gunshot wounds and their high sensitivity in detecting osseous lesions has often been reported in the literature. However, studies concerning in situ examinations of lodged projectiles with CT to determine the ammunition used are lacking.
Projectile visualizations are hampered in standard CT due to the presence of metal artifacts and the limited range of Hounsfield units (HU). The use of special reconstruction algorithms can overcome these limitations. For instance, using extended CT scale (ECTS) reconstruction supports detailed visualizations of metallic objects. In addition to projectile visualizations, X-ray attenuation measurements (CT numbers) of metallic objects can be used to differentiate materials in CT.
This study uses real forensic cases to demonstrate that—depending on the degree of deformation—a detailed visualization of lodged projectiles using ECTS can provide useful information regarding the ammunition used and allows accurate caliber measurements. Independent from the degree of deformation, the in situ classification of bullets, even fragmented bullets, according to their metallic components is feasible by dual-energy index (DEI) calculations. The assessment of a lodged projectile with CT images provides useful information on the case; thus, a close examination of lodged projectiles or bullet fragments should be a part of the overall radiological examination for cases of penetrating gunshot wounds.

Abstract

Computed tomography (CT) scans of gunshot wounds and their high sensitivity in detecting osseous lesions has often been reported in the literature. However, studies concerning in situ examinations of lodged projectiles with CT to determine the ammunition used are lacking.
Projectile visualizations are hampered in standard CT due to the presence of metal artifacts and the limited range of Hounsfield units (HU). The use of special reconstruction algorithms can overcome these limitations. For instance, using extended CT scale (ECTS) reconstruction supports detailed visualizations of metallic objects. In addition to projectile visualizations, X-ray attenuation measurements (CT numbers) of metallic objects can be used to differentiate materials in CT.
This study uses real forensic cases to demonstrate that—depending on the degree of deformation—a detailed visualization of lodged projectiles using ECTS can provide useful information regarding the ammunition used and allows accurate caliber measurements. Independent from the degree of deformation, the in situ classification of bullets, even fragmented bullets, according to their metallic components is feasible by dual-energy index (DEI) calculations. The assessment of a lodged projectile with CT images provides useful information on the case; thus, a close examination of lodged projectiles or bullet fragments should be a part of the overall radiological examination for cases of penetrating gunshot wounds.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Institute of Legal Medicine
Dewey Decimal Classification:340 Law
610 Medicine & health
510 Mathematics
Scopus Subject Areas:Health Sciences > Pathology and Forensic Medicine
Social Sciences & Humanities > Law
Uncontrolled Keywords:Pathology and Forensic Medicine, Law, General Medicine
Language:English
Date:1 February 2020
Deposited On:26 Feb 2020 11:01
Last Modified:22 Apr 2020 23:16
Publisher:Elsevier
ISSN:1752-928X
OA Status:Closed
Publisher DOI:https://doi.org/10.1016/j.jflm.2020.101919
PubMed ID:32090974

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