Photon-counting CT for bullet material differentiation: applications in forensic radiology

Abstract Background Gunshot deaths due to homicide or military encounters are a major health concern. Noninvasive bullet characterization is of major importance for patients with lodged bullets or in mass disasters with multiple cadavers, which must be prioritized for autopsy. Therefore, the aim of...

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Main Authors: Benedikt M. Schaarschmidt, Jan Hegmanns, Jörg Wulff, Viktor Haase, Sebastian Faby, Felix Baum, Christian Bäumer, Sebastian Zensen, Johannes Haubold, Benno Hartung
Format: Article
Language:English
Published: SpringerOpen 2025-05-01
Series:European Radiology Experimental
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Online Access:https://doi.org/10.1186/s41747-025-00586-x
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author Benedikt M. Schaarschmidt
Jan Hegmanns
Jörg Wulff
Viktor Haase
Sebastian Faby
Felix Baum
Christian Bäumer
Sebastian Zensen
Johannes Haubold
Benno Hartung
author_facet Benedikt M. Schaarschmidt
Jan Hegmanns
Jörg Wulff
Viktor Haase
Sebastian Faby
Felix Baum
Christian Bäumer
Sebastian Zensen
Johannes Haubold
Benno Hartung
author_sort Benedikt M. Schaarschmidt
collection DOAJ
description Abstract Background Gunshot deaths due to homicide or military encounters are a major health concern. Noninvasive bullet characterization is of major importance for patients with lodged bullets or in mass disasters with multiple cadavers, which must be prioritized for autopsy. Therefore, the aim of this study was to investigate whether brass and lead bullets can be differentiated using photon-counting CT (PCCT). Methods Nine different lead (n = 6) or brass (n = 3) bullets were investigated on a state-of-the-art PCCT using a clinically unavailable research mode. Here, four image sets were reconstructed for different energy thresholds (20, 55, 72, 90 keV). Three circular regions of interest were placed on the 20-keV threshold images by two readers and automatically copied to the three other threshold images. Based on measured HU mean and max values, dual-energy indices (DEI) were calculated for the low/high energy threshold pairs of 20/90, 55/90, and 72/90 keV. Results Significant differences of DEIs between lead and brass projectiles were observed for the 20/90 keV DEI for HU mean ± standard deviation values (Qr40 kernel, lead: -0.085 ± 0.021, brass: 0.024 ± 0.048) and HU max values (Qr40 kernel, lead: -0.093 ± 0.011, brass: 0.023 ± 0.057) (p < 0.001 for both). Differences decreased for the 55/90 and 72/90 keV DEIs between the two projectile materials but remained statistically significant. Conclusion In this PCCT phantom study, significant differences were observed between lead and brass bullets in the different energy threshold images. Relevance statement Photon-counting CT could be a promising tool for bullet identification as significant differences were found in the different energy threshold images for lead and brass bullets, with application in clinical and forensic radiology. Key Points In emergency settings, noninvasive bullet characterization is of importance for law enforcement. Bullet material characterization can be performed using photon-counting CT. These characteristics can be quantified in the four different energy threshold images. Graphical Abstract
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spelling doaj-art-274e0f01a7434dbb93c3e541c4d4f8c32025-08-20T02:15:14ZengSpringerOpenEuropean Radiology Experimental2509-92802025-05-01911910.1186/s41747-025-00586-xPhoton-counting CT for bullet material differentiation: applications in forensic radiologyBenedikt M. Schaarschmidt0Jan Hegmanns1Jörg Wulff2Viktor Haase3Sebastian Faby4Felix Baum5Christian Bäumer6Sebastian Zensen7Johannes Haubold8Benno Hartung9Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital EssenInstitute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital EssenWest German Proton Therapy Centre Essen (WPE)Computed Tomography, Siemens Healthineers AGComputed Tomography, Siemens Healthineers AGState Criminal Office North Rhine-WestphaliaWest German Proton Therapy Centre Essen (WPE)Institute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital EssenInstitute of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital EssenInstitute of Legal Medicine, University Hospital EssenAbstract Background Gunshot deaths due to homicide or military encounters are a major health concern. Noninvasive bullet characterization is of major importance for patients with lodged bullets or in mass disasters with multiple cadavers, which must be prioritized for autopsy. Therefore, the aim of this study was to investigate whether brass and lead bullets can be differentiated using photon-counting CT (PCCT). Methods Nine different lead (n = 6) or brass (n = 3) bullets were investigated on a state-of-the-art PCCT using a clinically unavailable research mode. Here, four image sets were reconstructed for different energy thresholds (20, 55, 72, 90 keV). Three circular regions of interest were placed on the 20-keV threshold images by two readers and automatically copied to the three other threshold images. Based on measured HU mean and max values, dual-energy indices (DEI) were calculated for the low/high energy threshold pairs of 20/90, 55/90, and 72/90 keV. Results Significant differences of DEIs between lead and brass projectiles were observed for the 20/90 keV DEI for HU mean ± standard deviation values (Qr40 kernel, lead: -0.085 ± 0.021, brass: 0.024 ± 0.048) and HU max values (Qr40 kernel, lead: -0.093 ± 0.011, brass: 0.023 ± 0.057) (p < 0.001 for both). Differences decreased for the 55/90 and 72/90 keV DEIs between the two projectile materials but remained statistically significant. Conclusion In this PCCT phantom study, significant differences were observed between lead and brass bullets in the different energy threshold images. Relevance statement Photon-counting CT could be a promising tool for bullet identification as significant differences were found in the different energy threshold images for lead and brass bullets, with application in clinical and forensic radiology. Key Points In emergency settings, noninvasive bullet characterization is of importance for law enforcement. Bullet material characterization can be performed using photon-counting CT. These characteristics can be quantified in the four different energy threshold images. Graphical Abstracthttps://doi.org/10.1186/s41747-025-00586-xBrassForensic ballisticsLeadTomography (x-ray computed)Wounds (gunshot)
spellingShingle Benedikt M. Schaarschmidt
Jan Hegmanns
Jörg Wulff
Viktor Haase
Sebastian Faby
Felix Baum
Christian Bäumer
Sebastian Zensen
Johannes Haubold
Benno Hartung
Photon-counting CT for bullet material differentiation: applications in forensic radiology
European Radiology Experimental
Brass
Forensic ballistics
Lead
Tomography (x-ray computed)
Wounds (gunshot)
title Photon-counting CT for bullet material differentiation: applications in forensic radiology
title_full Photon-counting CT for bullet material differentiation: applications in forensic radiology
title_fullStr Photon-counting CT for bullet material differentiation: applications in forensic radiology
title_full_unstemmed Photon-counting CT for bullet material differentiation: applications in forensic radiology
title_short Photon-counting CT for bullet material differentiation: applications in forensic radiology
title_sort photon counting ct for bullet material differentiation applications in forensic radiology
topic Brass
Forensic ballistics
Lead
Tomography (x-ray computed)
Wounds (gunshot)
url https://doi.org/10.1186/s41747-025-00586-x
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