Added Value of Dual-Energy Computed Tomography Versus Single-Energy Computed Tomography in Assessing Ferromagnetic Properties of Ballistic Projectiles

Winklhofer, Sebastian; Stolzmann, Paul; Meier, Andreas; Schweitzer, Wolf; Morsbach, Fabian; Flach, Patricia M.; Kneubuehl, Beat P.; Alkadhi, Hatem; Thali, Michael J.; Ruder, Thomas D.

doi:10.1097/rli.0000000000000032

Cited by 27 publications

(25 citation statements)

References 26 publications

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“…This was due to a combination of the limited spatial resolution of the clinical CT scanner and limited contrast within the bullet due to photon starvation. This is in contradiction with a previous study that, to the best of our knowledge, has unintentionally mistaken the manifestation of the cupping artifact, in terms of bright edges and a darker center, for the appearance of jacket and core, respectively [16]. Studies using industrial CT scanners, with higher resolution (13 μm) and tube voltage (320 kVp), were able to distinguish between the jacket and core.…”

Section: Discussioncontrasting

confidence: 99%

Is CT bulletproof? On the use of CT for characterization of bullets in forensic radiology

et al. 2019

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PurposeForensic investigations could benefit from non-invasive in situ characterization of bullets. Therefore, the use of CT imaging was explored for the analysis of bullet geometry and composition. Bullet visualization with CT is challenging as the metal constituents suffer from excessive X-ray attenuation due to their high atomic number, density, and geometry.MethodsA metal reference phantom was developed containing small discs of various common metals (aluminum, iron, stainless steel, copper, brass, tungsten, and lead). CT images were acquired with 70–150 kVp and 200–400 mAs and were reconstructed using an extended Hounsfield unit (HU) scale (− 10,240 to + 30,710). For each material, the mean CT number (HU) was measured to construct a metal database. Different bullets (n = 11) were scanned in a soft tissue-mimicking phantom. Bullet size and shape were measured, and composition was evaluated by comparison with the metal database. Also, the effect of bullet orientation within the CT scanner was evaluated.ResultsIn the reference phantom, metals were classified into three groups according to their atomic number (Z): low (Z ≤ 13; HU < 3000), medium (Z = 25–30; HU = 13,000–20,000), and high (Z ≥ 74; HU > 30,000). External bullet contours could be accurately delineated. Internal interfaces between jacket and core could not be identified. Cross-sectional spatial profile plots of the CT number along bullets’ short axis revealed beam hardening and photon starvation effects that depended on bullet size, shape, and orientation within the CT scanner. Therefore, the CT numbers of bullets were unreliable and could not be used for material characterization by comparison with the reference phantom.ConclusionCT-based characterization of bullets was feasible in terms of size and shape but not composition.

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Section: Discussioncontrasting

confidence: 99%

Is CT bulletproof? On the use of CT for characterization of bullets in forensic radiology

et al. 2019

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“…Our study demonstrates that DECT can distinguish ferromagnetic from nonferromagnetic bullets at extended CT scale. These findings are consistent with the theoretical principle of DEI and the results from precious studies (11,14,15,20). Indeed, DECT acquires data using two different energy levels, it is capable of differentiating materials with different atomic numbers despite similar attenuation coefficients.…”

Section: Mean Deisupporting

confidence: 89%

“…Also, we did not place a ROI on the bullet's jacket. Winklhofer and al. have shown that measurements on the jacket are unhelpful (11). In addition, some of our bullets are from the early 20 th century but ancient weapons are still in use nowadays (30,31).…”

Section: Mean Deimentioning

confidence: 99%

“…Bullets are often made of non-ferromagnetic materials and will not cause patient injuries due to movement or dislodgment in tissue (10). But there are a significant number of ferromagnetic bullets (2,(11)(12)(13). These ferromagnetic bullets can exhibit movement which can be regarded as dangerous for the surrounding tissue.…”

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confidence: 99%

“…Dual-energy can discriminate elements with different atomic number (20) and therefore could be useful to distinguish ferromagnetic from non-ferromagnetic ballistic projectiles. Bullets are often made of steel (iron), lead, copper, brass (a copper-zinc alloy) and melchior (a copper-nickel-zinc alloy) (11)(12)(13). These different elements have significant difference between their atomic number: iron is 26, lead is 82, copper is 29, zinc is 30 and nickel is 28.…”

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confidence: 99%

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Is dual-energy computed tomography helpful to determinate the ferromagnetic property of bullets?

Diallo

Auffret

Deloire

et al. 2018

Journal of Forensic Radiology and Imaging

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Objectives: The goal of this ex vivo study was to determine if Dual-Energy Computed Tomography (DECT) can discriminate ferromagnetic bullets from non-ferromagnetic bullets. Methods: Twelve different bullets, placed in the center of the scanner on a gelatin phantom, underwent DECT evaluation. These projectiles were both ancient bullets from the 19Th century (eg. 8mm 1890 ECP) and recent bullets from the late 20th century (eg. 9mm Lüger; 7.92mm Mauser; 7mm sport carabin). Two independent radiologists who were blinded to the properties of bullets performed all measurement on an external workstation with extended CT scale. Regions of interest (ROI) were placed in the core of each projectile. From these data, a dual-energy index (DEI) was calculated. A bootstrap method with a p value of less than 0.05 was used to demote statistical significance. Results: Five bullets were ferromagnetic and seven were non-ferromagnetic. The DEI calculated were significantly (p<0.05) different between the ferromagnetic and nonferromagnetic projectiles. There were no significant difference (p>0.05) for intrareader and interreader agreement analysis. Conclusion: Dual-energy CT, despite several limitations, could be a valid method to differentiate ferromagnetic from non-ferromagnetic bullets in an ex-vivo environment with extended CT-scale. This approach could contribute to MR safety but further studies are necessary before using dual-energy CT as a routine technique for screening gunshots victims.

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Gunshot Trauma

Gassend,

Riva,

Magnin

2024

Forensic Imaging of Trauma

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Added Value of Dual-Energy Computed Tomography Versus Single-Energy Computed Tomography in Assessing Ferromagnetic Properties of Ballistic Projectiles

Cited by 27 publications

References 26 publications

Is CT bulletproof? On the use of CT for characterization of bullets in forensic radiology

Is CT bulletproof? On the use of CT for characterization of bullets in forensic radiology

Is dual-energy computed tomography helpful to determinate the ferromagnetic property of bullets?

Gunshot Trauma

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