Inconsistency in 9mm bullets measured with non-destructive X-ray computed tomography

Kumar, Jagadeesha; Landheer, Dirk; Barnes-Warden, Jane; Fenne, Paul; Attridge, Alex; Williams, Mark A.

doi:10.1016/j.forsciint.2011.07.018

Cited by 10 publications

(15 citation statements)

References 17 publications

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“…For clarity, the Cartesian plot (described in Section 2.3.3) is shown alongside a polar representation. This data is representative of the other bullets in the sample and overall jacket thickness variations have a similar distribution to those reported by Kumar et al [15] -although with a greater variation towards the tip of the bullet. The same interesting 'ring' feature near the tip is present in all of the GM bullets, visualised as a red band in the thickness plot.…”

Section: Pre-impact Comparisonsupporting

confidence: 87%

“…Bullets were scanned using an appropriate electron acceleration voltage and a copper filter to exclude low energy X-rays, which prevents detector saturation and helps mitigate beam hardening effects which can cause artefacts in the reconstructed volume. A full discussion of this procedure and subsequent analysis is provided in [15] and [17]. All bullets were scanned prior to ballistic testing (Section 3) and then re-analysed using an identical method.…”

Section: Ct Scanningmentioning

confidence: 99%

“…An analysis tool has been developed in-house, using Matlab, to calculate the jacket thickness [15] and [19]. The image slice stack is first loaded into computer memory and a cross sectional profile at 0° is computed from the 3D stack of images.…”

Section: Calculation Of Jacket Thicknessmentioning

confidence: 99%

“…This procedure is repeated for profiles at other (discrete) angles until the whole surface of the bullet has been analysed. The reader is referred to [15] for a thorough discussion of the accuracy and validity of this method, including its verification against other physical assessment methods.…”

Section: Calculation Of Jacket Thicknessmentioning

confidence: 99%

“…Following the method prescribed by Kumar et al [15] (summarised in Section 2), a set of 20, nominally identical, bullets were CT scanned prior to being subjected to ballistic performance tests under controlled conditions. The deformed projectiles were then re-scanned in order to observe and quantify the degree of deformation resulting from the impacts, with a view to correlating these ballistic performance indicators with geometric features of the un-deformed bullets prior to impact.…”

Section: Introductionmentioning

confidence: 99%

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Inconsistency in 9mm bullets: Correlation of jacket thickness to post-impact geometry measured with non-destructive X-ray computed tomography

Thornby

Landheer²,

Williams³

et al. 2014

Forensic Science International

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Copyright and reuse:The Warwick Research Archive Portal (WRAP) makes this work by researchers of the University of Warwick available open access under the following conditions. Copyright © and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable the material made available in WRAP has been checked for eligibility before being made available. Copies of full items can be used for personal research or study, educational, or not-forprofit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way."NOTICE: this is the author's version of a work that was accepted for publication in Forensic Science International. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Forensic Science International, Volume 234 (2014) DOI:http://dx.doi.org/10.1016/j.forsciint.2013.11.002" A note on versions:The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP url' above for details on accessing the published version and note that access may require a subscription. AbstractFundamental to any ballistic armour standard is the reference projectile to be defeated. Typically, for certification purposes, a consistent and symmetrical bullet geometry is assumed, however variations in bullet jacket dimensions can have far reaching consequences. Traditionally, characteristics and internal dimensions have been analysed by physically sectioning bullets -an approach which is of restricted scope and which precludes subsequent ballistic assessment. The use of a non-destructive X-ray computed tomography (CT) method has been demonstrated and validated (Kumar et al., 2011 [15]); the authors now apply this technique to correlate bullet impact response with jacket thickness variations. A set of 20 bullets (9 mm DM11) were selected for comparison and an image-based analysis method was employed to map jacket thickness and determine the centre of gravity of each specimen. Both intra-and inter-bullet variations were investigated, with thickness variations of the order of 200 μm commonly found along the length of all bullets and angular variations of up to 50 μm in some. The bullets were subsequently impacted against a rigid flat plate under controlled conditions (observed on a high-speed video camera) and the resulting deformed projectiles were re-analysed. The results of the experiments demonstrate a marked difference in ballistic performance between bullets from different man...

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Section: Pre-impact Comparisonsupporting

confidence: 87%

Section: Ct Scanningmentioning

confidence: 99%

Section: Calculation Of Jacket Thicknessmentioning

confidence: 99%

Section: Calculation Of Jacket Thicknessmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Inconsistency in 9mm bullets: Correlation of jacket thickness to post-impact geometry measured with non-destructive X-ray computed tomography

Thornby

Landheer²,

Williams³

et al. 2014

Forensic Science International

Self Cite

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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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Deterring gun crime materially using forensic coatings

Sermon

Worsley

Cheng

et al. 2012

Forensic Science International

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Inconsistency in 9mm bullets measured with non-destructive X-ray computed tomography

Cited by 10 publications

References 17 publications

Inconsistency in 9mm bullets: Correlation of jacket thickness to post-impact geometry measured with non-destructive X-ray computed tomography

Inconsistency in 9mm bullets: Correlation of jacket thickness to post-impact geometry measured with non-destructive X-ray computed tomography

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

Deterring gun crime materially using forensic coatings

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