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Identification of bullets based on their metallic components and X-ray attenuation characteristics at different energy levels on CT


Gascho, Dominic; Zoelch, Niklaus; Richter, Henning; Buehlmann, Alexander; Wyss, Philipp; Schaerli, Sarah (2019). Identification of bullets based on their metallic components and X-ray attenuation characteristics at different energy levels on CT. American Journal of Roentgenology, 213(3):W105-W113.

Abstract

OBJECTIVE. This study aimed to identify bullets on the basis of their metallic components and to distinguish between ferromagnetic and nonferromagnetic bullets using CT. MATERIALS AND METHODS. Eight ferromagnetic, steel-jacketed lead bullets, four nonferromagnetic, non–steel-jacketed lead bullets, and four nonferromagnetic solid bullets composed of copper or copper and zinc alloys which we refer to here as “Cu(Zn) bullets,” were scanned by CT at 80, 100, 120, and 140 kVp. Attenuation values (in Hounsfield units) were measured on an extended CT scale (ECTS) in the core and at the edge of the bullets and were used to calculate the dual-energy index (DEI). RESULTS. Although all nonferromagnetic bullets significantly differed from ferromagnetic bullets, the significant differences were solely attributed to the higher DEI of solid Cu(Zn) bullets compared with that of all-lead bullets. The lead bullets with ferromagnetic, steel-containing jackets did not differ from the lead bullets with nonferromagnetic, non–steel-containing jackets on the basis of DEIs obtained from core and edge measurements. Solid Cu(Zn) bullets could be clearly distinguished from lead bullets regardless of the metallic components of the jackets using DEI calculations from CT numbers on an ECTS. The DEIs based on the dual-energy pair 120 and 140 kVp appear to be the most appropriate for distinguishing between these two types of bullets. CONCLUSION. This study provides new scientific knowledge regarding metals and their characteristics at different tube voltage levels. The abilities of clinically approved dual-energy CT allow differentiation of bullets composed of low-atomic-number (Z) metals from bullets composed of high-Z metals via DEI calculations from CT numbers on an ECTS.

Abstract

OBJECTIVE. This study aimed to identify bullets on the basis of their metallic components and to distinguish between ferromagnetic and nonferromagnetic bullets using CT. MATERIALS AND METHODS. Eight ferromagnetic, steel-jacketed lead bullets, four nonferromagnetic, non–steel-jacketed lead bullets, and four nonferromagnetic solid bullets composed of copper or copper and zinc alloys which we refer to here as “Cu(Zn) bullets,” were scanned by CT at 80, 100, 120, and 140 kVp. Attenuation values (in Hounsfield units) were measured on an extended CT scale (ECTS) in the core and at the edge of the bullets and were used to calculate the dual-energy index (DEI). RESULTS. Although all nonferromagnetic bullets significantly differed from ferromagnetic bullets, the significant differences were solely attributed to the higher DEI of solid Cu(Zn) bullets compared with that of all-lead bullets. The lead bullets with ferromagnetic, steel-containing jackets did not differ from the lead bullets with nonferromagnetic, non–steel-containing jackets on the basis of DEIs obtained from core and edge measurements. Solid Cu(Zn) bullets could be clearly distinguished from lead bullets regardless of the metallic components of the jackets using DEI calculations from CT numbers on an ECTS. The DEIs based on the dual-energy pair 120 and 140 kVp appear to be the most appropriate for distinguishing between these two types of bullets. CONCLUSION. This study provides new scientific knowledge regarding metals and their characteristics at different tube voltage levels. The abilities of clinically approved dual-energy CT allow differentiation of bullets composed of low-atomic-number (Z) metals from bullets composed of high-Z metals via DEI calculations from CT numbers on an ECTS.

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Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Institute of Legal Medicine
Dewey Decimal Classification:510 Mathematics
Uncontrolled Keywords:Radiology Nuclear Medicine and imaging, General Medicine
Language:English
Date:1 September 2019
Deposited On:20 Jun 2019 06:20
Last Modified:23 Aug 2019 01:03
Publisher:American Roentgen Ray Society
ISSN:0361-803X
OA Status:Closed
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.2214/ajr.19.21229
PubMed ID:31120788

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