Ruder Thomas D, Thali Yannick, Bolliger Stephan A, Somaini-Mathier Sandra, Thali Michael J, Hatch Gary M, Schindera Sebastian T
Department of Forensic Medicine and Imaging, Institute of Forensic Medicine, University of Zurich, Winterthurerstrasse 190/52, 8057, Zurich, Switzerland.
Forensic Sci Med Pathol. 2013 Jun;9(2):163-9. doi: 10.1007/s12024-012-9398-y. Epub 2012 Dec 21.
The goal of this study was to investigate the use of dual-energy computed tomography (CT) in differentiating frequently encountered foreign material on CT images using a standard single-source CT scanner. We scanned 20 different, forensically relevant materials at two X-Ray energy levels (80 and 130 kVp) on CT. CT values were measured in each object at both energy levels. Intraclass correlation coefficient (ICC) was used to determine intra-reader reliability. Analysis of variance (ANOVA) was performed to assess significance levels between X-Ray attenuation at 80 and 130 kVp. T test was used to investigate significance levels between mean HU values of individual object pairings at single energy levels of 80 and 130 kVp, respectively. ANOVA revealed that the difference in attenuation between beam energies of 80 kVp compared to 130 kVp was statistically significant (p < 0.005) for all materials except brass and lead. ICC was excellent at 80 kVp (0.999, p < 0.001) and at 130 kVp (0.998, p < 0.001). T test showed that using single energy levels of 80 and 130 kVp respectively 181/190 objects pairs could be differentiated from one another based on HU measurements. Using the combined information from both energy levels, 189/190 object pairs could be differentiated. Scanning with different energy levels is a simple way to apply dual-energy technique on a regular single-energy CT and improves the ability to differentiate foreign bodies with CT, based on their attenuation values.
本研究的目的是利用标准单源CT扫描仪，探讨双能计算机断层扫描（CT）在CT图像上鉴别常见异物的应用。我们在CT上以两个X射线能量水平（80和130 kVp）扫描了20种不同的、与法医学相关的材料。在两个能量水平下测量每个物体的CT值。组内相关系数（ICC）用于确定阅片者内部的可靠性。进行方差分析（ANOVA）以评估80和130 kVp时X射线衰减之间的显著性水平。T检验用于分别研究80和130 kVp单能量水平下各个物体配对的平均HU值之间的显著性水平。方差分析显示，除黄铜和铅外，所有材料在80 kVp与130 kVp束能量之间的衰减差异具有统计学意义（p < 0.005）。ICC在80 kVp时为优秀（0.999，p < 0.001），在130 kVp时为优秀（0.998，p < 0.001）。T检验表明，分别使用80和130 kVp的单能量水平，181/190的物体对可根据HU测量值相互区分。利用两个能量水平的组合信息，189/190的物体对可被区分。在常规单能量CT上采用不同能量水平扫描是应用双能技术的一种简单方法，基于异物的衰减值，可提高CT鉴别异物的能力。
