Postmortem Computed Tomography in Firearm Homicides: A Retrospective Case Series,

Postmortem computed tomography (PMCT) is integrated into the evaluation of decedents in several American medical examiner offices and medicolegal death investigative centers in many other countries. We retrospectively investigated the value of PMCT in a series of firearm homicide cases from a statewide centralized medical examiner’s office that occurred during 2016. Autopsies were performed or supervised by board-certified forensic pathologists who reviewed the PMCT scans prior to autopsy. PMCT scans were re-evaluated by a forensic radiologist blinded to the autopsy findings and scored by body region (head–neck, thoracoabdominal, and extremities). Injury discrepancies were scored using a modified Goldman classification and analyzed with McNemar’s test. We included 60 males and 20 females (median age 31 years, range 3–73). Based on PMCT, 56 (79.1%) cases had injuries relevant to the cause of death in a single body region (24 head–neck region, 32 thoracoabdominal region). Out of these 56 cases, 9 had a missed major diagnosis by PMCT outside that region, including 6 extremity injuries visible during standard external examination. Yet all had evident lethal firearm injury. We showed that PMCT identifies major firearm injuries in homicide victims and excludes injuries related to the cause of death in other regions when a single body region is injured. Although PMCT has a known limited sensitivity for soft tissue and vascular pathology, it can be combined with external examination to potentially reduce or focus dissections in some of these cases depending on the circumstances and medicolegal needs.     

青少年肩关节X线片的骨龄研究

目的探讨青少年肩关节X线影像与年龄间的关系。方法对太原地区267名年龄在12～22岁的青少年拍摄肩关节X线片,根据X线片上的不同年龄特征,筛选出5个与年龄变化密切相关的影像标志点,进行分级评分,提出了肩关节X线片判定年龄的观察指标及分级标准,并使用SPSS包进行数据处理,建立了利用肩关节X线片判定青少年年龄的判别方程。结果判别方程y=9.517+0.518x1+0.913x2+0.465x3+0.436x4经方差分析,F>0.01,回归高度显著。将全部样本进行计算机方程回代检验,符合率为±1S72.01%,±2S96.3%,其结果达到了设计与统计学要求。方程具有实用价值。结论本项研究证实了青少年肩关节X线影像与年龄之间存在相关关系,并为司法鉴定时根据肩关节X线片判断年龄提供依据,同时也为人类学研究积累了资料。     

Chemical trace XRF analysis to detect sharp force trauma in fresh and burned bone

Forensic anthropologists may not always be able to differentiate heat-induced fractures from fractures with other aetiologies, namely sharp force traumas, with clear nefarious impact on medico-legal conclusions. The objective of this study was to experimentally investigate if blade chemical traces are transferred to defleshed bone tissue and if they remain there after a burning event. This was accomplished by prompting sharp force traumas in 20 macerated fresh pig ribs with five different instruments, namely a stainless steel knife, an artisanal knife and a ceramic kitchen knife, a small axe and a large axe. Another pig rib was used as control, not being subjected to any trauma. All instruments were probed by X-ray fluorescence (XRF) to establish the composition of each blade. Bone samples, both pre-burned and post-burned (at 500 °C, 700 °C, 900 °C and 1100 °C), were then probed by XRF. All sharp force instruments left detectable chemical traces on pre-burned bone, although not in all samples. Furthermore, traces were still detected after experimental burning in most cases. Potentially, XRF can provide relevant information about the aetiology of fractures in burned and unburned bones, although the effect of soft tissues and diagenesis must still be investigated.     

CT在肋骨骨折认定中的价值及骨折的力学分析

目的探讨在法医学鉴定中普通X线片难以确定的肋骨骨折,以CT技术加以显示的方法,并阐明肋骨骨折的力学原理。方法对17例普通X线技术显示困难的肋骨骨折行CT扫描,采用薄层平滑和高分辨率重建、表面遮盖法和多平面重建观察,确定肋骨骨折的部位、数量、形态、移位和骨痂形成情况等信息。结果17例X线平片难以确定的骨折,通过上述CT扫描和后处理重建技术,均得到满意的结果。通过骨折力学分析和影像观察,将间接暴力导致肋骨骨折的力矩分成垂直和旋转两类,从而提出垂直型和旋转型肋骨骨折的分类。结论对普通X线平片难以确定的肋骨骨折,建议采用薄层CT扫描,沿肋骨长轴多平面重建观察,结合肋骨骨折的力学原理,有助于避免将急性旋转型肋骨骨折误诊为陈旧骨折。     

Morphological and spectroscopic measurements of plastic bags for the purpose of discrimination

The discrimination of noncolored transparent polyethylene bags was studied by several nondestructive and semidestructive analytical methods. X-ray diffraction, infrared spectroscopy, and optical microscopy (differential interference contrast microscopy and phase contrast microscopy) were applied to polyethylene films. X-ray diffraction was used to distinguish variations in the crystalline phase, infrared spectroscopy was used to distinguish variations in the molecular components, and optical microscopy was used to distinguish the different surface morphologies. The results show that X-ray diffraction classifies the crystalline phase of the film depending on whether it is made from low-density polyethylene, linear low-density polyethylene, or high-density polyethylene; that infrared spectroscopy is useful to distinguish the molecular components and it is the most discriminating technique; and that optical microscopy discriminate films easily by their morphological differences.     

足弓破坏法医临床学鉴定的影像学理论与实践

足弓破坏是现行GB18667-2002《道路交通事故受伤人员伤残评定》标准针对足损伤后伤残等级评定特别给出的命名,临床与法医学界对此问题的阐述尚较少见,有必要在实践工作的基础上加以总结。足在纵、横方向上形成凸向上方的弓形外观,分别为内侧纵弓、外侧纵弓及横弓。足弓作用主要在于吸收震荡,起到保护作用,具备静态与动态两种态势。足弓可借鉴静态体重负荷下X线摄足弓侧位片进行测量。足损伤致跗、跖骨骨折愈合后足弓X线测量值背离临床医学足弓正常参考值和/或维持足弓功能作用的肌肉、韧带严重损伤,可谓足弓破坏。足弓骨性构架的动力结构内侧纵弓或承载负重的外侧纵弓中任意一个破坏,必定影响横弓,符合一足足弓结构破坏1/3以上的限定要件;而内侧纵弓及外侧纵弓均破坏,横弓必定破坏,符合一足足弓结构破坏的限定要件。     

Nondestructive Differentiation of Polyester Single White Fibers Using Synchrotron Radiation Microbeam X-ray Fluorescence Spectrometry with Vertical Focusing

In this study, the nondestructive differentiation of individual white polyester clothing fibers was accomplished via synchrotron radiation microbeam X-ray fluorescence (SR-μ-XRF) analysis. SR-μ-XRF with vertical focusing is a useful nondestructive method for the analysis of a single polyester clothing fiber. Kirkpatrick–Baez (KB) mirror was used to vertically focus 20 keV X-rays for the analysis of 22 individual white polyester fibers taken from clothing commonly sold in Japan. SR-μ-XRF with a vertical focused 2 μm (V) × 300 μm (H) beam was approximately 12.8 times more sensitive than SR-XRF with an unfocused 300 μm (V) × 300 μm (H) beam for the detection of elements in single fibers. The minimum detection limits (MDLs) of the SR-μ-XRF method were 8.15 ppm for Cl and 0.06 ppm for Br. In addition to Ti in TiO₂ delustering agents, Zr and Nb impurities in the delustering agents were detected in individual fibers. Sb from a polymerization catalyst and Co from a transesterification catalyst were also detected in individual fibers. Comparing the Ti K_β/Sb L_α,β and Zr K_α/Nb K_α X-ray intensity ratios was a useful way to distinguish individual clothing fibers, and 98% of the fibers were differentiated when additional trace elements were used as discrimination indicators.     

铁铬合金菜刀遗留金属颗粒的成分评价方法

目的检测铁铬合金菜刀遗留的金属颗粒成分,并建立可行的评价指标及方法。方法使用滤纸擦蹭菜刀制作金属遗留微小颗粒样本,应用扫描电镜-X射线能谱仪(scanning electron microscopy and energy dispersive X-ray spectrometer,SEM-EDX)的GSR颗粒分析功能检测遗留金属颗粒成分,计算遗留金属颗粒中铁、铬相对含量比。结果铁铬合金菜刀遗留金属颗粒内所含铁、铬相对含量比,在大部分菜刀间差异有统计学意义(P0.05)。结论使用GSR颗粒分析功能量化检测铁铬合金菜刀遗留金属颗粒内铁、铬相对含量比,为此类致伤工具的认定建立可行的评价方法。     

基于X-射线衍射法检测甲基苯丙胺晶体并推断来源

目的采用X-射线衍射法(XRD)建立一种快速检测甲基苯丙胺晶体并推断其来源的方法。方法对18起案件中的53份甲基苯丙胺样本进行XRD检验。结果通过分析主要特征峰强度比例,可以得到毒品的定性分析结果,以及样本的晶型取向信息;通过分析XRD谱图中毒品的特征峰半峰宽信息可以得到毒品的结晶度;对样本中明显的杂质峰进行比对,即可得到毒品来源信息参考。结论该方法简便快捷、无损样本、无污染,能够快速、准确、高效地分析结晶状毒品,为确定制贩毒集团上下线及涉毒案件串并案提供佐证。     

微束X射线荧光光谱法检测电流损伤皮肤金属化

目的建立微束X射线荧光光谱（μ-probe X-ray fluorescence,μ-XRF）检测电流损伤皮肤金属化的方法。方法新西兰大白兔32只,随机分为黄铜电击组、紫铜电击组、铁电击组、铝合金电击组,每组8只。电极一极固定于左后腿中部,另一极固定于左前腿,建立电击模型。提取左后腿触电部位皮肤,以及对侧右后腿相应部位皮肤作为对照,应用μ-XRF光谱仪对电流损伤皮肤内金属元素进行测定。结果正常对照组皮肤中检测出磷、氯、钾、钙元素成分;在电击组皮肤中,除正常皮肤检出的元素外,黄铜电击组检测出铜、锌元素,紫铜电击组检出铜元素,铁电击组检出铁元素,铝合金电击组检出铝元素。渗透到电流损伤皮肤内的金属元素呈不均匀分布。结论μ-XRF光谱法检测皮肤金属化可作为诊断电流损伤的特征性指标,并可为触电材料的推断提供依据。