Forensic Imaging最新文献

Terrorism is a global issue and a constant international threat.

Post-mortem imaging through post-mortem computed tomography (PMCT) techniques entered the panorama of methods used for forensic investigations, and are largely applied worldwide. In particular, since they can show the skeletal system and major parenchymal alterations and aid the localization of foreign bodies, they have been already applied in disasters related to terrorism attack, for identification of the victims, the documentation of injuries, and reconstruction of the event.

The aim of this paper is to explore the potentials of PMCT methods in forensic investigations related to terrorism attack.

Objectives

Investigating the impact of three common maceration techniques on the collagen content and autofluorescence of porcine bone, to ascertain the most suitable preparation method for bone undergoing ALS analysis.

Materials and methods

Hot water (80°C), biological washing powder (55°C), and enzymatic (55°C) maceration were used to prepare thirty porcine ribs (Sus scrofa domesticus) (n=10). Ribs were photographed before and after maceration using blue light (Crime-Lite 2, 450nm), coupled with an orange camera filter. Thermogravimetric analysis was used to quantify collagen content, and a bespoke computer program: The Osteo-Fluorescence Calculator (OFC) was used to quantify bone fluorescence.

Results

Ribs macerated in hot water exhibited homogenous fluorescence and produced a 5.5% average increase in fluorescence levels (n=10, s.d.=9.36, p=0.012) alongside a 11.2% loss in collagen content (n=10, s.d.=0.09, p=0.023). Biological washing powder was destructive to bone surfaces and produced an average collagen loss of 22.9% (n=10, s.d.=0.05, p= <0.001), while fluorescence was augmented (54.49%) and inconsistent (n=10, s.d.=27.46, p=0.180). Enzymatic maceration produced an average increase in fluorescence of 23.2% (n=10, s.d.=23.72, p=0.180), with a mostly consistent appearance except for some dark patches, and experienced a 19.5% loss in collagen content (n=10, s.d.=0.09, p=0.001).

Conclusions

Hot water maceration produced fluorescence results comparable to fresh bone with little impact on bone collagen and provides a suitable preparation technique for osseous ALS examination. Biological washing powder was destructive to bone collagen and produced exaggerated, inconsistent fluorescence and therefore should be avoided. Enzymatic maceration was the fastest method but requires an optimised formulation.

Accurate age-at-death (AAD) estimation is integral in establishing biological profiles in forensic anthropology, though standardized multivariate techniques are lacking. The current study developed and tested a three-dimensional convolutional neural network and three model variations with 1,224 de-identified cranial CT scans from the New Mexico Decedent Image Database. Each model required an input of an individual's cranial CT scan and outputted an AAD estimation. Model 3 was superior, successfully predicting AAD within 1.5 decades.

Forensic imaging is frequently utilised to aid medico-legal investigations worldwide on both the living and the deceased, but little is published or known about current forensic imaging practices across Australia and New Zealand (ANZ). The ANZ branch of the International Association of Forensic Radiographers (IAFR) aimed to gather information on current forensic imaging practices across ANZ, focussing on examinations, training, staffing and how participants felt they could benefit from training and guidance in the future. An online survey was distributed to a range of forensic and imaging facilities in 2020. 47 participants responded who answered 34 questions. The results showed that forensic imaging involved both the living and deceased in a variety of environments. Participants felt the need for more forensic imaging training, including the most performed forensic imaging examinations. Departmental training, policies and procedures for forensic imaging and related examinations varied widely. The results indicated a lack of standardisation across imaging facilities in ANZ. The region would benefit from forensic imaging guidelines, as well as further training and resources to support practitioners performing these examinations.

Virtual anthropology is an ever-growing sub-field within forensic anthropology that is being applied across a variety of forensic anthropological research areas (Franklin et al, 2016). However, no previous studies have investigated the impact of participant confidence levels in analysing 3D virtual skeletal models. This study explores the feasibility of estimating sex and age from 3D virtual skull and os coxa models, aiming to investigate the feasibility of moving the field of forensic anthropology into virtual lab spaces. A total of 71 participants completed an online survey requiring analysis of published virtual 3D skeletal models. Participants were asked to rate their confidence in the methodology and overall sex/age estimation, as well as preference for assessment method for each skeletal model. Statistical Analysis revealed that level of experience in analysing dry bones was found to not be associated with higher confidence in analysing 3D virtual remains (p=0.360 for sex of skull; p=0.494 for sex of os coxa; p=0.845 for age of os coxa). Confidence ratings for students in analysing skeletal remains in person did not predict perceived difficulty of analysing 3D virtual skeletal models (p=0.717 for sex of skull; p=0.579 for sex of os coxa; p=0.733 for age of os coxa). Prior 3D virtual experience did make a difference in confidence levels in the estimation of skull-sex and os coxa-age models (p=003 and p=0.001). Yet, prior 3D experience did not impact confidence levels with os coxa-sex (p=0.093). To provide insight into the results, the social cognitive concept of the ‘self-efficacy’ theory is discussed.

The Forensic Capability Network (FCN) Visual Technologies Research Group (VTRG) is a collective of academics, consultants, forensic practitioners, and law enforcement with expertise in the developing field of 3D forensic science (3DFS) that was established in 2020. This short communication provides an oversight into the development of the working group and 3DFS as a new subdiscipline of Forensic Science. As a collaborative venture, the VTRG provides a platform to create and disseminate knowledge and experience to improve the efficiency, effectiveness, and strength of partnerships across the criminal justice system. So far, the VTRG has established a user network and has gathered intelligence regarding the current use 3DFS across England and Wales. A clear demand for 3D services has been identified, however, the lack operational guidelines, standardised operating procedures, training or certification, ethical recommendations, quality assurance policies, or formal oversight remains a concern. The VTRG therefore aim to focus future work on promoting effective knowledge transfer and supporting the empirical research that underpins best practice guidance.

Conventional 3D rendering methods of computed tomography (CT) as well as post-mortem data CT (PMCT) sometimes do not seem to be authentic enough, especially for relatively thin bones. This can be a problem when imaging intact anatomy and considering fractures of the facial or temporal bones, where defects or holes may be visualized instead of thin bone structures. The technical aspect of this is that all currently used visualization methods (volume rendering, cinematic rendering and particle tracing, shaded surfaces and iso-surfaces) are defined by a CT-density threshold, whereas the user at least implicitly expects the bone to have a certain minimum density CT. However, some bone regions, typically those with relatively thin bone, do not meet these expectations, and lowering the threshold for visualization then results in all sorts of non-bone tissue being seen in the rendered images. To provide a more authentic PMCT visualization of bone, we identified a mixed data gradient model that improves the data from CT by increasing the CT density of low-density bone regions (but not of non-bone tissues). That delivers more satisfactory results for otherwise unmodified volume rendering. As pre-processing before 3D rendering, both hard and soft kernel data are used to obtain a 3D density map, a grayscale co-occurrence matrix is determined using a $3\times 3\times 3$ kernel as the 3D gradient map, and these are then combined to obtain the final gradient model for mixed data.

We herein present a forensic case wherein sequential computed tomography (CT) images of fatal “cocaine body packer syndrome” were shown on antemortem CT (AMCT) and postmortem CT (PMCT). While passing through customs at an international airport, a man was detained. Abdominal X-ray revealed multiple capsule-like structures inside the bowel, and the capsules were confirmed to be cocaine using an onsite immunoassay drug-screening device. He was admitted to the hospital under police surveillance and subjected to AMCT, which revealed multiple capsules in his colon. He died 2 days after admission; he was diagnosed with drug poisoning, which is referred to as “body packer syndrome” A forensic autopsy was conducted using PMCT, toxicology, and histology. This case offered a unique chance to photograph interior cocaine drug containers using AMCT and PMCT. PMCT outlined a specific location of the suspected ruptured cocaine capsules that were not identified on AMCT and before autopsy, thereby enabling a speculative hypothesis regarding accidental versus suicidal death.

Estimating sex from unknown human skeletal remains is an important component in forensic anthropology. Currently, both morphological and morphometric methods are used for sex estimation. These methods employ landmarks to make morphological comparisons between and within groups. Manual landmarking has been regarded as time-consuming and subjective. To decrease observer subjectivity and reduce measurement errors, an automated three-dimensional (3D) method was developed. This study aimed to validate the utilisation of the automatic placement of anatomical and sliding landmarks on 3D pelvis models for shape analysis using Computed Tomography (CT) scans.

Computed Tomography scans of adult South Africans were obtained from Steve Biko Academic Hospital, Pretoria, South Africa. In this study, automatic landmarking was validated on 130 3D reconstructions of the adult human pelvis. Eighteen anatomical and 260 sliding landmarks were registered on 130 3D models of the same individuals manually and automatically using the MeVisLab © v 2.7.1 software. Landmark datasets were acquired using both landmarking methods and compared using reproducibility testing and geometric morphometric (GMM) analysis. Reproducibility testing of both landmark datasets demonstrated minimal dispersion errors (<2 mm), indicating the reliability and repeatability of both landmarking methods. Variance analysis showed that pelvis shape sex-related variation was statistically significant (p <0.05) using both methods. In addition, cross-validated discriminant function analysis (DFA) yielded accuracies between 82.98 – 97.73% and 65.91 – 93.18% using automatic and manual placement of landmarks, respectively.

In forensics using 3D automatic approaches, and advanced statistical analysis might allow forensic anthropologists to estimate sex in a more accurate and repeatable way.