Forensic Imaging最新文献

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.

Objectives

Smile photographs retrieved from the internet can provide ante-mortem dental evidence to augment human identification. However, currently, the process is not validated and there is no agreed methodology. This study aims to evaluate the potential evidentiary value of dental data from these photographs for identification purposes.

Materials and methods

This study compared retrospective smile photographs from the internet with current smile photographs of ten (10) subjects using three (3) methods. 1. Conventional visual comparison of facial and dental features performed qualitatively noting the distinctive features. 2. Comparison of incisal edge tracings. 3. Semi-quantitative superimposition involving the computation of total correspondence scores and Index of Correspondence (IC). For each method, a score of 0–3 was allocated to score level of match. Matching scores were compared and statistically analysed.

Results

Individualising features could be visualised from smile photographs. For comparison, dental features visible in the photographs were reliable and consistent. Based on incisal edge tracing and dental superimposition, nine of ten current photographs were accurately matched to ones taken at an earlier time. Correct matches yielded significantly greater outcomes than incorrect matches when using incisal edge tracing and dental superimposition (p < 0.01). Grading outcomes from both methods are moderately positively correlated. Furthermore, both incisal edge tracing and dental superimposition significantly improved correct match grades (p < 0.05).

Conclusion

Photographs of people smiling retrieved from the internet can show distinctive features of the dentition. Semi-quantitative parameters can enhance the amount of dental information obtained from photographs which may assist in identification. Several methods are proposed to maximise information extracted from photographs.

The International Association of Forensic Radiographers (IAFR) facilitated a session at the online congress of the International Society of Forensic Radiology and Imaging in May 2021. The session provided an overview of forensic imaging and the role of the forensic radiographer across a range of six countries. This review summarises the common themes and differences, as well as recommending a wider survey of forensic institutes and forensic radiographers and noting an opportunity for the IAFR to provide online education to meet the postgraduate education and training needs of radiographers internationally.

Introduction

Estimating the time of death is one of the key questions in forensics. Currently, the estimated time of death in advanced decomposed bodies is often done by assessing subjective postmortem characteristics. Multiple methods are available to assess the time of death by postmortem CT scan. However, the relationship between the settling ratio of the liver and postmortem interval has never been established.

Objective

To assess the relationship between the postmortem interval in advanced decomposed bodies and the settling ratio of the liver on postmortem computed tomography.

Research method

This research is a retrospective descriptive correlation study. The sample group is deceased that have undergone computed tomography before autopsy at the Institute of Forensic Science, Ministry of Justice and Department of Forensic Medicine, Chulalongkorn University. The 105 deceased are divided into 3 groups based on time of death: 1 – 3 days 3 – 5 days, and 5 – 7 days. The bodies are subjected to computed tomography and the settling ratio of the liver is measured.

Results

The settling ratio of the liver and the postmortem interval are statistically correlated across several reference lines. The reference point between the midclavicular line and the 12th thoracic spine (mid-clavicle – T12) has the highest correlation coefficient of −0.515, considered a strong correlation, and no other factors are found that correlate with the time of death from the ordinal logistic regression model analysis.

Conclusion

The settling ratio of the liver and the postmortem interval are statistically correlated between multiple reference lines. The settling ratio of the liver can be developed as a method to estimate the time of death in combination with other methods.