The effect of constitutive pigmentation on the measured emissivity of human skin.

BACKGROUND: The measurement of body temperature has become commonplace in the current COVID-19 pandemic. Body temperature can be measured using thermal infrared imaging, a safe, non-contact method that relies on the emissivity of the skin being known to provide accurate readings. Skin pigmentation affects the absorption of visible light and enables us to see variations in skin colour. Pigmentation may also affect the absorption of infrared radiation and thus affect thermal imaging. Human skin has an accepted emissivity of 0.98 but the effect of different skin pigmentation on this value is not known. In this study, we investigated the influence of different skin pigmentation on thermal emissivity in 65 adult volunteers. METHODS: A reference object of known emissivity (electrical tape) was applied to participant's skin on the inner upper arm. Tape and arm were imaged simultaneously using a thermal infrared camera. The emissivity was set on the camera to the known value for electrical tape. The emissivity was altered manually until the skin temperature using thermal imaging software was equal to the initial tape temperature. This provided the calculated emissivity value of the skin. Participants were grouped according to skin pigmentation, quantified using the Fitzpatrick skin phototyping scale and reflectance spectrophotometry. Differences in emissivity values between skin pigmentation groups were assessed by one-way ANOVA. RESULTS: The mean calculated emissivity for the 65 participants was 0.972 (range 0.96-0.99). No significant differences in emissivity were observed between participants when grouped by skin pigmentation according to the Fitzpatrick scale (p = 0.859) or reflectance spectrophotometry (p = 0.346). CONCLUSION: These data suggest that skin pigmentation does not affect thermal emissivity measurement of skin temperature using thermal infrared imaging. This study will aid further research into the application of thermal infrared imaging as a screening or bedside diagnostic tool in clinical practice.

Postmortem Computed Tomography: An Overview for Forensic Nurses Involved in Death Investigation.

The traditional invasive autopsy has been considered the "gold standard" for death investigation worldwide. However, this has now been challenged by a new minimally invasive approach that utilizes cross-sectional radiological imaging to investigate the death. Globally, postmortem computed tomography is the most commonly used modality and is becoming increasingly available throughout the world. Forensic nurses working in association with coroners and medical examiners' offices, as well as mass fatality incidents, now need to update their knowledge base to understand these innovative techniques, the advantages and disadvantages to their use, and how they impact on medicolegal death investigation and the care of the deceased and bereaved. Using the example of the coroner system of England and Wales, this article provides a comparison between the traditional invasive autopsy and postmortem radiological alternatives and presents the impact postmortem radiology is now having on death investigation.

Myocardial Infarction Due to Coronary Artery Injury following High Force Blunt Trauma to the Upper Chest: A Case Illustrating the Prehospital, Hospital and Autopsy Findings.

Myocardial infarction (MI) is a rare complication of blunt chest trauma (BCT). We describe an extensive antero-lateral MI due to thrombosis of the left main stem coronary artery following a blow to the lower face and upper anterior chest during an industrial accident in a 52-year-old male. The patient presented with acute left ventricular failure. Our case highlights MI as an important differential in a BCT patient presenting with hypoxia where lung pathology has been excluded. We aim to highlight the importance of cardiac assessment in trauma scenarios particularly where patients are unable to report symptoms. Our patient sadly did not survive his injuries. This case describes MI following BCT from the initial prehospital presentation through to postmortem findings and adds to the limited literature on the pathological mechanisms underpinning this rare complication.

How taphonomic alteration affects the detection and imaging of striations in stab wounds.

Stabbing with a kitchen knife is a common method of homicide in Europe. Serrated knives may leave tool markings (striations) in tissues. Documentation of striations is necessary for their use as forensic evidence. Traditional methods (physical casting and photography) have significant limitations, and micro-computed tomography (micro-CT) has been trialled in cartilage to "virtually cast" wounds. Previous research has shown the proportion of striations in cartilage falls following decomposition. This project has investigated the effects of taphonomic alteration and documentation methods of striations in porcine skin. Fresh, decomposed, mummified, burnt and waterlogged stab wounds in a porcine analogue were excised and imaged using photography, stereo-optical microscopy and micro-CT. The proportion of striations in each taphonomic group was determined from the images by independent analysts. Striations were observed more frequently in serrated blade wounds, although they were also identified in non-serrated blade wounds. The proportion of wounds showing striations declined following decomposition. An inversely proportional linear correlation between advancing decomposition and proportion of striations existed. Dehydration (mummification and burning) rendered serrated and non-serrated blade wounds indistinguishable. Water composition affected the preservation of striations. Identification of striations gradually declined after decomposition in tap water, but persisted to a point when left in brackish water. All three techniques imaged striations; however, the optimum technique was stereo-optical microscopy due to practical advantages and specific limitations affecting photography and micro-CT. This study demonstrates the effects of taphonomic alteration on striations and suggests stereo-optical microscopy is the optimum method for their documentation.