Abstract
BackgroundThe 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.MethodsA 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.ResultsThe 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).ConclusionThese 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.
Highlights
Temperature measurement is important for medical diagnosis and treatment, and has become much more widely used during the COVID-19 pandemic
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)
These data suggest that skin pigmentation does not affect thermal emissivity measurement of skin temperature using thermal infrared imaging
Summary
Temperature measurement is important for medical diagnosis and treatment, and has become much more widely used during the COVID-19 pandemic. Infrared thermography (IRT) provides a non-contact, highly sensitive and accurate measurement of skin surface temperature and its distribution [1,2,3]. Any object with a temperature above absolute zero emits electromagnetic radiation, known as infrared or thermal radiation. This emitted radiation is detected by IRT imaging systems to generate temperature readings and a visual representation of the temperature distribution across a surface. Transmitted and reflected radiation do not relate to the object’s temperature and must be accounted for to provide an accurate measurement. Body temperature can be measured using thermal infrared imaging, a safe, noncontact method that relies on the emissivity of the skin being known to provide accurate readings. We investigated the influence of different skin pigmentation on thermal emissivity in 65 adult volunteers
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
