CORONAVIRUS AND ELEVATED BODY TEMPERATURE
CORONAVIRUS AND ELEVATED BODY TEMPERATURE
COVID-19 and other viral diseases often trigger fever in humans, which raise body temperature as an immune response to infection. While all fevers elevate body temperature, not all increases in body temperature are due to an immune response. Body temperatures vary person to person and are easily influenced by physical activity, warm weather, and medication. While anticipating these variations is important, elevated body temperature remains one of the more telling signs that an individual may be fighting infection. When it comes to accurately measuring body temperature for medical purposes, a dedicated medical device, such as an internal thermometer, is required.
Skin temperature is primarily influenced by body temperature and is one of the most accessible indicators of an immune response, but can be heavily influenced by environmental temperature, physical activity, and circulation. Infrared technology makes non-contact, socially-distanced skin temperature screening possible. Under the right conditions, thermal screening for elevated skin temperature is a fast, safe method to detect individuals that may be experiencing an abnormally high body temperature or fever.
There are several factors that influence the accuracy of skin temperature screening with thermal imaging. Assuming your camera is fit for the job and equipped with proper screening software, one of the most important details for accurate skin temperature measurements is to focus on the corner of the eye. While the forehead is easier to quickly screen, it is more susceptible to environmental interferences and more likely to generate measurement errors. Research has shown that the corner of the eye—the region medially adjacent to the inner canthus—provides a more accurate estimate of core body temperature than other areas of skin. This is because skin at the canthi is thin (decreasing insulating effects), is less exposed to environmental factors, and is directly over major arteries which increase blood flow and heat transfer.
Realizing the difference between skin temperature and body temperature is a key first step towards implementing a non-contact screening solution. Using thermal imaging cameras to detect elevated skin temperatures helps industrial spaces, government facilities, and small businesses safeguard the health of employees and visitors. Understanding the purpose of elevated skin temperature screening, recognizing its limitations, and capturing accurate measurements are elemental in returning to work safely.
FLIR Infrared cameras can be used for detecting elevated body temperature (EBT) which may result from a person who has a high fever due to either illness or virus.
Below is some useful information for understanding EBT screening using FLIR’s Thermal Imaging cameras.
FLIR Systems’ thermal cameras are not medical devices. They do not detect the Coronavirus or fevers. They
are extremely effective, however, at detecting deviations in the external temperature of objects and people.
With this capability, FLIR thermal cameras are commonly used as non-contact screening tools to detect differences in skin surface temperatures and pattern changes. In fact, FLIR has received approval for certain cameras from the United States Food and Drug Administration (FDA) to screen in high-traffic public places like airports, train stations, and subway stations. During the screening process, to obtain an accurate temperature reading, it is recommended that the camera focus on a single person and the intended target be as close to the camera as possible. If a person has been detected with an elevated body temperature during screening, those individuals should be further examined with a medical device to verify if they have a fever.
Our products see Infrared energy and measure surface temperature differences only which can be an indication of an elevated temperature and an issue with that individual. The FLIR camera is an industrial camera and when used in the “screening mode” it can identify individuals in a population that show higher than average temperature in relation to the rest of the sampled population.
We recommend the Exx and T series model cameras for screening as these have a “Screening mode” built into the FLIR camera and are the easiest to deploy solution for Elevated Body Temperature Screening.
The attached video explains how our cameras work.
As you can see its very straight forward and easy to use. We recommend the camera runs for around 10 minutes to stabilize in that environment before you start to screen people. With camera purchases Infratek will provide training for you to effectively use the cameras in fever scanning mode.
Medical Thermography experts have traditionally chosen 320×240 pixel or higher resolutions and a camera that supports focusable optics. This starts with the FLIR E75 and T530 cameras. These conditions are not met by the FLIR Ex series, Cx series or consumer grade cameras such as the FLIR One for iPhone or Android phones. This largely has to do with resolution and a concept called “spot size”. Experts have confirmed that there is a correlation between the eye canthus temperature (tear duct area) and core temperature. The tear duct is a small area and you need to put enough pixels on it to make a good measurement. The lower resolution cameras with fixed focus aren’t optimized for this task. Even with the recommended cameras, you’ll find that maximum reported temperature is a function of distance, so you’ll want to set your alarm limits and do your screening at a fixed distance.
The E75 (1.3mm spot) can be used at 1.00m distance
The E85 (1.1mm spot) can be used at 1.25m distance
The E95 (0.9mm spot) can be used at 1.50m distance
Higher resolution will not only give you a better stand-off distance but also the ability to detect smaller temperature differences. If you’re routing the HDMI output to an external monitor at a guard desk, the image from the higher resolution cameras like the E95 or T540 looks much better.
T series tiltable Optical Block Form Factor is more ergonomic for handheld use however the Exx series cameras will be better balanced on tripod due to their central centre of gravity. A quality tripod should be used to handle the weight of the camera
The product pages for the recommended Flir Exx and T series cameras, and with resolution and prices are shown below.
Please note that:
⦁ the T530 is essentially the E75 but with a rotating lens
⦁ the T540 is essentially the E95 but with a rotating lens
IMAGE 1 from an E95 at 1.5m distance with standard 24 degree lens, note the hot tracking cursor (red triangle) in the inner medial canthus of the eye at 36.5 degrees (Emissivity = 0.98 for human skin) which is normal and close to but slightly lower than the normal core body temperature due to heat loss on the outside of the body. The screening mode on the EXX and T series allows a temperature differential alarm to be set when measured against a population sample.