With the increase in infections by Covid-19, various products for the detection of fever in people have appeared on the market. For a guaranteed measurement of body temperature, the system must meet the requirements defined by the International Electrotechnical Commission (IEC) in the UNE-EN IEC 80601-2-59: 2019 standard.
UNE-EN IEC 80601-2-59: 2019 standard requirements
UNE-EN IEC 80601-2-59: 2019 standard specifies the minimum requirements of resolution, accuracy, safety and performance of thermographic scanning systems for an effective measurement of body temperature and fever detection.
➢ Temperature measurement in eye canthus
➢ High camera resolution (> 320×240 pixels)
➢ The face must fill > 75% of the width of the image
➢ Caps, hats, glasses, … must be removed
➢ The black body and the face must have same focus
➢ No temperature detection for groups
➢ Stable black body with ± 0.1ºC precision
➢ Resolution must be less than 1 mm in the eye canthus
We must measure Body Temperature and not Skin Temperature
Skin temperature can be affected by many different factors, like sweating, environment temperature, medications or alcohol consumption,…
Facial temperature measurement using infrared thermometers is not a reliable solution for the fever detection.
Main reasons for not using infrared thermometers:
· The measurement is only in the area where we point with the thermometer and the result of the measurement also depends on the distance at which we place the thermometer from the person (a few centimeters from the face in this case), so it is difficult to have repeatability in measurements.
· From the pointed area, the thermometer only gives an average value of all the points in that area. It does not allow the automatic detection and measurement of the hot spot in the face, which is the eye canthus, as some thermal imaging camera systems do.
· It does not comply with the UNE-EN IEC 80601-2-59: 2019 standard that establishes the eye canthus as the area to be measured, since it is this point that has a greater correlation with the internal temperature of the body.
· It does not comply with the UNE-EN IEC 80601-2-59: 2019 standard which establishes the need for a temperature reference source (black body) to achieve the necessary accuracy.
Eye canthus measurement
The UNE-EN IEC 80601-2-59: 2019 standard indicates that the Canthus (inner corner of the eye) is known to provide a reasonable indicative body temperature reading, and that all other methods are inaccurate. The Canthus is the best area for fever screening due to the stability of measurement since this region is directly over the inner carotid artery.
For an accurate measurement of the eye canthus temperature it is necessary at least 4×4 pixels to cover this area.
The canthus is approximately 3 mm. in diameter, so it is necessary a resolution of at least 320×240 pixels in order to measure the temperature in that region accurately.
The face must fill > 75% of the width of the image.
The UNE-EN IEC 80601-2-59: 2019 standard indicates that a black body reference must be in focus at the same time as the subjects face, to ensure camera stability and compensating for any potential drift.
The black body and the face of the person need to be in the same image captured by the thermographic camera, and the image area covered with enough pixels to generate accurate results. By having this black body within the camera’s field of view the system can be calibrated in real-time.
FeverTIR | Fever detection system
The Fever Detection System FeverTIR is designed to quickly and accurately measure people’s body temperature without contact. The system alerts about people who exceed the established maximum body temperature, detecting possible cases of fever, one of the most obvious symptoms of Covid-19 infection, as well as similar contagious diseases.
· Accuracy ±0.3°C
· Resolution: 384×288
· Traceable calibration certificate
· Fully compliant with UNE-EN IEC 80601-2-59: 2019 standard