Due to the infectious COVID-19 pandemic, there is a massive spike in demand for thermal imaging systems (infrared thermographic systems or thermal imaging devices and cameras) for mass screening of people at public events, facilities, airports, and businesses.
Thermal imaging solutions play an essential role in helping governments and organizations worldwide in their coordinated response to the rapid spread of the virus.
One reason is the quick and mass identification of high fever, one of the typical early symptoms associated with the disease. A significant elevation of surface skin temperature beyond the normal range can be an early indicator of illness, including the infection.
Notably, this isn’t the first time the world depends on thermal imaging devices on a big scale. These non-contact temperature screening devices, including IR thermal cameras, were widely used during outbreaks of H1N1 influenza (or the swine flu), Severe Acute Respiratory Syndrome (or SARS), and Ebola. They have been since deployed in many countries as one of the measures to detect and help contain viral outbreaks.
These devices provide thermal imaging for body temperature solutions that can quickly and accurately identify people with elevated core body temperatures. They offer facilities and buildings with an additional layer of protection from increased exposure to the coronavirus. The speed of measurement and the convenience of not sterilizing them after each use before applying to the next person makes them suitable for situations where mass temperature screening is mandatory.
How does it work?
All objects emit some kind of infrared radiation, and it’s one of the ways that heat is transferred. Infrared is invisible to the naked eye. Thermal imaging devices detect the temperature by recognizing and capturing different levels of infrared light.
All non-contact temperature screening devices, including the temporal artery thermometers (also known as forehead thermometers or thermometer guns that measure the temperature of the temporal artery in the forehead), are equipped with infrared (IR) sensors that quickly measure surface temperature without making any contact with a person’s skin. AI algorithms are integrated into advanced solutions to help target temperature reading on parts of the body, typically the forehead or close to the eyes.
They also use blackbody devices to help calibrate the temperature measurement, especially in less controlled environments where the elements can influence the reading. The blackbody calibration consists of a target object with precisely known or controlled temperature. By deploying blackbody calibration, the device establishes an accurate relationship between grey level and temperature. This method eliminates false temperature alarms, caused by environmental influence, and improving the accuracy of the parameters.
Fever detection vs. diagnosis
It is important to note that fever is a symptom of many medical conditions other than infectious diseases. Therefore, detecting a fever is not a conclusive test for infection. Thermal body temperature solutions are a tool that can support the identification of a key symptom, but they do not diagnose COVID-19. Body temperature solutions are not a medical solution. They can only help organizations identify people showing symptoms.
The evidence from the ECRI Clinical Evidence Assessment showed that non-contact temperature screening methods were ineffective for detecting infected staff or visitors entering health care facilities or for screening travelers. Fever can result from conditions (including the absence of a specific illness) other than viral infections. Therefore, it is necessary to use confirmatory tests to determine truly infected individuals, along with temperature screening.
Parameters affecting screening outcomes
Screening outcomes of non-contact IR temperature screening devices depend strongly on several factors, including the performance characteristics of the camera that can usually be adjusted using camera software. Other factors include:
- the environmental temperature (environments that are too warm or too cold can affect the accuracy of the target temperature reading)
- the operating distance from individuals being tested (operators wielding the devices too close or not close enough to the person undergoing screening can produce false high- or unusually low-temperature readings)
- the use of medications that suppress a fever or elevate body temperature
physical activity, such as running.
- relative humidity and ambient temperature
- external optics temperature and transmission
Some of the top pros and cons of thermal imaging devices for mass temperature screening are as follows:
- Non-invasive and no physical contact
- No need for personal protective equipment (PPE) and OSHA-required training for temperature takers
- Faster results compared to typical forehead or oral (mouth) thermometers
- Higher accuracy and low waiting time
- High measurement capacity in high throughput areas, such as ports of entry, airports, train stations, sporting events, etc.
- Promotes positive behavior
- Accuracy depends on the careful setup, calibration, and operation
- Right environment and location needed for efficiency
- Indicates lower surface skin temperature, compared to oral tests
- Reconfirmation of fever is required with another method
- The person handling the device needs proper training and should follow instructions.