Thermal Imaging Systems and COVID-19

In this pandemic situation, lots of technologies are used to evaluate the temperature of the human body by maintaining the social distance. Here, some of the research prefer thermal imaging systems to measure temperature on the skin surface. Usually, thermal imaging systems have an IR thermal camera and temperature reference source to calculate the temperature.

Thermal Imaging Systems and COVID-19

Basically, the thermal imaging system includes Thermal Scopes, Thermal Cameras, Thermal Monoculars, Thermal Binoculars, Thermal Clip-on Scopes, Thermal Pastes, Thermometers, and so on. 

Thermal imaging equipment should be used correctly to accurately measure the skin temperature of humans without getting physically close to the examining person for whom temperature is needed to check. 

When compared to other human body temperature measuring tools like NCITs (Non-Contact Infrared Thermometers) or Oral thermometers, thermal imaging systems do not need closer contact to calculate the temperature.

However, the accuracy of the thermal imaging systems is a questionable one. While taking the skin temperature of many people at the same time, accuracy errors may occur. The thermal imaging systems should be carefully set-up and always maintain a time gap between examining various peoples.

In fact, the thermal imaging-based screening test is not an effective testing way to find out whether the particular person is definitively infected by the COVID-19 virus. Because most people with the COVID-19 virus may not have a fever. Therefore, a diagnostic test should be done to identify whether someone has a COVID-19 virus.

These thermal imaging systems have been preferred and used by many countries during this pandemic condition and make the best part in decreasing the spread of Covid-19 disease.

How Thermal Imaging Works?

Thermal imaging systems are a thermal tool that creates images and it works based on the heat energy. The higher the range of the temperature of the human body or other objects, the more infrared radiation is emitted back to the system.

The lens present in the thermal imaging system focuses on heat radiation (Wiki) that gets emitted from the human skin surface. This system has a phased array made up of IR which is used to scan the heat source. The output of the scanning process produces a special image known as a thermogram.

Then the thermogram is shifted to a signal processing device that processes the data and converts it into a readable display.

Types of Thermal Imaging Systems

Two basic types of thermal imaging systems.

Cryogenically-Cooled Systems: More expensive one. These systems can detect a change in temperature which is less than one-quarter of a degree.

Un-Cooled Systems: Common thermal imaging system. One can use the system instantly when it is turned on which is cheaper and requires less maintenance.

Benefits of Thermal Imaging Systems

  • The examiner with a thermal imaging system can easily maintain the social distance with the people. And here, the examiner who works with a thermal imaging system can do their job from the isolated or different room.
  • The thermal imaging system is used to measure the temperature of someone’s body temperature exactly when the system is operated correctly.
  • The thermal imaging system is an effective and quick way to measure surface skin temperature when compared to other temperature measuring methods like the forehead or oral thermometer. In fact, these two methods require physical contact with the testing person.

What are the Limitations of Thermal Imaging Systems?

A thermal imaging system just measures the outer skin surface temperature of the human body and it is an initial or basic measurement. Yet, it is not working properly when measuring the temperature of multiple people without any time gap.

Skin surface temperature is always lower than the oral temperature. Therefore it is not an effective way. To correct this temperature difference, the thermal system should be modified.

Thermal Imaging systems will work properly, when…

  • The imaging systems are used in the correct surrounding
  • The systems are operated and set up correctly
  • The person is prepared based on the instructions
  • The examiner handling the system is trained properly

How to Use Thermal Imaging Systems – Preparation

Before working with the thermal imaging system, the examiner or person who handles the equipment should read and follow all manufacturer instructions. This will help that person to ensure whether the system is set up properly and where it can be placed to estimate surface skin temperature precisely.

Prepare the place to apply Thermal Imaging System

  • Maintain the room temperature between 68 – 76 °F (20 – 24 °C) and humidity between 10 – 50 %.
  • Don’t keep items that create an impact on the temperature measurement.
  • Avoid reflective things like glass, mirrors, and metallic surfaces to reduce reflected infrared radiation.
  • Make sure that the room has no air or minimum air movement.
  • Direct sunlight should not pass through the room and also it should be away from radiant heat sources like portable heaters, stoves, etc.
  • Better avoid using incandescent light, halogen, and quartz tungsten halogen light bulbs.

How to prepare the Thermal Imaging System

  • Switch on the thermal imaging system 30 minutes before using it.
  • Fewer Thermal Imaging systems need the calibrated blackbody which is the tool for inspecting the calibration of an IR temperature sensor during the testing process. 
  • This will ensure the accuracy of the system. To find out whether the system requires a calibrated blackbody or not, read the manufacturer’s instructions.

Prepare the Person for Testing

  • Before examining the person, the examiner who handles the imaging system has to ensure the following:
  • While testing with the thermal system, the person evaluated should not have face obstructions like scarf, mask, or glasses. In this pandemic condition, most health workers and people wear masks or shields to reduce the spread of coronavirus. But while measuring the temperature, these protective masks and sheets may lead to inaccurate calculation of temperature.
  • Hair should not cover their face, and the face should be clean and dry. 
  • After bathing or doing exercise, the person evaluated has to wait for 15 to 30 minutes in the normal room.

Using the Thermal Imaging System

Thermal Image
During training, a firefighter with the 96th Civil Engineer Squadron fire department uses a thermal imaging camera to see through smoke, enabling him to pinpoint hot spots and keep track of the crew, at Eglin Air Force Base, Fla., June 21, 2007.

Prefer Measuring a single person’s surface skin temperature at a time.

The person for whom you want to measure the temperature should be in a fixed position and a particular distance from the system as mentioned in the manufacturer instructions.

The thermal image area must include the person’s face and the calibrated blackbody if it is used.

The increased skin surface temperature determined using a thermal imaging system will not confirm the fever. You need to use various ways to confirm a fever. Other tests related to COVID-19 have to be done to confirm the coronavirus.

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