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Expert Advice for Selecting Thermal Imaging Technology

Business July 16, 2020

People across industries want to get back into the office, but not without fear that viruses wait for their arrival. Organizations across industries are searching for solutions to screen people for illness returning to the office in many ways, including with thermal imaging technology to measure elevated body temperatures.

Many manufacturers developed elevated skin temperature (EST) measurement systems as an initial screening tool to minimize the spread of contagious viruses. Designed with thermal imaging cameras, EST screening solutions seek to identify elevated skin temperature from a safe distance. Compared to handheld infrared thermometers, requiring a few inches for effective measurement, EST systems screen effectively from several feet.

As people return to the office and other work environments, EST solutions spiked in demand. However, it’s important to determine whether an EST system is right for your work environment. AVI’s engineers conducted research of several EST solutions and found that device quality, system setup, environment, and test execution are all critical to the success of these devices and solutions.

To note, a system — including the technology, environment, and execution —that fluctuates is not appropriate for EST. Consistent, accurate readings are critical for these solutions to work properly.

AVI’s engineering team recommends that you examine these considerations closely before using EST systems at your workplace:

Test Execution

There are two primary approaches to EST: tear-duct and forehead screening.

Tear-Duct Screening

Experts agree that tear-duct screening is preferred as it relies on a local artery for measurement. Blood flow is close to the skin’s surface, supporting a more accurate reading.

Tear-duct screening requires that people stand still for a few seconds with their glasses removed. The sensor must have an unobstructed view of the tear duct, or inner canthus.

Forehead Screening

Forehead screening can be subject to environmental influence and perspiration, potentially skewing results.

Some forehead screening systems measure multiple people simultaneously. People should still socially distance themselves during screening.

It is important to note that screening multiple people at once yields inaccurate results frequently. The Food and Drug Administration (FDA) writes this:

“Thermal imaging systems have not been shown to be accurate when used to take the temperature of multiple people at the same time. The accuracy of these systems depends on careful set-up and operation, as well as proper preparation of the person being evaluated.”

In addition to the area of focus, consistent distance is an important factor. For example, if the system is calibrated to conduct measurements 6 feet from the camera, all test subjects should be 6 feet from the camera.

Ambient air temperature and humidity impact test results so a person may read warmer at closer distances and cooler further away. It’s best to mark the specific location on the floor so the systems screens people at the same distance consistently.

The Environment

The environment, particularly a lobby or building entrance, should maintain a stable temperature and humidity.

Fluctuations in temperature and humidity impact the results of EST screenings. The FDA recommends a stable temperature from 68 to 76 degrees Fahrenheit and stable humidity from 10 to 50 percent. A consistent environment helps readings measure more accurately.

Some environments require additional components to screen people with a confidence.

One such component is a reference emitter used to compare the measurement of a person’s face. Think of it as a base template. The emitter is positioned next to the person in the camera’s view to help increase accuracy and confidence.

The downsides to additional components are added cost and complexity. High accuracy sensor technology paired with proper test execution negates the need for the extra components, which keeps costs down and tests consistent.

Sensor Technology

We all know the higher the resolution the better the picture. The same is true with thermal cameras used in EST. In general, the more pixels available for temperature measurement, the better the result. The fewer pixels the sensor employs for EST, the closer the test subject should stand for measurement.

Today’s marketplace is filled with various EST screening options. These include:

  • Tablets
  • Handheld cameras

  • Tripod and fixed install

  • Single and multi-person solutions 

Depending on how an organization chooses to use EST, false-positive and false-negative test results can have a range of impacts personnel, including flagging people for illness incorrectly and vice versa.

AVI engineers recommend that the full resolution of the thermal sensor should be devoted to a single test subject to support an accurate result. The minimum resolution for EST is 320 by 240 pixels. A quality sensor coupled with proper test methods minimizes negative impacts.

FDA Issues Temporary Directives Related to EST

In response to the COVID-19 pandemic, the FDA issued a temporary directive, permitting non-FDA listed hardware for use in EST screening applications. This was done to increase access of thermal imaging technology for the duration of the health emergency.

The results of this directive took form in many technologies entering the market, many of which are questionable. It may be possible for the FDA to rescind the temporary directive due to extensive use of inferior sensor technology, or upon the conclusion of the health emergency. This scenario may leave organizations with large investments in low-quality EST solutions in a difficult position.

It’s important to us that the systems we recommend are appropriate for your organization. Our engineers have taken steps to research and select appropriate technologies for various EST applications. We want to help you make this most important decision to protect your employees.

At AVI, we believe that thermal technology can be an effective component to office safety as part of a comprehensive approach to employee well-being. There are many types of thermal technology available and AVI’s experts can help you make the best decisions for your organization. Contact us today for further information.

Keith Yandell contributed to this blog post. He is the audiovisual manager at AVI Systems, formerly the director of engineering. He has more than 20 years of experience in the AV industry.


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