As discussed further below, scientific studies support that certain telethermographic systems, also known as thermal imaging systems, may be used to measure surface skin temperature. These systems include an infrared thermal camera and may have a temperature reference source. In this document, they are referred to as thermal imaging systems.

Thermal imaging systems and non-contact infrared thermometers (NCITs) use different forms of infrared technology to measure temperature. For information about NCITs, please refer to the fact sheet on Non-contact Infrared Thermometers.

Thermal Imaging Systems and COVID-19

• When used correctly, thermal imaging systems generally have been shown to accurately measure someone’s surface skin temperature without being physically close to the person being evaluated. Thermal imaging systems offer certain benefits in that other methods need a closer proximity or contact to measure temperature (for example, non-contact infrared thermometers or oral thermometers).
• Temperature-based screening, such as thermal imaging, is not effective at determining if someone definitively has COVID-19 because, among other things, a person with COVID-19 may not have a fever. A diagnostic test must be performed to determine if someone has COVID-19.
• 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.
• Thermal imaging systems have been used by several countries during epidemics, although information about their effectiveness as part of efforts to reduce the spread of disease has been mixed.
• The FDA issued the Enforcement Policy for Telethermographic Systems During the Coronavirus Disease 2019 (COVID-19) Public Health Emergency guidance to help expand the availability of thermal imaging systems and mitigate thermometer shortages during the public health emergency. The guidance sets forth an enforcement policy that is intended to apply to all thermal imaging systems that are intended for medical purposes for the duration of the public health emergency related to COVID-19, and provides recommendations regarding performance and labeling of such systems.

Figure 1 demonstrates the proper thermal imaging setup for processing of individual people in a public area.

Benefits of Thermal Imaging Systems

• The person who handles the thermal imaging system is not required to be physically close to the person being evaluated. In fact, the person who handles the thermal imaging system could be in a different area or room.
• The thermal imaging system may measure surface skin temperature faster than the typical forehead or oral (mouth) thermometer that requires a close distance or physical contact with the person being evaluated.
• Scientific studies show that, when used correctly, thermal imaging systems generally measure surface skin temperature accurately.

Limitations of Thermal Imaging Systems

• Although these systems may be in use for initial temperature assessment to triage individuals in high throughput areas (for example, airports, businesses and sporting events), the systems have not been shown to be effective when used to take the temperature of multiple people at the same time. They should not be used for “mass fever screening.”
• These systems measure surface skin temperature, which is usually lower than a temperature measured orally. Thermal imaging systems must be adjusted properly to correct for this difference in measurements.
• These systems work effectively only when all the following are true:
  • The systems are used in the right environment or location.
  • The systems are set up and operated correctly.
  • The person being assessed is prepared according to instructions.
  • The person handling the thermal imaging system is properly trained.

Proper Use of Thermal Imaging Systems

The person who handles the system should follow all manufacturer instructions to make sure the system is set up properly and located where it can measure surface skin temperature accurately.

The person who handles the system should be trained to properly prepare both the location where the system will be used, and the person being evaluated, to increase accuracy. For details, see the standards and scientific papers listed under References below.

Preparing the Area where You will Use a Thermal Imaging System

• Room temperature should be 68-76 °F (20-24 °C) and relative humidity 10-50 percent.
• Try to control other items that could impact the temperature measurement:
  • Avoid reflective backgrounds (for example, glass, mirrors, metallic surfaces) to minimize reflected infrared radiation.
  • Use in a room with no draft (movement of air), out of direct sunlight and away from radiant heat (for example, portable heaters, electrical sources).
  • Avoid strong lighting (for example, incandescent, halogen and quartz tungsten halogen light bulbs).

Figure 2 demonstrates the proper thermal imaging room setup.

Preparing the Thermal Imaging System

• Some systems require the use of a calibrated blackbody (a tool for checking the calibration of an infrared temperature sensor) during evaluation to make sure measurements are accurate. Check the manufacturer’s instructions to determine if a calibrated blackbody is needed. Some devices do not require one.
• Turn on the entire system 30 minutes before use to warm it up.

Preparing the Person Being Evaluated

The person handling the system should make sure the person being evaluated:

• Does not have any face obstructions before measurement (such as a mask, glasses, hat, headband, or scarf), the person’s hair is pulled away from the face, and the person’s face is clean and dry.
• Does not have a higher or lower face temperature from wearing excessive clothing or head covers (for example, headbands, bandanas) or from using facial cleansing products (for example, cosmetic wipes).
• Has waited at least 15 minutes in the measurement room or 30 minutes after exercising, strenuous physical activity, bathing, or using hot or cold compresses on the face.

Figure 3 demonstrates the proper thermal imaging setup for processing of individual people using a calibrated blackbody background.

Using the Thermal Imaging System

• Measure only one person’s surface skin temperature at a time.
• Position the person at a fixed distance (follow the manufacturer’s instructions for use) from the thermal imaging system, directly facing the camera.
• The image area should include the person’s whole face and the calibrated blackbody, if using one.
• If an increased temperature is seen using the thermal imaging system, you should use a different method to confirm a fever. Public health officials can help you determine if the fever is a sign of infection.

Questions about Using Thermal Imaging Systems during COVID-19

Q: Are thermal imaging systems effective for screening people for fevers in places like nursing homes, airports, and hospital emergency rooms?

A: When using a thermal imaging system, it is important to assess whether the system will provide the intended results in high throughput areas. We understand that these devices are being used for initial temperature assessment and triage of individuals for elevated temperatures in medical and non-medical environments. They should not be used for measuring temperatures of many people at the same time in crowded areas, in other words “mass fever screening” is not recommended.

Based on where the system will be used, there may be more appropriate methods to initially assess and triage people, especially if there is a risk that infected people would not be identified right away. For example:

• In a nursing home, inaccurate temperature measurement or a missed contagious person without a fever could spread infection among nursing home residents. So, in this case, other assessment options and following infection control practices may be more effective.
• In airports, workplaces, grocery stores, concert venues, or other areas where you are trying to screen large groups of people for mass fever screening, diagnostic testing may be too difficult because of the time and costs needed to screen and get results. These systems will likely miss most individuals with COVID-19 who are contagious. Thermal imaging systems could be considered as one method for initial temperature assessment in these types of settings when used as part of a larger approach to risk management.
• In a hospital emergency room, a thermal imaging system may help to quickly assess temperature and triage patients to determine who needs more evaluation or isolation.

Q: Are thermal imaging systems effective as the sole means of diagnosing COVID-19?

A: No. A fever or higher body temperature is only one possible symptom of a COVID-19 infection. Thermal imaging systems generally detect a high body temperature accurately when used appropriately. They do not detect any other infection symptoms, and many people with COVID-19 can be contagious without a fever. Also, a high body temperature does not necessarily mean a person has a COVID-19 infection.

All fevers measured by thermal imaging systems should be confirmed by another method and followed by more diagnostic evaluations for other symptoms, as appropriate.

Q: How can thermal imaging systems help with the COVID-19 response?

A: To help address urgent public health concerns raised by shortages of temperature measurement products and expand the availability of telethermographic systems used for initial body temperature for triage use during this COVID-19 public health emergency, the FDA is applying regulatory flexibility for certain telethermographic systems as outlined in its enforcement policy.

When a high body temperature is identified by thermal imaging, an additional evaluation should follow (for example, doctor evaluations or interview, laboratory testing and patient observation).

Q: Are thermal imaging systems used for body temperature assessment considered medical devices?

A: As discussed in the enforcement policy, telethermographic systems are devices when they are intended for a medical purpose. To determine if these products are intended for a medical purpose, FDA will consider whether:

1. They are labeled or otherwise intended for use by a health care professional;
2. They are labeled or otherwise for use in a health care facility or environment; and
3. They are labeled for an intended use that meets the definition of a device, for example, body temperature measurement for diagnostic purposes, including in non-medical environments.

Q: How does a thermal imaging system differ from a thermometer?

A: Both thermal imaging systems and non-contact infrared thermometers (NCIT) can measure surface temperatures without contact. An NCIT measures surface temperature in a single location, whereas a thermal imaging system can measure temperature differences across multiple locations, creating a relative temperature map of a region of the body. The enforcement policy in the guidance applies to use of thermal imaging systems to determine initial body temperature measurements.

There is a separate enforcement policy that applies to certain NCITs and other clinical electronic thermometers: Enforcement Policy for Clinical Electronic Thermometers During the Coronavirus Disease 2019 (COVID-19) Public Health Emergency.

References

Note, this information is applicable to thermal imaging systems that are intended for a medical purpose. This means that the system is intended for use in the diagnosis of disease or other conditions, or in the cure, mitigation, treatment or prevention of disease and, therefore, meets the definition of “device” set forth in Section 201(h) of the Federal Food, Drug, and Cosmetic Act.

For more information on FDA’s policies for these devices, and recommendations on their design, labeling, and use during the COVID-19 Public Health Emergency, please review the following:

Enforcement Policy for Telethermographic Systems During the Coronavirus Disease 2019 (COVID-19) Public Health Emergency: Guidance for Industry and Food and Drug Administration Staff

Additional information on these devices can be found at:

IEC 80601-2-59: Medical electrical equipment – Part 2-59: Particular requirements for basic safety and essential performance of screening thermoghraphs for human febrile temperature screening. 2017, International Electrotechnical Commission & International Organization for Standardization.

ISO/TR 13154: Medical electrical equipment — Deployment, implementation and operational guidelines for identifying febrile humans using a screening thermograph. 2017, International Organization for Standardization.

Ghassemi, P., et al. (2018). “Best practices for standardized performance testing of infrared thermographs intended for fever screening.” PLoS ONE 13(9): e0203302External Link Disclaimer.

Comparing Temperature Sensor Devices

• Industrial infrared temperature sensors are inexpensive and used everywhere in home and industrial. Your microwave for example.  They read surface temperature if aimed properly and clean and calibrated (all sensors require cleaning and calibration)
  • The Heimann sensor is the first we encountered. The HPTA32x32 (64 pixel) “thermopile array”.
  • Melexis makes several models (all TO-39)
  • Mitsubishi, Elo and many others make these.
  • They have been adapted for reading temperatures of foreheads basically and are at the low end of the accuracy scale.
  • None of these are FDA approved or submitted.
• Thermal Imaging Cameras
  • These are a whole magnitude higher weight-class.  Several of them are specifically designed for supplemental elevated body temperature.  They do this by zooming and focusing on specific areas of the face like tearducts.  IR Arrays have limited spatial resolution and must average many regions and samples in order to provide a general value.
  • FLIR is the manufacturer most used.  They have several which certified by FDA and others submitted.
  • Another option is ICI though there are some questions on FDA 510 (we cannot locate them) as well as some components used.

 
Temperature Related More Reading

• Thermal Imaging Cameras – FDA Recommendations
• Temperature Kiosk Commentary
• Temperature Screening Kiosk KMA Public Service Announcement
• Tech Brief – Limits of elevated body temperature screening
• NRF COVID Resources – Industry Partner Resource Headquarters
• Temperature Check Kiosks – Olea
• Temperature Kiosk with Remote Services Frank Mayer & Associates, Inc.
• Temperature Sensing Digital Signage Platform by Mimo Monitors
• Contactless kiosk – temperature screening kiosks – Pyramid
• Tech Brief – Temperature Elevated & Body Temperature EBT
• Thermal Sensing Solution Kiosks
• Pyramid health screening kiosk Covid-19
• Honeywell AI-Driven Thermal Imager Detects Elevated Body Temperature
• Free COVID-19 Services Kiosk Manufacturers Association

From KMA Global Jun2020

As government and corporate America develop post-COVID-19 action plans for responsibly reopening the country, some businesses are scrambling to keep up with the demand for thermal cameras, which many believe can help identify novel coronavirus cases via elevated temperature detection.

We see many RFPs from governmental agencies for temperature and thermal sensing devices.  Federal such FEMA and the Veterans Administration among them.

There are also several pitfalls and challenges with this technology when it comes to detecting somebody with an elevated body temperature. Things that can affect the accuracy of the measurement are:

• Makeup
• Physiological Stress
• Sweating
• Insufficient Camera Resolution
• Measuring the wrong location on the face
• Not using a reference black body for calibration
• Using the wrong camera
• Subject motion

Some observations:

• The fact that the key measurement is temperature would seem to imply that the manufacturer has a superior device or at least a documented device. Does your supplier describe the sensor for you, or do they provide specifications?
• Some solutions utilizing non-FDA-approved devices in the cause of health condition check have been withdrawn due to potential liability issues the device manufacturer might be subjected to.
• Does the camera support a black body calibration?
• Cameras have a NETD factor which is basically the noise floor it will factor and then read the signal. Almost like squelch discrimminators in RF radios. Being able to filter noise out from the measurement is crucial. What is the factor and spec?
• ADA and height can be a factor — Some solutions provide AI which automatically detects the face and focuses. Others will not.
• Reflected light impacts the measurement. In junior high I entered the Science Fair and for my project I demonstrated Albedo.  A black man or a hispanic or a white person can all measure differently.
• Are you reading body temperature or facial temperature.

In conclusion, the most important questions to ask a potential supplier are:

• What is the spatial resolution?
• How long has your solution/camera been on the market?
• Has your solution been used successfully during the SARS outbreak?
• What is the ideal distance to subject during screening?
• Does your camera have a 510k approval?

Too often we see these days a rush to market by vendors all over the world all touting their thermal imagers without specifications.

It is worth noting that the FDA issued wide guidance when antibody test kits were being offered. Rather than test them they went the open market test route which resulted in many thousands of people being misdiagnosed and localities and countries (UK e.g.) spending millions of dollars and getting the wrong results.

Additional questions relating to FDA should be asked:

1. Y or N — Is it tested and labeled 80601?
2. Y or N – do you have test results of alternative performance criteria currently allowed by FDA
3. Y or N – is there prominent labeling that this device cannot be used as sole measurement?
4. Y or N – is there a clear indicator that the device is NOT approved by FDA?
5. Y or N – is there a clear description of the main device along with its specifications and calibration procedures?

More Temperature Kiosk Resources

• Non-contact Infrared Thermometers
• Thermal Imaging Systems (Infrared Thermographic Systems / Thermal Imaging Cameras)
• From FDA 2020 — Measuring a person’s temperature can be done in several ways. One method to measure a person’s surface temperature is with the use of non-contact infrared thermometers (NCITs). NCITs may be used to reduce cross-contamination risk and minimize the risk of spreading disease. While typically 98.6°F (37.0°C) is considered a “normal” temperature, some studies have shown that “normal” body temperature can be within a wide range, from 97°F (36.1°C) to 99°F (37.2°C). Before NCITs are used, it is important to understand the benefits, limitations, and proper use of these thermometers. Improper use of NCITs may lead to inaccurate measurements of temperature.
• From FDA — The FDA issued the Enforcement Policy for Telethermographic Systems During the Coronavirus Disease 2019 (COVID-19) Public Health Emergency guidance to help expand the availability of thermal imaging systems and mitigate thermometer shortages during the public health emergency. The guidance sets forth an enforcement policy that is intended to apply to all thermal imaging systems that are intended for medical purposes for the duration of the public health emergency related to COVID-19, and provides recommendations regarding performance and labeling of such systems.

This is the letter from the FDA in April 2020 on Enforcement Policy that companies might try and use.

FDA recommends that the device:

1) Is tested and labeled consistent with the following standard: IEC 80601-2-59:2017: Medical electrical equipment – Part 2-59: Particular requirements for the basic safety and essential performance of screening thermographs for human febrile temperature screening; OR

2) Is tested using alternative performance specifications that provide similar results to IEC 80601-2-59:2017. This could include:

a) The laboratory temperature accuracy of a screening telethermographic system, including the measurement uncertainty, is less than or equal to ±0.5°C (±0.9°F) over the temperature range of at least 34-39°C (93.2-102.2°F);

b) The system includes an accurate blackbody temperature reference source; 10

c) Both stability and drift are less than 0.2°C (0.36°F) within a timeframe specified by the manufacturer; and

d) The device risk assessment addresses all potential safety issues, including: i) Electrical safety; ii) Electromagnetic compatibility; iii) Mechanical safety; iv) Excessive temperatures and other hazards; v) Accuracy of controls, instruments, and information display; vi) Considerations for software associated with Programmable Electrical Medical Systems including network connections;11 and vii)Usability.

In addition, FDA recommends that the devices described above use labeling that helps users better understand the device, such as:

1) The labeling includes a prominent notice that the measurement should not be solely or primarily relied upon to diagnose or exclude a diagnosis of COVID-19, or any other disease;

2) The labeling includes a clear statement that: a) Elevated body temperature in the context of use should be confirmed with secondary evaluation methods (e.g., an NCIT or clinical grade contact thermometer);12

10 This is usually a blackbody (idealized physical body that absorbs all incident electromagnetic radiation) with known temperature and emissivity that can be used for thermal drift compensation.

11 For more information on this recommendation, see Clause 201.14 of IEC 80601-2-59: 2017. 12 This labeling recommendation is consistent with IEC 80601-2-59: 2017. Contains Nonbinding Recommendations 6 b) Public health officials, through their experience with the device in the particular environment of use, should determine the significance of any fever or elevated temperature based on the skin telethermographic temperature measurement; c) The technology should be used to measure only one subject’s temperature at a time; and d) Visible thermal patterns are only intended for locating the points from which to extract the thermal measurement.

3) The labeling includes a clear description of:

a) Device performance specifications and the methodology and frequency of any calibration needed to maintain the labeled specifications;12

b) How to use the thermal image to make a temperature measurement to within the stated device accuracy;

c) A description and purpose of the blackbody reference source (used for thermal drift compensation) and its importance in obtaining an accurate temperature assessment;

d) The reference body site used for temperature estimation, including any calibration or correction needed to estimate the temperature at that location, and the accuracy of the measurement at the reference site (e.g., oral, tympanic membrane);

e) How different environmental and system setup factors can affect the measurement, including the body site chosen for measurement, the condition of the screening site (e.g., screening background, ambient temperature and humidity, airflow);13

f) Different factors to consider in the design of the facility protocol (e.g., installation, viewing angle, blackbody temperature reference source); 14

g) The installation procedures and qualification testing that should be performed during installation or when imaging equipment is being relocated;15 and

h) The appropriate imaging distance based on the spatial resolution and performance of the camera. 16

4) The labeling references and is consistent with the guidelines in ISO/TR 13154: 2017: Medical electrical equipment — Deployment, implementation and operational guidelines for identifying febrile humans using a screening thermograph; and

5) The labeling highlights the differences in design, indications, or functions, as applicable, compared to the unmodified, FDA-cleared version of the product or includes a clear identification that the device is not FDA-cleared or approved. For the current edition of the FDA-recognized standard(s) referenced in this document, see the FDA Recognized Consensus Standards Database. 17

For more information regarding use of consensus standards in regulatory submissions, refer to FDA guidance titled “Appropriate Use of Voluntary Consensus Standards in Premarket Submissions for Medical Devices.”

If you would like to understand more about the models and options that are available KMA is happy to provide information on any and all advertised solutions. As always we recommend beginning with members of the KMA who understand and observe standard regulations such ADA, FDA, EMV, PCI, HIPAA and UL.

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Proper Use of NCITs

The person using the device should strictly follow the manufacturer’s guidelines and instructions for use for the specific NCIT being used. The manufacturer’s instructions for use typically include the following information and recommendations for proper use:

Preparing the Environment and NCIT:

The use environment may impact the performance of the NCIT. Instructions will typically include recommendations for optimal use, such as the following:

• Use in a draft-free space and out of direct sun or near radiant heat sources.
• Determine if conditions are optimal for use. Typically, the environmental temperature should be between 60.8-104 ºF (16-40 ºC) and relative humidity below 85 percent.
• Place the NCIT in the testing environment or room for 10-30 minutes prior to use to allow the NCIT to adjust to the environment.

Cleaning Between Uses:

For cleaning NCITs between uses, follow the instructions in the Cleaning and Disinfecting section of the product instructions. Most NCITs should never be immersed in water or other liquids.

Preparing the Person being Evaluated:

In preparation for taking a temperature measurement with an NCIT, the person using the NCIT should typically ensure that

• The test area of the forehead is clean, dry and not blocked during measurement.
• The person’s body temperature or temperature at the forehead test area has not been increased or decreased by wearing excessive clothing or head covers (for example headbands, bandanas), or by using facial cleansing products (for example cosmetic wipes).

Using the NCIT:

As previously noted, the person using the device should strictly follow the manufacturer’s guidelines and instructions for use for the specific NCIT being used. In particular, the following are typical instructions for NCIT usage.

• Hold the NCIT sensing area perpendicular to the forehead and instruct the person to remain stationary during measurement(s). (See Figure 1)
• The distance between the NCIT and forehead is specific to each NCIT. Consult the manufacturer’s instructions for correct measurement distances.
• Do not touch the sensing area of the NCIT and keep the sensor clean and dry.

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Figure 1: Correct Use – Forehead unobstructed, and NCIT perpendicular to forehead and used at distance identified in manufacturer’s instructions.

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Figure 2: Incorrect Use – Not perpendicular to forehead

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Figure 3: Incorrect Use – Forehead exposed to direct sunlight outdoors

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References

Note, this information is applicable to NCITs which are intended for a medical purpose which means that the NCIT is intended for use in the diagnosis of disease or other conditions, or in the cure, mitigation, treatment or prevention of disease and, therefore, meets the definition of “device” set forth in Section 201(h) of the Federal Food, Drug and Cosmetic Act.

Enforcement Policy for Clinical Electronic Thermometers During the Coronavirus Disease 2019 (COVID-19) Public Health Emergency

Guidance on the Content of Premarket Notification [510(K)] Submissions for Clinical Electronic Thermometers

U.S. National Library of Medicine: MedlinePlus. (2019 February). Body Temperature Norms. https://medlineplus.gov/ency/article/001982.htm

ASTM E1965-98(2016),Standard Specification for Infrared Thermometers for Intermittent Determination of Patient TemperatureExternal Link Disclaimer, ASTM International, West Conshohocken, PA, 2016, www.astm.org DOI: 10.1520/E1965-98R16

ISO 80601-2-56:2017(E) Medical electrical equipment – Part 2-56: Particular requirements for basic safety and essential performance of clinical thermometers for body temperature measurementExternal Link Disclaimer. 2017, International Organization for Standardization.