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:
- Physiological Stress
- 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 quick 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- Some solutions utilizing non-FDA-approved devices in the cause of health condition check have been withdrawn due to potential liability issues the device manufacturer might be subjected to.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:
- Y or N — Is it tested and labeled 80601?
- Y or N – do you have test results of alternative performance criteria currently allowed by FDA
- Y or N – is there prominent labeling that this device cannot be used as sole measurement?
- Y or N – is there a clear indicator that the device is NOT approved by FDA?
- Y or N – is there a clear description of the main device along with its specifications and calibration procedures?
This is the letter from the FDA in April 2020 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.”1
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.