Thermal
Imaging Systems in COVID-19
Measuring
a person’s temperature can be done in several ways. 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). A core issue is there
are no independent tests of thermal camera performance /accuracy and no
independent standards to measure against. This has allowed manufacturers to
tout products meant for body/fire detection as a fever solution, or falsely
claim pinpoint accuracy at long distances. We urge caution against buying
low-cost thermal solutions from any manufacturer.
Thermal
imaging systems and non-contact infrared thermometers (NCITs) use different
forms of infrared technology to measure temperature.
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:
Ø The systems are used in the right
environment or location.
Ø The systems are set up and operated
correctly.
Ø The person being assessed is prepared
according to instructions.
Ø 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
Ø 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.
Ø
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:
Ø 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.
Ø 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).
Ø 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.
Thermal camera selecting guide
Unlike
regular cameras, not many customers are aware of certain key factors that they
need to consider when selecting a thermal camera. This is mainly because
thermal cameras are still a relatively new concept for many security customers.
1. Accuracy
In border
surveillance, some thermal camera can accurately detect the people or object
more than 150 meters away. Thermal imaging cameras are often not just to detect
higher or lower temperatures but also the calculate the differences. This means
that the readings should be as accurate as possible. Most top-end cameras
provide a +/- 2% accuracy. The distance at which the camera can maintain this
accuracy is also critical.
2. Temperature range
Thermal cameras have a
range within which they can detect temperature. You should purchase a camera
that would meet your temperature needs. For example, the cameras used at
airports now are for human temperature monitoring. Hence their range just needs
to include the highest and lowest points that a human body can sustain.
However, in the industrial segment, the temperature may be higher.
3. Resolution
Thermal cameras tend to
have lower resolution compared to their regular counterparts, and hence this
should be an essential consideration before purchase. The size of the area you
need to capture and the nature of the target will decide the resolution you
need. If you need to capture small objects in detail, high-resolution cameras
will be necessary.
4. Cybersecurity
Developments in IP has
enabled thermal cameras to connect with other network devices and be part of
the IT infrastructure. You will need to find companies that provide NDAA
compliant products.
Avigilon H4 Thermal Elevated Temperature
Detection camera is embedded with edge-based analytics to detect faces and
notify operators of elevated skin temperature.
3S
Vision T9078- Dome
Camera, T9079- Dome Camera, T6078- Bullet
Camera, T6079- Bullet
Camera, T6041- Bullet
Camera, T6051- Bullet
Camera, T6061- Bullet
Camera.
FLIR FLIR Axxx-EST series, T5xx-EST
series, Exx-EST series & TG 165(Hand Held type).
AMETEK VIRALERT 3 human body temperature
screening system for buildings and facilities
MOBOTIX MOBOTIX TR (Thermal Radiometry)
technology makes it possible to measure thermal radiation - even from people.
AXIS Axis Q19, Q29, Q86, Q87 & Modular
Camera
Honeywell
HRCF-FD384H-
Temperature Detecter 7.8mm, HRCF-FD640H - Temperature Detecter 15mm,
HRCF-KIT-FD384H - Temperature Detection kit 7.8mm -tripod, HRCF-KIT-FD640H - Temperature
Detection kit 15mm – tripod, HRCF-KIT2-FD640H- Temperature Detection kit 15mm -
tripod (no laptop), HRCF-KIT2-FD384H- Temperature Detection kit 7.8mm -tripod
(no laptop).
Lilin P3T6522E2 & P3T6522E2-F – Dome Camera,
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:
- They are labeled or otherwise intended for use
by a health care professional;
- They are labeled or otherwise for use in a
health care facility or environment; and
- 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.
Temperature
gun uses not recommendate.
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.
