detection of elevated body temperature · according to iec 80601‐2‐59, the detector of the...

Detection of Elevated Body Temperature Thermal Imaging Solutions from InfraTec

InfraTec GmbH

Infrarotsensorik und Messtechnik

Gostritzer Straße 61 – 63

01217 Dresden / GERMANY

Phone +49 351 82876‐610

Fax +49 351 82876‐543

E‐mail [email protected]

www.InfraTec.eu

Headquarters

InfraTec infrared LLC

5048 Tennyson Pkwy.

Plano TX 75024 / USA

Phone +1 844‐226‐3722 (toll free)

E‐mail thermo@InfraTec‐infrared.com

www.InfraTec‐infrared.com

USA office

© InfraTec 08/2020 (All the stated product names and trademarks remain in property of their respective owners.)

The current Corona pandemic has worldwide led to a high demand for thermal imaging systems to detect elevated

body temperature. Many companies and organisations are interested in using thermal screening to quickly, reliably

and contactlessly identify potentially ill persons at the entrance to their premises in order to protect others from

infection.

What solutions does InfraTec offer to detect elevated body temperature?

InfraTec provides complete, ready to use solutions tailored to the detection of elevated body temperature. Our

cameras offer high thermal and spatial resolution making them faster and more reliable than those using low

resolution. The camera combined with our application specific software, display and control computer and a tripod is

all you need to get you started. Packages are based on the following core components depending on your choices:

Thermal cameras of the series VarioCAM® High Definition, VarioCAM® HDx or PIR uc 605

Excellent thermal resolution up to 0.02 K

Measurement accuracy in special HiPrec mode up to ± 0.8 K

Geometric resolution up to (1,024 × 768) IR pixels (XGA) allowing for multiple‐person screening

Thermography software THERMAL‐CHECK

Automatic optical and optionally acoustic alarm

Algorithm‐based accuracy up to ± 0.3 K

In the selectable automatic mode the system will automatically detect if a person is facing the camera and take a

measurement of the body temperature

Accessories for a direct start

Tripod to mount the camera

Laptop to configure and control the system and for reporting (with configurable privacy settings)

Comprehensive InfraTec service

24‐hour service hotline

Warranty up to 48 months

Software update service free of charge for up to 36 months

Upgrade options for using the camera system for other measurement tasks


InfraTec GmbH




Phone +49 351 82876‐610

Fax +49 351 82876‐543


www.InfraTec.eu

Headquarters


5048 Tennyson Pkwy.


Phone +1 844‐226‐3722 (toll free)



USA office


Which advantages does the InfraTec solution offer when detecting elevated body temperature?

Highest accuracy up to ± 0.3 K

Operation without additional reference temperature radiator possible

Having the largest number of pixels our system can screen multiple people at the same time, faces at different

heights (children for example) or distances from the camera. Only the high number of pixels gives you the same

reliability over a larger field of view as required in the specifications for the size of the optimal measurement area

according to IEC 80601‐2‐59

How is the thermographic screening proceeded?

The thermal camera and software are ready for use in just a few steps. Here, measurement distances, which result

from the device configuration, have to be kept exactly in order to avoid errors during screening itself and thus to be

able to achieve a reliable result.

1. Choosing a suitable screening position

The screening must be carried out in an indoor

environment with constant room temperature

The persons to be screened should stand in front of a

homogeneous, matt surface at room temperature

(for example panel wall or fabric)

2. Setting up the system

The thermal camera is mounted on the tripod

according to the maximum distances to be observed

(see information on configuration)

Determining the correct measurement distance to

the person (placing a floor marker for orientation)

Legend 1 Thermal camera on tripod 5 Position of the person

2 Monitor with result display 6 Background (matt) optimal to prevent

3 Distance from the camera to the person interference radiation from the environment

4 Field of view of the camera (VGA: up to 64 cm

(25 inches), XGA: up to 102 cm (45 inches))

7 Control plane with fixed distance to the camera lens


InfraTec GmbH




Phone +49 351 82876‐610

Fax +49 351 82876‐543


www.InfraTec.eu

Headquarters


5048 Tennyson Pkwy.


Phone +1 844‐226‐3722 (toll free)



USA office


3. Powering up the system

Turn on the thermal camera approximately 30 minutes prior to use for optimal equilibrium

Connect the thermal camera to the computer (included in the scope of delivery depending on the package)

according to the instructions

Start the THERMAL‐CHECK software

4. Confirm or configure the alarm set points

Hint: "no person" indicates that there is currently no person monitored, you may still see the last image taken.

5. Start of the screening process

The screening will start automatically. As soon as a (test) person’s face is in the marked area (inner green frame), the

measurement is performed. "OK" indicates the measurement has not crossed the alarm threshold.


InfraTec GmbH




Phone +49 351 82876‐610

Fax +49 351 82876‐543


www.InfraTec.eu

Headquarters


5048 Tennyson Pkwy.


Phone +1 844‐226‐3722 (toll free)



USA office


6. If the temperature is above the alarm set point

The result part of the screen will turn red and depending on your configuration additional audio‐visual alarms may be

triggered.

Optical alarm (optional additional acoustic alarm) when the temperature range defined in advance is exceeded

Thermographic screening for the detection of elevated body temperatures in detail

Certainly, thermal cameras can neither detect a virus itself nor whether a person is carrying a virus! However, these

cameras enable the precise non‐reactive, contactless measurement of surface temperatures while using the technical

temperature measurement technology known as thermography or thermal imaging. Hence, they are highly suitable

for the quick and easy detection of elevated body temperatures, which can be an indication of a possible virus

infection. Such indications must, of course, always be followed by other examination methods that allow a reliable

positive or negative statement about the disease and to initiate appropriate actions! The term "detecting a fever" in

the sense of a (medical) fever diagnosis is actually not permitted as a designation for the above‐mentioned

thermographic recording of elevated body temperatures with thermal cameras under strict observation: One reason is

that fever is a complex medical phenomenon. The other reason is that, from a purely formal point of view, the

cameras used are "only" technical measuring devices and not medical diagnostic instruments.

Thermography systems measure surface temperatures based on the emitted heat radiation, for example the

temperature of the human skin surface. However, this is different from the internal body temperature, the so‐called

body core temperature. The temperature of the skin surface depends on the ambient temperature (summer, winter,

direct sunlight, and so on). In addition, a light film of water can produce evaporative cooling due to perspiration.

Furthermore, beards, haircuts, face masks, etc. cause many areas of the skin on the face to be optically "covered" and

the heat radiation cannot reach the camera unhindered. Thus, the skin surface in most parts of the face is rather

unsuitable for reliable and repeatable thermographic temperature measurement.


InfraTec GmbH




Phone +49 351 82876‐610

Fax +49 351 82876‐543


www.InfraTec.eu

Headquarters


5048 Tennyson Pkwy.


Phone +1 844‐226‐3722 (toll free)



USA office


Only a few regions on the head are really useful for thermographic screening:

The auditory canal It displays the body core temperature very well and is used for non‐contact

temperature measurement with manually applied so‐called ear thermometers, which

are approved as medical diagnostic instruments. However, measurement by

thermography is not practical, as the test person would have to be positioned very

precisely in relation to the camera and, in addition, the ear canal is often covered by

the hairstyle.

The oral cavity It is in principle very suitable. In this case, however, the test persons would have to

position themselves in front of the thermal camera with their mouths wide open,

which is not effective in terms of hygiene.

The eye region Especially that part where the tear ducts are located, just below these small areas,

strong blood vessels ensure a temperature that is very close to the core body

temperature. Their excellent suitability for detecting elevated body temperature by

means of frontal thermography of the facial area has been proven in several studies.

However, they are only a few mm2 in size, which means that high demands are placed

on the geometric resolution of the camera. Furthermore, the eyes must not be

covered by glasses.

Punctual measurement at the inner corner of the eye

InfraTec, therefore, consistently uses thermographic temperature measurement at the inner eyelid corner for the

detection of elevated body temperature as the demonstrably safest and most reliable method for thermal screening.


InfraTec GmbH




Phone +49 351 82876‐610

Fax +49 351 82876‐543


www.InfraTec.eu

Headquarters


5048 Tennyson Pkwy.


Phone +1 844‐226‐3722 (toll free)



USA office


The following requirements are essential

A) Requirements for the geometrical resolution of thermal cameras

Since the regions to be measured each have a dimension of approximately (3 × 3) mm² (0.014 square inches), a

high spatial resolution of 1 mm2 (1 mm is 1/25 of an inch) (size of a measurement pixel on the object to be

measured) is required to reliably avoid measurement errors caused by geometric factors.

A sufficiently large field of view is necessary to capture people of different heights without the need to constantly

move the camera. This requires a certain minimum number of measurement pixels or minimum detector formats.

According to IEC 80601‐2‐59, the detector of the thermal camera must have at least (320 × 240) measurement

pixels, whereby the face of the test person must be covered with at least (240 × 180) pixels (here approximately

56 % of all measurement pixels). In this case, the camera would have to be repeatedly moved by hand or people

would have to get on and off a step in order to be able to take a measurement.

Considerably higher flexibility is offered by more powerful thermal cameras with considerably more than

(320 × 240) measuring pixels. These enable a sufficiently large field of view (FOV), for example to take

thermographs of several people at the same time. This also ensures that the facial area or the eyelid angle of each

individual subject is still filled with enough measurement pixels to have a good measurement in a reasonable time.

In order to meet the criterion of high spatial resolution required by the international standard, InfraTec offers the

following preferred configurations (assuming 20 cm (8 inches) to be the width of the face being screened):

Thermal camera Detector

format

Opening

angle

Possible

measurement

range

(A)

FOV

(B)

Filled FOV

width by

face area

Max.

number of

persons per

camera

PIR uc 605 /

Standard lens

(640 × 480) (32.9 × 24.2)° ≤ 1.1 m /

≤ (3.6) feet

≤ (63 × 47) cm /

≤ (25 × 19) inches

approx. 31 % 1

PIR uc 605 /

Telephoto lens

(640 × 480) (12.4 × 9.3)° ≤ 3.0 m /

≤ (9.8) feet

≤ (65 × 49) cm /

≤ (26 × 19) inches

approx. 31 % 1

VarioCAM® HDx /

Standard lens (VGA)

(640 × 480) (30.4 × 23.1)° ≤ 1.17 m /

≤ (3.84) feet

≤ (64 × 48) cm /

≤ (25 × 19) inches

approx. 31 % 1

VarioCAM® HDx /

Telephoto lens (VGA)

(640 × 480) (15.5 × 11.6)° ≤ 2.35 m /

≤ (7.71) feet

≤ (64 × 48) cm /

≤ (25 × 19) inches

approx. 31 % 1

VarioCAM® High Definition /

Standard lens (XGA)

(1,024 × 768) (32.4 × 24.6)° ≤ 1.76 m /

≤ (5.77) feet

≤ (102 × 77) cm /

≤ (40 × 30) inches

approx. 20 % 2

VarioCAM® High Definition /

Telephoto lens (XGA)

(1,024 × 768) (16.5 × 12.4)° ≤ 3.52 m /

≤ (11.55) feet

≤ (102 × 77) cm /

≤ (40 × 30) inches

approx. 20 % 2

This overview illustrates that with larger detector formats, there is more flexibility with regard to the number of

persons that can be screened at the same time and their height (for example, (1.5 ... 2) m ((4.9 … 6.6) feet)), without

having to constantly reposition the camera to meet the criterion of the required spatial resolution. To achieve more

flexibility with regard to different person sizes it would also be conceivable to tilt the camera by 90° to get more pixel

in the vertical. The measurement distance can, of course, be further reduced within the bounds of possibility in order

to improve the spatial resolution. However, the field of view will then become correspondingly smaller and the

demands on the lateral placement of the test persons will increase. The angle of incidence, which determines the

relationship between the measurement distance and the field of view size, can be varied by selecting the IR lens.

Compared to telephoto lenses, standard InfraTec lenses offer the advantage of a larger field of view as well as a larger

depth of field, which makes it easier to keep the permissible tolerances of the measurement distance, thus ensuring a


InfraTec GmbH




Phone +49 351 82876‐610

Fax +49 351 82876‐543


www.InfraTec.eu

Headquarters


5048 Tennyson Pkwy.


Phone +1 844‐226‐3722 (toll free)



USA office


smoother screening process and higher throughput. The correct distances of the person to the lens of the selected

camera can be taken from the values in table columns A and B. With the VarioCAM® High Definition, two persons can

be screened at the same time due to the larger field of view (important: additional partition wall absolutely

necessary).

Legend 1 Thermal camera on tripod 4 Position of the person/two persons (only possible with partition

wall using VarioCAM® High Definition with XGA resolution)

2 Distance from the camera to the person 5 Portable partition wall (matt) for shielding from interference

radiation from the environment

3 Horizontal field of view of the camera

B) How accurately can thermographic systems be used to measure an elevated body temperature? Usually, absolute temperature measurement accuracies of thermographic systems are specified to ± 2 K or ± 2 %

under the assumption of black body measurement and to ± 1 K or ± 1 % for very good systems. This measurement

uncertainty is related to the operating temperature range of the camera, which is often specified as (‐20 ... 50) °C /

(‐4 … 122) F. In room temperature environments and in restricted measurement ranges, they are much more precise

(up to ± 0.8 K in HiPrec mode), but not as accurate as, for example, contact thermometers.

Solutions from InfraTec with optimised measurement accuracy: Comparative analysis, for which InfraTec systems are

ideally suited, is one way of further improving measurement accuracy. With the help of the innovative thermography

software THERMAL‐CHECK the moving average or median of the measured temperatures of the inner eyelid angles of

the last for example 10 test persons without detected increased body temperature is continuously determined and

used as a reference. This is based on the fact that test persons with elevated body temperature are a rare exception,

whereas inconspicuous test persons include the objectively occurring environmental variations to which all test

persons are subject in the reference. In addition, the user (operator) defines a temperature threshold of for example

(1 ... 2) K above this reference value, and if this temperature threshold is exceeded, a corresponding message or alarm

is issued. This comparative analysis has proven to be very robust under practical conditions. If a person should have a

correspondingly higher temperature, this is reliably detected (up to ± 0.3 K accuracy). This method can be practiced

with InfraTec's high‐quality thermal camera series VarioCAM® High Definition without additional aids such as

reference temperature radiators.

detection of elevated body temperature · according to iec 80601‐2‐59, the detector of the...

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