Infrared thermograph helps to detect and contain the spreading of swine & bird flu and other viral diseases.
 Growing international exchange, travel, and economic migration require a consistent, prompt, effective and international viral disease prevention policy.
 Elevated human body temperature, or fever, is a convincing and reliable indicator of most human viral infections. Since the outbreak of severe acute respiratory syndrome (SARS), public health authorities around the world have been looking for a fast, easy, contactless, non-invasive and reliable method to detect elevated human body temperature differences.
 Thermograph is such a method. It has become vital to control body temperature of risk groups such as travellers and proven itself as a monitoring tool that has substantially contributed to reduce the spreading of swine flu in many countries and regions.
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The ThermaCAM automatically detects the hottest temperature within an area, set by the operator. A color alarm makes it easy to decide whether a person needs further examination or not.
 Viral infections spread rapidly at places where large crowds gather such as airports. But viral contagious diseases unfortunately do not end with SARS. While the latter has taken lives of some 10% of the infected people, the H5N1 strain of swine influenza, in its current early stage in Asia and Europe, has a death rate of over 50%. So far, the spread of H5N1 virus from person to person has been very rare and has not continued beyond one person.
  Nonetheless, because all influenza viruses have the ability to change, scientists are concerned that H5N1 virus one day could be able to infect humans and spread easily from one person to another.
 Infrared thermograph: an effective tool to detect elevated body temperatures for swine flu
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 An infrared camera is a very effective tool to detect people infected with a viral disease at a very early stage. It produces thermal images or heat pictures which allow displaying even the smallest temperature differences.
 Human body temperature is a complex phenomenon. Humans are homoeothermic; they radiate heat, which must be lost to the environment. The interface between that heat production and the environment is the skin. This dynamic organ is constantly adjusting the optimum balance between the physiologic demands of the body and external environmental conditions.
 Infrared thermograph provides a visual map of skin temperatures in real time. In addition, infrared cameras are very sensitive devices. FLIR Systems ThermaCAM series measure temperature differences as small as 0.08 ºC. The symptoms of most infectious diseases are similar – malaise, sore throat, coughs and of course fevers. Consequently, it is extremely easy to detect whether a person carries the risk of having an infectious disease or not. All that needs to be done is make an infrared image of the subject and measure if his/her body temperature exceeds a certain value.
 Thanks to the infrared camera’s built-in functions like colour and sound alarms that can be set to go off when a certain temperature threshold is being exceeded, the operator can instantly decide whether the subject needs to be referred for medical examination or not. As the infrared camera produces images in real-time, at a rate of 50 Hz, the total evaluation process takes less than a second.
 This makes infrared technology very useful for rapidly screening large numbers of people. However, a few things need to be taken into account.Â
The application: measuring the temperature of the human body for swine flu
 A person’s general skin temperature is not equal to the person’s core temperature. The most practical spot on the body giving the most reliable result (where the skin temperature approaches the core temperature of the human body) is in the corner of the eyes where the lachrymal duct comes to the surface.
 It is therefore recommended to take subjects in front of the camera at a marked distance, in general at 1 to 1.6 meters away from the camera lens, so that the face fills the entire image.
 The subject only needs to look into the camera for less than a second. As the highest temperature will be measured in the corner of the eyes, people can continue to wear a mouth mask or their headwear without influencing the measurement. Glass and plastic do not transmit infrared radiation, so people need to remove their glasses in order to be examined.
 It would be advisable to set up the infrared camera at places with long queues such as passport or customs control points as persons should be screened on an individual basis. It is also recommended, though not mandatory, to install the camera on a tripod and connect it to a video screen, to facilitate the working conditions of the camera operator.
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Camera setup to detect temperature differences for swine flu
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Even when FLIR Systems ThermaCAM series cameras can measure temperature differences as small as 0.08°C, absolute temperature readings have an accuracy of ± 2°C. This means that if we measure a body temperature in the corner of the eye of 36°C, the real temperature could be somewhere between 34°C and 38°C.
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Proof that Infrared works
It is not necessary to measure absolute temperatures to determine whether a person has an elevated temperature or not. The following procedure has been initially followed to determine if infrared measurement works: after measuring the true body temperature of approx. 10 to 25 healthy people with a medical ear
thermometer and the face temperature of these same people with a ThermaCAM infrared camera, the average temperature difference is calculated: true body temperature minus face temperature.
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Experience has shown that this average temperature difference is fairly constant and varies between 0.8 and 1.2°C depending on the environmental conditions of the test area, such as ambient temperature, air conditioning, wind, weather conditions etc. This corresponds to the principle that the body temperature of a feverish person is about 1°C higher compared to a healthy person. Whether that average temperature turns out to be 32, 34, or 36°C is not relevant. It should be correlated to the core temperature and remain stable.
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In practice, the camera is installed and can be used immediately: ThermaCAM automatically calculates the average temperature of the first 10 scanned people and then defines their average. Then, an alarm should be set to go off when the measured temperature reaches an average plus 1°C.
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The purpose is to differentiate the people who are well from those that have fever and not to measure absolute body temperatures. The absolute error measured on both the threshold values and the subjects tested will be the same, as long as the camera is stable. Â
A unique FLIR Systems feature:
The Automatic Temperature Compensator (ATC
FLIR Systems has equipped its ThermaCAM infrared cameras with an Automatic Temperature Compensator (ATC) to avoid generating false alarm. The ATC constantly calculates a moving average of the body temperatures from the last 10 scanned people. The two highest and the two lowest values are not taken into account when making this calculation. Based on the outcome of this calculation the ATC automatically adjusts the generation of visible and audible alarms, greatly improving the reliability of the screening.
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Quickly scanning a large number of people by using infrared cameras with colour AND sound alarms
Temperatures are measured by full radiometric infrared cameras, not by infrared imagers. FLIR Systems offers its ThermaCAM series as optimum solutions. These systems can be battery-operated for over 2 hours or continuously connected to main power. Adhering to the IP 54 standard, they can be used either indoor or outdoor.
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The ThermaCAM series have built-in functions to measure the highest temperature inside a given field view area. The camera will automatically detect the hottest spot. Its value is immediately displayed on the built-in LCD of the camera or on a connected video monitor. The cameras have also been optimized for fever detection as they recalibrate themselves more frequently.
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A built-in colour alarm function enables an immediate decision whether the subject requires further examination: all areas, which are hotter than a predefined temperature value, can be immediately recognized on the infrared image.
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In addition, FLIR Systems cameras are equipped with a sound alarm. If the temperature exceeds a predefined value, a buzzer alarm will go off. A subject activating the alarm, can easily be taken aside for further examination on site or in a medical centre for swine flu.
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A small investment to protect public health from swine flu
Major airports in South-East Asia are already using FLIR Systems cameras and have successfully applied this methodology to screen all people entering and leaving the country. It is a quick and contactless method, which is perfectly safe for both the camera operator and the screened subject. The results are extremely satisfactory.
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The FLIR Systems ThermaCAM cameras have proven themselves as tools that can be operated by non-specialists after a few hours of training. They enable a quick and accurate scan of a large number of people to trace fever, a major symptom of viral infections.
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 As some officials have put it, it is a very small investment to protect public health worldwide fro swine & bird flu.
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 Using a FLIR Systems ThermaCAM for detecting possible SARS patients:
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• Assure that there are no hot objects such as lamps in the field of view
of the camera. The camera should be turned on at least 30 minutes
before measurement starts and carefully focused.
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• Set the emissivity value to 0.98.
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• Determine the average temperature of a healthy person by using an ear thermometer and an infrared camera (or utilise the built-in ATC function).
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• Add 1°C to the average temperature of a healthy person to obtain the critical temperature.
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• Set an area in the infrared camera.
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• Set the colour and sound alarms to signal if the temperature within the area is higher than the critical temperature.
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• Bring the subjects to be tested, one by one, in front of the camera. Each for about 1 second.
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• If the alarms signal, detour the subject for further examination.
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Setting up a ThermaCAM with Automatic Temperature Compensator (ATC) for viral disease detection. FLIR Systems infrared camera’s can help to prevent the spreading of viral diseases such as swine & bird flu.
 This application story is from FLIR SystemsÂ
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