ITMI20100102A1 - METHOD AND EQUIPMENT FOR THE DETERMINATION OF THE BODY TEMPERATURE OF AT LEAST ONE SUBJECT - Google Patents

Description

â € œMETHOD AND EQUIPMENT FOR DETERMINING THE BODY TEMPERATURE OF AT LEAST ONE SUBJECTâ €

The present invention relates to a method and an apparatus for determining the body temperature of at least one subject.

In particular, the present method and the present apparatus find particular application in determining the temperature of a plurality of subjects who are or are crossing a certain area, such as a transit area in an airport or a hospital room, or a € ™ other public area.

As is known, in recent years, the need has become extremely felt to be able to measure the body temperature of a plurality of subjects very quickly and in a non-invasive way.

The spread of fears of pandemics (think of â € œavianâ € flu or â € œswineâ € flu) has made it necessary to more effective controls on subjects in transit, in particular on entry, in a specific country, area or place.

Think for example of airports, areas of intense passage of people from various countries that can lead to a very rapid spread of the infection.

In this situation, in the past years, controls have spread, particularly with reference to subjects coming from countries at risk, at the airports.

However, it is clear that measuring the body temperature of one subject at a time in transit and passage areas for such a large number of people is impractical and an obstacle to an efficient and fluid operation of the airport.

For this reason, also Î "use of non-invasive and sufficiently rapid temperature detection thermometers, have proved in this situation not ideal for preventing delays, queues and congestion in correspondence with the control areas, although performing very well the task of detecting subjects with fever.

In the light of the problems highlighted above, some studies have been carried out and, as a solution, thermal imaging cameras have been proposed, in particular infrared, capable of detecting the radiation coming from a specific area under control and, thanks to the intensity of the latter, to trace a temperature map of the area under control.

Moreover, the survey can be carried out continuously or dynamically in such a way as to be able to examine the passage of a flow of subjects in real time.

In other words, one or more thermal imagers control areas of forced access in which the subjects in transit must pass by estimating, in the light of the infrared radiation spectrum received, the temperature gradients in the area under control.

The thermal cameras highlighted above, while allowing a continuous and extremely rapid check on a plurality of subjects in transit, are however affected by some drawbacks and / or operating limits.

First of all, the thermal imaging cameras known today require the necessary presence of operators for the identification of subjects with fever.

In fact, today it is not possible to automate the decision process identifying the subject with fever by separating it from the one without fever without the assistance of one or more operators.

Typically, in fact, the temperature profile is rendered through colors ranging from dark (lower temperatures) to bright red or white (higher temperatures).

In some applications it is then possible by selecting a specific subject and in particular a point of the detected image, to have automatically, through a conversion software, the detected temperature of that point, or the maximum temperature inside the detection area.

However, the maximum temperature in the detection area may not necessarily be traced back to the actual temperature of a subject, as it could instead be an object such as a cup of coffee or a mobile phone or a lit cigarette.

On the other hand, in systems in which the maximum temperature inside the considered area is highlighted, it may happen that more subjects present fever, but the system would only highlight the one with the highest temperature while the others would be â € œignoredâ € €.

In this situation, the technical purpose underlying the invention is to solve the drawbacks highlighted above.

A first object of the invention is to provide a methodology and an apparatus that allow a more accurate identification of subjects suffering from fever than of healthy ones, possibly also allowing an automation of this process.

A further object of the invention is to allow more precise measurements by eliminating the systematic errors due to the main environmental effects.

A further objective of the invention is to make available an intelligent device that in fact has costs completely comparable with the thermal imaging cameras currently on the market, while guaranteeing much improved performance.

These and other objects are substantially achieved by a method and by a relative apparatus for determining the body temperature of at least one subject in accordance with the attached claims.

Further characteristics and advantages will become clearer from the detailed description of a preferred, but not exclusive, embodiment of a method and of an apparatus as described below.

The description will be made hereafter with reference to the accompanying figures, provided for illustrative purposes only and therefore not limitative in which:

Fig. 1 is a schematic view of an embodiment of an apparatus in accordance with the invention;

Fig. 2 shows an exemplary view of an image detected by means of a thermal imager in accordance with the present invention,

With reference to the figures cited with 1, an apparatus for determining the body temperature of at least one subject S.

In particular, this equipment is normally called a thermal camera, or thermographic camera, and is a particular camera, sensitive to infrared radiation, capable of obtaining images or thermographic recordings. In other words, the device is able to acquire at least images in the infrared field and to display the irradiation measurement in two dimensions. In general, through the use of a thermal imager, non-destructive and non-invasive checks are carried out as the radiation in the infrared range of the electromagnetic spectrum is detected and correlated measurements are carried out with the emission of these radiations.

In particular, it is the instrument capable of detecting the temperatures of the bodies analyzed by measuring the infrared intensity emitted by the bodies under examination.

All objects at a temperature above absolute zero emit radiation in the infrared range and the relationship is numerically quantifiable thanks to Planck's law.

In general, thermography allows you to view absolute values and temperature variations of people or objects regardless of their illumination in the visible range.

The amount of radiation emitted increases proportionally to the fourth power of the absolute temperature of an object as clearly established by the Stefan-Boltzmann law which defines the correlation between radiation and temperature according to the following formula:

q = EGT ^

Where σ is the Stefan-Boltzmann constant and ε à ̈ remissivity of the emitting surface (variable between the theoretical limits of 0 and 1), while T is the absolute temperature.

Starting from the detected radiation, therefore, temperature maps of the exposed surfaces are obtained.

The image is generally built on a matrix of a certain number of pixels and a certain number of lines and the instrument's electronics are able to quickly read the energy value stored by each single pixel and generate a corresponding image, in black and white or in false colors, of the observed object.

The operating spectral range of thermal imaging cameras is, as mentioned, that of infrared and in general the most commonly used band suitable for measurements of values close to the environmental temperatures of interest is that of far infrared (LW).

Overall, a thermographic or IR system consists of a camera (thermal imager) 1 connected to (or including on board) an image processing and recording system.

The infrared detectors have the task of identifying the consistency of the radiation that strikes them and to analyze the radiant surface point by point, to arrive at the definition of the heat map.

From the structural point of view, the apparatus 1 for determining the body temperature of at least one subject S comprises an acquisition system 2 of an image relating to at least one predefined area 3 within which there is at least one and preferably a plurality of subjects S are found (or pass through it) whose body temperature is to be known.

The apparatus obviously comprises suitable optical means 5 to allow focusing and image acquisition; these means 5 are constituted by standard lenses and telephoto lenses and chosen according to the specific application to which the thermal imager will be destined as better explained below.

The apparatus then comprises an infrared sensor 6 which may be by way of example only, and not limiting, a sensor of the flat matrix, single matrix or dot matrix microbolometric type.

The sensors 6 can be either uncooled or cooled (generally with peltier cells or stirling pump).

The material that makes up the sensor affects the thermal sensitivity of the thermal imager, which is the smallest difference in temperature detectable by a thermal imager.

It is evident that a high thermal sensitivity identifies the most imperceptible temperature differences and therefore the lower its value, the higher the measurement resolution of the thermal imager and the higher the image quality.

By way of example, thermal imaging cameras with thermal sensitivity lower than at least 80 mK can be used.

Obviously, the temperature measurement range of the apparatus for determining body temperature in accordance with the invention must be centered in the range of the normal human body temperature, i.e. between 30 and 45 degrees centigrade with the best performance confined around the temperature of 37 °.

Since the equipment in accordance with the invention will generally be destined to acquire images of moving subjects or in any case be able to perform this type of scans as well, the acquisition frequency is a fundamental parameter for the use of the camera.

The measurement of the temperature of a moving object must be carried out with good acquisition frequencies to avoid the phenomenon of â € œsmearingâ € on the image, which prevents having an accurate temperature measurement. In general, acquisition frequencies above 60 Hertz are preferred.

Therefore the instrument also includes a processing unit 7 capable of acquiring, with the appropriate frequencies, the electrical signal emitted by the infrared sensor 6 following the acquisition of the image or heat map.

The same processing unit 7 is able to process the received signal and to show the detected thermal image on a suitable display 8 present in the equipment (or in an external system - a computer for example).

In particular, it is possible to appropriately select the (false) display colors linked to the different temperatures with the desired degree of precision.

in other words, it is possible to display with different colors variations in temperatures from 32 to 43 degrees, for example, with colder colors for the lowest temperatures up to warmer colors for the highest temperatures.

Through the device it is possible to measure the temperature of each single point of the image; In fact, a module 8 is present in the instrument (or in the post-processing software) which is able to correlate irradiation with temperature by means of the aforementioned Stefan-Boltzmann law.

It should be noted, however, that the device also comprises a real image sensor 10 capable of acquiring the real image relating to the same predefined area 3 which contains the subjects of which one wishes to know at body temperature.

In other words, the thermal imaging camera object of the invention also comprises a common sensor 10 currently used in commercial cameras or video cameras capable of acquiring an image in the visible spectrum (visible light).

The detected signal is acquired by the same processing unit 7 and can be shown on the aforementioned display 8 either as an alternative to the thermographic image, or jointly with it in superimposition,

In particular, a real digital image is automatically recorded for each infrared image detected.

In this way, the system always has two corresponding and simultaneous images available.

Optionally, the equipment can include suitable integrated LEDs or other lighting system 11 which guarantee excellent visibility in the image acquisition zones 3.

Advantageously, the processing unit 7 is able to analyze the image acquired by means of an appropriate recognition module 12 to identify at least one area of interest 13 of the subject 5.

In detail, the instrument is therefore able to acquire Î "image coming from the predefined area 3 and to carry out on this last acquired image a predetermined number of calculations capable of carrying out the aforementioned recognition of the area of interest 13 of the subject 5.

In particular, it is preliminarily advantageous to be able to identify one or more chosen areas of each of the subjects of interest (for example) between the forehead, eyes, temples, neck, auricle, etc.

Note that the recognition operation can alternatively be carried out on the infrared image acquired in detail by the sensor 6 (in this case the real image sensor 10 in the visible light spectrum could be totally optional) or even carry out the recognition directly on the image real acquired by the second sensor 10.

This second option is now commercially more advantageous as there are methods available that already operate the recognition of the face of a subject implemented in cameras and camcorders, including amateur ones. In general, the teachings of, for example, one or more of the American patents US 6940545, US 7218759 or US 2009/0190803 can be used, which allow an analysis of the image to identify the areas of interest in it.

Obviously the interest for the present invention is to identify not so much the face of a subject, as the specific areas of interest highlighted above which are the best for the subsequent thermal analysis. In fact, once the specific area of interest 13 has been identified, the analysis of infrared radiation is carried out on the latter.

The determination of the subject's body temperature takes place in fact as a function of the infrared radiation detected coming from the area of interest.

In general, with specific reference to the area of interest (for example the forehead), the determination of the maximum intensity radiation coming from the aforementioned area is determined and then the determination of the body temperature as a function of this maximum radiation detected.

The importance of determining the actual area of interest is linked to the possibility of improving the accuracy of the measurements and also to the possibility of automating the calculation of the temperature of a subject avoiding errors. In fact, the recognition of the zone whose temperature is to be measured makes it possible to prevent the software from being misled by calculating and reporting temperatures outside the predetermined ranges linked to heat sources not of interest (see zone 4 in figure 2).

Consider, for example, hot drinks carried by subjects, electronic equipment that heat, or even a simple cigarette, which would involve the detection of high temperatures, but of elements of no interest for the detection.

Vice versa, the identification of the precise area 13 where to carry out the measurement thanks to the recognition software allows first of all to eliminate the problems mentioned above.

Furthermore, the methodology according to the invention also provides for a correction phase of the detected temperature to determine the actual body temperature. First of all, the correction phase will be (or could be) according to the area of interest of origin of the infrared radiation.

It is in fact evident that the origin of the infrared radiation from the forehead, rather than from the neck (jugular artery) or from the temples, may require a different corrective parameter.

In fact, it should be noted that in general the external temperature of the various portions of the body not only differs from the internal temperature, but differs significantly differently depending on the point of detection (the temperature of the forehead is generally lower than that of the temple and so on).

It should also be noted that this correction can be carried out, alternatively, with corrective functions or even with parametric tables with fixed correction data, also obtained experimentally.

A second correction, opportune or necessary, is vice versa a function of the ambient temperature in which the subjects whose temperature is to be measured are located.

In fact, a subject with the same internal temperature who is in an environment with low temperatures will have a lower surface body temperature than the same subject with the same internal temperature who is in a warm environment.

Therefore, a first corrective parameter could be linked to the ambient temperature of the environment in which the subject is at the moment of detection or also to the ambient temperature (different from that in the detection area) in which the subject is found. for a predetermined time interval such as to substantially influence and stabilize the temperature of interest immediately before detection.

For example, think of subjects whose temperature is detected at the entrance to an air-conditioned area and coming from an area with a different temperature.

A subject who is outside at low temperatures and therefore enters an entrance and the temperature is immediately detected, will obviously have his own surface temperature stabilized with reference to the external temperature and not with reference to that of the place of measurement.

In this case the ambient temperature as a corrective reference could be the external one.

Furthermore, a corrective phase may also take into account a predetermined predetermined detection temperature for a majority of the plurality of subjects. In other words, without intervening with corrections related to environmental parameters or to the detection zone 13, the thermal detection is carried out on a plurality of subjects who are expected to be in good health on average (temperature of about 37 °). In this case, the temperature detected for this plurality of subjects will be corrected in such a way as to assume the value of 37 ° as the internal temperature of most of the subjects who have the same thermal radiation emitted by the corresponding area of interest and the differences will then be evaluated. compared to subjects with a higher temperature.

In other words, it is assumed that most of the subjects whose temperature is measured have a normal value and therefore, if the temperature detected for these subjects were, for example, 35 °, it would be corrected to 37 °, also automatically correcting all other temperatures.

In this sense, it could also be possible to simply highlight those subjects who have a temperature in the area of interest higher, in addition to a certain threshold, than the average of the subjects whose temperature was measured over the time interval.

In other words, instead of determining a precise body temperature to establish the presence of subjects with fever, it is considered that most of the subjects whose temperature is measured do not have febrile phenomena and only those subjects who have a higher temperature are reported. . The above obviously always referring to surveys linked to the identified area of interest, the same for all subjects, in such a way as to be reliable and automatable.

It should be noted that the methodology described above is particularly suitable for temperature measurements in high traffic areas, such as airports, factories, schools, museums, hospitals (in the latter case with particular reference to visitors).

One or more thermal imaging cameras positioned in correspondence with compulsory accesses, for example of passengers entering the country, allows to measure the internal temperature of a plurality of subjects in a reliable way and to report in real time those potentially suffering from febrile diseases.

The device can also be associated with an automatic access control system, for example consisting of a gate or turnstile that locks automatically to prevent the passage of the â € œsuspectâ € subject.

By operating as described Î “the equipment is able to eliminate false positives linked to high temperatures not of the subjects of interest, and also to carry out precise measurements thanks to the correction steps highlighted above. Obviously, a further possible application of the thermal imaging camera is in hospitals or in any public place to detect the temperature of visitors and / or passers-by.

For example, the thermal imaging camera can be positioned in correspondence with accesses to hospital wards with critically ill patients in such a way as to be able to selectively deny entry to visitors with fever.

In a further advantageous, albeit secondary, aspect of the invention, a phase of recognition of a face and / or of another body characteristic of a specific subject can also be envisaged in such a way that with the comparison with faces and / or other corresponding and pre-memorized bodily characteristics, it is also possible to identify the subject.

In this way it is not only possible to detect a certain temperature, but also to associate it with a specific identified subject / patient.

A possible application of this methodology would be extremely advantageous in hospitals or health facilities.

In fact, it is possible to memorize faces or in any case identification parameters of certain patients that can be subsequently recognized and / or identified through the thermal imaging camera.

A thermal imager positioned in correspondence of a hospital room could be able to detect not only the temperature of a subject, but also, for example, his face, recognizing the patient's identity and therefore automatically memorizing the patient's temperature. If the device is placed over the bed, it may continuously detect the subject's temperature.

In these cases, these devices may be able to automatically emit an alarm by signaling the patient (s) with fever at the very moment in which the fever occurs, i.e. when the body temperature exceeds a certain control threshold. This threshold can also be of low temperature, for example in the case of a deceased patient.

The system can also be associated with traditional control systems used by security control personnel such as controls using â € œmetal detectorsâ €, X-ray detectors or equivalent systems in airports, courts, etc.

In these cases, a person who shows a â € œsuspiciousâ € temperature alerts the relative alarm signal and is invited to a special area where medical personnel can carry out the necessary medical checks.

In a simpler and alternative embodiment to the one described above, it is envisaged to provide a fixed (or substantially fixed) structure or panel to which each person to whom it is requested must approach.

By observing the panel directly and frontally at a predetermined distance (for example about 50 cm) the infrared radiation coming from the area of interest is received (for example, but not limited to, the forehead) and the body temperature of the subject is calculated from this.

In particular, the correct distance can be signaled by the device itself by means of signaling (for example an acoustic â € œbipâ €); by way of example, ultrasound can be used to establish whether the subject has reached the optimal position for measurement.

When the subject is at the right distance, the sensor mounted on the panel detects the radiation coming from the subject and then a control unit calculates the body temperature according to the detected radiation and the ambient temperature. In other words, the real internal temperature will be obtained by correcting the temperature detected on the forehead (or other area of interest) on the basis of the stored or detected ambient temperature.

In case of presence of temperature above a certain threshold (for example suspected fever) an alarm is issued (for example audible and / or visual).

The use of an eventual parabolic wave guide to bring the infrared radiation to the sensor can allow, if necessary, to reduce the sensor field of view and make the measurement more accurate.

Claims (10)

CLAIMS 1. Method for determining the body temperature of a subject comprising the following steps: - detect an image relating to a predefined area including at least one subject whose body temperature you want to know; analyze the image by means of a recognition module to identify at least one area of interest of the subject; detecting infrared radiation coming from at least said area of interest; determining a body temperature of the subject as a function of the infrared radiation detected coming from said area of interest. 2. Method according to the preceding claim, in which it is envisaged to detect an image relating to a predefined area comprising a plurality of subjects whose body temperature is to be known; analyze the image using a recognition module to identify at least one area of interest of a predetermined number of said plurality of subjects; detecting an infrared radiation coming from said areas of interest of each subject of said predetermined number; determining a body temperature of each subject of said predetermined number as a function of the detected infrared radiation coming from the respective area of interest. 3. Method according to any one of the preceding claims, in which the step of analyzing the image involves identifying one or more areas of interest, particularly selected from the forehead, eyes, temples, neck, auricle of said subject and detecting an infrared radiation coming from from one or more of said areas of interest, in particular Î "identification of the area of interest being set manually or being managed automatically by the device. Method according to any one of the preceding claims, in which the detection phase comprises a sub-phase of determining a radiation of maximum intensity coming from said area of interest, the determination of the body temperature of the subject being carried out as a function of the maximum radiation detected coming from said area of interest. Method according to any one of the preceding claims, in which the determination of the body temperature comprises a step of calculating the detected temperature as a function of the intensity of infrared radiation received and a step of correcting the detected temperature to determine the body temperature. Method according to the preceding claim in which the correction step comprises a correction as a function of the region of interest from which the infrared radiation originates, in particular the correction being carried out as a function of a corrective parameter depending on the region of interest. 7. Method according to claim 5, in which the correction step comprises a correction as a function of the ambient temperature, in particular in which the subject is at the moment of detection or in which the subject has been for a predetermined time interval such as to substantially influence and stabilize the temperature of the area of interest immediately before detection. 8. Method according to claim 5, characterized in that the correction step comprises a correction as a function of an expected detection temperature predetermined a priori for a majority of said plurality of subjects. 9. Method according to any one of the preceding claims, further comprising an identification step of the subject whose temperature is to be known, in particular the recognition module by recognizing the face and / or another bodily characteristic of the subject and a module of comparison by comparing the face and / or another relevant body feature with a corresponding face and / or a corresponding body feature pre-stored to identify the subject. 10. Device for determining the body temperature of at least one subject comprising: at least one thermal imager and / or a camera capable of detecting an image relating to a predefined area including at least one subject whose body temperature is to be known; a recognition module for analyzing the detected image and identifying at least one area of interest of the subject; - means for detecting an infrared radiation coming from at least said area of interest; means for determining a body temperature of the subject as a function of the detected infrared radiation coming from said area of interest.