RU2848139C1 - Thermal imager - Google Patents

Abstract

FIELD: medical technology.

SUBSTANCE: invention relates to medical technology. The thermal imager contains a liquid crystal display (2), a USB video camera (3), a laser rangefinder (4), a thermal matrix sensor (5) and a microcontroller (6) connected to a power supply unit (1). Additionally, a USB hub (7), a thermal point sensor (8) and a laser pointer (9) are included. The thermal imager is designed to display the diagnosed area on a personal computer screen in the form of a pixel matrix overlaid with a coordinate grid indicating the temperature of each pixel, and with the ability to capture a television image by recording a sequence of thermal images with a specified polling frequency of the thermal matrix sensor, as well as with the ability to determine the size of the area of interest directly on a personal computer screen.

EFFECT: increased accuracy of absolute temperature measurement and dynamics of its change.

1 cl, 2 dwg

Description

The invention relates to medical equipment, namely to thermal imaging equipment for medical diagnostics.

A thermal imager is known that contains a photosensitive unit including a lens, a cryostat, an input window of the cryostat, a photodetector matrix, a silicon multiplexer, a cooling system, a cold screen, an electronic system for analog signal processing, and also contains a digital unit consisting of an electronic module with an analog-to-digital converter (ADC) and a computer connected to it, a power source, and a monitor connected to the digital unit. The thermal imager's photodetector matrix is made on the basis of indium arsenide and also contains a communication line, the digital unit is implemented in a shielded housing separated from the photosensitive unit and is connected to the photosensitive unit via a communication line, the electronic module with the ADC contains a differential amplifier, a signal processor and a microcircuit for communication with the computer bus, the electronic system of analog signal processing is configured to control the matrix via a silicon multiplexer and executive systems (a system for calibrating the sensitivity of the matrix elements and a system for focusing the lens), also contains a calibration system built into the photosensitive unit, and a printer, a keyboard, a mouse manipulator connected to the digital unit. The photodetector matrix has a dimension of 128x128 elements, can be square or rectangular and contain m x n elements, where m, n ~ 100 - 1000. The photosensitive elements of the matrix are capacitors with an MOS structure, they can also be photodiodes. The lens has a focal length F exceeding 90.01 m and a relative aperture ranging from F/0.5 to F/16. The power supply is connected to the electronic analog signal processing system, matrix control, and actuator systems. It is also connected to the digital unit. A computer power supply (RU 2152138 C1) is also used as a power source.

The disadvantage of this technical solution is the use of a photosensitive unit cooled by a cryostat, the need to use a system for calibrating the sensitivity of the matrix elements and a focusing system, which significantly complicates the operation of the system.

There is known an implementation of a method for displaying the temperature field of a biological object (RU 2452925 C1), which includes measuring the temperature of the object at fixed points in the area being examined, transmitting the measurement result at each fixed point to a computer equipped with a computer program, processing the measurement results in the computer and using the processing results to form an image of the temperature field of the area being examined of the object, wherein the formation of the image of the temperature field is carried out by a computer program on the image of the area being examined of the object, characterized in that the image of the area being examined of the object is entered into the computer database and displayed on the monitor screen before the start of measuring the temperature, wherein the points for measuring the temperature in the area being examined of the object are displayed on the image of the object on the monitor screen and involve designating points for measuring the temperature on the image of the area being examined with an orientation towards anatomical landmarks inherent in this area in a quantity minimally sufficient for monitoring any pathological process in this area the points for measuring the temperature, designated on the image of the area being examined, are obtained from the computer memory; the points for measuring the temperature are designated on the image of the area being examined manually; Temperature measurements at fixed points within the surveyed area are performed while maintaining a standardized distance and angle between the surveyed area of the human body and the infrared sensor, sufficient to ensure repeatability of successive temperature measurements at the same points on the surface of the surveyed area of the human body throughout the entire monitoring period. The image of the surveyed area is taken as a photograph. The image of the surveyed area is taken as a 2D (two-dimensional) or 3D (three-dimensional) model image, and the monitoring results are generated as a text message; the monitoring results are generated as a graphic message. The monitoring results are generated as an audio message. The computer is implemented, for example, on standard SoC platforms based on the ARMv9 core, or similar ones with similar performance and power consumption, for example, ARM architecture, x86. Standard platforms such as Android 2.3, Qt, Windows Mobile, or similar ones, ensuring the efficient functioning of the device, are used as the base software. An additional memory unit, such as a flash card, can be disconnected for subsequent use of the stored data on a personal computer. The memory unit is organized as a relational database or flat file storage. SQLite, for example, can be used as a relational database. The screen is, for example, touch-sensitive, using a resistive or capacitive matrix. The screen has a diagonal of, for example, 3.5", with a resolution of, for example, 320x240 pixels, and a color depth of, for example, 16-bit RGB. The infrared sensor is based on a standard infrared sensor with maximum sensitivity in the temperature range of biological objects of 20-45°C. The infrared sensor is based on, for example, the MLX90614 sensor. The housing of the disease monitoring device has at least two openings, with an infrared sensor installed in at least one of said openings, and a camera lens installed in the other opening. Temperature measurements are performed at several points in a dot pattern simultaneously using more than one infrared sensor.

The device is additionally provided with a remote module comprising the housing of at least one infrared sensor, provided with a means for ensuring a specified distance and angle between the examined area of the human body and the infrared sensor and connected to the device for monitoring diseases using a flexible cable.

The disadvantages of this method include limited positioning of measurement points, difficulty in repeating the measurement point location, and low density of temperature measurement points. The principle by which points of interest are selected is unclear. Using a camera in a single unit with a point sensor is cumbersome and uninformative, and therefore pointless. There is no ability to measure temperature dynamics.

Thermal imagers from NEC, type AT7X/AT8X (http://nec-infrared.ru/teplovizor_18.html) were chosen as a prototype.

Thermal Imaging Camera Specifications

Displaying an image Thermal imager AT7X-Standard Thermal imager AT8X-Standard IR detector resolution 640x480 pixels 1024x768 pixels NETD <0.04°C (@30°C) <0.04°C (@30°C) Spatial resolution 0.68mrad (24°);
1.31 mrad (48°);
0.34 mrad (12°);
0.17 mrad (6°); 0.36 mad (28°);
0.63 mrad (45°);
0.17 mrad (12°);
Displaying information 5.8" super-bright display with a resolution of 1280*768 pixels Touch screen Capacitive touch display Uncooled detector Detector material Amorphous silicon or vanadium oxide Spectral range 7.5 ~ 14 um Standard lens 24° 28° Additional Objectives 48° 12° 6° etc. 45° 12° Focusing range 0.5 m~0 (24°\48°);
1 m~00 (12°):
4 m~0 (6°) 0.5 m~0 (28°);
1 m~0 (12°);
Lens definition Automatic identification Focus mode Manual, automatic, electronic Frequency of the I/K detector 30 Hz Scaling 1X-8X continuous Temperature measurement parameters Standard range -20°С ~ 150°С, 0°С ~ 410°С, 300°С ~ 650°С Optional range +300°С ~ + 650°С \ +300°С ~ +2,000°С \ (high temperature range) Measurement error ±2°С or 2% of reading Viewfinder parameters Viewfinder Built-in, color, resolution 1024x768 pixels Visible light parameters Digital camera Built-in 500W digital camera with LED lamps Laser rangefinder parameters Laser range 0.01m ~ 40m Laser rangefinder accuracy ±1cm or 1% Laser display The position is automatically displayed on the infrared image. Displaying an image Palette Ten palettes such as metal tarnish/grayscale/inverted etc. PIP (picture in picture) Displaying an infrared image area on a visible image IMIX (mixing) Supported Merger Supported Isotherms Supported Super resolution Increases the number of pixels by 4 times GPS Built-in GPS, automatically adds location information to images, screen reader support included Wireless data transmission Wi-Fi Transfer infrared images to your mobile phone/computer via Wi-Fi Bluetooth Support recording and playback via Bluetooth headsets USB interface USB interface Uses USB to transfer images from the device's SD card to a PC Measurements and analysis Point, line, area Support up to 10 points, up to 5 lines and up to 10 areas simultaneously Full Screen Max/Min Automatically captures maximum/minimum temperature on screen Temperature difference Automatic calculation of temperature difference during measurement Calibration of unevenness Manual / automatic by sensor signal Emissivity correction Automatic, based on the emissivity of the input parameter Atmospheric transmittance correction Automatic, based on input parameters Measurements and analysis Text annotation Select a text annotation from the list of presets and edit it in the thermal imager Sound annotation Supports voice annotation and saves it along with the thermal image Signaling Alarm mode Automatic audible and visual alarm for set temperature above/below Saving data Saving images 32G high-speed SD card (stores over 10,000 thermal images) Thermogram format jpg / png (includes radiometric data) Video image format jpg/ png IR video format H.264 video to SD card Video output Video output HDMI Video output interface Micro HDMI interface Nutrition Type Replaceable rechargeable lithium battery Supply voltage DC 12V Battery life from 3 hours at a temperature of 25°C Charger type Two-section Physical characteristics Weight 1.6 kg (including battery) Size 210x119x174 mm Environmental parameters Operating temperature -20°С ~ 55°С Storage temperature -40°С ~ 70°С Humidity <95%, RH Level of protection IP54 Tripod mount type UNC 1/4*-20

Fig. 1 shows a structural diagram of the implementation of such a thermal imager, which is used in medicine and is one of the most functional.

This thermal imager consists of a liquid crystal display, a USB video camera, a laser rangefinder, a thermal matrix sensor, and a microcontroller connected to a power supply unit. The liquid crystal display is connected to the output of the microcontroller, and the laser rangefinder, thermal matrix sensor, and video camera are connected to the input.

In this technical solution, the laser rangefinder is used for targeting and determining distances, but is not used to measure the area of interest (AOI) highlighted on the thermal image. Thermal imaging is purely qualitative, based on the colorized thermal image, which significantly reduces the reliability of the resulting data analysis. A significant drawback of this thermal imager is the lack of a precision thermal point sensor that would allow for highly accurate temperature measurement at the AOI and its dynamics, which is crucial for medical diagnostics.

The objective of the claimed invention is to create a thermal imager that allows for high-precision measurement of absolute temperature and the dynamics of its change.

In order to solve the stated problem, a thermal imager is provided, which comprises a liquid crystal display, a USB video camera, a laser rangefinder, a thermal matrix sensor and a microcontroller connected to a power supply unit, to the output of which the liquid crystal display is connected, and to the input of the laser rangefinder and thermal matrix sensor, as well as a USB distributor, a thermal point sensor and a laser pointer, wherein the first input of the USB distributor is connected to the USB video camera, the second input is connected to the second output of the microcontroller, and the output is configured to be connected to a personal computer, the output of the thermal point sensor is connected to the input of the microcontroller, wherein the thermal point sensor and laser pointer are connected to the power supply unit, wherein the thermal imager is configured to display on the screen of the personal computer the diagnosed area in the form of a matrix of pixels, on which a coordinate grid is superimposed indicating the temperature of each pixel, and with the ability to record a television image by recording a sequence of thermal images with a given sampling frequency of the thermal matrix sensor, as well as with the ability to determine the size of the area of interest directly on the personal computer screen.

The present invention differs from the prior art in that it incorporates an additional thermal point sensor, which enables the positioning of a detected point of interest and detailed investigation of its dynamic processes, storing and displaying temperature changes over time (sampling frequency from 0.1 sec to 1 sec). The use of a thermal matrix sensor, operating at a short distance (from 5 cm), in combination with a rangefinder, enables quantitative determination of the area of interest and its precise positioning.

The essence of the invention is explained in Fig. 2, which shows a block diagram of a thermal imager.

The thermal imager contains (Fig. 2) connected to power supply unit 1 liquid crystal display 2, USB video camera 3, laser rangefinder 4, thermal matrix sensor 5 and microcontroller 6, to the output of which is connected liquid crystal display 2, and to the input of laser rangefinder 4 and thermal matrix sensor 5, as well as USB distributor 7, thermal point sensor 8 and laser pointer 9, wherein the first input of USB distributor 7 is connected to USB video camera 3, the second input is connected to the second output of microcontroller 6, and the output is intended for connection to a personal computer, the output of thermal point sensor 8 is connected to the input of microcontroller 6, wherein thermal point sensor 8 and laser pointer 9 are connected to power supply unit 1. The thermal imager is made in a compact housing with a pistol-type handle, on the front panel of which are located: thermal matrix sensor 5, thermal point sensor 8, laser rangefinder 4, laser pointer 9, USB video camera 3. The main elements of the TVS-2 thermal imager are:

– matrix thermal imaging sensor (MTD) MLX90640 with a format of 24 × 32 pixels, pixel size of 20 µm, resolution when determining the temperature in each pixel of 0.1 °C;

– point thermal imaging sensor (TIS) MLX90614, temperature detection resolution 0.02 °C;

– wide-angle television (TV) camera type OV2643 with a format of 1200 × 1600 pixels and a viewing angle of 120°.

The thermal imager operates as follows: it is connected via USB to an external computer running the TermoLabs software. After launching the software, a thermal image window and a video image window will appear on the computer screen, with a field corresponding to the thermal imager's size highlighted. When using a low-resolution thermal matrix sensor (24x32) at short distances of 5 cm, the thermal pixel size is 1.5 mm. This spatial resolution of the thermal image is sufficient for medical practice. The area being diagnosed can be displayed on the computer screen as a pixel matrix, overlaid with an Excel coordinate grid indicating the temperature of each pixel.

The use of a laser rangefinder 4 allows one to determine the size of the zone of interest directly on the personal computer screen, to precisely position it using a light mark from a laser pointer 9 on a video image, and to carry out various computer processing.

Next, the physician positions the thermal imaging camera (TIC) over the area being diagnosed at a distance of 5 cm, performs a preliminary analysis of the thermal image, identifies the area of interest, and performs further processing and analysis of the obtained thermal data. Thermal imaging is recorded using software or the TV image capture button. When examining dynamic thermal processes, a long press of the TV image capture button (up to 5 seconds) records a sequence of thermal images at a specified sampling rate of thermal matrix sensor 5. By default, laser pointer 9 is activated, appearing as a red spot in the video image in the area of interest. When re-examining this area of interest, the laser pointer 9 spot allows for precise determination of the desired examination location. Once a point of interest is identified, where the absolute temperature value and its dynamics over time must be accurately determined, thermal point sensor 8 is activated, which measures the temperature with an accuracy of 0.02 degrees Celsius from a distance of 5 mm. Temperature polling can be varied from 0.1 seconds to 1 second in continuous monitoring mode. A temperature graph is displayed in a separate computer window and saved to memory. Since the developed thermal imager operates at short distances with a thermal matrix sensor in combination with a thermal point sensor and advanced software, it allows the thermal matrix sensor to be used for more detailed quantitative analysis, as well as for analyzing temperature dynamics at a point of interest.

Claims (1)

A thermal imager comprising a liquid crystal display, a USB video camera, a laser range finder, a thermal matrix sensor and a microcontroller connected to a power supply unit, the output of which is connected to the liquid crystal display, and to the input of which is connected the laser range finder and thermal matrix sensor, characterized in that a USB distributor, a thermal point sensor and a laser pointer are additionally introduced, wherein the first input of the USB distributor is connected to the USB video camera, the second input is connected to the second output of the microcontroller, and the output is configured to be connected to a personal computer, the output of the thermal point sensor is connected to the input of the microcontroller, wherein the thermal point sensor and the laser pointer are connected to the power supply unit, wherein the thermal imager is configured to display on the screen of the personal computer the diagnosed area in the form of a matrix of pixels, on which a coordinate grid is superimposed indicating the temperature of each pixel, and with the ability to record a television image by recording a sequence of thermal images with a given sampling frequency of the thermal matrix sensor, as well as with the ability to determine the size of the area of interest directly on the personal computer screen.