RU67422U1 - DEVICE FOR DETECTING AND LOCALIZING DAMAGED TISSUES- "METALIMFOSCAN" - Google Patents

Abstract

The utility model relates to medical equipment, namely to devices for detecting and localizing affected organs and tissues. The device includes a scintillation detection unit (hand probe), a control and monitoring panel. The detector is a scintillator with photodiode registration of light flashes. The built-in collimator of the detector is made of heavy alloys with a thickness of at least 12 g / cm ² and has an input window with a thickness of not more than 0.3 g / cm ² . The short part of the scintillation detection unit, comprising a detector and an integrated collimator, is located at an angle to the axis of its long part. The control and control panel has a controlled discriminator of the lower level of the recorded energies, which ensures registration only in the energy region of the photopeak of the selected radionuclide; linear passer for switching between tonal and binary-tonal modes; shaper of sub-ranges of counting speed (with automatic range switching) for outputting information on a linear LED scale and in the form of a tone sound signal; programmable counter for determining the digital value of the counting speed and setting the operating modes of the device.

The device allows for high accuracy in the detection and localization of affected organs and tissues, the ability to change operating modes (exposure time, settings for counting speed, integral counting mode), which together significantly increases the diagnostic capabilities. At the same time, the device is convenient to use, safe for the patient and medical personnel.

Description

The utility model relates to medical equipment, namely to devices for detecting and localizing affected organs and tissues, in particular lymph nodes, during examinations and surgical operations by recording the count rate of external gamma radiation of radionuclide pharmaceutical preparations (hereinafter radionuclides) after their administration to a patient .

In modern medicine, a significant place is occupied by the problem of accurate diagnosis of lesions of tissues and organs of a patient during surgical interventions and preoperative examinations, especially in cancer patients. Typically, for the purpose of diagnosis, methods of computed tomography, ultrasound, nuclear magnetic resonance, positron emission tomography, and devices to implement these methods are used. However, according to some authors (R.T. Scardino et al 2006), even the use of all the most advanced diagnostic methods at the preoperative stage does not allow a reliable assessment of the patient's condition (the presence or absence of lymphogenous and hematogenous metastases, the degree of damage to tissues and organs, the prevalence of damage) . Thus, the sensitivity of computed tomography (CT) and nuclear magnetic resonance imaging (MRI) in the diagnosis of lymphogenous metastasis does not exceed 60%. The use of positron emission tomography (PET) is very expensive and, nevertheless, despite the best resolution, this method has a fairly low sensitivity when assessing the patient's condition, as it is not able to track the presence of micro changes (for example, micrometastases up to 5 mm in size). In addition, the accuracy of these methods depends not only on the technical capabilities of the devices,

used for diagnosis, but also from the competence of an interpreter who interprets the results obtained, which also in some cases makes it difficult to obtain objective data about the patient’s condition. As for the methods and devices used to diagnose the condition of the patient’s organs and tissues at the surgical stage, it should be noted that the known methods are not popular with specialists, as they have low accuracy, and, in addition, serve as a distracting factor during the intervention.

On a technical level, a close analogue of the proposed device is the Radical gamma scanner, designed for transcutaneous and intraoperative detection of localized sources of photon radiation in the tissues and organs of patients during radioisotope diagnostics (1), which includes: a scintillation detection unit (hand probe) with an integrated collimator and cable, remote control with a screen for displaying information, power supply.

Unfortunately, this device has several disadvantages: for example, there is no possibility of changing the range of recorded photon radiation energies, which impairs the geometric resolution due to an increase in the fraction of the “background” radiation in the count rate; information about the counting speed is output only in the form of a digital indication and an audio signal, which complicates the localization (scanning) process, since when the dynamic range of the counting speed is more than 10 ⁴ pulses / s it is very difficult to determine the change in the counting speed by changing the tone of the sound signal due to limitations of auditory perception in humans. The detection system in the hand probe is made on a photomultiplier tube (PMT), which increases the diameter of the hand probe (up to 25 mm or more) and requires a PMT supply voltage of up to 1000 V, which leads to an increase in the potential risk of using the product. The hand probe is made in the form of a cylinder and its location in the surgeon’s hand when scanning in an orientation orthogonal to the object

increases the fatigue of the surgeon (especially taking into account the weight and diameter of the hand probe).

The purpose of the utility model is to create a device with higher accuracy in the detection and localization of affected organs and tissues, the ability to use various radionuclides, the ability to change operating modes (exposure time, settings for counting speed, integral counting mode), which together significantly increases the diagnostic capabilities. At the same time, the device should be convenient to use, safe for the patient and medical personnel.

The goal (technical result) is achieved by:

- use of a small-sized scintillation detection unit (hand probe) (size no more than · 22 · 180 mm, entrance window ⌀ 5 mm), having a heavy alloy collimator with a thickness of at least 12 g / cm, an entrance window with a thickness of not more than 0.3 g / cm ² , which allows to increase the geometric resolution due to the collimation of background radiation;

- the possibility of changing the range of recorded energies (registration of the counting rate only in the energy range of the photopeak of the used radionuclide), which allows to increase the geometric resolution by reducing the proportion of "background" radiation in the counting speed;

- the possibility of presenting the results of controlling the count rate of gamma-quanta simultaneously on a digital display, in analog form on a linear LED scale and in the form of a tone sound signal, while the range of recording the count rate in analog and sound channels is divided into sub-ranges (at least 5 under ranges with automatic switching), which allows to increase the geometric resolution by increasing the “sensitivity” of the analogue scale and tonal sound signal;

- the ability to quickly change the operating modes of the device (exposure time, setting the integrated counting mode and binary tone mode), which significantly increases the diagnostic capabilities, makes the device more versatile and convenient to use .;

- use of scintillator with photodiode registration of light flashes as a detector, which allows to reduce the dimensions of the hand probe (diameter not more than 22 mm) and does not require high-voltage power supply, which in turn reduces the potential risk of use and makes the hand probe more convenient;

- execution of a hand probe of a special form, when the short detecting part is rotated relative to the axis of the hand probe by a certain angle (for example, 20 °), which makes the hand probe more convenient for use and reduces the surgeon's fatigue.

The proposed device is presented in Fig. 1-3 and consists of a detection unit (hand probe, Fig. 1) with a cable and a control and monitoring panel (Fig. 2-3).

The detection unit (hand probe) is a cylindrical metal case bent at a certain angle (for example, 20 °), in the "short" part of which is a detector surrounded by a collimator, and in the "long" part is a charge-sensitive amplifier (ZCHU) for amplification and signal generation a detector and providing signal transmission over a cable of at least 3 m in length. A scintillator with photodiode registration of light flashes is used as a detector. The probe has dimensions ⌀22 · 180 mm, entrance window ⌀ 5 mm. The probe collimator is made of an alloy of heavy metals and has a thickness of at least 12 g / cm ² ; entrance window with a thickness of not more than 0.3 g / cm ² .

The control and control panel measures 257 × 156 × 256 mm; is a metal instrument housing, on the rear panel of the housing (figure 3) is a surge protector with a switch and

fuse (13, 14), on the front panel of the case (Fig. 2) there are: a knob for selecting the used radionuclides (1), a connector for connecting a hand probe (2), a button for selecting a measurement mode or a monitor lock (3), a measurement mode LED (4), lock mode LED (5), gamma-quanta digital counting reset button (6), mute / toggle switch (7), dynamic tone mode or binary (modulated) tone mode selector switch (8), knob volume control (9), LED the 1st indicator for turning on the power supply (10), a linear LED scale for indicating the range of the counting speed and the analog value of the counting speed (11), a programmable counter for determining the digital value of the counting speed and setting the operating modes of the device (12).

The gamma rays of the radionuclide introduced to the patient are recorded by a hand probe (detection unit). A scintillator with photodiode registration of light flashes is used as a detector. The electrical pulses of the photodiode are fed to the input of a charge-sensitive amplifier (hereinafter referred to as the RF amplifier) and converted into amplitudes proportional to the energy of the detected gamma rays.

The amplifier, the shaper, which is next to the MCH, the shaper amplifies and generates the MCH signal with the optimal constant rise and fall times to obtain the maximum signal to noise ratio. The rejection of background pulses and noise, the setting of the threshold of detected gamma-quanta is carried out by a discriminator, which is necessary for registration only in the photopic peak energy region of the selected radionuclide. The discrimination threshold for the selected radionuclide (the lower level of recorded energies for registration only in the photopic peak energy region) during examination of patients is set using the “Radionuclide” switch.

The pulses at the output of the amplifier-driver, with an amplitude above the discrimination voltage, cause the operation of a single vibrator,

which normalizes them in amplitude and duration. From the output of the single-vibrator, normalized pulses of positive polarity are transmitted through the communication line to the input of the control and measuring unit, shortened by the former and converted to voltage by the count rate converter. The counting speed varies widely, which complicates its direct presentation using an analogue scale and tone of sound, the range of perception of which is limited. Therefore, the voltage range of the counting speed transducer is subjected to piecewise linear compression by the sub-band generator with LED indication of the current measurement sub-range with limited limits of its variation. At the same time, within the current voltage sub-range, the counting speed can be determined visually using a linear light scale and by tone using a sub-band voltage converter into a tone of sound frequency. The sound volume is controlled by a resistor, and the sound itself can be turned on or off with the ON / OFF switch.

Digital registration of counting speed in a wide dynamic range is carried out using a programmable counter. To do this, in the measurement mode, impulses from an open collector circuit are applied to its counting input. The “MODE” button - “MEASURE / LOCK” is in the “MEASURE” position, the “MEASURE” LED is on. When you switch the mode button to the "LOCK" position, the counter readings are fixed, the "LOCK" LED turns on. The counter is reset if necessary by the "RESET" button.

The counter has output devices that can be programmed to operate if the set value of the counting speed is exceeded. If the tone modulation switch is "TONE / BIN." turned on, the sound starts to turn on and off periodically when the line skip is triggered, indicating that the set threshold for counting rate values is exceeded. In this mode, the doctor can determine the border of the lesion of the examined area or organ of the patient.

The device is powered by a single-phase alternating current circuit (220 + 22, minus 33) V / (50 ± 3) Hz through a line filter with a mains switch and fuses.

To power the photodiode of the detection unit, a voltage of 24 V is used, obtained from an AC / DC converter with an output voltage of ± 12 V. Other monitor circuits are powered by an AC / DC converter with output voltages of ± 12 V and ± 5 V. When the power is turned on, the LED " Network".

Functional diagram of the device shown in figure 4.

The proposed device has the following advantages:

1. The use of a small-sized hand probe (size no more than ⌀ 22 · 180 mm, input window ⌀ 5 mm), having a collimator made of heavy alloys with a thickness of at least 12 g / cm ² , the input window with a thickness of not more than 0.3 g / cm ² increase geometric resolution due to collimation of background radiation.

2. The ability to change the range of recorded energies (registration of the counting rate only in the energy range of the photopeak of the used radionuclide) allows you to increase the geometric resolution by reducing the proportion of "background" radiation in the counting speed.

3. The ability to present the results of controlling the count rate of gamma-quanta simultaneously on a digital display, in analog form on a linear LED scale and in the form of a tone sound signal (while the range of recording the count speed in analog and sound channels is divided into subbands with automatic switching) geometric resolution by increasing the "sensitivity" of the analogue scale and tonal sound signal.

4. The operational change of the device’s operating modes (exposure time, setting the integral counting mode and binary-tone mode) significantly increases the diagnostic capabilities, makes the device more versatile and convenient to use.

5. Using a scintillator with photodiode registration of light flashes as a detector allows you to reduce the size of the hand probe (diameter no more than 22 mm) and does not require high-voltage power, which reduces the potential risk of use and makes the hand probe more convenient.

6. The execution of a hand probe of a special shape (the short detecting part is rotated relative to the axis of the hand probe by a certain angle, for example, 20 ° makes the hand probe more convenient to use and reduces the surgeon's fatigue.

A device for the detection and localization of affected tissues works as follows:

The device is used to register gamma rays emitted by tissues and organs of patients after the introduction of radionuclides during examination of patients and surgical operations. Despite the presence of scattered and background radiation that reduces the contrast of the imaging of the tumor, its localization can be improved compared to gamma cameras due to the proximity of the hand probe detector to the control zone.

A hand probe with a control and monitoring panel also localizes such areas of radionuclide concentration as channels of the lymphatic vessels, lymph nodes, thyroid gland and other similar tissues. The device detects the presence of photon radiation of radionuclides and detects the difference in the number of photons emitted by various areas of the patient’s body or by an individual organ. Using a hand probe, the surgeon can track the flow of the radionuclide directly from

places of its introduction to other areas of its concentration. In this case, the device can emit a sound signal that varies in pitch, either increasing it or lowering it depending on the corresponding increase or decrease in the level of radioactivity. Changes in counting speed are also displayed on the digital and analog displays of the monitor.

The most appropriate monitor operation modes are as follows.

1. Scan mode - quick scan of the patient’s studied area for preliminary localization of the places of accumulation of the radionuclide.

In this mode, the doctor holds the manual probe for about 1 s (the time for updating the readings is reprogrammed in the counter) above the test site and, when changing the readings, moves it to another point 1 ÷ 2 cm away from the previous one.

The results of measurements of the counting speed are displayed on digital, analog displays and in the form of a tone sound signal with increasing tone with increasing counting speed. The counting speed can vary over a wide range, not covered by the analog display and the tone of the audio signal.

Therefore, the device automatically switches the ranges of counting speeds on a linear LED scale. The tone of the sound signal also automatically changes from high to low when moving to the next range of counting speeds and then increases with increasing counting speed.

2. Target check mode - a detailed study of the area of increased accumulation of the radionuclide in the same way as in the scanning mode, but with an increased programmable counting interval (about 3 s). To reduce the statistical error, the hand probe moves in small steps in the zone of accumulation of the radionuclide to identify places of maximum counting speed. The maximum count rate ptah in pulses per second is recorded by the doctor. Then, the maximum background count rate n _fmax in pulses per second of adjacent healthy tissue is determined. If necessary, by the value of n _max and

the ratio r = n _max / n _fmax specifies the minimum required measurement time Δt, s, for accurate localization of the lesion in the target account mode with a static error σ, in percent, according to the formula

3. Target counting mode - the exact location of the damaged tissue or organ is performed over the counting interval determined during the target check or set by the doctor based on restrictions on the time of the examination or operation. The place of damage is determined by the maximum counting speed and the high tone of sound in areas of increased accumulation of the radionuclide detected during scanning and target verification when moving the hand probe in small steps.

4. Binary tone mode - the boundary of the affected area is determined. In the binary tone mode, the control and monitoring panel can emit a tone-modulated sound signal when the threshold for the counting interval selected by the doctor (for example, 1 s) is set by the doctor programmatically set by the doctor. At the same time, when the manual probe is moved from healthy to damaged tissue, the device works first in tone mode at a counting speed below the threshold, and when the threshold counting speed is exceeded, the device goes into tone modulation mode for a time programmed by a doctor (for example, 1 ÷ 2 s) . The doctor moves the hand probe to an adjacent area of healthy tissue and again brings it closer to the area of increased counting speed, noticing an increase in the tone of the sound signal. If the count rate threshold is exceeded, a modulated tone signal is again generated. By repeating these procedures for other neighboring areas of the patient’s study area, the doctor determines the border of tissue and organ damage.

5. The mode of total counting - for the study of areas with low contrast distribution of small accumulations of radionuclide. In this mode, the measurement time is programmed on the pulse counter.

(determined by the doctor on the basis of the necessary statistical error to identify small differences in the samples, taking into account restrictions on the time of the examination and operation), and the total count is recorded on the counter display. The accumulation zones of the radionuclide are not determined by the count rate, but by the maximum total counts during the measurement. In total count mode, the meter may not be reprogrammed. In this case, the duration of the count and resetting of the testimony is set by the doctor manually using the buttons of the monitor.

Table 1 List of radionuclides used Radionuclide Photopic energy, keV (%) * Period
half-life * Front panel designation So-57 122 (88) 270 days Co57 Tc-99m 140 (89) 6.02 h Tc99m I-123 159 (83) 13.2 h 1123 In-111 179 (89); 247 (94) 2.8 days In111 I-131 364 (78) 8 days I131 F-18 511 (194) 111 min F18 Any - - ≥100 keV

Literature

1. http://www.amplituda.ru/index.php?module=issue&top, 04/27/2007 - SEC “Amplitude”, the detecting device “Radical”.

2. T.Yu. Skvortsova, Z. L. Brodskaya, M. S. Rudas, G. V. Kataeva, A. F. Gurchin, S. V. Medvedev, Comparative evaluation of radiopharmaceuticals in PET diagnostics of brain tumors, Medical visualization 1/2001 p. 67-74.

3. M.A. Chekalova, G.S. Allahverdyan, L.V. Demidov, N.V. Kokosadze, T.K. Kharatishvili, S.A. Khatyrev, Ultrasound tomography capabilities for assessing the local distribution of primary skin melanoma. Modern Oncology, Volume 8, N 4.

Claims (2)

1. A device for the detection and localization of affected organs and tissues, including a scintillation detection unit with a cable and a built-in collimator, a control and monitoring panel, a power supply, characterized in that a scintillator with photodiode registration of light flashes is used as a detector; the collimator is made of heavy alloys with a thickness of at least 12 g / cm ² and has an input window with a thickness of not more than 0.3 g / cm ² ; the control and control panel has: a controlled discriminator of the lower level of the recorded energies for registration only in the energy region of the photopeak of the selected radionuclide; linear passer for switching between tonal and binary-tonal modes; shaper of sub-ranges of counting speed with automatic range switching for outputting information on a linear LED scale and in the form of a tone sound signal; programmable counter for determining the digital value of the counting speed and setting the operating modes of the device. 2. The device according to claim 1, characterized in that the short part of the scintillation detection unit containing the detector and the built-in collimator is located at an angle to the axis of its long part.