A measuring instrument and measuring method for surface absorbed dose rate measurement of beta applicator

Abstract

The application discloses a measuring instrument and a measuring method for surface absorbed dose rate measurement of a beta applicator, and comprises a special ionization chamber for the applicator, a weak current measuring system, a power module, an upper computer, a positioning frame and a signal transmission line; wherein the output end of the special ionization chamber for the applicator is electrically connected with the input end of the weak current measuring system through the signal transmission line, and the output end of the weak current measuring system is in communication connection with the upper computer; the power module provides polarization voltage for the special ionization chamber for the applicator and working power for the weak current measuring system and the upper computer; and the positioning frame is used for adjusting the relative position between the measured beta applicator and the special ionization chamber for the applicator, so as to realize the measurement of the surface absorbed dose rate of the beta applicator.

Description

Technical Field

[0001] This invention relates to the field of radiation protection, and more specifically to a measuring instrument and method for measuring the absorbed dose rate on the surface of a β-adhesive patch. Background Technology

[0002] The surface absorbed dose rate of the β patch is a key dosimetric parameter for evaluating the output characteristics of the patch and controlling clinical dosage. It needs to be accurately measured in nuclear medicine therapy to ensure treatment efficacy and patient safety. It can also be used for radiation protection assessment and manufacturer's quality control.

[0003] Among existing methods for measuring the absorbed dose rate on the surface of beta patch, a relatively close technique is the extrapolation ionization chamber and its measurement method. This type of extrapolation ionization chamber typically employs a thin-film entrance window, a collecting electrode, and a guard ring structure. The sensitive volume depth (extrapolation distance) is adjusted using mechanisms such as a micrometer. The rate of change of the ionization chamber current with distance is measured at different extrapolation distances, and the current is extrapolated to a position close to zero to achieve calibration and measurement of the absorbed dose rate on the surface of the beta patch.

[0004] However, the above-mentioned extrapolation ionization chamber scheme still has shortcomings in daily rapid measurement scenarios: First, it usually requires manual and repeated adjustment of the electrode spacing and plotting of extrapolation curves to obtain results, which is time-consuming and requires high operator skills; Second, it has high requirements for the stability of the measurement environment, and after adjustment, it is often necessary to wait for the system to stabilize, which further prolongs the measurement cycle; Third, structural factors such as the area of ​​the detection window may lead to insufficient coverage of small-area applicators, requiring the introduction of additional conversion coefficients and compensation steps; Fourth, the device has a high manufacturing cost, which is not conducive to widespread application in medical institutions with limited resources. Summary of the Invention

[0005] To achieve the above and other related objectives, this invention discloses a measuring instrument for measuring the surface absorbed dose rate of a β-application, comprising: a dedicated ionization chamber for the application device, a weak current measurement system, a power module, a host computer, a positioning frame, and a signal transmission line; The output end of the dedicated ionization chamber of the patch applicator is electrically connected to the input end of the weak current measurement system via the signal transmission line, and the output end of the weak current measurement system is communicatively connected to the host computer. The power module provides polarization voltage to the ionization chamber of the patch applicator and provides operating power to the weak current measurement system and the host computer. The positioning frame is used to adjust the relative position between the beta patch being tested and the dedicated ionization chamber of the patch, so as to realize the measurement of the absorbed dose rate on the surface of the beta patch.

[0006] Preferably, the ionization chamber of the applicator is a gas current ionization chamber with a fixed electrode distance, and the wall material of the ionization chamber and the planar electrode material are tissue equivalent materials; the rear wall and side wall of the ionization chamber have shielding functions to eliminate external radiation interference and to include backscattered signals in the measured ionization current; the electrodes are made of high-purity graphite material to reduce memory effect.

[0007] Preferably, the weak current measurement system includes: a high-impedance amplifier, a pole-zero cancellation module, a comparator module, and an emitter follower output module; The high-impedance amplifier is connected to the output terminal of the dedicated ionization chamber of the patch applicator, and is used to perform charge integration on the weak current signal generated by the dedicated ionization chamber of the patch applicator and complete the current-to-voltage conversion. The input terminal of the zero-phase cancellation module is coupled to the output terminal of the high-impedance amplifier, and the voltage pulse long-tail effect is eliminated through the RC compensation network to suppress pulse accumulation and stabilize the baseline. The comparator module receives the shaped voltage signal and outputs a digital logic level based on a programmable threshold voltage. The emitter follower output module adopts a common collector electrode structure, which converts the high-impedance digital signal output by the comparator module into a low-impedance output to enhance the load-carrying capacity and isolate the influence of subsequent circuits.

[0008] Preferably, the measurable ionizing current range of the weak current measurement system is: to .

[0009] Preferably, the host computer includes a dose rate calculation module and a human-computer interaction module, wherein the dose rate calculation module is used for: The system receives signals transmitted by the weak current measurement system through a communication protocol and converts them into radiation dose values. It then corrects the radiation dose values ​​by combining the user-input information on the type, shape, area, temperature, and air pressure of the patch, thereby obtaining the β-pattern surface absorbed dose rate and displaying it in real time. The human-computer interaction module provides a main interface, a settings interface, and a data recording interface, and supports data calibration and measurement result export.

[0010] Preferably, the power module includes a rechargeable lithium battery, a switching power supply, and a linear power supply, wherein the switching power supply is used for initial voltage conversion, the linear power supply is used to output a regulated low-noise DC power supply, and the power module has a bipolar voltage output to switch the polarization voltage of the ionization chamber of the applicator to eliminate polarity effects.

[0011] Secondly, the present invention discloses a method for measuring the absorbed dose rate on the surface of a β-adhesive patch, characterized in that it includes: Calibration steps: Using a β-radiation absorbed dose standard device, the measurement voltage value of the measuring instrument is obtained under a specific β-reference radiation field, and the conversion coefficient between the measurement voltage and the absorbed dose rate is determined and written into the host computer. Measurement steps: Place the β patch to be tested on the positioning frame, install the ionization chamber of the patch on the positioning frame and adjust the relative position so that the β patch and the collecting electrode of the ionization chamber of the patch are lightly in contact and their central axes are aligned. The host computer is started and the shape and size of the β patch to be measured are input. The host computer outputs the surface absorbed dose rate of the β patch.

[0012] Preferably, the calibration step includes: The measured voltage value is read at a frequency greater than three times the time constant of the ionization chamber of the patch applicator, and the uncertainty of 20 consecutive independent voltage readings is calculated. When the uncertainty is less than 15%, the average value of the 20 consecutive readings is output as the voltage measurement value at that point. The polarity of the plates in the ionization chamber of the applicator is then changed and the above process is repeated 6 times. The absolute values ​​of the 6 measurements are then averaged to determine the measurement voltage in the specific β reference radiation field, which is used to determine the conversion coefficient.

[0013] Preferably, when the β-adhesive being tested cannot completely cover the collecting electrode of the dedicated ionization chamber of the β-adhesive, the host computer performs area correction on the measured surface absorbed dose rate of the β-adhesive, and the area correction satisfies the following formula: in, This represents the area-corrected absorbed dose rate at the surface of the β-application. The β-adhesive surface absorbed dose rate is obtained through direct measurement. The effective area where the β-application device overlaps with the collecting electrode. The area of ​​the collecting electrode is denoted as .

[0014] Thirdly, the present invention discloses a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the method described thereon.

[0015] By adopting the above technical solution, the dedicated ionization chamber for the applicator, the low-noise weak current measurement link, the switchable polarity power supply, the host computer processing, and the positioning frame are integrated into a single design. This transforms the acquisition of the absorbed dose rate on the surface of the β applicator from a complex operation relying on extrapolation curves into a repeatable geometric positioning and direct measurement combined with software calculation. This reduces the reliance on human experience in the measurement process and minimizes human error. The circuit structure, including pole-zero cancellation, comparison discrimination, and emitter-follower output, enhances the stable conversion and anti-interference capability of the weak ionization current. Furthermore, the combination of positive and negative polarity switching and result fusion mechanisms weakens the influence of polarity effects, which is beneficial to improving the consistency and reliability of measurement results. At the same time, the host computer supports the correction of applicator shape, effective area, and environmental parameters, as well as data recording and export. It also provides an area compensation strategy for applicators that cannot completely cover the collecting pole, thereby enhancing the adaptability to different specifications of β applicators and the value for field application promotion. Attached Figure Description

[0016] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. The drawings are provided for a better understanding of the invention and are not intended to limit the scope of this disclosure. In the drawings, the same or similar reference numerals denote the same or similar elements, wherein: Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention; Figure 2 This is a structural diagram of a weak current measurement system according to an embodiment of the present invention; Figure 3 This is a structural diagram of the power module according to an embodiment of the present invention.

[0017] Reference numerals in the attached diagram: 1. Dedicated ionization chamber; 2. Weak current measurement system; 3. Host computer; 4. Positioning frame; 5. Applicator bracket; 6. Ionization chamber bracket; 7. β-applicator under test. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Reference Figure 1 This invention provides a measuring instrument for measuring the surface absorbed dose rate of a β-application, comprising: a dedicated ionization chamber 1 for the application device, a weak current measurement system 2, a power module, a host computer 3, a positioning frame 4, and a signal transmission line; The output end of the dedicated ionization chamber 1 for the patch applicator is electrically connected to the input end of the weak current measurement system 2 via the signal transmission line, and the output end of the weak current measurement system 2 is communicatively connected to the host computer 3. The power module provides polarization voltage to the ionization chamber 1 of the patch applicator and provides working power to the weak current measurement system 2 and the host computer 3. The positioning frame 4 is used to adjust the relative position between the beta patch 7 and the dedicated ionization chamber 1 of the patch, so as to realize the measurement of the absorbed dose rate on the surface of the beta patch.

[0020] Preferably, the ionization chamber 1 of the applicator is a gas current ionization chamber with a fixed inter-electrode distance, and the wall material of the ionization chamber and the planar electrode material are tissue equivalent materials; the rear wall and side wall of the ionization chamber have shielding functions to eliminate external radiation interference and to include backscattered signals in the measured ionization current; the electrodes are made of high-purity graphite material to reduce memory effect.

[0021] Reference Figure 2 Preferably, the weak current measurement system 2 includes: a high-impedance amplifier, a pole-zero cancellation module, a comparator module, and an emitter follower output module; The high-impedance amplifier is connected to the output terminal of the dedicated ionization chamber 1 of the patch applicator, and is used to perform charge integration on the weak current signal generated by the dedicated ionization chamber 1 of the patch applicator and complete the current-to-voltage conversion. The input terminal of the zero-phase cancellation module is coupled to the output terminal of the high-impedance amplifier, and the voltage pulse long-tail effect is eliminated through the RC compensation network to suppress pulse accumulation and stabilize the baseline. The comparator module receives the shaped voltage signal and outputs a digital logic level based on a programmable threshold voltage. The emitter follower output module adopts a common collector electrode structure, which converts the high-impedance digital signal output by the comparator module into a low-impedance output to enhance the load-carrying capacity and isolate the influence of subsequent circuits.

[0022] Preferably, the measurable ionizing current range of the weak current measurement system 2 is: to .

[0023] Preferably, the host computer 3 includes a dose rate calculation module and a human-computer interaction module, wherein the dose rate calculation module is used for: The system receives signals transmitted by the weak current measurement system 2 through a communication protocol and converts them into radiation dose values. It then corrects the radiation dose values ​​by combining the user-input information on the type, shape, area, temperature, and air pressure of the patch, thereby obtaining the β-pattern surface absorbed dose rate and displaying it in real time. The human-computer interaction module provides a main interface, a settings interface, and a data recording interface, and supports data calibration and measurement result export.

[0024] Reference Figure 3 Preferably, the power module includes a rechargeable lithium battery, a switching power supply, and a linear power supply, wherein the switching power supply is used for preliminary voltage conversion, and the linear power supply is used to output a regulated low-noise DC power supply; the power module has a bipolar voltage output to switch the polarization voltage of the ionization chamber 1 of the applicator to eliminate polarity effects.

[0025] Preferably, the β-adhesive surface absorbed dose rate measuring instrument of this embodiment consists of an ionization chamber 1 for the adhesive applicator, a weak current measurement system 2, a power module, a host computer 3, a positioning frame 4, and a signal transmission line; wherein, the output end of the ionization chamber 1 for the adhesive applicator is electrically connected to the input end of the weak current measurement system 2 through the signal transmission line, and the output end of the weak current measurement system 2 is communicatively connected to the host computer 3; the power module provides polarization voltage to the ionization chamber 1 for the adhesive applicator and provides working power to the weak current measurement system 2 and the host computer 3 respectively; the positioning frame 4 is used to adjust the relative position between the β-adhesive applicator 7 under test and the ionization chamber 1 for the adhesive applicator.

[0026] The dedicated ionization chamber 1 for the applicator adopts a gas current ionization chamber structure with a fixed inter-electrode distance. The chamber wall material and the planar electrode material are selected from tissue equivalent materials (such as polystyrene or PMMA) to simulate the response of human tissue to beta rays. The rear wall and side walls of the ionization chamber are equipped with shielding structures to eliminate external radiation interference and to include backscattered signals in the measured ionization current, thereby improving measurement accuracy. The electrode material is preferably high-purity graphite to reduce the "memory effect", that is, the time required for the ionization chamber to recover to the normal response level after a large dose of irradiation.

[0027] The weak current measurement system 2 is the core electronic component. It adopts the IV conversion approach to achieve high-precision measurement and signal conditioning of the weak current output from the ionization chamber: the high-impedance amplifier is directly connected to the output of the ionization chamber to perform charge integration on the weak current pulses generated by the ionization chamber and convert them into voltage signals; the input of the pole-zero cancellation module is coupled to the output of the high-impedance amplifier, and the long-tail effect of the voltage pulse is eliminated through the RC compensation network, which suppresses pulse accumulation and stabilizes the baseline, significantly improving the counting pass rate under high counting rate conditions; the comparator module receives the shaped voltage signal and distinguishes it through a programmable threshold voltage, converting the analog pulses that meet the trigger conditions into standard digital logic levels to achieve noise suppression; the emitter follower output module adopts a common-collector structure to convert the high-impedance digital signal output by the comparator module into a low-impedance output, enhancing the load-carrying capacity and isolating the influence of the subsequent circuit on the signal processing of the previous stage, ensuring the integrity of the signal during long-distance transmission. Through the synergistic effect of the above modules, integrated processing of voltage conversion, waveform optimization, event identification, and impedance matching of ionization chamber signals is achieved. This results in high measurement accuracy, strong count rate adaptability, good baseline stability, and excellent output drive capability, making it particularly suitable for precise measurement of weak currents. The measurable output current range of the weak current measurement system 2 covers... to The range is designed to accommodate the dose rate measurement needs of commonly used clinical dressings.

[0028] The power supply module is a crucial component for the stable operation of the instrument, and its design fully considers portability, stability, and low noise requirements. The power supply module uses a rechargeable lithium battery as its primary power source, providing a stable DC power supply to the dedicated ionization chamber 1 and the weak current measurement system 2 through a combination of switching power supplies and linear power supplies. In this embodiment, the first switching power supply module and the first linear power supply module supply power to the dedicated ionization chamber 1, and the voltage of the dedicated ionization chamber 1 is controlled by an external controller. The second switching power supply module and the second linear power supply module supply power to the weak current measurement system 2. The switching power supply, characterized by high efficiency and small size, is used for initial voltage conversion. The linear power supply is used to further stabilize the output voltage, providing a clean and stable power supply to meet the needs of the noise-sensitive ionization chamber measurement system. Furthermore, considering the effects of temperature drift, humidity changes, and mechanical vibration, the power system uses low-temperature drift components and applies a protective coating to the PCB surface to ensure stable operation under various environmental conditions. Through these designs, the power supply module not only provides stable power support for the instrument but also effectively reduces interference to the measurement signal, improving the overall performance and reliability of the instrument. To eliminate the influence of the "polarity effect" on the measurement results, the power supply system is designed with bipolar voltage output, which can switch the positive and negative polarities of the polarization voltage of the ionization chamber as needed.

[0029] The host computer 3 is used for data processing, dose rate calculation, user interaction, and result display: it receives the signal transmitted by the weak current measurement system 2 through the communication protocol and converts it into radiation dose-related quantities; it corrects the measured values ​​by combining the information such as the type, shape, area, temperature, and air pressure of the patch input by the user, so as to obtain the absorbed dose rate of the patch surface and display it in real time; the host computer 3 software can provide a main interface, a settings interface, and a data recording interface, and supports data calibration, historical data query, and export to CSV or Excel files.

[0030] The positioning frame 4 is used to flexibly adjust the relative position between the applicator and the applicator-specific ionization chamber 1. The positioning frame 4 includes a support base, an applicator support 5, and an ionization chamber support 6. The placement or pasting method can be selected according to the type of applicator. During the measurement process, the ionization chamber and the surface of the applicator can be quickly aligned and positioned by adjusting the positioning frame 4 (e.g., axial and radial adjustment mechanism).

[0031] Secondly, the present invention discloses a method for measuring the absorbed dose rate on the surface of a β-adhesive patch, characterized in that it includes: Calibration steps: Using a β-radiation absorbed dose standard device, the measurement voltage value of the measuring instrument is obtained under a specific β-reference radiation field, and the conversion coefficient between the measurement voltage and the absorbed dose rate is determined and written into the host computer 3. Measurement steps: Place the β patch 7 to be tested on the positioning frame 4, install the ionization chamber 1 of the patch on the positioning frame 4 and adjust the relative position so that the β patch and the collecting electrode of the ionization chamber 1 of the patch are lightly touching and their central axes are aligned. Start the host computer 3 and input the shape and size of the β patch to be measured. The host computer 3 outputs the surface absorbed dose rate of the β patch.

[0032] Preferably, the calibration step includes: The measured voltage value is read at a frequency greater than three times the time constant of the dedicated ionization chamber of the patch applicator, and the uncertainty of 20 consecutive independent voltage readings is calculated. When the uncertainty is less than 15%, the average value of the 20 consecutive readings is output as the voltage measurement value at that point. Subsequently, the polarity of the electrode plate in the dedicated ionization chamber 1 of the applicator is changed and the above process is repeated 6 times. The absolute values ​​of the 6 measurements are then averaged to determine the measurement voltage in the specific β reference radiation field, which is used to determine the conversion coefficient.

[0033] The above describes the process of using a β-radiation absorbed dose standard device to obtain the voltage value corresponding to the measuring instrument under a specific β-reference radiation field, and thereby determining the conversion coefficient of "measured voltage - absorbed dose rate" and writing it into the host computer 3. The computer reads the voltage readings generated by the measuring instrument at a frequency greater than three times the time constant of the ionization chamber, and calculates the uncertainty of 20 consecutive independent voltage readings. When the uncertainty is less than 15%, the average value of the 20 readings is taken as the voltage measurement value at that point. Then, the polarity of the ionization chamber plates is changed and the above process is repeated 6 times. The absolute values ​​of the 6 measurements are taken and averaged to obtain the representative measured voltage under the β-reference radiation field, which is then compared with the absorbed dose rate given by the standard device to obtain the conversion coefficient and input into the host computer 3 software.

[0034] For ease of implementation, the conversion coefficients in the host computer 3 can be denoted as... , which represents the increase in absorbed dose rate corresponding to a unit measured voltage.

[0035] Preferably, in the measurement step, the dedicated ionization chamber 1 for the patch, the weak current measurement system 2, the host computer 3, and the power module are connected; the β patch 7 to be tested is placed on the patch bracket 5 of the positioning frame 4, and the dedicated ionization chamber 1 for the patch is installed on the ionization chamber bracket 6 of the positioning frame 4; the positioning frame 4 is adjusted so that the central axis of the patch and the central axis of the ionization chamber collecting electrode are on the same horizontal and vertical plane, and the patch is lightly touched to the ionization chamber collecting electrode; the power is turned on and the software of the host computer 3 is started, the shape and size of the patch to be tested are input, and the host computer 3 automatically displays the surface absorbed dose rate of the patch to be tested.

[0036] Preferably, to reduce the influence of polarity effects, this embodiment acquires the output voltage of the weak current measurement system 2 under both positive and negative polarization voltages during the measurement phase. and (Corresponding to positive and negative polarity measurements respectively).

[0037] The host computer 3 can obtain the synthesized measurement voltage for dose rate calculation in the following manner. : in, This is the output voltage when the polarization voltage is positive. This is the output voltage when the polarization voltage is negative.

[0038] The host computer 3 uses the conversion coefficients obtained from calibration The measured voltage is converted into the directly measured surface absorbed dose rate. At the same time, the measured values ​​are corrected by combining the temperature, air pressure and other information input by the user, so as to improve the consistency of the results under different environmental conditions.

[0039] For example, the following computational framework can be used: in, This is an environmental correction factor used to characterize the effects of temperature and air pressure (including relative humidity if necessary) on air density and ionization response. In its implementation, the host computer 3 can calculate based on preset reference conditions and the currently input environmental parameters. .

[0040] Preferably, when the β-adhesive patch 7 being tested cannot completely cover the collecting electrode of the dedicated ionization chamber 1 of the patch, the host computer 3 performs area correction on the measured surface absorbed dose rate of the β-adhesive patch, and the area correction satisfies the following formula: in, This represents the area-corrected absorbed dose rate at the surface of the β-application. The β-adhesive surface absorbed dose rate is obtained through direct measurement. The effective area where the β-application device overlaps with the collecting electrode. The area of ​​the collecting electrode is denoted as .

[0041] During the measurement process, the host computer 3 displays the collected data and the calculated dose rate results in real time. Once the data stabilizes, the measurement results can be saved to the local database and exported as CSV or Excel files for subsequent analysis and storage. After the measurement is completed, the data collection can be stopped and the patch removed to proceed to the next measurement cycle.

[0042] Thirdly, the present invention discloses a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the method described thereon.

[0043] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the meaning consistent with their meaning in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined.

[0044] For the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should understand that the embodiments of the present invention are not limited to the described order of actions, because according to the embodiments of the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions involved are not necessarily essential to the embodiments of the present invention.

[0045] As can be seen from the above description of the embodiments, those skilled in the art can clearly understand that this application can be implemented by means of software plus necessary general-purpose hardware platforms. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in various embodiments or some parts of the embodiments of this application.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A measuring instrument for measuring the surface absorbed dose rate of a β-adhesive patch, characterized in that, include: The patch applicator includes a dedicated ionization chamber, a weak current measurement system, a power module, a host computer, a positioning frame, and signal transmission lines. The output end of the dedicated ionization chamber of the patch applicator is electrically connected to the input end of the weak current measurement system via the signal transmission line, and the output end of the weak current measurement system is communicatively connected to the host computer. The power module provides polarization voltage to the ionization chamber of the patch applicator and provides operating power to the weak current measurement system and the host computer. The positioning frame is used to adjust the relative position between the beta patch being tested and the dedicated ionization chamber of the patch, so as to realize the measurement of the absorbed dose rate on the surface of the beta patch.

2. The measuring instrument for measuring the surface absorbed dose rate of a β-application according to claim 1, characterized in that, The dedicated ionization chamber of the applicator is a gas current ionization chamber with a fixed electrode distance. The chamber wall material and the planar electrode material are tissue-equivalent materials. The rear and side walls of the ionization chamber have shielding functions to eliminate external radiation interference and to include backscattered signals in the measured ionization current. The electrodes are made of high-purity graphite material to reduce memory effect.

3. The measuring instrument for measuring the surface absorbed dose rate of a β-adhesive patch according to claim 1, characterized in that, The weak current measurement system includes: a high-impedance amplifier, a pole-zero phase cancellation module, a comparator module, and an emitter follower output module; The high-impedance amplifier is connected to the output terminal of the dedicated ionization chamber of the patch applicator, and is used to perform charge integration on the weak current signal generated by the dedicated ionization chamber of the patch applicator and complete the current-to-voltage conversion. The input terminal of the zero-phase cancellation module is coupled to the output terminal of the high-impedance amplifier, and the voltage pulse long-tail effect is eliminated through the RC compensation network to suppress pulse accumulation and stabilize the baseline. The comparator module receives the shaped voltage signal and outputs a digital logic level based on a programmable threshold voltage. The emitter follower output module adopts a common collector electrode structure, which converts the high-impedance digital signal output by the comparator module into a low-impedance output to enhance the load-carrying capacity and isolate the influence of subsequent circuits.

4. The measuring instrument for measuring the surface absorbed dose rate of a β-adhesive patch according to claim 1, characterized in that, The measurable ionization current range of the weak current measurement system is: to .

5. The measuring instrument for measuring the surface absorbed dose rate of a β-adhesive patch according to claim 1, characterized in that, The host computer includes a dose rate calculation module and a human-computer interaction module. The dose rate calculation module is used for: The system receives signals transmitted by the weak current measurement system through a communication protocol and converts them into radiation dose values. It then corrects the radiation dose values ​​by combining the user-input information on the type, shape, area, temperature, and air pressure of the patch, thereby obtaining the β-pattern surface absorbed dose rate and displaying it in real time. The human-computer interaction module provides a main interface, a settings interface, and a data recording interface, and supports data calibration and measurement result export.

6. The measuring instrument for measuring the surface absorbed dose rate of a β-adhesive patch according to claim 1, characterized in that, The power module includes a rechargeable lithium battery, a switching power supply, and a linear power supply. The switching power supply is used for initial voltage conversion, and the linear power supply is used to output a regulated, low-noise DC power supply. The power module has a bipolar voltage output to switch the polarization voltage of the ionization chamber of the applicator to eliminate polarity effects.

7. A method for measuring the surface absorbed dose rate of a β-adhesive patch using the measuring instrument according to any one of claims 1-6, characterized in that, include: Calibration steps: Using a β-radiation absorbed dose standard device, the measurement voltage value of the measuring instrument is obtained under a specific β-reference radiation field, and the conversion coefficient between the measurement voltage and the absorbed dose rate is determined and written into the host computer. Measurement steps: Place the β patch to be tested on the positioning frame, install the ionization chamber of the patch on the positioning frame and adjust the relative position so that the β patch and the collecting electrode of the ionization chamber of the patch are lightly in contact and their central axes are aligned. The host computer is started and the shape and size of the β patch to be measured are input. The host computer outputs the surface absorbed dose rate of the β patch.

8. The method according to claim 7, characterized in that, The calibration steps include: The measured voltage value is read at a frequency greater than three times the time constant of the ionization chamber of the patch applicator, and the uncertainty of 20 consecutive independent voltage readings is calculated. When the uncertainty is less than 15%, the average value of the 20 consecutive readings is output as the voltage measurement value at that point. The polarity of the plates in the ionization chamber of the applicator is then changed and the above process is repeated 6 times. The absolute values ​​of the 6 measurements are then averaged to determine the measurement voltage in the specific β reference radiation field, which is used to determine the conversion coefficient.

9. The method according to claim 7, characterized in that, When the beta patch being tested cannot completely cover the collecting electrode of the dedicated ionization chamber of the patch, the host computer performs area correction on the measured surface absorbed dose rate of the beta patch. The area correction satisfies the following formula: in, This represents the area-corrected absorbed dose rate at the surface of the β-application. The β-adhesive surface absorbed dose rate is obtained through direct measurement. The effective area where the β-application device overlaps with the collecting electrode. The area of ​​the collecting electrode is denoted as .

10. A computer-readable storage medium having a computer program stored thereon, the computer program, when executed by a processor, implementing the method of any one of claims 7-9.

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