Ion beam radiotherapy dose measurement system

Abstract

The ion beam radiotherapy dose measurement system comprises an ion beam emitter, an acoustic sensor, a front-end receiving circuit and a back-end processing circuit. The ion beam emitter emits an ion beam towards a living body, so that the ion beam generates a dose peak point and generates a sound signal after reaching the living body. The acoustic sensor captures the sound signal and converts the sound signal into an electrical signal. The front-end receiving circuit is electrically connected with the acoustic sensor and is used for receiving the electrical signal output by the acoustic sensor to determine the time when the acoustic sensor receives the sound signal. The back-end processing circuit is electrically connected with the front-end receiving circuit and is used for calculating the position of the dose peak point and the dose distribution according to the time when the acoustic sensor receives the sound signal, in combination with the time of ion beam emission and the position of the acoustic sensor in the living body. The ion beam radiotherapy dose measurement system of the present patent application has the advantages of small volume, low cost, high precision and real-time measurement of dose distribution.

Description

[Technical Field]

[0001] This patent application relates generally to medical electronics, and more specifically to an ion beam radiotherapy dose measurement system. [Background Technology]

[0002] Compared to photon (such as X-ray) radiotherapy, ion beam (such as proton and heavy ion beams) radiotherapy offers advantages such as superior dose distribution, outstanding biological effects, and relatively short treatment time. Existing ion beam radiotherapy equipment generally uses nuclear medicine techniques, such as positron emission tomography (PET), to measure the dose range of protons or heavy ions. Such equipment is often large, expensive, and only achieves accuracy at the millimeter level, and it cannot measure dose distribution in real time during radiotherapy. [Summary of the Invention]

[0003] This patent application provides an ion beam radiotherapy dose measurement system that is small in size, low in cost, high in accuracy, and capable of real-time measurement of dose distribution.

[0004] In one embodiment, an ion beam radiotherapy dose measurement system includes: an ion beam emitter, an acoustic sensor, a front-end receiving circuit, and a back-end processing circuit. The ion beam emitter emits an ion beam toward a living organism, causing a dose peak upon arrival and generating an acoustic signal from that peak. The acoustic sensor captures the acoustic signal and converts it into a first electrical signal and a second electrical signal. The front-end receiving circuit receives the first and second electrical signals to determine the time at which the acoustic sensor receives the acoustic signal. The front-end receiving circuit includes a low-noise amplifier, a low-pass filter, and a comparator. The low-noise amplifier amplifies the first and second electrical signals and generates a third and fourth electrical signal. The low-noise amplifier includes a first resistor and two identical amplification units. Each amplification unit includes a first electronic switch, a second electronic switch, a third electronic switch, a fourth electronic switch, a fifth electronic switch, a second resistor, a first capacitor, and a second capacitor. The control electrode of the first electronic switch receives the first electrical signal or the second electrical signal. Its input electrode is electrically connected to the control electrode of the second electronic switch, and its output electrode is electrically connected to the output electrode of the second electronic switch through the second resistor. The first capacitor is connected in parallel with the second resistor. The third electrical signal or the fourth electrical signal is output between the ends of the first capacitor and the second resistor that are electrically connected to the output electrode of the second electronic switch. The two ends of the second capacitor are electrically connected to the input electrode and the output electrode of the first electronic switch, respectively. The input electrode of the second electronic switch is electrically connected to a reference voltage. The control electrode of the third electronic switch is electrically connected to a first bias voltage, its input electrode is electrically connected to a reference voltage, and its output electrode is electrically connected to the input electrode of the first electronic switch. The control electrode of the fourth electronic switch is electrically connected to a second bias voltage, its input electrode is electrically connected to the output electrode of the second electronic switch, and its output electrode is grounded. The control electrode of the fifth electronic switch is electrically connected to a third bias voltage, its input electrode is electrically connected to the output electrode of the first electronic switch, and its output electrode is grounded. The two ends of the first resistor are electrically connected to the input electrode of the fifth electronic switch in the two amplification units. The low-pass filter, electrically connected to the low-noise amplifier via an isolation capacitor, filters out out-of-band noise from the third and fourth electrical signals, improving the signal-to-noise ratio. The comparator, electrically connected to the low-pass filter, compares the output signal with a high threshold and a low threshold, determining whether the acoustic sensor has received a sound signal based on the comparison result, thus identifying the time when the acoustic sensor received the sound signal. The back-end processing circuit, electrically connected to the front-end receiving circuit, calculates the location of the dose peak and the dose distribution based on the time the acoustic sensor received the sound signal, combined with the ion beam emission time of the ion beam emitter and the location of the acoustic sensor within the biological body.

[0005] Preferably, the first, fourth, and fifth electronic switches are all N-type metal-oxide-semiconductor field-effect transistors (MOSFETs), and their control electrode is the gate, their input electrode is the drain, and their output electrode is the source. The second and third electronic switches are both P-type metal-oxide-semiconductor field-effect transistors (MOSFETs), and their control electrode is the gate, their input electrode is the source, and their output electrode is the drain.

[0006] In another embodiment, an ion beam radiotherapy dose measurement system includes: an ion beam emitter, an acoustic sensor, a front-end receiving circuit, and a back-end processing circuit. The ion beam emitter emits an ion beam toward a living organism, causing a dose peak upon arrival and generating an acoustic signal from that peak. The acoustic sensor captures the acoustic signal and converts it into an electrical signal. The front-end receiving circuit is electrically connected to the acoustic sensor and receives the electrical signal output by the acoustic sensor to determine the time when the acoustic sensor receives the acoustic signal. The back-end processing circuit is electrically connected to the front-end receiving circuit and calculates the location of the dose peak and the dose distribution based on the time when the acoustic sensor receives the acoustic signal, combined with the time of ion beam emission by the ion beam emitter and the location of the acoustic sensor within the living organism.

[0007] Preferably, the ion beam radiotherapy dose measurement system further includes a visualization module for displaying the location of the dose peak point and the dose distribution in real time.

[0008] Preferably, the front-end receiving circuit includes a low-noise amplifier, a low-pass filter, and a comparator. The low-noise amplifier is electrically connected to the acoustic sensor and amplifies the electrical signal output by the acoustic sensor. The low-pass filter is electrically connected to the low-noise amplifier and filters out out-of-band noise from the amplified electrical signal output by the acoustic sensor, improving the signal-to-noise ratio. The comparator is electrically connected to the low-pass filter and compares the electrical signal output by the low-pass filter with a high threshold and a low threshold. Based on the comparison result, it determines whether the acoustic sensor has received a sound signal and determines the time when the acoustic sensor received the sound signal. The gain of the front-end receiving circuit is evenly distributed across the low-noise amplifier, the low-pass filter, and the comparator.

[0009] Preferably, the low-noise amplifier includes a first signal input terminal, a second signal input terminal, a first signal output terminal, and a second signal output terminal. The first signal input terminal is used to receive a first electrical signal output by the acoustic sensor, the second signal input terminal is used to receive a second electrical signal output by the acoustic sensor, the first signal output terminal is used to output a third electrical signal, and the second signal output terminal is used to output a fourth electrical signal.

[0010] Preferably, the two input terminals of the low-pass filter are electrically connected to the first signal output terminal and the second signal output terminal respectively through a corresponding DC blocking capacitor to perform AC coupling and remove the DC offset in the third and fourth electrical signals.

[0011] Preferably, the low-noise amplifier includes a first resistor and two identical amplification units. The first resistor is electrically connected to the two amplification units. The two amplification units respectively receive the first electrical signal and the second electrical signal, and respectively generate the third electrical signal and the fourth electrical signal.

[0012] Preferably, each amplification unit includes a first electronic switch, a second electronic switch, a third electronic switch, a fourth electronic switch, a fifth electronic switch, a second resistor, a first capacitor, and a second capacitor. The first and second electronic switches form a feedback loop. The third, fourth, and fifth electronic switches form a current source with a first bias voltage. The first capacitor limits the output bandwidth of the low-noise amplifier and reduces its output noise. The second capacitor compensates for the out-of-band zero caused by the first capacitor, improving the accuracy of the dose peak point location calculation.

[0013] Preferably, the control electrode of the first electronic switch receives the first electrical signal or the second electrical signal, its input electrode is electrically connected to the control electrode of the second electronic switch, and its output electrode is electrically connected to the output electrode of the second electronic switch through the second resistor. The first capacitor is connected in parallel with the second resistor. The third electrical signal or the fourth electrical signal is output between the ends of the first capacitor and the second resistor that are respectively electrically connected to the output electrode of the second electronic switch. The two ends of the second capacitor are respectively electrically connected to the input electrode and the output electrode of the first electronic switch. The input electrode of the second electronic switch is electrically connected to a reference voltage. The control electrode of the third electronic switch is electrically connected to the first bias voltage, its input electrode is electrically connected to the reference voltage, and its output electrode is electrically connected to the input electrode of the first electronic switch. The control electrode of the fourth electronic switch is electrically connected to a second bias voltage, its input electrode is electrically connected to the output electrode of the second electronic switch, and its output electrode is grounded. The control electrode of the fifth electronic switch is electrically connected to a third bias voltage, its input electrode is electrically connected to the output electrode of the first electronic switch, and its output electrode is grounded. The two ends of the first resistor are respectively electrically connected to the input electrode of the fifth electronic switch in the two amplification units.

[0014] Compared with existing technologies, the ion beam radiotherapy dose measurement system of this patent application is small in size, low in cost, high in accuracy, and can realize real-time measurement of dose distribution. [Attached Image Description]

[0015] Figure 1 This is a schematic diagram of an ion beam radiotherapy dose measurement system according to an embodiment of this patent application;

[0016] Figure 2 yes Figure 1 The diagram shows the structural block diagram of the front-end receiving circuit of the ion beam radiotherapy dose measurement system.

[0017] Figure 3 yes Figure 2 The circuit diagram shown is of the low-noise amplifier in the front-end receiving circuit.

Detailed Implementation Methods

[0018] The ion beam radiotherapy dose measurement system of this patent application will now be described in detail with reference to the accompanying drawings and embodiments.

[0019] Figure 1 This is a schematic diagram of an ion beam radiotherapy dose measurement system according to an embodiment of this patent application. See also: Figure 1 The ion beam radiotherapy dose measurement system 100 includes: an ion beam emitter 101, an acoustic sensor 103, a front-end receiving circuit 105, a back-end processing circuit 107, and a visualization module 109.

[0020] The ion beam emitter 101 is used to emit an ion beam (such as a proton beam or a heavy ion beam) toward a living organism. Upon reaching the organism, the ion beam generates a dose peak point P within the organism (such as a human body) and produces a sound signal originating from that dose peak point P. Specifically, the accumulation of heat around the dose peak point P causes a change in the volume of the organism's internal tissues, generating pressure, which is then converted into a sound signal.

[0021] The acoustic sensor 103 is used to capture the sound signal generated at the peak dose point P and convert the sound signal into an electrical signal. Multiple acoustic sensors 103 can be used, each located at a different part of the organism. In this embodiment, the electrical signal is a voltage signal.

[0022] The front-end receiving circuit 105 is electrically connected to the acoustic sensor 103 and is used to receive the electrical signal output by the acoustic sensor 103 to determine the time when the acoustic sensor 101 receives the sound signal. In this embodiment, the front-end receiving circuit 105 is an analog circuit.

[0023] The back-end processing circuit 107 is electrically connected to the front-end receiving circuit 105. It is used to calculate the position of the dose peak point P based on the time when the acoustic sensor 101 receives the sound signal, combined with the time when the ion beam emitter emits the ion beam and the position of the acoustic sensor in the biological body, and to deduce the dose distribution of the ion beam radiotherapy.

[0024] The visualization module 109 is electrically connected to the back-end processing circuit 107 and is used to display the position and dose distribution of the dose peak point P in real time for medical personnel to refer to.

[0025] like Figure 2 As shown, the front-end receiving circuit 105 includes a low-noise amplifier 201, a low-pass filter 203, and a comparator 205. The gain of the front-end receiving circuit 105 is evenly distributed across the low-noise amplifier 201, the low-pass filter 203, and the comparator 205. For example, the low-pass filter 203 is allocated a portion of the gain (e.g., 20dB). This distribution avoids the use of an open-circuit architecture low-noise amplifier, thereby avoiding external bias circuitry, while improving the controllability of the frequency response and reducing the time-domain sensitivity of the front-end receiving circuit 105, which is beneficial for improving measurement accuracy.

[0026] Specifically, the low-noise amplifier 201 is electrically connected to the acoustic sensor 103 and is used to amplify the electrical signal output by the acoustic sensor 103. The low-noise amplifier 201 includes a first signal input terminal 201a, a second signal input terminal 201b, a first signal output terminal 201c, and a second signal output terminal 201d. The first signal input terminal 201a and the second signal input terminal 201b are both electrically connected to the acoustic sensor 103 and are used to receive a first electrical signal V1 and a second electrical signal V2, respectively. The first signal output terminal 201c is used to output a third electrical signal V3. The second signal output terminal 201d is used to output a fourth electrical signal V4.

[0027] The low-pass filter 203 is used to filter out out-of-band noise from the amplified electrical signals (i.e., the third and fourth electrical signals) output by the acoustic sensor 103, thereby improving the signal-to-noise ratio (SNR) of the ion beam radiotherapy dose measurement system. In this embodiment, the two input terminals of the low-pass filter 203 are electrically connected to the first signal output terminal 201c and the second signal output terminal 201d respectively through a corresponding DC blocking capacitor 207 to perform AC coupling, removing the DC offset in the third electrical signal V3 and the fourth electrical signal V4, thereby avoiding the use of any external calibration circuit, simplifying the circuit, and reducing power consumption.

[0028] The comparator 205 is electrically connected to the two output terminals of the low-pass filter 203. It is used to compare the electrical signal output by the low-pass filter 203 with a high threshold (e.g., +5mV) and a low threshold (e.g., -5mV), and determine whether the acoustic sensor 101 has received a sound signal based on the comparison result, so as to determine the time when the acoustic sensor 101 receives the sound signal.

[0029] like Figure 3As shown, the low-noise amplifier 201 includes two symmetrically structured amplification units 300 and a first resistor 311. The first resistor 311 is electrically connected to the two amplification units 300. The two amplification units 300 are used to generate the third electrical signal and the fourth electrical signal, respectively. Of course, in other embodiments, the structure of the amplification unit 300 may also be the same.

[0030] Specifically, each amplification unit 300 includes a first electronic switch 301, a second electronic switch 302, a third electronic switch 303, a fourth electronic switch 304, a fifth electronic switch 305, a second resistor 306, a first capacitor 307, and a second capacitor 309.

[0031] The first electronic switch 301 and the second electronic switch 302 are used to form a feedback loop. The third electronic switch 303, the fourth electronic switch 304, and the fifth electronic switch 305 are used to form a current source with a first bias voltage VA. The first capacitor 307 is used to limit the output bandwidth of the low-noise amplifier 201 and reduce its output noise. However, the first capacitor 307 generates an out-of-band zero, limiting the out-of-band frequency response and causing a phase shift, which leads to a deviation in the calculated position of the dose peak point P; the second capacitor 309 is used to compensate for the out-of-band zero caused by the first capacitor 307, thereby correcting the deviation in the calculated position of the dose peak point P and improving the accuracy of the calculated position of the dose peak point P.

[0032] Specifically, the control electrode of the first electronic switch 301 receives either the first electrical signal V1 or the second electrical signal V2 (i.e., one amplification unit 300 receives the first electrical signal V1, and the other amplification unit 300 receives the second electrical signal V2). Its input electrode is electrically connected to the control electrode of the second electronic switch 302, and its output electrode is electrically connected to the output electrode of the second electronic switch 302 through the second resistor 306. The first capacitor 307 is connected in parallel with the second resistor 306. The third electrical signal V3 or the fourth electrical signal V4 is output between the ends of the first capacitor 307 and the second resistor 306 that are electrically connected to the output electrode of the second electronic switch 302 (i.e., one amplification unit 300 outputs the third electrical signal V3, and the other amplification unit 300 outputs the fourth electrical signal V4). The two ends of the second capacitor 309 are electrically connected to the input and output electrodes of the first electronic switch 301, respectively. The input electrode of the second electronic switch 302 is electrically connected to a reference voltage VDD.

[0033] The control electrode of the third electronic switch 303 is electrically connected to the first bias voltage VA, the input electrode is electrically connected to the reference voltage VDD, and the output electrode is electrically connected to the input electrode of the first electronic switch 301.

[0034] The control electrode of the fourth electronic switch 304 is electrically connected to a second bias voltage VB, the input electrode is electrically connected to the output electrode of the second electronic switch 302, and the output electrode is grounded.

[0035] The control electrode of the fifth electronic switch 305 is electrically connected to a third bias voltage VC, the input electrode is electrically connected to the output electrode of the first electronic switch 301, and the output electrode is grounded.

[0036] The two ends of the first resistor 311 are electrically connected to the input terminals of the fifth electronic switch 305 in the two amplification units 300, respectively.

[0037] In this embodiment, the first electronic switch 301, the fourth electronic switch 304, and the fifth electronic switch 305 are all N-type metal-oxide-semiconductor field-effect transistors (MOS-FETs), and their control electrode is the gate (G), their input electrode is the drain (D), and their output electrode is the source (S); the second electronic switch 302 and the third electronic switch 303 are both P-type metal-oxide-semiconductor field-effect transistors, and their control electrode is the gate (G), their input electrode is the source (S), and their output electrode is the drain (D).

[0038] The first electronic switch 301 and the second electronic switch 302 have a relatively large area and are located in the weak inversion region, where Vgs-Vth = 50mV~80mV (where Vgs is the voltage difference between the gate and source terminals, and Vth is the threshold voltage). This reduces flicker noise power and improves the efficiency of the first electronic switch 301 and the second electronic switch 302. Flicker noise is caused by slow, random fluctuations in the emitted electrons due to localized frequency variations in the electronic device; these variations typically occur at lower frequencies (upper frequency limit approximately 500 Hz).

[0039] The first resistor, 311, has a very low resistance value, Rx, approximately 100 ohms, which helps reduce thermal noise. Thermal noise refers to the noise caused by the Brownian motion of electrons in passive components (such as resistors) in communication equipment; it is also known as resistor noise.

[0040] The low-noise amplifier 201 features high input impedance and low power consumption. Multiple simulations have demonstrated that the peak position error is within 1% to 1.5%, and for an ion beam energy of 200 MeV, the maximum error in the position of the dose peak point P is less than 1 mm.

[0041] Compared with existing technologies, the ion beam radiotherapy dose measurement system of this patent application can utilize acoustic measurement to determine the location of the dose peak point, thereby achieving real-time measurement of the dose distribution. Furthermore, because the ion beam radiotherapy dose measurement system uses fewer electronic components, it is small in size and low in cost. Moreover, by allocating a portion of the gain of the front-end receiving circuit to the low-pass filter, the gain requirement for the low-noise amplifier is reduced, thus lowering noise requirements. Simultaneously, the use of an open-circuit amplifier is avoided, eliminating the need for external bias circuitry, improving the controllability of the frequency response, and reducing the time-domain sensitivity of the front-end receiving circuit 105, which is beneficial for improving measurement accuracy, resulting in high measurement precision for the ion beam radiotherapy dose measurement system.

[0042] The above description is merely a preferred embodiment of this patent application and is not intended to limit this patent application in any way. Although this patent application discloses preferred embodiments as described above, it is not intended to limit this patent application. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of this patent application. Any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technology of this patent application without departing from the scope of the technical solution of this patent application shall fall within the scope of the technical solution of this patent application.

Claims

1. An ion beam radiotherapy dose measurement system, characterized in that, It includes: The system comprises an ion beam emitter, an acoustic sensor, a front-end receiving circuit, and a back-end processing circuit. The ion beam emitter emits an ion beam toward a living organism, causing the ion beam to reach the organism and generate a dose peak point, and generating an acoustic signal from the dose peak point. The acoustic sensor captures the acoustic signal and converts it into a first electrical signal and a second electrical signal. The front-end receiving circuit receives the first electrical signal and the second electrical signal to determine the time when the acoustic sensor receives the acoustic signal. The front-end receiving circuit includes a low-noise amplifier, a low-pass filter, and a comparator. The low-noise amplifier amplifies the first and second electrical signals and generates a third and fourth electrical signal. The low-noise amplifier includes a first resistor and two identical or symmetrical amplification units. Each amplification unit includes a first electronic switch, a second electronic switch, a third electronic switch, a fourth electronic switch, a fifth electronic switch, a second resistor, a first capacitor, and a second capacitor. The control electrode of the first electronic switch receives the first or second electrical signal, its input electrode is electrically connected to the control electrode of the second electronic switch, and its output electrode is electrically connected to the output electrode of the second electronic switch through the second resistor. The first capacitor is connected in parallel with the second resistor. The third or fourth electrical signal is output between the first capacitor and the second resistor, which are respectively electrically connected to the output electrode of the second electronic switch. The two ends of the second capacitor are electrically connected to the input and output electrodes of the first electronic switch, respectively. The input electrode of the second electronic switch is connected to a reference... The control electrode of the third electronic switch is electrically connected to a first bias voltage, its input electrode is electrically connected to a reference voltage, and its output electrode is electrically connected to the input electrode of the first electronic switch. The control electrode of the fourth electronic switch is electrically connected to a second bias voltage, its input electrode is electrically connected to the output electrode of the second electronic switch, and its output electrode is grounded. The control electrode of the fifth electronic switch is electrically connected to a third bias voltage, its input electrode is electrically connected to the output electrode of the first electronic switch, and its output electrode is grounded. The two ends of the first resistor are respectively electrically connected to the input electrode of the fifth electronic switch in the two amplification units. The low-pass filter is electrically connected to the low-noise amplifier through an isolation capacitor and is used to filter out out-of-band noise of the third and fourth electrical signals to improve the signal-to-noise ratio. The comparator is electrically connected to the low-pass filter and is used to compare the electrical signal output by the low-pass filter with the high threshold and the low threshold, and to determine whether the acoustic sensor has received a sound signal based on the comparison result, so as to determine the time when the acoustic sensor receives the sound signal. The back-end processing circuit is electrically connected to the front-end receiving circuit and is used to calculate the location of the dose peak point and the dose distribution based on the time when the acoustic sensor receives the sound signal, the time when the ion beam emitter emits the ion beam, and the location of the acoustic sensor in the biological body.

2. The ion beam radiotherapy dose measurement system according to claim 1, wherein, The first electronic switch, the fourth electronic switch, and the fifth electronic switch are all N-type metal-oxide-semiconductor field-effect transistors, and their control electrode is the gate, their input electrode is the drain, and their output electrode is the source. Both the second and third electronic switches are P-type metal-oxide-semiconductor field-effect transistors, and their control electrodes are gate electrodes, input electrodes are source electrodes, and output electrodes are drain electrodes.

3. An ion beam radiotherapy dose measurement system, characterized in that, It includes: An ion beam emitter, an acoustic sensor, a front-end receiving circuit, and a back-end processing circuit are included. The ion beam emitter is used to emit an ion beam toward a living organism, such that the ion beam generates a dose peak point after reaching the organism, and generates an acoustic signal from the dose peak point. The acoustic sensor is used to capture the acoustic signal and convert the acoustic signal into an electrical signal. The front-end receiving circuit is electrically connected to the acoustic sensor and is used to receive the electrical signal output by the acoustic sensor in order to determine the time when the acoustic sensor receives the sound signal. The back-end processing circuit is electrically connected to the front-end receiving circuit. It is used to calculate the location of the dose peak and the dose distribution based on the time the acoustic sensor receives the sound signal, the time the ion beam emitter emits the ion beam, and the location of the acoustic sensor within the organism. The front-end receiving circuit includes a low-noise amplifier, a low-pass filter, and a comparator. The low-noise amplifier is electrically connected to the acoustic sensor and amplifies the electrical signal output by the acoustic sensor. The low-pass filter is electrically connected to the low-noise amplifier and filters out out-of-band noise from the amplified electrical signal output by the acoustic sensor, improving the signal-to-noise ratio. The comparator is electrically connected to the low-pass filter and compares the electrical signal output by the low-pass filter with a high threshold and a low threshold. Based on the comparison result, it determines whether the acoustic sensor has received a sound signal and determines the time when the acoustic sensor received the sound signal. The gain of the front-end receiving circuit is evenly distributed across the low-noise amplifier, low-pass filter, and comparator.

4. The ion beam radiotherapy dose measurement system according to claim 3, wherein, The low-noise amplifier includes a first signal input terminal, a second signal input terminal, a first signal output terminal, and a second signal output terminal; the first signal input terminal is used to receive a first electrical signal output by the acoustic sensor, the second signal input terminal is used to receive a second electrical signal output by the acoustic sensor, the first signal output terminal is used to output a third electrical signal, and the second signal output terminal is used to output a fourth electrical signal.

5. The ion beam radiotherapy dose measurement system according to claim 4, wherein, The two input terminals of the low-pass filter are electrically connected to the first signal output terminal and the second signal output terminal respectively through a corresponding DC blocking capacitor to perform AC coupling and remove the DC offset in the third and fourth electrical signals.

6. The ion beam radiotherapy dose measurement system according to claim 4, wherein, The low-noise amplifier includes a first resistor and two amplification units with identical or symmetrical structures; the first resistor is electrically connected to the two amplification units; the two amplification units respectively receive the first electrical signal and the second electrical signal, and respectively generate the third electrical signal and the fourth electrical signal.

7. The ion beam radiotherapy dose measurement system according to claim 6, wherein, Each amplification unit includes a first electronic switch, a second electronic switch, a third electronic switch, a fourth electronic switch, a fifth electronic switch, a second resistor, a first capacitor, and a second capacitor; the first electronic switch and the second electronic switch are used to form a feedback loop; the third electronic switch, the fourth electronic switch, and the fifth electronic switch are used to form a current source with a first bias voltage; the first capacitor is used to limit the output bandwidth of the low-noise amplifier and reduce its output noise; the second capacitor is used to compensate for the out-of-band zero caused by the first capacitor and improve the accuracy of the dose peak point location calculation.

8. The ion beam radiotherapy dose measurement system according to claim 7, wherein, The control electrode of the first electronic switch receives the first electrical signal or the second electrical signal; its input electrode is electrically connected to the control electrode of the second electronic switch; and its output electrode is electrically connected to the output electrode of the second electronic switch through the second resistor. The first capacitor is connected in parallel with the second resistor. The third electrical signal or the fourth electrical signal is output between the ends of the first capacitor and the second resistor that are electrically connected to the output electrode of the second electronic switch. The two ends of the second capacitor are electrically connected to the input electrode and the output electrode of the first electronic switch, respectively. The input electrode of the second electronic switch is electrically connected to a reference voltage. The control electrode of the third electronic switch is electrically connected to the first bias voltage; its input electrode is electrically connected to the reference voltage; and its output electrode is electrically connected to the input electrode of the first electronic switch. The control electrode of the fourth electronic switch is electrically connected to a second bias voltage; its input electrode is electrically connected to the output electrode of the second electronic switch; and its output electrode is grounded. The control electrode of the fifth electronic switch is electrically connected to a third bias voltage; its input electrode is electrically connected to the output electrode of the first electronic switch; and its output electrode is grounded. The two ends of the first resistor are electrically connected to the input electrode of the fifth electronic switch in the two amplification units.

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