RU2841321C2 - Neutron dose detector and neutron capture therapy device - Google Patents

Abstract

FIELD: medical science.

SUBSTANCE: group of inventions relates to neutron capture therapy. Neutron dose detector comprises a neutron detector, a signal processing unit, a counter configured to count a signal output from the signal processing unit to obtain a count rate, and a count rate correction unit configured to correct the count rate, wherein count rate correction unit comprises pulse resolution time calculation part, first count rate is recorded by counter, when neutron beam flow is a flow of first neutron beam, second counting rate is recorded by the counter, when the neutron beam stream is a stream of the second neutron beam, pulse resolution time calculation part is configured to calculate the pulse resolution time based on the first count rate, the first neutron beam flux, the second count rate and the second neutron beam flux, wherein the first neutron beam flux is less than the second neutron beam flux.

EFFECT: high accuracy of determining neutron radiation dose of an investigated object.

10 cl, 7 dwg

Description

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

[0001] The invention relates to the field of irradiation with radioactive rays, and in particular to a device for detecting a neutron dose and a device for neutron capture therapy.

LEVEL OF TECHNOLOGY

[0002] With the development of nuclear technology, radiation therapy such as Cobalt-60, linear accelerator, electron beam or the like has become one of the main means for treating cancer. However, traditional photon or electron therapy is limited by the physical conditions of the radioactive rays themselves, and thus will also harm a large number of normal tissues along the path of the beam when killing tumor cells. In addition, due to the different sensitivity of tumor cells to radioactive rays, traditional radiation therapy often has a weak curative effect on radioresistant malignant tumors (such as glioblastoma multiforme and melanoma) with radioresistance.

[0003] In order to reduce radiation damage to normal tissues around tumors, the concept of targeted therapy in chemotherapy is applied to radiation therapy. As for tumor cells with high radioresistance, radiation sources with high relative biological effectiveness (RBE), such as proton therapy, heavy particle therapy, neutron capture therapy, etc., are also being actively developed at present. Here, neutron capture therapy combines the two above-mentioned concepts, such as boron neutron capture therapy. Due to the specific aggregation of boron-containing drugs in tumor cells and the interaction with the precise control of the neutron beam, it is possible to select cancer treatment better than traditional radioactive rays.

[0004] During boron capture therapy, the radiation dose applied to the patient must be accurately controlled by the stronger radioactive beams of the neutron beam performing radiation therapy on the patient. However, in the preparation of the therapy plan, there are still problems of inaccurate setting of the preset radiation parameters such as the neutron radiation dose and inaccurate determination of the actual radiation dose.

[0005] In addition, during actual irradiation, an event sometimes occurs where a command is input by mistake or the relevant commands and irradiation parameters are changed due to the operator or the doctor accidentally touching the control panel by mistake, so that the medical risk increases.

DISCLOSURE OF THE ESSENCE OF THE INVENTION

[0006] In order to solve the above-mentioned problems, the invention proposes a neutron dose detection device and a neutron capture therapy device capable of applying an accurate dose of neutron irradiation to a patient. The neutron dose detection device comprises a detector configured to detect a neutron and output a signal, a signal processing unit configured to process a signal output from the detector, a counter configured to count the signal output from the signal processing unit to obtain a count rate, and a count rate correction unit configured to correct the count rate.

[0007] In addition, the count rate correction unit may calculate the corrected count rate C _k using formula (1-1)

[0008] (1-1),

[0009] where K is the count rate correction factor and C _t is the real-time count rate recorded by the counter.

[0010] In addition, the count rate correction unit may calculate the count rate correction coefficient K using the formula (1-2)

[0011] (1-2),

[0012] where n is the number of pulses recorded by the counter per unit of time, and m is the number of signal pulses actually generated in the detector per unit of time.

[0013] In addition, the count rate correction unit may output the formula (1-4) by combining the formula (1-2) with the formula (1-3) to calculate the count rate correction coefficient K

[0014] (1-3)

[0015] (1-4),

[0016] where τ is the pulse resolution time.

[0017] In addition, the count rate correction unit can calculate the pulse resolution time τ using formula (1-5)

[0018]

(1-5)

[0019] where I ₁ is the flux of the first neutron beam, C ₁ is the count rate recorded by the counter when the flux of the neutron beam is equal to I ₁ , I ₂ is the flux of the second neutron beam, C ₂ is the count rate recorded by the counter when the flux of the neutron beam is equal to I ₂ .

[0020] In addition, the detector may comprise one or more of a He-3 proportional counter, a BF ₃ proportional counter, a fission chamber, a boron ionization chamber, or a scintillation detector.

[0021] In addition, the neutron dose detection device may further comprise a conversion unit configured to convert the count rate into a neutron flux density or neutron dose rate, and an integration unit configured to integrate the neutron flux density or neutron dose rate to obtain the neutron dose.

[0022] In addition, the neutron dose detection device may further comprise a display configured to display the neutron dose.

[0023] The neutron capture therapy device includes the above-mentioned neutron dose detection device.

[0024] In addition, the neutron capture therapy device may further comprise a neutron beam irradiation system comprising a neutron beam generation module configured to generate a neutron beam, and a beam adjustment module configured to adjust the neutron beam and comprising a moderator configured to slow down the neutron beam, and a reflector configured to direct the deflected neutron back into the moderator.

BRIEF DESCRIPTION OF DRAWINGS

[0025] Fig. 1 is a schematic diagram of a neutron beam irradiation system of a neutron capture therapy device according to the invention.

[0026] Fig. 2 is a schematic diagram of a beam forming housing of a neutron capture therapy device according to the present invention.

[0027] Fig. 3 is a schematic diagram of a neutron beam irradiation system and a detection system of a neutron capture therapy device according to the invention.

[0028] Fig. 4 is a schematic diagram of a neutron dose detection device in a first embodiment of a neutron capture therapy device according to the invention.

[0029] Fig. 5 is a schematic diagram of a neutron dose detection device in a second embodiment of a neutron capture therapy device according to the invention.

[0030] Fig. 6 is a schematic diagram of a monitoring system of a neutron capture therapy device according to the invention.

[0031] Fig. 7 is a schematic diagram of a system for preventing incorrect operation in combination with a display portion and an input portion of a neutron capture therapy device according to the invention.

IMPLEMENTATION OF THE INVENTION

[0032] In order to make the purpose, technical solutions and technical effects of the invention more clear and to enable those skilled in the art to implement them accordingly, the invention will be further described in detail below with reference to the accompanying drawings and embodiments of the invention.

[0033] In the following description, the terms “first”, “second”, etc. may be used to describe various elements, however, these elements are not limited to these terms, and these terms are used only to distinguish the described objects without any order or technical meaning.

[0034] Radiation therapy is a common means for treating cancer, and boron neutron capture therapy (BNCT) is an effective means for treating cancer and has been increasingly used in recent years. As shown in Fig. 1-7, a neutron capture therapy device irradiating a neutron beam of a predetermined neutron dose to an object to be irradiated such as a patient S to perform BNCT includes a neutron beam irradiation system 1, a detection system, a monitoring system 3, a correction system, and a malfunction prevention system. The neutron beam irradiation system 1 is configured to generate a neutron beam suitable for performing neutron irradiation therapy on the patient S. The detection system is configured to detect irradiation parameters such as a neutron dose or the like during the neutron irradiation therapy. The monitoring system 3 is configured to control the entire neutron beam irradiation process. The correction system is designed to correct the preset neutron dosage. The malfunction prevention system is designed to prevent the relevant personnel from entering improper commands and information into the monitoring system 3.

[0035] BNCT produces two highly charged particles ⁴ He and ⁷ Li by using the characteristic of boron ( ¹⁰ B) drug having a high capture site for thermal neutron and through neutron capture ^{of 10} B(n,α) ⁷ Li and nuclear fission reaction. The two highly charged particles each have an average energy of about 2.33 MeV and also the characteristics of high linear energy transfer (LET) and short range. The LET and range of ⁴ He particles are 150 keV/μm and 8 μm, respectively, the LET and range of highly charged particles ⁷ Li are 175 keV/μm and 5 μm, respectively, and the total range of the two highly charged particles is approximately equivalent to the size of the cell, so that radiation damage to the body can be limited to the cellular level. The boron drug is selectively assembled into tumor cells. After the neutron beam hits the body of patient S, it undergoes a nuclear reaction with the boron in the body of patient S, resulting in the formation of two highly charged particles ⁴ He and ⁷ Li, and the two highly charged particles ⁴ He and ⁷ Li locally destroy tumor cells without causing too much damage to normal tissues.

[0036] As shown in Fig. 1, the neutron beam irradiation system 1 comprises a neutron beam generation module 11 and a beam adjustment module 12 configured to adjust the neutron beam generated by the neutron beam generation module 11.

[0037] The neutron beam generation module 11 generates a neutron beam irradiating the patient S and comprises an accelerator 111 configured to accelerate a charged particle beam, a target 112 configured to interact with the charged particle beam to generate a neutron beam, and a charged particle beam transporting portion 113 located between the accelerator 111 and the target 112 and configured to transport the charged particle beam. The charged particle beam transporting portion 113 transports the charged particle beam to the target 112 and has one end connected to the accelerator 111 and the other end connected to the target 112. In this case, the charged particle beam transporting portion 113 is provided with a beam control device, such as a beam adjustment portion (not shown), a charged particle scanning portion (not shown), etc. The beam adjustment part controls the direction of movement and the diameter of the charged particle beam. The charged particle beam scanning part scans the charged particle beam and controls the irradiation position of the charged particle beam relative to the target 112.

[0038] The accelerator 111 may be a cyclotron, a synchrotron, a synchrocyclotron, a linear accelerator, etc. A commonly used target 112 includes a lithium (Li) target and a beryllium (Be) target. A beam of charged particles is accelerated to an energy sufficient to overcome the Coulomb repulsion of the nuclei of the target 112 and undergoes a nuclear reaction ^{of 7} Li(p, n) ⁷ Be with the target 112 to generate a neutron beam. The nuclear reaction discussed typically includes ⁷ Li(p, n) ⁷ Be and ⁹ Be(p, n) ⁹ B. Typically, the target 112 comprises a target layer and an antioxidant layer located on the side of the target layer and configured to prevent oxidation of the target layer, wherein the antioxidant layer is made of aluminum or stainless steel.

[0039] In embodiments of the invention, the accelerator 111 accelerates charged particles to allow them to undergo a nuclear reaction with a target 112 to provide a neutron source. In other embodiments, the neutron source may be provided by using a nuclear reactor, a D-T neutron generator, a D-D neutron generator, etc. However, regardless of whether the neutron source is provided by accelerating charged particles to allow them to undergo a nuclear reaction with the target 112, as provided in the invention, or the neutron source is provided by a nuclear reactor, a D-T neutron generator, a D-D neutron generator, etc., a mixed irradiation field is generated, that is, the generated beam includes a high-speed neutron beam, an epithermal neutron beam, a thermal neutron beam and a gamma ray. During BNCT, the higher the content of other radiation beams (collectively called radiation beam contamination) except epithermal neutron, the greater the proportion of non-selective dose deposition in normal tissues, so that the radiation causing unnecessary dose deposition can be minimized.

[0040] The International Atomic Energy Agency (IAEA) has made five recommendations on the air beam quality factor for the neutron source used in clinical BNCT. The five recommendations can compare the advantages and disadvantages of different neutron sources and serve as a reference for the selection of the neutron generation path and the design of the beam shaping housing 121. The five recommendations are as follows:

[0041] Epithermal neutron flux > 1 x 10 ⁹ n/cm ² s;

[0042] Prompt neutron contamination < 2 x 10 ^-13 Gy- ^cm2 /n;

[0043] Photon pollution < 2 x 10 ^-13 Gy- ^cm2 /n;

[0044] Ratio of thermal and epithermal neutron flux < 0.05;

[0045] Ratio of epithermal neutron current to flux > 0.7.

[0046] Note: An epithermal neutron has an energy region between 0.5 eV and 40 keV, a thermal neutron has an energy region less than 0.5 eV, and a fast neutron has an energy region greater than 40 keV.

[0047] As shown in combination with Fig. 2 and 3, the beam adjustment module 12 is configured to adjust the mixed irradiation beams generated in the neutron beam generation module 11 to minimize contamination of the irradiation beam ultimately irradiating the patient S and to focus the epithermal neutron for treating the patient S on the part of the patient S to be irradiated. The beam adjustment module 12 comprises a beam shaping housing 121 configured to slow down and shield the neutron beam, and a collimator 122 configured to focus the epithermal neutron on the part of the patient S to be irradiated. In particular, the beam shaping housing 121 comprises a moderator 1211 configured to slow down the neutron beam generated from the target 112 into the energy region of the epithermal neutron, a reflector 1212 configured to direct the deflected neutron back into the moderator 1211 for increasing the intensity of the epithermal neutron beam, a thermal neutron absorber 1213 configured to absorb the thermal neutron to prevent excessive dose deposition in superficial normal tissues during therapy, and a radiation shield 1214 configured to shield neutron and photon leaks to reduce dose deposition in normal tissues in the non-irradiated region. In other embodiments of the invention, the thermal neutron absorber may not be provided, instead the thermal neutron is absorbed by substances contained in the moderator or reflector, or it may be provided that the moderator and the thermal neutron absorber are made as a single unit. In other embodiments, the radiation shield may not be provided, instead the radiation shield may be made of the same material as the reflector, or it may be provided that the reflector and the radiation shield are made as a single unit.

[0048] The moderator 1211 can be formed by stacking several different materials. The material of the moderator 1211 is selected in accordance with factors such as the energy of the charged particle beam, etc. For example, when the energy of the proton beam from the accelerator 111 is 30 MeV and a Be target is used, the material of the moderator 1211 is lead (Pb), iron, aluminum (Al), or calcium fluoride. When the energy of the proton beam from the accelerator 111 is 11 MeV and a Be target is used, the material of the moderator 1211 is heavy water (D ₂ O), or lead fluoride, etc. In a preferred embodiment of the invention, the moderator 1211 is formed by mixing MgF ₂ and LiF, which is 4.6% MgF ₂ by weight, the reflector 1212 is made of Pb, and the thermal neutron absorber 1213 is made of ⁶ Li. The radiation shield 1214 includes a photon shield and a neutron shield. Here, the photon shield is made of Pb, and the neutron shield is made of polyethylene (PE). The moderator 1211 can be made in a biconical shape, as disclosed in Fig. 2, or in a cylindrical shape, as disclosed in Fig. 3. The reflector 1212 is located around the moderator 1211 and has a shape adaptively changed in accordance with the shape of the moderator 1211.

[0049] As shown in Fig. 3, the detection system comprises a neutron dose detection device 21 configured to detect a neutron dose of a neutron beam in real time, a temperature detection device 22 configured to detect a temperature of a target 112, a displacement detection device 23 configured to detect whether a patient S creates a displacement during therapy, and a boron concentration detection device (not shown) configured to detect a boron concentration in the body of a patient S.

[0050] As shown in combination with Fig. 4, the neutron dose detection device 21 comprises a detector 211 configured to receive a neutron and output a signal, a signal processing unit 212 configured to process a signal output from the detector 211, a counter 213 configured to count the signal output from the signal processing unit 212 to obtain a count rate, a conversion unit 214 configured to convert the count rate recorded by the counter 213 into a neutron flux density or a neutron dose rate, an integration unit 215 configured to integrate the neutron flux density or the neutron dose rate to obtain a neutron dose, and a display 218 configured to display the neutron dose. The detector 211, the signal processing unit 212 and the counter 213 form a count rate channel 20.

[0051] The detector 211 may be located in the beam forming housing 121, may also be located in the collimator 122, or may also be located in any position near the beam forming housing 121, provided that the position in which the detector 211 is located can be adapted to detect the neutron dose of the neutron beam.

[0052] The detector 211 capable of detecting a neutron dose of a neutron beam in real time is provided with an ionization chamber and a scintillation detector. In this case, the ionization chamber structure is used as a substrate in the He-3 proportional counter, the BF ₃ proportional counter, the fission chamber and the boron ionization chamber, and the scintillation detector contains an organic material or an inorganic material. When detecting a thermal neutron, the scintillation detector usually adds an element of a high thermal neutron capture section such as Li, or B, etc. A certain element in two types of detectors captures a neutron entering the detector or undergoes a nuclear fission reaction with a neutron entering the detector to release highly charged particles and nuclear fission fragments, which generate a large number of ionization pairs in the ionization chamber or the scintillation detector, and these charges are collected and form an electric signal. The signal processing unit 212 performs noise reduction, conversion and separation processing of the electric signal, and the electric signal is converted into a pulse signal. A neutron pulse signal and a γ-pulse signal are distinguished by analyzing the magnitude of the voltage pulse. The separated neutron pulse signal is continuously recorded by the counter 213 to obtain the counting rate (n/s) of the neutron. The conversion unit 214 calculates and converts the counting rate by means of internal software, programs or the like to obtain the neutron flux density (cm ^-2 s ^-1 ) and further calculates and converts the neutron flux density to obtain the neutron dose rate (Gy/s). Finally, the integration part integrates the neutron dose rate to obtain the real-time neutron dose.

[0053] Below is a brief description using the fission chamber, scintillator detector and BF ₃ detector as examples.

[0054] When a neutron beam passes through a fission chamber, it is separated by gas molecules inside the fission chamber or by the fission chamber wall to form an electron and a positively charged ion, which are called an ion pair, as described above. Due to the high voltage electric field applied in the fission chamber, the electron moves toward the central anode wire and the positively charged ion moves toward the surrounding cathode wall, so that a measurable electrical signal is generated.

[0055] Substances such as optical fiber or the like in a scintillation detector absorb energy and then generate visible light, which uses ionizing radiation to excite an electron in a crystal or molecule to an excited state. The fluorescence emitted when the electron returns to the ground state is collected and then serves to detect a neutron beam. The visible light emitted by the scintillation detector and the neutron beam is converted into an electrical signal by a photomultiplier tube and output.

[0056] The BF ₃ detector is housed in the beam forming housing 121 and is configured to receive the irradiation of a neutron beam, the B element in the BF ₃ detector undergoes a nuclear reaction ^{of 10} B(n, alpha) ⁷ Li with a neutron, wherein the alpha particles generated by the nuclear reaction and the electric particles ^{of 7} Li are collected by a high-voltage electrode under the action of a voltage to generate an electric signal. The electric signal is transmitted to the signal processing unit 212 through a coaxial cable, is subject to signal amplification, filtering and shaping to obtain a pulse signal. The processed pulse signal is transmitted to the counter 213 for counting pulses in it to obtain a counting rate (n/s) by which the neutron beam intensity, that is, the neutron dose, can be measured in real time.

[0057] The temperature detection device 22 is a thermocouple, wherein two conductors with different components (called thermocouple wires or hot electrodes) are connected at both ends to form a loop. When the temperature of the connection point differs, an electromotive force can be generated in the loop. This phenomenon is called a thermoelectric effect, and the electromotive force is called a thermoelectric potential. The thermocouple performs temperature measurement using this principle, wherein one end directly adapted to measure the temperature of the medium is called a working end (also known as a measuring end), and the other end is called a cold end (also known as a compensation end). The cold end is connected to a display instrument or a mixed instrument, wherein the display instrument can indicate the thermoelectric potential generated by the thermocouple. Of course, as known to those skilled in the art, the temperature detection device 22 can also be any detector 211 capable of detecting temperature, such as a resistance thermometer and the like.

[0058] The displacement detection device 23 is an infrared signal detector, and the infrared detector operates by detecting infrared rays emitted by a human body. The infrared detector detects infrared rays from the outside, and then collects the infrared rays on the infrared sensor. The infrared sensor generally uses a pyroelectric element that emits charges to the outside when the temperature of the infrared rays changes, and an alarm signal is generated after the charges are detected and processed. The detector 211 is designed to detect radiation from a human body. Therefore, the radiation-sensitive element must be very sensitive to infrared rays with a wavelength of about 10 μm. Of course, it is well known to those skilled in the art that the displacement detection device 23 may be any detection device suitable for detecting a change in the displacement of an object to be irradiated, such as a displacement sensor. The displacement sensor determines whether the object to be irradiated moves, in accordance with a change in the displacement of the object to be irradiated relative to a certain reference object. It is also well known to those skilled in the art that the displacement detection device 23 can not only be configured to detect a change in the displacement of the object to be irradiated, but also to detect a change in the displacement of the support element and/or the treatment table fixing the object to be irradiated, thereby indirectly determining a change in the displacement of the object to be irradiated.

[0059] During the neutron beam irradiation therapy of the patient S, boron is continuously supplied to the patient S as needed. The concentration of boron can be detected by inductively coupled plasma spectroscopy, high-resolution alpha autoradiography, charged ion spectroscopy, a neutron capture chamber, nuclear magnetic resonance imaging and magnetic resonance imaging, positive electron emission tomography, fast γ-ray spectroscopy, etc., and the device involved in the above detection method is called a boron concentration detection device.

[0060] The invention is described using the example of calculating the concentration of boron in the body of a patient S by detecting a γ-ray emitted by the patient S. A neutron beam enters the patient's body and reacts with boron to generate a γ-ray. By measuring the amount of γ-ray, it is possible to calculate the amount of boron reacting with the neutron beam, thereby calculating the concentration of boron in the body of the patient S. The device for detecting the concentration of boron is configured to measure the concentration of boron in the body of the patient S in real time, when the neutron beam irradiation system 1 performs neutron beam irradiation therapy with respect to the patient S.

[0061] A boron concentration detection device detects γ-rays (478 keV) generated by a reaction between a neutron and boron to measure a boron concentration, wherein a boron distribution measurement system (PG (Prompt-γ)-SPECT) capable of measuring single-energy γ-rays to measure a boron concentration distribution is used as the boron concentration detection device. The boron concentration detection device includes a γ-ray detection part and a boron concentration calculation part. The γ-ray detection part detects information related to γ-rays emitted from the body of the patient S, and the boron concentration calculation part calculates the boron concentration in the body of the patient S according to the information related to γ-rays detected by the γ-ray detection part. The γ-ray detection portion may use a scintillator and various other γ-ray detection devices. In the embodiment of the invention, the γ-ray detection portion is located near the tumor of patient S, for example, at a distance of about 30 cm from the tumor of patient S.

[0062] The detector 211 of the above-mentioned neutron dose detection device 21, configured to detect a neutron dose of a neutron beam, belongs to a pulse detector, wherein the shortest time interval between two successively incident neutrons, discriminated by the detector 211, is defined as a pulse resolution time τ(s). The detector 211 may not accurately record other incident neutrons during the time τ after the neutron has fallen on the detector 211, which is therefore also called a dead time.

[0063] The sensitivity of the detector 211 detecting a neutron is the ratio of the total output of the detector 211 to the corresponding total input. For the detector 211 of the neutron dose detection device 21 given as an example in the invention, its input physical quantity is a neutron beam, and its output physical quantity is generally an optical signal or an electrical signal. The higher the ratio of the total output to the corresponding total input, the higher the sensitivity of the detector 211 detecting a neutron. The higher the neutron detection sensitivity, the shorter the pulse resolution time τ corresponding to detector 211. In general, to reduce statistical error, detector 211 with high neutron detection sensitivity detects a low-density beam, and detector 211 with low neutron detection sensitivity detects a high-density beam.

[0064] Various embodiments of the invention are described in detail below. For simplicity, the same component has the same reference numeral in different embodiments, while similar components are distinguished by the same reference numeral plus ‘ ’ or ‘ ' ’ for different embodiments.

[0065] In the first embodiment of the invention disclosed in Fig. 4, the neutron dose detection device 21 is provided with only a count rate channel 20. For accurate detection of neutron doses of neutron beams of different densities, in the second embodiment disclosed in Fig. 5, the neutron dose detection device 21' comprises at least two count rate channels 20'. The detector 211' of each count rate channel 20' has a different neutron detection sensitivity. In addition, the neutron dose detection device 21' further comprises a count rate channel selection unit 216 configured to select the corresponding count rate channel 20' in accordance with the current power of the accelerator 111 or the neutron beam flux. In particular, in the second embodiment, the neutron dose detection device 21' comprises at least two count rate channels 20', a count rate channel selection unit 216 configured to select a corresponding count rate channel 20' from the at least two count rate channels 20', a conversion unit 214 configured to convert the count rate recorded by the count rate channel 20' selected by the count rate channel selection unit 216 into a neutron flux density or a neutron dose rate, and an integration unit 215 configured to integrate the neutron flux density or the neutron dose rate to obtain the neutron dose.

[0066] The two count rate channels 20' are called respectively a first count rate channel 201 and a second count rate channel 202. The first count rate channel 201 comprises a first detector 2011 configured to receive a neutron and output a signal, a first signal processing unit 2012 configured to process a signal output from the first detector 2011, and a first counter 2013 configured to count the signal output from the first signal processing unit 2012. The second count rate channel 202 comprises a second detector 2021 configured to receive a neutron and output a signal, a second signal processing unit 2022 configured to process a signal output from the second detector 2021, and a second counter 2023 configured to count the signal output from the second signal processing unit 2022. The count rate channel selection unit 216 selects the corresponding count rate channel 20 in accordance with the current power of the accelerator 111 or the neutron beam flux. The conversion unit 214 converts the count rate recorded by the count rate channel 20 selected by the count rate channel selection unit 216 into a neutron flux density or a neutron dose rate. The integration unit 215 integrates the neutron flux density or the neutron dose rate to obtain the neutron dose.

[0067] In general, the neutron flux that can be generated when the accelerator 111 is at maximum power is defined as the maximum neutron flux. When the real-time detected neutron flux is less than half of the maximum neutron flux, it is considered a small neutron flux. When the real-time detected neutron flux is greater than or equal to half of the maximum neutron flux, it is considered a large neutron flux.

[0068] The sensitivity of the first detector 2011 detecting a neutron is a first sensitivity, the sensitivity of the second detector 2021 detecting a neutron is a second sensitivity, and the first sensitivity is lower than the second sensitivity. Specifically, the first detector 2011 is wrapped with a large amount of neutron-absorbing materials such as B ₄ C, Cd, or filled with a low-pressure working gas, or is made in a small size, thereby reducing the sensitivity of neutron detection. When the neutron flux is large, the first detector 2011 is used for detection, so that the loss in counting rate due to the pulse resolution time can be reduced. Compared with the first detector 2011, the second detector 2021 is wrapped with a small amount of neutron-absorbing materials, or is not wrapped with a material at all, or is filled with a high-pressure working gas, or is made in a large size, so that the second sensitivity is greater than the first sensitivity. When the neutron flux is small, the second detector 2021 is used for detection, so that the statistical error of the count rate caused by the low count rate can be reduced.

[0069] Accordingly, the sensitivity of the first neutron detecting count rate channel 201 is less than the sensitivity of the second neutron detecting count rate channel 202. The count rate selecting unit selects the corresponding count rate channel 20' in accordance with the current power of the accelerator 111 or the neutron flux. For example, in a case where the maximum beam intensity of the accelerator 111 is 10 mA, when the beam intensity of the accelerator 111 exceeds 5 mA, the count rate recorded by the first counter 2013 of the first count rate channel 201 with the first sensitivity is selected for transmission to the conversion unit 214 for dose calculation; wherein, when the beam intensity of the accelerator 111 is less than 5 mA, the count rate recorded by the second counter 2023 of the second count rate channel 202 with the second sensitivity is selected for transmission to the conversion unit 214 for dose calculation. A more accurate count rate is selected by the count rate selection unit for transmission to the conversion unit 214 for dose calculation, thereby obtaining an accurate neutron irradiation dose.

[0070] The neutron dose detection device 21 is provided with at least two count rate channels with different neutron detection sensitivities, that is, a first count rate channel 201 and a second count rate channel 202, and the count rate channel selection unit 216 selects a more accurate count rate according to the actual situation for calculating the neutron dose, so that the count rate loss error caused by the pulse resolution time can be reduced. At this time, the statistical error caused by the low count rate is taken into account, so that the accuracy of the neutron dose detection in real time is improved, thereby improving the accuracy of the neutron dose of the neutron beam irradiating the patient S.

[0071] In other embodiments of the invention, the count rate channels 20 and 20' may have any number of count rate channels as needed.

[0072] Furthermore, in the embodiments of the invention as illustrated above, the count rate channel 20 is selected in accordance with the power of the accelerator 111, the neutron flux, and the like. In other embodiments of the invention, the count rate channel 20' can be selected in accordance with the distance between the detector 211 and the neutron source. For example, when the detector 211 is located at a position distant from the neutron source, the second count rate channel 202 with the second sensitivity is selected; while when the detector 211 is located at a position close to the neutron source, the first count rate channel 201 with the first sensitivity is selected.

[0073] The detector 211 of the above-mentioned neutron dose detecting device 21 refers to a pulse detector. In general, a pulse detector has a time resolution problem. An incident neutron reacts with the detector 211 to generate a signal pulse, which may be followed by a time interval τ. All other signal pulses generated during the time interval may be regarded by the detector 211 as the same signal pulse. In this case, provided that the time interval between any two signal pulses is less than τ, the second pulse may not be recorded. Therefore, the count rate recorded by the counter 213 has a deviation and must be corrected. The conversion unit 214 obtains the accurate neutron flux density in real time and the neutron dose rate D _t (Gy/s) according to the corrected count rate C _k in combination with the dose conversion factor.

[0074] As again shown in combination with Fig. 4 and 5, in addition, the neutron dose detection device 21 further comprises a count rate correction unit 217 configured to correct the count rate. The count rate correction unit 217 comprises a count rate correction calculation part, a count rate correction coefficient calculation part, and a pulse resolution time calculation part.

[0075] The count rate correction calculation portion calculates the corrected count rate C _k using formula (1-1)

[0076]

(1-1)

[0077] where K is the count rate correction coefficient; and

[0078] C _t – real-time count rate recorded by counter 213.

[0079] The calculation part of the count rate correction coefficient calculates the count rate correction coefficient K according to the formula (1-2)

[0080] (1-2),

[0081] where n is the number of pulses recorded by counter 213 per unit of time, i.e. the real-time count rate (n/s) per unit of time; and

[0082] m is the number of signal pulses actually generated in detector 211 per unit of time, i.e. the number of neutrons (n/s) reacting with detector 211 per unit of time.

[0083] When the number of neutrons entering the detector 211 for the reaction per unit time is m, and the number of pulses actually recorded by the counter 213 per unit time is n, the time when the counting tube may not operate is nτ, while the total number of neutrons that enter the counting tube at this time and cannot be recorded is mnτ, that is, the counting loss is m-n, and formula (1-3) is obtained from:

[0084] (1-3)

[0085] Formula (1-3) is substituted into formula (1-2) to obtain formula (1-4)

[0086]

(1-4)

[0087] From the above formula, it can be determined that when the pulse resolution time τ is known, the count rate correction factor can be calculated using a combination of the number of pulses recorded by the counter 213 and the formula (1-4), and the count rate correction factor can be substituted into the formula (1-1) to calculate the corrected count rate.

[0088] Conventional methods for calculating the pulse resolution time include the dual source method and the reactor power method. These two methods require two natural neutron sources or reactors for calculation and have a relatively high cost. Embodiments of the invention provide for calculating the pulse resolution time based on the monitoring system of the neutron capture therapy device, which makes full use of existing devices and resources to reduce the cost.

[0089] Specifically, first, the accelerator 111 is operated in a low flux state, and at this time, the neutron beam flux is the first neutron beam flux I ₁ , and the count rate recorded by the counter 213 is C ₁ . Theoretically, due to the low flux state, the detector 211 is not affected by the pulse resolution time, and there are signal pulses that may not be recorded. Then, the accelerator 111 is switched to a high flux state, and at this time, the neutron beam flux is the second neutron beam flux I ₂ , and the count rate recorded by the counter 213 is C ₂ . At this time, the count rate is affected by the pulse resolution time, so that a part of the signal pulses is not recorded, and a part of the pulse resolution time calculation calculates the pulse resolution time τ according to the formula (1-5)

[0090]

(1-5)

[0091] When the position of the detector 211 does not change, it is not necessary to calculate the pulse resolution time every time the device is operated. However, after a long period of operation of the detector 211, the operating parameters of the detector 211 may change, causing a change in the pulse resolution time, so it is necessary to periodically calculate the pulse resolution time.

[0092] The count rate correction part 217 can calculate the pulse resolution time of the detector 211 and can calculate a count rate correction coefficient according to the pulse resolution time, so that the count rate error caused by the pulse resolution time is corrected, the accuracy of real-time neutron dose detection is further improved, and the accuracy of the neutron dose of the neutron beam irradiating the patient S is further improved.

[0093] Before radiation therapy, the total neutron dose to be delivered to the patient S, the neutron flux density or neutron dose rate or current during irradiation, and the required irradiation time, irradiation angle and other irradiation parameters during irradiation are obtained by modeling, calculation, and the like. For convenience of description, the above parameters are collectively referred to as preset irradiation parameters. In other embodiments of the invention, a part or more of the parameters not mentioned, including the above parameters, can be understood as preset irradiation parameters, called preset neutron dose (Gy), preset neutron flux density (cm ^-2 s ^-1 ), preset neutron dose rate (Gy s ^-1 ), preset current (A), preset irradiation time (s), and the like, respectively. During irradiation, due to the change of some coefficients, the irradiation parameters need to be adjusted periodically according to the relevant parameters detected by the detection system. The irradiation parameter detected by the detection system is called the real-time irradiation parameter, and the adjusted irradiation parameter is called the adjusted irradiation parameter. The adjusted irradiation parameter can be the preset irradiation parameter or the adjusted irradiation parameter.

[0094] As shown in Fig. 6, the monitoring system 3 comprises an input portion 31 configured to input preset irradiation parameters, a storage portion 32 configured to store the irradiation parameters, a control portion 33 configured to execute a treatment plan in accordance with the irradiation parameters stored in the storage portion 32, a reading portion 34 configured to read the real-time irradiation parameters detected by the detection system, a calculation portion 35 configured to calculate the real-time irradiation parameters and the preset irradiation parameters/corrected irradiation parameters stored in the storage portion 32, a determination portion 36 configured to determine, in accordance with the calculation result of the calculation portion 35, whether a correction of the irradiation parameters is required, a correction portion 37 configured to correct a portion of the irradiation parameters stored in the storage portion 32 when the determination portion 36 determines that a correction of the irradiation parameters is necessary, and a display portion 38 configured to with the ability to display the remaining irradiation time or the remaining irradiation time and other irradiation parameters in real time.

[0095] Before the correction of the preset irradiation parameters, the irradiation parameters stored in the storage portion 32 are the preset irradiation parameters, the irradiation parameters corrected by the correction portion 37 are also the preset irradiation parameters, the remaining irradiation time displayed by the display portion 38 is the difference between the preset irradiation time and the real-time irradiation time, and the irradiation time displayed by the display portion 38 is the preset irradiation time. After the correction of the preset irradiation parameters, the irradiation parameters stored in the storage portion 32 are the corrected irradiation parameters, the irradiation parameters corrected by the correction portion 37 are also the corrected irradiation parameters, the remaining irradiation time displayed by the display portion 38 is the corrected remaining irradiation time, and the irradiation parameters displayed by the display portion 38 are the corrected irradiation parameters. Of course, the preset irradiation parameters and the corrected irradiation parameters can also be displayed simultaneously.

[0096] In other embodiments of the invention, the input portion 31, the storage portion 32, etc. may not be provided.

[0097] The monitoring system 3 is electrically connected to the detection system, so that the corresponding information detected by the detection system can be transmitted to the monitoring system 3. The display 218 of the neutron dose detection device 21 in the detection system and the display part 38 of the monitoring system 3 can be the same device, in general - a display screen.

[0098] The operation process of the monitoring system 3 is shown in Fig. 6, and the specific details are described below.

[0099] In step S1, preset irradiation parameters such as a preset neutron flux density or a preset neutron dose rate or a preset current, a preset neutron dose, a preset irradiation time, a preset boron concentration and other irradiation parameters are input by the input part 31.

[00100] In step S2, the irradiation parameters are stored in the storage portion 32.

[00101] In step S3, the treatment plan is executed by the control part 33 in accordance with the irradiation parameters stored in the storage part 32.

[00102] In step S4, the real-time irradiation parameters detected by the detection system are read by the reading portion 34.

[00103] In step S5, the irradiation parameters stored in the storage portion 32 and the real-time irradiation parameters read by the reading portion 34 are calculated by the calculating portion 35.

[00104] In step S6, whether the irradiation parameters stored in the storage portion require adjustment is determined by the determining portion 36 in accordance with the calculation result of the calculating portion 35.

[00105] In step S7, the latest irradiation parameters in the storage portion 32 are adjusted by the correction portion 37 in response to the determination by the determination portion 36 that the irradiation parameters stored in the storage portion 32 need to be adjusted; and

[00106] the corrective action is not performed by the correction part 37, in response to the determination by the determination part 36 that the irradiation parameters stored in the storage part 32 do not need to be corrected.

[00107] In step S8, the remaining irradiation time or the remaining irradiation time and other irradiation parameters are displayed by the display portion 38 in real time in accordance with the irradiation parameters stored in the storage portion 32.

[00108] During the operation of the monitoring system 3, the reading part 34 periodically reads the irradiation parameters in real time, for example, reads the irradiation parameters in real time every 5 minutes, and transmits the irradiation parameters in real time to the calculating part 35 for corresponding calculation. In response to a difference between the irradiation parameter in real time and the preset irradiation parameter calculated by the calculating part 35, which is greater than the first threshold value, or in response to the irradiation parameter in real time, which is greater than the second threshold value, or less than the third threshold value, the determining part 36 can issue a command that the irradiation parameters should be corrected. Then, the correction part 37 corrects the irradiation parameters stored in the storage part 32. In contrast, the determining part 36 issues a command that the irradiation parameters do not need to be corrected. At this time, the correction part 37 does not correct the irradiation parameters stored in the storage part 32. For example, in response to a difference between the neutron dose rate and the preset neutron dose rate calculated by the calculation part 35 exceeding a preset first threshold value, or in response to a difference between the real-time neutron flux density and the specified neutron flux density calculated by the calculation part 35 exceeding a preset first threshold value, or in response to a difference between the real-time boron concentration and the preset boron concentration calculated by the calculation part 35 exceeding a preset first threshold value, or in response to a difference between the adjusted remaining irradiation time and the remaining irradiation time (the difference between the preset irradiation time and the actual realized irradiation time or the last adjusted remaining irradiation time) calculated by the calculation part 35 exceeding a preset first threshold value, or in response to the calculation part 35 obtaining by comparison that the real-time neutron dose rate or the real-time neutron flux density or the real-time boron concentration exceeds the preset second threshold value or less than the preset third threshold value.

[00109] Before correcting the preset irradiation parameters, the storage portion 32 stores the preset irradiation parameters, and the display portion 38 displays the remaining irradiation time and other preset irradiation parameters in real time. After correcting the preset irradiation parameters, the storage portion 32 stores the latest set of corrected irradiation parameters, and the display portion 38 displays the corrected remaining irradiation time and the latest set of other corrected irradiation parameters in real time. The display portion 38 also specifically displays which irradiation parameters, in addition to the remaining irradiation time, can be selected according to actual needs. The display portion 38 can display all of the irradiation parameters, and can also display a part of the irradiation parameters. In general, the display portion 38 displays information such as the remaining irradiation time, the irradiation dose in real time, the boron concentration, and the like.

[00110] In the embodiments disclosed in the invention, the calculation part 35 combines the real-time neutron dose D _r detected by the neutron dose detection device 21 and the preset neutron dose D _total input by the input part 31 to obtain the adjusted remaining irradiation time t _r by calculation. Here, t ₀ is the preset irradiation time, t is the real-time irradiation time detected by the detection system, i.e., the realized irradiation time, – the average value of the neutron dose in the period t, and P is the percentage of the real-time neutron dose relative to the preset neutron dose. P is calculated using formula (2-1)

[00111]

(2-1)

[00112] When P is less than 97%, the adjusted remaining irradiation time t _r is calculated using formula (2-2) and formula (2-3)

[00113]

(2-2)

[00114]

(2-3)

[00115] At this time, the correction part 37 is required to correct only the preset irradiation time or the corrected remaining irradiation time stored in the storage part 32.

[00116] When P is greater than or equal to 97%, the correction portion 37 adjusts the neutron dose rate to a first neutron dose rate lower than the preset neutron dose rate and increases the irradiation time accordingly to prevent the patient S from absorbing excess neutrons. The first neutron dose rate is from 1/7 to 1/2 of the preset neutron dose rate. Preferably, the neutron dose rate is adjusted to 1/5 of the preset neutron dose rate I _d , that is, the first neutron dose rate is I _d /5, and the adjusted remaining irradiation time t _r is calculated according to the formula (2-4)

[00117]

(2-4)

[00118] At this time, the correction part 37 is required to change the remaining irradiation time and the preset neutron dose rate in the storage part 32 to the adjusted remaining irradiation time t _r and the adjusted neutron dose rate, respectively, and the control part 33 carries out the treatment plan in accordance with the adjusted irradiation parameters. In other embodiments, the neutron dose rate may be adjusted to other ratios such as 1/3, 1/4, 1/6, 1/7, etc. of the preset neutron dose rate in order to prevent the patient S from absorbing excess neutrons when irradiated with a neutron beam with a high neutron dose rate. In addition, the correction part 37 may adjust the neutron dose rate when P is greater than or equal to 90%, or greater than or equal to 95%, or greater than or equal to other ratios, and the specific ratio may be preset according to actual situations. Of course, whether the neutron dose rate needs to be adjusted to the first neutron dose rate less than the preset neutron dose rate can also be determined without the P value calculated by the calculation part 35, instead, after the condition that the neutron dose rate should be adjusted by any percentage of the real-time neutron dose to the preset neutron dose based on the preset neutron dose, the threshold value is set manually and input into the storage part 32 through the storage input part 31. When the detected real-time neutron dose is greater than or equal to the threshold value, the determining part 36 determines that the irradiation parameters need to be adjusted, wherein the correction part 37 is adapted to adjust the neutron dose rate to be the first neutron dose rate less than the preset neutron dose rate.

[00119] In the above embodiments of the invention, when P is less than 97%, the calculation unit 35 calculates the irradiation time required to complete the irradiation with a preset neutron dose based on the condition of maintaining the neutron dose rate constant in real time. In other embodiments of the invention, the goal of completing the irradiation with a preset dose within a preset irradiation time is achieved by changing the neutron dose rate or the boron concentration while maintaining the irradiation time constant. Methods for changing the neutron dose rate include changing the accelerator power, changing the thickness of the target layer of the target 112, and the like. The adjusted neutron dose rate I _r is calculated according to the formula (2-5)

[00120]

(2-5)

[00121] Since the neutron dose rate is calculated from the neutron flux density through a conversion factor, and the neutron flux density is obtained by integrating the neutron count rate, the corrected neutron dose rate is equivalent to the corrected neutron flux density and the neutron count rate.

[00122] When carried out when P is greater than or equal to 97%, in order to prevent the patient S from absorbing excess neutrons when irradiated with a neutron beam at a high neutron dose rate, the neutron dose rate is still adjusted to 1/5 of the preset neutron dose rate, and the adjusted remaining irradiation time t _r is calculated by the formula (2-4).

[00123] When the actual realized irradiation time reaches the preset irradiation time or when the actual irradiated neutron dose reaches the preset neutron dose, the control part sends a command to the neutron capture therapy device to stop irradiation.

[00124] The monitoring system 3 is provided with a correction part 37 that corrects the irradiation parameters stored in the storage part 32 and configured to execute the therapy plan, so that the neutron dose of the neutron beam irradiating the patient is substantially consistent with the preset neutron dose, and the accuracy of the neutron dose of the neutron beam irradiating the patient S is further improved. Meanwhile, when the percentage of the real-time neutron dose to the preset neutron dose is greater than or equal to 97%, the neutron dose rate is reduced and the irradiation time is correspondingly increased in order to prevent the patient S from absorbing excess neutrons when irradiated with a neutron beam with a high neutron dose rate, which also has the effect of improving the accuracy of the neutron dose of the neutron beam irradiating the patient S.

[00125] In the above embodiments of the invention, it may be determined whether a correction of the preset irradiation parameters is required according to the real-time neutron dose obtained by the neutron dose detection device 21, and the corrected irradiation parameters are calculated according to the real-time irradiation parameters and the preset irradiation parameters. In other embodiments of the invention, it may be determined whether a correction of the preset parameters is required according to the real-time irradiation parameters detected by the temperature detection device 22, the offset detection device 23, or the boron concentration detection device, and the corrected irradiation parameters are calculated according to the real-time irradiation parameters detected by these detection devices. For example, when the boron concentration detection device detects that the boron concentration in the patient's body S does not correspond to the preset boron concentration or does not fall within the preset range, the correction part 37 adjusts the remaining irradiation time or adjusts the boron delivery rate to the patient's body. In general, it is difficult to adjust the boron concentration in the patient's body S in a short period of time when the radiation therapy is approaching its end. At this time, in general, the remaining irradiation time is selected to correct it.

[00126] The accuracy of the neutron beam irradiation dose is of critical importance in practical therapy. Excessive irradiation doses may cause potential harm to patient S, and too small irradiation doses may reduce the quality of therapy. Both the calculation error in calculating the preset neutron dose and the deviation between the real-time irradiation parameter and the preset irradiation parameter during actual irradiation may cause inaccurate neutron irradiation dosage. Therefore, in addition to the irradiation parameters adjusted in real time, the calculation of the preset irradiation parameters is also of critical importance during actual irradiation. Therefore, a correction system is needed to correct the preset neutron dose to ensure that the neutron irradiation dose applied to patient S is more accurate. When adjusting the preset neutron beam dose, the influence of such factors as patient positioning deviation S, real-time neutron dose rate deviation, boron concentration in the patient's body, neutron flux, etc. should be taken into account.

[00127] The correction factors used by the correction system include the neutron correction factor K ₁ and the boron correction factor K _2. Here, the neutron correction factor K ₁ is related to the positioning correction factor K _p and the neutron beam intensity correction factor K _i . The boron correction factor K ₂ is related to the boron concentration correction factor K _b and the boron self-shielding effect correction factor K _s .

[00128] The deviation between the real-time neutron dose rate and the preset neutron dose rate may directly result in a deviation of the neutron dose finally irradiating the patient. Therefore, a position correction coefficient K _p and a neutron beam intensity correction coefficient K _i are introduced to correct the neutron irradiation dose.

[00129] The self-shielding effect means that at different boron concentrations, the trajectory of the neutron beam irradiating a part of the tumor also differs. In particular, the higher the boron concentration in the patient's body S, the lower the penetrating power of the neutron beam, the shorter the path of the neutron beam irradiating the tumor, and thus the neutron beam can react with boron in a shallower path. On the contrary, the longer the path of the neutron beam irradiating the tumor, the deeper the path in which the neutron beam can react with boron. In particular, a first value of the boron concentration in the patient's body is obtained using a boron concentration detection device, a first path of the neutron beam irradiating a part of the tumor is provided, and a first boron correction coefficient is obtained using a correction system. A second value of the boron concentration in the patient's body is obtained using a boron concentration detection device, a second path of the neutron beam irradiating a part of the tumor is provided, and a second boron correction coefficient is obtained using a correction system. In this case, the first value of the boron concentration is greater than the second value of the boron concentration, the first path is less than the second path, and the first boron correction coefficient is less than the second boron correction coefficient. Therefore, when calculating the neutron irradiation dose, the influence of the self-shielding effect on the actual effect of neutron beam irradiation and its irradiation path should be taken into account; to correct the neutron irradiation dose, the coefficient K _b of boron concentration correction and the coefficient K _s of boron self-shielding effect correction are introduced.

[00130] In particular, the neutron correction coefficient K ₁ , the positioning correction coefficient K _p and the neutron beam intensity correction coefficient K _i are calculated according to formula (3-1), formula (3-2) and formula (3-3), respectively, and the corresponding formulas are as follows.

[00131]

(3-1)

[00132]

(3-2)

[00133]

(3-3)

[00134] where D is the actual therapy dose, i.e. the dose D _r of neutrons in real time, measured by the neutron dose detection device 21;

[00135] D ₀ – uncorrected preset neutron dose;

[00136] I is the actual neutron beam intensity, i.e. the real-time neutron dose rate, measured by the neutron dose detection device 21; and

[00137] I ₀ is the theoretical beam intensity, i.e. the preset neutron dose rate introduced by the input part 31.

[00138] The boron correction coefficient _K2 , the boron concentration correction coefficient _Kb , and the boron self-protective effect correction coefficient _Ks are calculated according to formula (3-4), formula (3-5), and formula (3-6), respectively, and the corresponding formulas are as follows.

[00139]

(3-4)

[00140]

(3-5)

[00141]

(3-6)

[00142] where B is the actual concentration of boron in the body of the patient S, that is, the real-time concentration of boron detected by the boron concentration detection device;

[00143] B ₀ – the set value of the boron concentration in the therapy plan, i.e. the preset concentration of boron introduced using the input part 31;

[00144] ϕ _B is the thermal neutron flux in the body of patient S when the boron concentration distribution is B; and

[00145] ϕ _B0 is the thermal neutron flux in the body of patient S when the boron concentration distribution is B ₀ .

[00146] The uncorrected preset neutron dose D ₀ is calculated using formula (3-7) as follows.

[00147] (3-7)

[00148] The adjusted preset dose D _total of neutrons in the therapy plan is calculated using formula (3-8) as follows.

[00149] (3-8)

[00150] where D _B is the dose at a boron concentration of 1 ppm, has a unit of measurement of Gy;

[00151] B _con – the actual measured concentration of boron, has the unit of measurement ppm;

[00152] D _f – dose of fast neutrons, has a unit of measurement of Gy;

[00153] D _th – dose of thermal neutrons, has a unit of measurement of Gy;

[00154] RBE _n – relative biological effectiveness (RBE) of the neutron;

[00155] D _r – gamma radiation dose, has a unit of measurement Gy; and

[00156] RBE _r – RBE gamma radiation.

[00157] During actual therapy, the correction system adjusts the preset neutron dose in the pre-designed therapy plan to prevent an inaccurate neutron dose from being applied to patient S.

[00158] The correction system comprehensively takes into account the influence of factors such as the positioning deviation of the patient S, the deviation of the real-time neutron dose rate, the real-time boron concentration, etc. on the preset neutron dose, and inputs a neutron correction coefficient _K1 and a boron correction coefficient _K2 to correct the preset neutron dose, so that the accuracy of the neutron dose emitted to the patient S from the source is ensured.

[00159] During the actual therapy, after the input portion 31 completes the input of the preset irradiation parameters, the operator starts the neutron capture therapy device to perform radiation therapy. After the irradiation starts, the input function of the input portion 31 is locked, and the corresponding irradiation parameters cannot be input again, thus it can be ensured that the situation can be prevented that the incorrect parameters and commands are input due to an accidental touch or an operating error during irradiation. However, when the therapy process is somewhat inconsistent with the ideal state, the irradiation may be stopped or continued according to the abnormal state, and the parameters may not be adjusted in time or the commands may not be changed in time during irradiation. However, when the operation interface is simply set to real-time operation, the irradiation parameters and control commands can still be input by the input portion 31 after the irradiation starts, thus it can be ensured that the correct irradiation parameters and commands can be input in real time during irradiation. However, there is still a risk that the irradiation result is affected by inputting incorrect parameters and commands or re-entering operation commands due to erroneous operation during irradiation.

[00160] As shown in Fig. 7, the neutron capture therapy device is provided with a control interface. The control interface consists of the above-mentioned input portion 31, the display portion 38, the information correctness confirmation button 51, the irradiation start button 52, the irradiation pause button 53, the irradiation cancel button 54, and the report generation button 55. The operator activates the information correctness confirmation button 51 to transmit a signal to the monitoring system 3 that all the information is confirmed as correct. After the monitoring system 3 receives the signal that all the information is confirmed as correct, the necessary condition for starting the neutron capture therapy device for irradiation with a neutron beam is met. After the monitoring system 3 receives the signal that all the information is confirmed as correct, the irradiation start button 52 is activated, and the sufficient condition for starting the neutron capture therapy device for irradiation with a neutron beam is met. After the neutron capture therapy device is started, the neutron beam irradiation can be paused by the irradiation pause button 53, and the neutron beam irradiation can be cancelled by the irradiation cancel button 54. After the irradiation is completed, the report generation button 55 can be activated to automatically generate a report related to the radiation therapy. When the neutron beam irradiation is paused, this means that all the irradiation parameters and commands remain unchanged. When the irradiation start button 52 is activated again, the neutron beam irradiation is performed with the original irradiation parameters and commands. When the neutron beam irradiation is cancelled, this means that all the irradiation parameters and commands are cleared. When the neutron beam irradiation is performed again, the irradiation parameters and commands must be entered again, and the information correctness confirmation button 51 and the irradiation start button 52 are activated successively.

[00161] The abnormal operation prevention system comprehensively considers the two factors of operability and safety, and is provided with a secondary confirmation part and a protection part to ensure safe and accurate irradiation, while the system is not deprived of real-time operability. Before the operator activates the secondary confirmation part to transmit a signal to the neutron capture therapy device that all the information is confirmed as error-free, the neutron capture therapy device cannot be started to execute the radiation therapy plan, that is, the irradiation start button 52 cannot be activated. During the start of the protection part, the input part 31, which can change and input the irradiation parameters and commands, and the report generation button 55 are blocked.

[00162] In embodiments of the invention, the secondary confirmation part is an information correctness confirmation button 51 on the control interface. Before the physician starts the program for executing the treatment plan, the corresponding information must be confirmed twice. After the operator confirms that the input is correct and presses the information correctness confirmation button 51 to input a command into the monitoring system 3 that the information is confirmed as correct, the device can be started to execute the treatment plan, thereby reducing the risk of erroneous input of incorrect control commands due to an erroneous operation. For example, before performing radiation therapy on a patient S, the physician must check the patient information (such as name, gender, age, etc.), irradiation parameters (such as irradiation dose, collimator number, etc.), or the like. After checking that all the information is correct, the irradiation start function can be activated only by pressing the information correctness confirmation button 51 on the control interface. Otherwise, even if the doctor presses the 52 button to start irradiation, the device refuses to start neutron beam irradiation and gives a prompt that the information is not confirmed.

[00163] In embodiments of the invention, the protective part is the irradiation start button 52. After the irradiation start button 52 starts the therapy plan, the input function of the input part 31 is blocked, and no information can be input. In particular, before the radiation therapy, the corresponding irradiation commands and parameters are input via the input part 31. After inputting the corresponding irradiation parameters and commands into the monitoring system 3, the operator checks whether the corresponding irradiation parameters and commands are correct. After confirming that the corresponding irradiation parameters and commands are correct, the operator activates the information correctness confirmation button 51, after which the input part 31 can be blocked, and the corresponding irradiation parameters and commands cannot be changed or added via the input part 31 to prevent incorrect input. The corresponding parameters and commands of irradiation can be entered again only after the input part 31 is unlocked. In embodiments of the invention, after pressing the irradiation pause button 53 or the irradiation cancel button 54, the radiation therapy is stopped. At the same time, the input part 31, which is configured to enter the corresponding information, is unlocked, after which the corresponding information can be changed or added via the input part 31. Of course, the input part can be automatically unlocked after the completion of the radiation therapy. In this way, incorrect input is prevented, while the operability of the system is ensured. For example, after checking that the information about the patient S, the irradiation parameters and other information are correct, the medical staff presses the information correctness confirmation button 51 on the control interface, and then presses the irradiation start button 52. Then the system starts the radiation therapy. At this time, the input part 31, which is configured to enter the corresponding information, is locked, and the information cannot be entered.

[00164] Until the completion of the radiation therapy, the report generation button 55 is also locked, and the report generation button 55 can be automatically unlocked only after the completion of the radiation therapy, that is, the function of generating a therapy report can be turned on.

[00165] The protection part is not limited to being applied to the irradiation start button 52 as in the above embodiment, but is also applicable to other important buttons and parameter input windows. In addition, the means for implementing the secondary confirmation and protection of the button may be software or hardware, for example, the protection part may also be a key or a switch on the control panel. Before the key or switch is turned on, some operations may not be performed, and the corresponding operations can be performed only when the key or switch is turned on.

[00166] In embodiments of the invention, the irradiation commands and parameters are entered via a touch screen. In other embodiments, a key (e.g., a mechanical key) may be used for entry.

[00167] The malfunction prevention system can not only provide the functions of setting parameters and inputting control commands if necessary, but also reduce the incorrect input of parameters or repeated input of commands due to an operation error or other reasons, which reduces the risk in the operation of the device.

[00168] In the neutron capture therapy device according to the invention, the neutron dose detection device 21 is provided with at least two count rate channels with different neutron detection sensitivities, that is, a first count rate channel 201 and a second count rate channel 202, and a count rate channel selection unit 216 that selects a more accurate count rate according to the actual situation, for calculating the neutron dose, so that the count rate loss error caused by the pulse resolution time can be avoided. In this case, the statistical error caused by the low count rate is taken into account, so that the accuracy of the neutron dose detection in real time is improved, thereby improving the accuracy of the neutron dose of the neutron beam irradiating the patient S. In addition, the neutron dose detection device 21 is also provided with a count rate correction unit 217, which can calculate the pulse resolution time of the detector 211 and can calculate a count rate correction coefficient in accordance with the pulse resolution time, so that the count rate error caused by the pulse resolution time is corrected, further improving the accuracy of the neutron dose detection in real time, and further improving the accuracy of the neutron beam dose irradiating the patient S.

[00169] The neutron capture therapy device according to the invention is also provided with a monitoring system 3. The monitoring system 3 is provided with a correction part 37 that periodically corrects the irradiation parameters stored in the storage part 32 and configured to execute a therapy plan, so that it is ensured that the neutron dose of the neutron beam irradiating the patient S is substantially consistent with the preset neutron dose, and the accuracy of the neutron dose of the neutron beam irradiating the patient S is further improved. In addition, when the percentage of the real-time neutron dose to the preset neutron dose is greater than or equal to 97%, the neutron dose rate is reduced and the irradiation time is correspondingly increased in order to prevent the patient S from absorbing excess neutrons when irradiated with a neutron beam with a high neutron dose rate, which also has the effect of improving the accuracy of the neutron dose of the neutron beam irradiating the patient S.

[00170] The neutron capture therapy device according to the invention is also provided with a correction system. The correction system comprehensively takes into account the influence of factors such as the positioning deviation of the patient S, the real-time neutron dose rate deviation, the real-time boron concentration, or the like on the preset neutron dose, and inputs a neutron correction coefficient K ₁ and a boron correction coefficient K ₂ to correct the preset neutron dose, so that the accuracy of the neutron dose of the neutron beam irradiating the patient S from the source is ensured.

[00171] Finally, the neutron capture therapy device according to the invention can apply a precise dose of neutron beam radiation to a patient and reduce the risk caused by erroneous operation of the device, provided that the operability of the device is ensured.

[00172] The neutron capture therapy device according to the invention is not limited to the solution described above in the examples of its embodiments and the designs shown in the drawings. Obvious changes, replacements or modifications of materials, shapes and positions of components in them based on the invention are included in the scope of legal protection of the invention.

Claims (24)

1. A neutron dose detection device comprising a detector configured to detect a neutron and output a signal, a signal processing unit configured to process a signal output from the detector, a counter configured to count the signal output from the signal processing unit to obtain a count rate, and a count rate correction unit configured to correct the count rate, wherein the count rate correction unit comprises a pulse resolution time calculation part, the first count rate is recorded by the counter when the neutron beam flux is the flux of a first neutron beam, the second count rate is recorded by the counter when the neutron beam flux is the flux of a second neutron beam, the pulse resolution time calculation part is configured to calculate the pulse resolution time based on the first count rate, the flux of the first neutron beam, the second count rate and the flux of the second neutron beam, wherein the flux of the first neutron beam is less than the flux of the second neutron beam. 2. The neutron dose detection device according to claim 1, wherein the pulse resolution time calculation portion is periodically configured to calculate the pulse resolution time τ using formula (1-5) (1-5), where in the low flux state I ₁ is the flux of the first neutron beam; C ₁ – the first count rate recorded by the counter when the neutron beam flux is equal to I ₁ ; I ₂ – flux of the second neutron beam; in the high flux state; C ₂ is the second count rate recorded by the counter when the neutron beam flux is I ₂ . 3. The neutron dose detection device according to claim 2, wherein the count rate correction unit comprises a count rate correction calculation part, the count rate correction calculation part is configured to periodically calculate the corrected count rate C _k using formula (1-1) (1-1), where K is the count rate correction coefficient; Ct – real-time count rate recorded by the counter. 4. The neutron dose detection device according to claim 3, wherein the count rate correction unit comprises a part for calculating the count rate correction coefficient, wherein the part for calculating the count rate correction coefficient is configured to periodically calculate the count rate correction coefficient K using formula (1-2) (1-2), where n is the number of pulses recorded by the counter per unit of time; m – the number of signal pulses actually generated in the detector per unit of time. 5. The neutron dose detection device according to claim 4, wherein the count rate correction unit is configured to derive formula (1-4) by combining formula (1-2) with formula (1-3) for periodically calculating the count rate correction coefficient K (1-3), (1-4), where τ is the pulse resolution time. 6. A neutron dose detection device according to claim 1, comprising at least two count rate channels and a count rate channel selection unit configured to select one of the at least two count rate channels, wherein the count rate channel comprises a detector configured to detect a neutron and output a signal, a signal processing unit configured to process a signal output from the detector, and a counter configured to count the signal output from the signal processing unit to obtain the count rate, wherein the count rate channels comprise at least a first count rate channel comprising a first detector and a second count rate channel comprising a second detector, wherein the sensitivity of the first detector detecting the neutron differs from the sensitivity of the second detector detecting the neutron. 7. A neutron dose detection device according to claim 6, wherein a beam of charged particles accelerated by an accelerator undergoes a nuclear reaction with a target to generate a neutron, and the count rate channel selection unit is configured to select a count rate channel in accordance with the accelerator power, the neutron beam flux, or the distance between the detector and the neutron source, wherein a more accurate count rate is selected by the count rate channel selection unit for transmission to calculate the dose. 8. The neutron dose detection device according to claim 6, wherein, when the neutron beam flux is large, the first detector is used for detection, when the neutron beam flux is small, the second detector is used for detection, and the sensitivity of the first detector is less than the sensitivity of the second detector. 9. The neutron dose detection device according to claim 1, further comprising a conversion unit configured to convert the count rate into a neutron flux density or neutron dose rate, and an integration unit configured to integrate the neutron flux density or neutron dose rate to obtain the neutron dose. 10. A neutron capture therapy device comprising a neutron dose detection device according to claim 1 and comprising a neutron beam irradiation system comprising a neutron beam generation module configured to generate a neutron beam, and a beam adjustment module configured to adjust the neutron beam and comprising a moderator configured to slow down the neutron beam, and a reflector configured to direct the deflected neutron back into the moderator.