WO2017054556A1 - 用于中子捕获治疗系统的辐射线检测系统及辐射线检测方法 - Google Patents

用于中子捕获治疗系统的辐射线检测系统及辐射线检测方法 Download PDF

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WO2017054556A1
WO2017054556A1 PCT/CN2016/090271 CN2016090271W WO2017054556A1 WO 2017054556 A1 WO2017054556 A1 WO 2017054556A1 CN 2016090271 W CN2016090271 W CN 2016090271W WO 2017054556 A1 WO2017054556 A1 WO 2017054556A1
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neutron
radiation
charged particle
treatment system
particle beam
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PCT/CN2016/090271
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English (en)
French (fr)
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刘渊豪
陈韦霖
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南京中硼联康医疗科技有限公司
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Priority claimed from CN201510629532.6A external-priority patent/CN106552321A/zh
Priority claimed from CN201520760006.9U external-priority patent/CN205073542U/zh
Application filed by 南京中硼联康医疗科技有限公司 filed Critical 南京中硼联康医疗科技有限公司
Priority to EP16850180.7A priority Critical patent/EP3342459B1/en
Priority to JP2018515882A priority patent/JP2018529437A/ja
Publication of WO2017054556A1 publication Critical patent/WO2017054556A1/zh
Priority to US15/913,008 priority patent/US20180250528A1/en
Priority to US17/516,775 priority patent/US11740370B2/en

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N5/1048—Monitoring, verifying, controlling systems and methods
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N5/1048—Monitoring, verifying, controlling systems and methods
    • A61N5/1071—Monitoring, verifying, controlling systems and methods for verifying the dose delivered by the treatment plan
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N5/1042—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy with spatial modulation of the radiation beam within the treatment head
    • A61N5/1043—Scanning the radiation beam, e.g. spot scanning or raster scanning
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N5/1048—Monitoring, verifying, controlling systems and methods
    • A61N5/1064—Monitoring, verifying, controlling systems and methods for adjusting radiation treatment in response to monitoring
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N5/1048—Monitoring, verifying, controlling systems and methods
    • A61N5/1064—Monitoring, verifying, controlling systems and methods for adjusting radiation treatment in response to monitoring
    • A61N5/1065—Beam adjustment
    • A61N5/1067—Beam adjustment in real time, i.e. during treatment
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T3/00—Measuring neutron radiation
    • G01T3/008—Measuring neutron radiation using an ionisation chamber filled with a gas, liquid or solid, e.g. frozen liquid, dielectric
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T3/00—Measuring neutron radiation
    • G01T3/06—Measuring neutron radiation with scintillation detectors
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N2005/1085—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy characterised by the type of particles applied to the patient
    • A61N2005/1087—Ions; Protons
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N2005/1085—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy characterised by the type of particles applied to the patient
    • A61N2005/109—Neutrons
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
    • A61N5/00—Radiation therapy
    • A61N5/10—X-ray therapy; Gamma-ray therapy; Particle-irradiation therapy
    • A61N2005/1092—Details
    • A61N2005/1094—Shielding, protecting against radiation

Definitions

  • the present invention relates to a radiation detection system, and more particularly to a radiation detection system for a neutron capture treatment system; the present invention also relates to a radiation detection method, and more particularly to a neutron capture treatment system Radiation detection method.
  • neutron capture therapy combines the above two concepts, such as boron neutron capture therapy, by the specific agglomeration of boron-containing drugs in tumor cells, combined with precise neutron beam regulation, providing better radiation than traditional radiation. Cancer treatment options.
  • BNCT Boron Neutron Capture Therapy
  • boron-containing ( 10 B) drugs with 10 B(n, ⁇ ) 7 Li neutron capture and nuclear splitting reactions.
  • Two heavy charged particles of 4 He and 7 Li are produced. 1 and 2, which respectively show a schematic diagram of a boron neutron capture reaction and a 10 B(n, ⁇ ) 7 Li neutron capture nuclear reaction equation, the average energy of the two charged particles is about 2.33 MeV, which has high linearity.
  • Linear Energy Transfer (LET) short-range characteristics, the linear energy transfer and range of ⁇ particles are 150 keV/ ⁇ m and 8 ⁇ m, respectively, while the 7 Li heavy particles are 175 keV/ ⁇ m and 5 ⁇ m.
  • the total range of the two particles is approximately equivalent.
  • a cell size so the radiation damage caused by the organism can be limited to the cell level.
  • the boron-containing drug is selectively accumulated in the tumor cells, with appropriate neutron source, it can cause too much damage to normal tissues. Under the premise, the purpose of locally killing tumor cells is achieved.
  • a neutron capture treatment system for example, by attaching a gold wire for measuring a neutron beam to an irradiated body in advance, removing the gold wire in the middle of the irradiation of the neutron beam, and measuring the amount of radiation of the gold wire. To measure the dose of the neutron beam in the middle of the irradiation. And controlling (eg, stopping, etc.) neutron capture treatment according to the measured irradiation dose The treatment system is such that the neutron beam is irradiated to the irradiated body at a planned irradiation dose.
  • the irradiation dose rate of the neutron beam is changed after measuring the amount of radiation of the gold wire for some reason, it is not possible to sufficiently correspond to the fluctuation of the neutron beam, and it is possible to make the irradiation dose according to the plan. It is difficult to irradiate the neutron beam to the irradiated body. That is to say, in the above neutron capture treatment system, the neutron beam irradiation dose cannot be detected in real time.
  • the neutron capture treatment system comprising a charged particle beam, a charged particle beam for passing a charged particle beam a neutron generating portion that undergoes a nuclear reaction with a charged particle beam to generate a neutron beam, a beam shaping body for adjusting a neutron beam flux and quality generated by a neutron generating portion, and a beam shaping body adjacent to the beam shaping body a beam exit, wherein the neutron generating portion is housed in the beam shaping body, and the radiation detecting system comprises a radiation detecting device disposed inside the beam shaping body or outside the beam shaping, and the radiation detecting device is configured to detect the charged particles in real time.
  • a neutron beam or a generated gamma ray that is overflowed by a neutron generating portion after a nuclear reaction with a neutron generating portion.
  • the radiation detecting system further includes control means for issuing a human-perceived signal based on the detection result of the radiation detecting means to confirm the next operation of the neutron capture treatment system.
  • human-perceived signals may be signals that can be sensed by human functional organs such as auditory, visual, tactile, or olfactory, such as one of various signals such as an audible alarm, an alarm light, vibration, and a pungent odor. Many forms.
  • the neutron capture treatment system further includes an accelerator for accelerating the charged particle beam, the control device including a control portion and a display portion, the control portion displays the detection result of the radiation detection system through the display portion and feeds the detection result to the accelerator to confirm
  • the display unit can be a common display device such as a television or a liquid crystal display.
  • the radiation detecting device is a free chamber or a scintillation detecting head, and the radiation detecting system estimates the intensity of the neutron beam by detecting the signal to adjust the charged particle beam and control the irradiation dose.
  • Common radiation detection systems that enable real-time detection include two different detection principles: ionization chamber and scintillation detector.
  • the neutron beam detection system detects the neutron beam
  • the He-3 proportional counter the BF 3 proportional counter
  • the split free chamber and the boron ionization chamber are used as the base of the ionization chamber structure.
  • the ionization chamber is used as the inflatable type. Ionization chamber.
  • a scintillation probe can be used, and the scintillation probe can be divided into organic and inorganic materials.
  • the scintillation probe is added with a high thermal neutron capture cross section such as Li or B. element.
  • the neutron energy detected by such detectors is mostly thermal neutrons, which are heavy-charged particles and nuclear fission fragments released by the element or neutron capture or nuclear fission reaction, in the ionization chamber or A large number of ion pairs are generated in the scintillation probe.
  • the current signal can be converted into a voltage pulse signal through appropriate circuit conversion. By analyzing the magnitude of the voltage pulse, the neutron signal and the gamma signal can be easily distinguished.
  • the gas pressure in the ionization chamber, the concentration of the crackable material or boron coating, or the concentration of the high-neutron capture cross-section element in the scintillation probe can be appropriately reduced, so that the pair can be effectively reduced.
  • the sensitivity of neutrons avoids signal saturation.
  • the neutron beam detecting system of the present embodiment employs a free chamber.
  • the neutron beam passes through the free chamber, it acts freely with the gas molecules of the free chamber or the wall of the free chamber to generate electrons and positively charged ions.
  • the electrons and positively charged ions are referred to as the ion pairs described above.
  • the free chamber has an applied electric field high voltage, the electrons move toward the central anode wire, and the positively charged ions move toward the surrounding cathode wall, thereby generating a measurable electronic pulse signal.
  • the energy required to generate a pair of ions for a gas molecule is referred to as the average free energy, which varies depending on the type of gas, such as an average free energy of air of about 34 eV. If there is a 340 keV neutron beam or gamma ray, the air will produce about 10k ion pairs.
  • the neutron beam detecting system in this embodiment employs a scintillation probe.
  • Some substances emit visible light when they absorb energy. This substance is called a scintillating substance. It uses free radiation to excite electrons in the crystal or molecule to an excited state, and the fluorescence emitted when the electrons return to the ground state is collected for neutron beam monitoring.
  • the visible light emitted by the scintillation probe and the neutron beam can be converted into electrons by a photomultiplier tube, and then multiplied and amplified.
  • the electron multiplication magnification can reach 107 to 108.
  • the number of electrons output from the anode is proportional to the energy of the incident neutron beam, so the scintillation probe can measure the energy of the neutron beam or gamma ray.
  • the beam shaping body includes a reflector, a retarding body surrounded by the reflector and adjacent to the neutron generating portion, a thermal neutron absorber adjacent to the retarding body, and a radiation shield disposed in the beam shaping body.
  • Another aspect of the present invention is to provide a radiation detecting method for improving the accuracy of a neutron beam irradiation dose of a neutron capture treatment system
  • the neutron capture treatment system includes a charged particle beam for passing a charged particle beam a charged particle beam inlet, a neutron generating unit that generates a neutron beam by nuclear reaction with the charged particle beam, a beam shaping body for adjusting the neutron beam flux and quality generated by the neutron generating portion, and adjacent to the beam a beam exit of the beam shaping body, wherein the neutron generating portion is housed in the beam shaping body;
  • the radiation detecting system comprises a radiation detecting device disposed inside the beam shaping body or outside the beam shaping, and the radiation detecting device is configured to detect The neutron beam or the generated gamma ray that is emitted by the neutron generating portion after the nuclear particle beam undergoes a nuclear reaction with the neutron generating portion;
  • the detecting method includes a detecting step, and the detecting step detects in real time that
  • the detection method further includes a control step of controlling the next operation of the neutron capture treatment system based on the detection result in the detection step.
  • the neutron capture treatment system further comprises an accelerator for accelerating the charged particle beam, the controlling step controlling the accelerator to confirm the next operation of the accelerator based on the detection result in the detecting step.
  • the control device includes a display portion, and the detecting method further includes a display step of displaying the detection result in the detecting step via the display portion.
  • the detecting method further includes an estimating step of estimating the intensity of the neutron beam based on the detection result in the detecting step to adjust the charged particle beam and controlling the irradiation dose.
  • Figure 1 is a schematic diagram of a boron neutron capture reaction.
  • Figure 2 is a 10 B(n, ⁇ ) 7 Li neutron capture nuclear reaction equation.
  • FIG 3 is a plan view of a radiation detecting system for a neutron capture treatment system in an embodiment of the present invention.
  • Neutron capture therapy has been increasingly used as an effective means of treating cancer in recent years, with boron neutron capture therapy being the most common, and neutrons supplying boron neutron capture therapy can be supplied by nuclear reactors or accelerators.
  • Embodiments of the invention take the accelerator boron neutron capture treatment as an example.
  • the basic components of the accelerator boron neutron capture treatment typically include an accelerator, target and heat removal for accelerating charged particles (eg, protons, deuterons, etc.).
  • Systems and beam shaping bodies in which accelerated charged particles interact with metal targets to produce neutrons, depending on the desired neutron yield and energy, the energy and current of the accelerated charged particles, and the physicochemical properties of the metal target.
  • the nuclear reactions that are often discussed are 7 Li(p,n) 7 Be and 9 Be(p,n) 9 B, both of which are endothermic.
  • the energy thresholds of the two nuclear reactions are 1.881 MeV and 2.055 MeV, respectively. Since the ideal neutron source for boron neutron capture therapy is the superheated neutron of the keV energy level, theoretically, if proton bombardment with energy only slightly higher than the threshold is used.
  • a metallic lithium target that produces relatively low-energy neutrons that can be used clinically without too much slow processing.
  • proton interaction cross sections for lithium metal (Li) and base metal (Be) targets and threshold energy Not high, in order to generate a sufficiently large neutron flux, a higher energy proton is usually used to initiate the nuclear reaction.
  • the ideal target should have a high neutron yield, produce a neutron energy distribution close to the epithermal neutron energy zone (described in detail below), no excessively strong radiation generation, safe and inexpensive to operate, and high temperature resistance.
  • a target made of lithium metal is used in the embodiment of the present invention.
  • the material of the target can also be made of other metallic materials than the metal materials discussed above.
  • the requirements for the heat removal system vary depending on the selected nuclear reaction.
  • 7 Li(p,n) 7 Be has a lower melting point and thermal conductivity coefficient of the metal target (lithium metal), and the requirements for the heat removal system are higher.
  • 9 Be(p,n) 9 B is high.
  • a nuclear reaction of 7 Li(p,n) 7 Be is employed in an embodiment of the invention.
  • the nuclear reaction of the charged particles from the nuclear reactor or the accelerator produces a mixed radiation field, that is, the beam contains low-energy to high-energy neutrons and photons; for deep tumors in boron
  • Sub-capture treatment in addition to super-thermal neutrons, the more radiation content, the greater the proportion of non-selective dose deposition in normal tissue, so these will cause unnecessary doses of radiation should be minimized.
  • the human head tissue prosthesis is used for dose calculation in the embodiment of the present invention, and the prosthetic beam quality factor is used as the neutron shot. The design reference for the bundle will be described in detail below.
  • the International Atomic Energy Agency has given five air beam quality factor recommendations for clinical neutron sources for clinical boron neutron capture therapy. These five recommendations can be used to compare the pros and cons of different neutron sources and provide The reference basis for selecting the neutron generation route and designing the beam shaping body.
  • the five recommendations are as follows:
  • Epithermal neutron beam flux Epithermal neutron flux>1x 10 9 n/cm 2 s
  • the superheated neutron energy region is between 0.5eV and 40keV, the thermal neutron energy region is less than 0.5eV, and the fast neutron energy region is greater than 40keV.
  • the neutron beam flux and the concentration of boron-containing drugs in the tumor determine the clinical treatment time. If the concentration of the boron-containing drug in the tumor is high enough, the requirement for the flux of the neutron beam can be reduced; conversely, if the concentration of the boron-containing drug in the tumor is low, a high-flux superheated neutron is required to give the tumor a sufficient dose.
  • the IAEA's requirement for the epithermal neutron beam flux is that the number of epithermal neutrons per square centimeter per second is greater than 10 9 .
  • the neutron beam at this flux can roughly control the treatment of current boron-containing drugs. In one hour, short treatment time, in addition to the advantages of patient positioning and comfort, can also make more effective use of boron-containing drugs in the tumor for a limited residence time.
  • fast neutron contamination is defined as the fast neutron dose accompanying the unit's superheated neutron flux.
  • the IAEA's recommendation for fast neutron contamination is less than 2x 10 -13 Gy-cm 2 /n.
  • ⁇ -rays are strong radiation, which will non-selectively cause dose deposition of all tissues in the beam path. Therefore, reducing ⁇ -ray content is also a necessary requirement for neutron beam design.
  • ⁇ -ray pollution is defined as the unit of superheated neutron flux.
  • the gamma dose is recommended by IAEA for gamma ray contamination to be less than 2 x 10 -13 Gy-cm 2 /n.
  • thermal neutrons Due to the fast decay rate and poor penetrability of thermal neutrons, most of the energy is deposited on the skin tissue after entering the human body. In addition to melanoma and other epidermal tumors, thermal neutrons are needed as the neutron source for boron neutron capture therapy. Deep tumors such as tumors should reduce the thermal neutron content.
  • the IAEA's ratio of thermal neutron to superheated neutron flux is recommended to be less than 0.05.
  • the ratio of neutron current to flux represents the directionality of the beam. The larger the ratio, the better the forward neutron beam, and the high forward neutron beam can reduce the surrounding normal tissue dose caused by neutron divergence. It also increases the elasticity of the treatment depth and posture.
  • the IAEA's ratio of neutron current to flux is recommended to be greater than 0.7.
  • the prosthesis is used to obtain the dose distribution in the tissue, and the prosthetic beam is derived from the normal tissue and the dose-depth curve of the tumor. Quality factor.
  • the following three parameters can be used to compare the benefits of different neutron beam treatments.
  • the tumor dose is equal to the depth of the maximum dose of normal tissue. At this post-depth, the tumor cells receive a dose that is less than the maximum dose of normal tissue, ie, the advantage of boron neutron capture is lost. This parameter represents the penetrating ability of the neutron beam. The greater the effective treatment depth, the deeper the tumor depth that can be treated, in cm.
  • the effective dose rate of the tumor is also equal to the maximum dose rate of normal tissues. Because the total dose received by normal tissues is a factor that affects the total dose of tumor, the parameters affect the length of treatment. The greater the effective dose rate, the shorter the irradiation time required to give a tumor dose, the unit is cGy/mA. -min.
  • the effective therapeutic dose ratio received by the tumor and normal tissue is called the effective therapeutic dose ratio; the calculation of the average dose can be obtained by integrating the dose-depth curve.
  • the following embodiments are also used in the present invention to evaluate the neutron beam dose performance. Good and bad parameters:
  • Irradiation time ⁇ 30min (the proton current used by the accelerator is 10mA)
  • RBE Relative Biological Effectiveness
  • an aspect of the present embodiment is to provide a radiation detecting system for improving the accuracy of a neutron beam irradiation dose of a neutron capture treatment system; another aspect of the embodiment is to provide an improved neutron.
  • a method of radiation detection that captures the accuracy of the neutron beam exposure dose of a treatment system.
  • the neutron capture treatment system includes an accelerator 10, a beam expander 20, a charged particle beam inlet for passing the charged particle beam P, a charged particle beam P, and a nuclear reaction with the charged particle beam P to generate a neutron beam N.
  • the sub-generation unit T, the beam shaping body 30 for adjusting the neutron beam flux and quality generated by the neutron generation unit T, and the beam shaping body 30 The beam exit 40 and the object 50 illuminated by the beam exiting the beam exit 40.
  • the accelerator 10 is used to accelerate the charged particle beam P, and may be an accelerator suitable for an accelerator type neutron capture treatment system such as a cyclotron or a linear accelerator; the charged particle beam P here is preferably a proton beam; the beam expanding device 20 is disposed at Between the accelerator 10 and the neutron generating portion T; the charged particle beam inlet is adjacent to the neutron generating portion T and housed in the beam shaping body 30, as shown in Fig.
  • the neutron generating portion T is housed in the beam shaping body 30, where the neutron generating portion T is preferably lithium metal;
  • the beam shaping body 30 includes the reflector 31 and is surrounded by the reflector 31
  • the retarding body 32 adjacent to the neutron generating portion T, the thermal neutron absorber 33 adjacent to the retarding body 32, the radiation shield 34 provided in the beam shaping body 30, the neutron generating portion T and the self-charged portion The charged particle beam P incident at the entrance of the particle beam undergoes a nuclear reaction to generate a neutron beam N, the neutron beam defines a major axis, and the retarding body 32 decelerates the neutron generated from the neutron generating portion T to the superheated neutron energy region.
  • the reflector 31 will deviate from the principal axis of the neutron
  • the thermal neutron absorber 33 is used to absorb thermal neutrons to avoid excessive doses with shallow normal tissue during treatment, and the radiation shield 34 is used to shield leaking neutrons and photons. Reducing the normal tissue dose in the non-irradiated area; the beam exit 40 may also be referred to as a neutron beam convergence or collimator that reduces the width of the neutron beam to concentrate the neutron beam;
  • the beamlet illuminates the target portion of the object 50 to be illuminated.
  • a radiation detecting system for improving the accuracy of a neutron beam irradiation dose of a neutron capture treatment system comprising a radiation detecting device 60 and a control device 70 disposed inside the beam shaping body 30 or outside the beam shaping body 30,
  • the radiation detecting device 60 is for detecting in real time the neutron beam or the generated gamma ray which is generated by the neutron generating portion T after the charged particle beam P has undergone a nuclear reaction with the neutron generating portion T.
  • the control device 70 issues a human-perceived signal based on the detection result of the radiation detecting device to confirm the next operation of the neutron capture therapy system.
  • human-perceived signals may be signals that can be sensed by human functional organs such as auditory, visual, tactile, or olfactory, such as one of various signals such as an audible alarm, an alarm light, vibration, and a pungent odor. Many forms.
  • the neutron capture treatment system further includes an accelerator for accelerating the charged particle beam
  • the control device 70 includes a control portion 71 and a display portion 72, and the control portion 71 displays the detection result of the radiation detecting system through the display portion 72 and displays the detection result
  • the accelerator 10 is fed back to confirm the next operation of the accelerator, and the display portion can be a common display device such as a television or a liquid crystal display.
  • Common radiation detection systems that enable real-time detection include two different detection principles: ionization chamber and scintillation detector.
  • the neutron beam detection system detects the neutron beam
  • the He-3 proportional counter the BF 3 proportional counter
  • the split free chamber and the boron ionization chamber are used as the base of the ionization chamber structure.
  • the ionization chamber is used as the inflatable type. Ionization chamber.
  • a scintillation probe can be used, and the scintillation probe can be divided into organic and inorganic materials.
  • the scintillation probe is added with a high thermal neutron capture cross section such as Li or B. element.
  • the neutron energy detected by such detectors is mostly thermal neutrons, which are heavy-charged particles and nuclear fission fragments released by the element or neutron capture or nuclear fission reaction, in the ionization chamber or A large number of ion pairs are generated in the scintillation probe.
  • the current signal can be converted into a voltage pulse signal through appropriate circuit conversion. By analyzing the magnitude of the voltage pulse, the neutron signal and the gamma signal can be easily distinguished.
  • the gas pressure in the ionization chamber, the concentration of the crackable material or boron coating, or the concentration of the high-neutron capture cross-section element in the scintillation probe can be appropriately reduced, so that the pair can be effectively reduced.
  • the sensitivity of neutrons avoids signal saturation.
  • the neutron beam detecting system of the present embodiment employs a free chamber.
  • the neutron beam passes through the free chamber, it acts freely with the gas molecules of the free chamber or the wall of the free chamber to generate electrons and positively charged ions.
  • the electrons and positively charged ions are referred to as the ion pairs described above.
  • the free chamber has an applied electric field high voltage, the electrons move toward the central anode wire, and the positively charged ions move toward the surrounding cathode wall, thereby generating a measurable electronic pulse signal.
  • the energy required to generate a pair of ions for a gas molecule is referred to as the average free energy, which varies depending on the type of gas, such as an average free energy of air of about 34 eV. If there is a 340 keV neutron beam or gamma ray, the air will produce about 10k ion pairs.
  • the neutron beam detecting system in this embodiment employs a scintillation probe.
  • Some substances emit visible light when they absorb energy. This substance is called a scintillating substance. It uses free radiation to excite electrons in the crystal or molecule to an excited state, and the fluorescence emitted when the electrons return to the ground state is collected for neutron beam monitoring.
  • the visible light emitted by the scintillation probe and the neutron beam can be converted into electrons by a photomultiplier tube, and then multiplied and amplified.
  • the electron multiplication magnification can reach 107 to 108.
  • the number of electrons output from the anode is proportional to the energy of the incident neutron beam, so the scintillation probe can measure the energy of the neutron beam or gamma ray.
  • the radiation detection system estimates the intensity of the neutron beam by detecting the signal to adjust the charged particle beam and control the irradiation dose.
  • the neutron beam detecting system whether disposed in the beam shaping body or disposed adjacent to the beam shaping body, can be used to detect neutrons in the beam shaping body at the set position.
  • a detection device for the intensity variation and spatial distribution of the beam can be selected.
  • the neutron capture treatment system includes a charged particle beam for passing the charged particle beam a charged particle beam inlet, a neutron generating unit that generates a neutron beam by nuclear reaction with the charged particle beam, a beam shaping body for adjusting the neutron beam flux and quality generated by the neutron generating portion, and adjacent to a beam exit of the beam shaping body, wherein the neutron generating portion is housed in the beam shaping body;
  • the radiation detecting system comprises a radiation detecting device disposed inside the beam shaping body or outside the beam shaping, and the radiation detecting device is used for Detecting a neutron beam or a generated gamma ray that is discharged by a neutron generating portion after a nuclear reaction with a neutron generating portion;
  • the detecting method includes a detecting step, and the detecting step detects a nuclear reaction of the charged particle beam with the neutron
  • the detection method further includes a control step of controlling the next operation of the neutron capture treatment system based on the detection result in the detection step.
  • the neutron capture treatment system further comprises an accelerator for accelerating the charged particle beam, the controlling step controlling the accelerator to confirm the next operation of the accelerator based on the detection result in the detecting step.
  • the control device includes a display portion, and the detecting method further includes a display step of displaying the detection result in the detecting step via the display portion.
  • the detecting method further includes an estimating step of estimating the intensity of the neutron beam based on the detection result in the detecting step to adjust the charged particle beam and controlling the irradiation dose.
  • the radiation detecting system for a neutron capture treatment system disclosed in the present invention is not limited to the contents described in the above embodiments and the structures represented in the drawings. Obvious modifications, substitutions, or alterations of the materials, shapes and positions of the components in the present invention are within the scope of the invention as claimed.

Abstract

本发明的一方面在于提供一种提高中子捕获治疗系统的中子束照射剂量的精确度的辐射线检测系统，中子捕获治疗系统包括带电粒子束、用于通过带电粒子束的带电粒子束入口、经与带电粒子束发生核反应从而产生中子束的中子产生部、用于调整经中子产生部产生的中子射束通量与品质的射束整形体和邻接于射束整形体的射束出口，其中，中子产生部容纳在射束整形体内，辐射线检测系统包括设置在射束整形体内或者射束整形体外的辐射线检测装置，辐射线检测装置用于实时检测带电粒子束经与中子产生部发生核反应后由中子产生部溢出的中子束或者生成的γ射线。本发明的另一方面在于提供一种提高中子捕获治疗系统的中子束照射剂量的精确度的辐射线检测方法。

Description

用于中子捕获治疗系统的辐射线检测系统及辐射线检测方法 技术领域
本发明涉及一种辐射线检测系统，尤其涉及一种用于中子捕获治疗系统的辐射线检测系统；本发明还涉及一种辐射线检测方法，尤其涉及一种用于中子捕获治疗系统的辐射线检测方法。
背景技术
随着原子科学的发展，例如钴六十、直线加速器、电子射束等放射线治疗已成为癌症治疗的主要手段之一。然而传统光子或电子治疗受到放射线本身物理条件的限制，在杀死肿瘤细胞的同时，也会对射束途径上大量的正常组织造成伤害；另外由于肿瘤细胞对放射线敏感程度的不同，传统放射治疗对于较具抗辐射性的恶性肿瘤(如：多行性胶质母细胞瘤(glioblastoma multiforme)、黑色素细胞瘤(melanoma))的治疗成效往往不佳。
为了减少肿瘤周边正常组织的辐射伤害，化学治疗(chemotherapy)中的标靶治疗概念便被应用于放射线治疗中；而针对高抗辐射性的肿瘤细胞，目前也积极发展具有高相对生物效应(relative biological effectiveness,RBE)的辐射源，如质子治疗、重粒子治疗、中子捕获治疗等。其中，中子捕获治疗便是结合上述两种概念，如硼中子捕获治疗，借由含硼药物在肿瘤细胞的特异性集聚，配合精准的中子射束调控，提供比传统放射线更好的癌症治疗选择。
硼中子捕获治疗(Boron Neutron Capture Therapy,BNCT)是利用含硼(10B)药物对热中子具有高捕获截面的特性，借由10B(n,α)7Li中子捕获及核分裂反应产生4He和7Li两个重荷电粒子。参照图1和图2，其分别示出了硼中子捕获反应的示意图和10B(n,α)7Li中子捕获核反应方程式，两荷电粒子的平均能量约为2.33MeV，具有高线性转移(Linear Energy Transfer,LET)、短射程特征，α粒子的线性能量转移与射程分别为150keV/μm、8μm，而7Li重荷粒子则为175keV/μm、5μm，两粒子的总射程约相当于一个细胞大小，因此对于生物体造成的辐射伤害能局限在细胞层级，当含硼药物选择性地聚集在肿瘤细胞中，搭配适当的中子射源，便能在不对正常组织造成太大伤害的前提下，达到局部杀死肿瘤细胞的目的。
而在中子捕获治疗系统中的射束检测和诊断属于一个很重要的课题，这直接关乎于照射治疗的剂量和效果。现有技术有揭示一种中子捕获治疗系统中，例如通过预先对被照射体贴附中子束测定用的金丝，在中子束的照射中途取下金丝并测定该金丝的辐射化量，来测定照射中途的中子束的照射剂量。并且根据该测定的照射剂量来控制(例如停止等)中子捕获治 疗系统，以便使中子束以按照计划的照射剂量来照射至被照射体。
但是此时，例如若因某种原因而在测定金丝的辐射化量之后中子束的照射剂量率有所变动，则无法与该种变动充分对应，而有使以按照计划的照射剂量来将中子束照射至被照射体处一事变得困难之虞。也就是说，在上述中子捕获治疗系统中，不能实时的检测中子束照射剂量。
因此，有必要提出一种能够提高中子束照射剂量的精确度的用于中子捕获治疗系统的辐射线检测系统及辐射线检测方法。
发明内容
本发明的一个方面在于提供一种提高中子捕获治疗系统的中子束照射剂量的精确度的辐射线检测系统，中子捕获治疗系统包括带电粒子束、用于通过带电粒子束的带电粒子束入口、经与带电粒子束发生核反应从而产生中子束的中子产生部、用于调整经中子产生部产生的中子射束通量与品质的射束整形体和邻接于射束整形体的射束出口，其中，中子产生部容纳在射束整形体内，辐射线检测系统包括设置在射束整形体内或者射束整形体外的辐射线检测装置，辐射线检测装置用于实时检测带电粒子束经与中子产生部发生核反应后由中子产生部溢出的中子束或者生成的γ射线。
辐射线检测系统进一步包括控制装置，控制装置根据辐射线检测装置的检测结果发出人类感知的信号以确认中子捕获治疗系统的下一步作业。这种人类感知的信号可以是听觉、视觉、触觉或嗅觉等人类功能器官能够感知的信号，如发出声响的警报器、报警灯、振动、发出刺鼻的气味等多种信号中的一种或多种形式。
中子捕获治疗系统进一步包括用于将带电粒子束加速的加速器，控制装置包括控制部和显示部，控制部将辐射线检测系统的检测结果通过显示部显示出来并且将检测结果反馈给加速器以确认加速器的下一步作业，显示部可以为电视或液晶显示器等常见的显示设备。
辐射线检测装置为游离室或闪烁探测头，辐射线检测系统通过检测信号推算中子束发生强度从而调整带电粒子束并控制照射剂量。
可实现实时检测的常见辐射线检测系统有电离室及闪烁探测头两种不同检测原理。其中中子束检测系统检测中子束时，采用电离室结构为基底的有He-3比例计数器、BF3比例计数器、分裂游离室、硼电离室，检测γ射线时，采用电离室为充气式电离室。而检测中子束和γ射线均可以采用闪烁探测头，闪烁探测头则可以分为有机与无机材料，对于侦检热中子用途，其闪烁探测头多添加Li或B等高热中子捕获截面元素。简而言之，此类侦检器探测的中子能量多为热中子，皆为倚靠元素与中子发生捕获或核裂变反应所释出的重荷电粒子及核裂变碎片，于电离室或闪烁探测头内产生大量电离对(ion pair)，这些电荷被收集后，经过适当的电路转换，便可将电流信号转为电压脉冲信号。透过分析电压脉冲的大小，则可以轻易地分辨出中子信号及γ信号。在高强度中子场中，如BNCT，则可以适当地减少电离室的气体压力、可裂材或硼涂布的浓度或闪烁探测头内高中子捕获截面元素的浓度，便可以有效降低 其对中子的灵敏度，避免信号饱和的情况发生。
作为一种优选地，本实施例中中子束检测系统采用游离室。当中子束通过游离室时，与游离室内部气体分子或游离室的壁部发生游离作用，生成电子与带正电荷的例子，此电子和正电荷离子称为上述的离子对。由于游离室内有外加电场高压，因此电子朝中央阳极丝移动，正电荷离子朝周围的阴极壁移动，因而产生可测得的电子脉冲信号。使气体分子产生一离子对所需能量称为平均游离能，该值根据气体种类而异，如空气的平均游离能约为34eV。若有340keV的中子束或γ射线，会使空气产生约10k个离子对。
作为另一种优选地，本实施例中中子束检测系统采用闪烁探测头。某些物质吸收能量之后会放出可见光，此种物质称为闪烁物质。它是利用游离輻射将晶体或分子中的电子激发至激态，而当电子回到基态时放出的荧光被收集后用来作中子束监测。闪烁探测头与中子束作用后所发射的可见光，可利用光电倍增管将可见光转化为电子，再倍增放大，通常电子倍增放大率可达107至108。阳极输出的电子数与入射的中子束能量成正比，因此闪烁探测头能测量中子束或γ射线的能量。
射束整形体包括反射体、被反射体包围并邻接于中子产生部的缓速体、与缓速体邻接的热中子吸收体和设置在射束整形体内的辐射屏蔽。
本发明的另一个方面在于提供一种提高中子捕获治疗系统的中子束照射剂量的精确度的辐射线检测方法，其中，中子捕获治疗系统包括带电粒子束、用于通过带电粒子束的带电粒子束入口、经与带电粒子束发生核反应从而产生中子束的中子产生部、用于调整经中子产生部产生的中子射束通量与品质的射束整形体和邻接于射束整形体的射束出口，其中，中子产生部容纳在射束整形体内；辐射线检测系统包括设置在射束整形体内或者射束整形体外的辐射线检测装置，辐射线检测装置用于检测带电粒子束经与中子产生部发生核反应后由中子产生部溢出的中子束或者生成的γ射线；检测方法包括检测步骤，检测步骤实时检测带电粒子束经与中子产生部发生核反应后由中子产生部溢出的中子束或者生成的γ射线。
检测方法进一步包括控制步骤，控制步骤根据在检测步骤中的检测结果，控制中子捕获治疗系统的下一步作业。
作为一种优选地，中子捕获治疗系统进一步包括用于将带电粒子束加速的加速器，控制步骤根据在检测步骤中的检测结果，控制加速器以确认加速器的下一步作业。
控制装置包括显示部，检测方法进一步包括显示步骤，显示步骤将在检测步骤中的检测结果经由显示部显示出来。
检测方法进一步包括推算步骤，推算步骤根据在检测步骤中的检测结果推算中子束发生强度从而调整带电粒子束并控制照射剂量。
附图说明
图1是硼中子捕获反应示意图。
图2是10B(n,α)7Li中子捕获核反应方程式。
图3是本发明实施例中的用于中子捕获治疗系统的辐射线检测系统的平面示意图。
具体实施方式
中子捕获治疗作为一种有效的治疗癌症的手段近年来的应用逐渐增加，其中以硼中子捕获治疗最为常见，供应硼中子捕获治疗的中子可以由核反应堆或加速器供应。本发明的实施例以加速器硼中子捕获治疗为例，加速器硼中子捕获治疗的基本组件通常包括用于对带电粒子(如质子、氘核等)进行加速的加速器、靶材与热移除系统和射束整形体，其中加速带电粒子与金属靶材作用产生中子，依据所需的中子产率与能量、可提供的加速带电粒子能量与电流大小、金属靶材的物化性等特性来挑选合适的核反应，常被讨论的核反应有7Li(p,n)7Be及9Be(p,n)9B，这两种反应皆为吸热反应。两种核反应的能量阀值分别为1.881MeV和2.055MeV，由于硼中子捕获治疗的理想中子源为keV能量等级的超热中子，理论上若使用能量仅稍高于阀值的质子轰击金属锂靶材，可产生相对低能的中子，不须太多的缓速处理便可用于临床，然而锂金属(Li)和铍金属(Be)两种靶材与阀值能量的质子作用截面不高，为产生足够大的中子通量，通常选用较高能量的质子来引发核反应。
理想的靶材应具备高中子产率、产生的中子能量分布接近超热中子能区(将在下文详细描述)、无太多强穿辐射产生、安全便宜易于操作且耐高温等特性，但实际上并无法找到符合所有要求的核反应，本发明的实施例中采用锂金属制成的靶材。但是本领域技术人员熟知的，靶材的材料也可以由其他除了上述谈论到的金属材料之外的金属材料制成。
针对热移除系统的要求则根据选择的核反应而异，如7Li(p,n)7Be因金属靶材(锂金属)的熔点及热导系数差，对热移除系统的要求便较9Be(p,n)9B高。本发明的实施例中采用7Li(p,n)7Be的核反应。
无论硼中子捕获治疗的中子源来自核反应堆或加速器带电粒子与靶材的核反应，产生的皆为混合辐射场，即射束包含了低能至高能的中子、光子；对于深部肿瘤的硼中子捕获治疗，除了超热中子外，其余的辐射线含量越多，造成正常组织非选择性剂量沉积的比例越大，因此这些会造成不必要剂量的辐射应尽量降低。除了空气射束品质因素，为更了解中子在人体中造成的剂量分布，本发明的实施例中使用人体头部组织假体进行剂量计算，并以假体射束品质因素来作为中子射束的设计参考，将在下文详细描述。
国际原子能机构(IAEA)针对临床硼中子捕获治疗用的中子源，给定了五项空气射束品质因素建议，此五项建议可用于比较不同中子源的优劣，并供以作为挑选中子产生途径、设计射束整形体时的参考依据。这五项建议分别如下：
超热中子射束通量Epithermal neutron flux>1x 109n/cm2s
快中子污染Fast neutron contamination<2x 10-13Gy-cm2/n
光子污染Photon contamination<2x 10-13Gy-cm2/n
热中子与超热中子通量比值thermal to epithermal neutron flux ratio<0.05
中子电流与通量比值epithermal neutron current to flux ratio>0.7
注：超热中子能区在0.5eV到40keV之间，热中子能区小于0.5eV，快中子能区大于40keV。
1、超热中子射束通量：
中子射束通量和肿瘤中含硼药物浓度共同决定了临床治疗时间。若肿瘤含硼药物浓度够高，对于中子射束通量的要求便可降低；反之，若肿瘤中含硼药物浓度低，则需高通量超热中子来给予肿瘤足够的剂量。IAEA对于超热中子射束通量的要求为每秒每平方厘米的超热中子个数大于109，此通量下的中子射束对于目前的含硼药物而言可大致控制治疗时间在一小时内，短治疗时间除了对病人定位和舒适度有优势外，也可较有效利用含硼药物在肿瘤内有限的滞留时间。
2、快中子污染：
由于快中子会造成不必要的正常组织剂量，因此视之为污染，此剂量大小和中子能量呈正相关，因此在中子射束设计上应尽量减少快中子的含量。快中子污染定义为单位超热中子通量伴随的快中子剂量，IAEA对快中子污染的建议为小于2x 10-13Gy-cm2/n。
3、光子污染(γ射线污染)：
γ射线属于强穿辐射，会非选择性地造成射束路径上所有组织的剂量沉积，因此降低γ射线含量也是中子束设计的必要要求，γ射线污染定义为单位超热中子通量伴随的γ射线剂量，IAEA对γ射线污染的建议为小于2x 10-13Gy-cm2/n。
4、热中子与超热中子通量比值：
由于热中子衰减速度快、穿透能力差，进入人体后大部分能量沉积在皮肤组织，除黑色素细胞瘤等表皮肿瘤需用热中子作为硼中子捕获治疗的中子源外，针对脑瘤等深层肿瘤应降低热中子含量。IAEA对热中子与超热中子通量比值建议为小于0.05。
5、中子电流与通量比值：
中子电流与通量比值代表了射束的方向性，比值越大表示中子射束前向性佳，高前向性的中子束可减少因中子发散造成的周围正常组织剂量，另外也提高了可治疗深度及摆位姿势弹性。IAEA对中子电流与通量比值建议为大于0.7。
利用假体得到组织内的剂量分布，根据正常组织及肿瘤的剂量-深度曲线，推得假体射束 品质因素。如下三个参数可用于进行不同中子射束治疗效益的比较。
1、有效治疗深度：
肿瘤剂量等于正常组织最大剂量的深度，在此深度之后的位置，肿瘤细胞得到的剂量小于正常组织最大剂量，即失去了硼中子捕获的优势。此参数代表中子射束的穿透能力，有效治疗深度越大表示可治疗的肿瘤深度越深，单位为cm。
2、有效治疗深度剂量率：
即有效治疗深度的肿瘤剂量率，亦等于正常组织的最大剂量率。因正常组织接收总剂量为影响可给予肿瘤总剂量大小的因素，因此参数影响治疗时间的长短，有效治疗深度剂量率越大表示给予肿瘤一定剂量所需的照射时间越短，单位为cGy/mA-min。
3、有效治疗剂量比：
从大脑表面到有效治疗深度，肿瘤和正常组织接收的平均剂量比值，称之为有效治疗剂量比；平均剂量的计算，可由剂量-深度曲线积分得到。有效治疗剂量比值越大，代表该中子射束的治疗效益越好。
为了使射束整形体在设计上有比较依据，除了五项IAEA建议的空气中射束品质因素和上述的三个参数，本发明实施例中也利用如下的用于评估中子射束剂量表现优劣的参数：
1、照射时间≤30min(加速器使用的质子电流为10mA)
2、30.0RBE-Gy可治疗深度≥7cm
3、肿瘤最大剂量≥60.0RBE-Gy
4、正常脑组织最大剂量≤12.5RBE-Gy
5、皮肤最大剂量≤11.0RBE-Gy
注：RBE(Relative Biological Effectiveness)为相对生物效应，由于光子、中子会造成的生物效应不同，所以如上的剂量项均分别乘上不同组织的相对生物效应以求得等效剂量。
请参见图3，本实施例的一个方面在于提供一种提高中子捕获治疗系统的中子束照射剂量的精确度的辐射线检测系统；本实施例的另一个方面在于提供一种提高中子捕获治疗系统的中子束照射剂量的精确度的辐射线检测方法。
其中，中子捕获治疗系统包括加速器10、扩束装置20、用于通过带电粒子束P的带电粒子束入口、带电粒子束P、经与带电粒子束P发生核反应从而产生中子束N的中子产生部T、用于调整经中子产生部T产生的中子射束通量与品质的射束整形体30、邻接于射束整形体30 的射束出口40和被经射束出口40处出来的射束照射的待照体50。其中，加速器10用来给带电粒子束P加速，可以为回旋加速器或者直线加速器等适用于加速器型中子捕获治疗系统的加速器；这里的带电粒子束P优选为质子束；扩束装置20设置在加速器10及中子产生部T之间；带电粒子束入口紧邻中子产生部T并容纳在射束整形体30内，如图3所示的在中子产生部T及扩束装置之间的三个箭头作为带电粒子束入口；中子产生部T容纳在射束整形体30内，这里的中子产生部T优选为锂金属；射束整形体30包括反射体31、被反射体31包围并邻接于中子产生部T的缓速体32、与缓速体32邻接的热中子吸收体33、设置在射束整形体30内的辐射屏蔽34，中子产生部T与自带电粒子束入口入射的带电粒子束P发生核反应以产生中子束N，中子束限定一根主轴，缓速体32将自中子产生部T产生的中子减速至超热中子能区，反射体31将偏离主轴的中子导回主轴以提高超热中子射束强度，热中子吸收体33用于吸收热中子以避免治疗时与浅层正常组织造成过多剂量，辐射屏蔽34用于屏蔽渗漏的中子和光子以减少非照射区的正常组织剂量；射束出口40亦可称作中子束收敛部或者准直器，其减小中子束的宽度以将中子束聚集；经射束出口40射出的中子束照射待照体50的目标部位。
用于提高中子捕获治疗系统的中子束照射剂量的精确度的辐射线检测系统，包括设置在射束整形体30内或者射束整形体30外的辐射线检测装置60和控制装置70，辐射线检测装置60用于实时检测带电粒子束P经与中子产生部T发生核反应后由中子产生部T溢出的中子束或者生成的γ射线。
控制装置70根据辐射线检测装置的检测结果发出人类感知的信号以确认中子捕获治疗系统的下一步作业。这种人类感知的信号可以是听觉、视觉、触觉或嗅觉等人类功能器官能够感知的信号，如发出声响的警报器、报警灯、振动、发出刺鼻的气味等多种信号中的一种或多种形式。
中子捕获治疗系统进一步包括用于将带电粒子束加速的加速器，控制装置70包括控制部71和显示部72，控制部71将辐射线检测系统的检测结果通过显示部72显示出来并且将检测结果反馈给加速器10以确认加速器的下一步作业，显示部可以为电视或液晶显示器等常见的显示设备。
可实现实时检测的常见辐射线检测系统有电离室及闪烁探测头两种不同检测原理。其中中子束检测系统检测中子束时，采用电离室结构为基底的有He-3比例计数器、BF3比例计数器、分裂游离室、硼电离室，检测γ射线时，采用电离室为充气式电离室。而检测中子束和γ射线均可以采用闪烁探测头，闪烁探测头则可以分为有机与无机材料，对于侦检热中子用途，其闪烁探测头多添加Li或B等高热中子捕获截面元素。简而言之，此类侦检器探测的中子能量多为热中子，皆为倚靠元素与中子发生捕获或核裂变反应所释出的重荷电粒子及核裂变碎片，于电离室或闪烁探测头内产生大量电离对(ion pair)，这些电荷被收集后，经过适当的电路转换，便可将电流信号转为电压脉冲信号。透过分析电压脉冲的大小，则可以轻易地分辨出中子信号及γ信号。在高强度中子场中，如BNCT，则可以适当地减少电离室的气体 压力、可裂材或硼涂布的浓度或闪烁探测头内高中子捕获截面元素的浓度，便可以有效降低其对中子的灵敏度，避免信号饱和的情况发生。
作为一种优选地，本实施例中中子束检测系统采用游离室。当中子束通过游离室时，与游离室内部气体分子或游离室的壁部发生游离作用，生成电子与带正电荷的例子，此电子和正电荷离子称为上述的离子对。由于游离室内有外加电场高压，因此电子朝中央阳极丝移动，正电荷离子朝周围的阴极壁移动，因而产生可测得的电子脉冲信号。使气体分子产生一离子对所需能量称为平均游离能，该值根据气体种类而异，如空气的平均游离能约为34eV。若有340keV的中子束或γ射线，会使空气产生约10k个离子对。
作为另一种优选地，本实施例中中子束检测系统采用闪烁探测头。某些物质吸收能量之后会放出可见光，此种物质称为闪烁物质。它是利用游离輻射将晶体或分子中的电子激发至激态，而当电子回到基态时放出的荧光被收集后用来作中子束监测。闪烁探测头与中子束作用后所发射的可见光，可利用光电倍增管将可见光转化为电子，再倍增放大，通常电子倍增放大率可达107至108。阳极输出的电子数与入射的中子束能量成正比，因此闪烁探测头能测量中子束或γ射线的能量。
辐射线检测系统通过检测信号推算中子束发生强度从而调整带电粒子束并控制照射剂量。
本领域技术人员熟知地，中子束检测系统不论设置在射束整形体内也好，还是设置在邻近射束整形体处，只要在所设置位置之处能够用来检测射束整形体内的中子束的强度变化及空间分布的检测装置则可以选用。
与上述辐射线检测系统对应的是一种提高中子捕获治疗系统的中子束照射剂量的精确度的辐射线检测方法，其中，中子捕获治疗系统包括带电粒子束、用于通过带电粒子束的带电粒子束入口、经与带电粒子束发生核反应从而产生中子束的中子产生部、用于调整经中子产生部产生的中子射束通量与品质的射束整形体和邻接于射束整形体的射束出口，其中，中子产生部容纳在射束整形体内；辐射线检测系统包括设置在射束整形体内或者射束整形体外的辐射线检测装置，辐射线检测装置用于检测带电粒子束经与中子产生部发生核反应后由中子产生部溢出的中子束或者生成的γ射线；检测方法包括检测步骤，检测步骤实时检测带电粒子束经与中子产生部发生核反应后由中子产生部溢出的中子束或者生成的γ射线。
检测方法进一步包括控制步骤，控制步骤根据在检测步骤中的检测结果，控制中子捕获治疗系统的下一步作业。
作为一种优选地，中子捕获治疗系统进一步包括用于将带电粒子束加速的加速器，控制步骤根据在检测步骤中的检测结果，控制加速器以确认加速器的下一步作业。
控制装置包括显示部，检测方法进一步包括显示步骤，显示步骤将在检测步骤中的检测结果经由显示部显示出来。
检测方法进一步包括推算步骤，推算步骤根据在检测步骤中的检测结果推算中子束发生强度从而调整带电粒子束并控制照射剂量。
本发明揭示的用于中子捕获治疗系统的辐射线检测系统并不局限于以上实施例所述的内容以及附图所表示的结构。在本发明的基础上对其中构件的材料、形状及位置所做的显而易见地改变、替代或者修改，都在本发明要求保护的范围之内。

Claims (10)

  1. 一种用于中子捕获治疗系统的辐射线检测系统，其特征在于：所述中子捕获治疗系统包括带电粒子束、用于通过所述带电粒子束的带电粒子束入口、经与所述带电粒子束发生核反应从而产生中子束的中子产生部、用于调整经所述中子产生部产生的中子射束通量与品质的射束整形体和邻接于所述射束整形体的射束出口，其中，所述中子产生部容纳在所述射束整形体内，所述辐射线检测系统包括设置在所述射束整形体内或者所述射束整形体外的辐射线检测装置，所述辐射线检测装置用于实时检测带电粒子束经与所述中子产生部发生核反应后由所述中子产生部溢出的中子束或者生成的γ射线。
  2. 根据权利要求1所述的用于中子捕获治疗系统的辐射线检测系统，其特征在于：所述辐射线检测系统进一步包括控制装置，所述控制装置根据所述辐射线检测装置的检测结果发出人类感知的信号以确认所述中子捕获治疗系统的下一步作业。
  3. 根据权利要求2所述的用于中子捕获治疗系统的辐射线检测系统，其特征在于：所述中子捕获治疗系统进一步包括用于将所述带电粒子束加速的加速器，所述控制装置包括控制部和显示部，所述控制部将所述辐射线检测系统的检测结果通过所述显示部显示出来并且将检测结果反馈给所述加速器以确认所述加速器的下一步作业。
  4. 根据权利要求1-3中任一项所述的用于中子捕获治疗系统的辐射线检测系统，其特征在于：所述辐射线检测装置为游离室或闪烁探测头，所述辐射线检测系统通过检测信号推算中子束发生强度从而调整带电粒子束并控制照射剂量。
  5. 根据权利要求1-3中任一项所述的用于中子捕获治疗系统的辐射线检测系统，其特征在于：所述射束整形体包括反射体、被所述反射体包围并邻接于所述中子产生部的缓速体、与所述缓速体邻接的热中子吸收体和设置在所述射束整形体内的辐射屏蔽。
  6. 一种用于中子捕获治疗系统的辐射线检测方法，其特征在于：所述中子捕获治疗系统包括带电粒子束、用于通过所述带电粒子束的带电粒子束入口、经与所述带电粒子束发生核反应从而产生中子束的中子产生部、用于调整经所述中子产生部产生的中子射束通量与品质的射束整形体和邻接于所述射束整形体的射束出口，其中，所述中子产生部容纳在所述射束整形体内；辐射线检测系统包括设置在所述射束整形体内或者所述射束整形体外的辐射线检测装置，所述辐射线检测装置用于检测带电粒子束经与所述中子产生部发生核反应后由所述中子产生部溢出的中子束或者生成的γ射线；所述检测方法包括检测步骤，所述检测步骤实时检测带电粒子束经与所述中子产生部发生核反应后由所述中子产生部溢出的中子束或者生成的γ射线。
  7. 根据权利要求6所述的用于中子捕获治疗系统的辐射线检测方法，其特征在于：所述检测方法包括控制步骤，所述控制步骤根据在所述检测步骤中的检测结果，控制所述中子捕获治疗系统的下一步作业。
  8. 根据权利要求7所述的用于中子捕获治疗系统的辐射线检测方法，其特征在于：所述中子捕获治疗系统进一步包括用于将所述带电粒子束加速的加速器，所述控制步骤根据在所述检测步骤中的检测结果，控制所述加速器以确认所述加速器的下一步作业。
  9. 根据权利要求6-8中任一项所述的用于中子捕获治疗系统的辐射线检测方法，其特征在于：所述控制装置包括显示部，所述检测方法包括显示步骤，所述显示步骤将在所述检测步骤中的检测结果经由所述显示部显示出来。
  10. 根据权利要求6-8中任一项所述的用于中子捕获治疗系统的辐射线检测方法，其特征在于：所述检测方法包括推算步骤，所述推算步骤根据在所述检测步骤中的检测结果推算中子束发生强度从而调整带电粒子束并控制照射剂量。
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