High-resolution compton gamma camera

Abstract

A high-resolution Compton gamma camera, relating to the technical field of gamma measurement, and comprising: a high-gas-pressure tank (1) provided with a window (2), a metal film (3) being sealedly provided at the window (2), and a plurality of flange interfaces (4) being formed on the side wall or the bottom of the high-gas-pressure tank (1); a time projection chamber detector (5) which is provided in the high-gas-pressure tank (1) and is used for implementing gamma ray Compton scattering conversion and three-dimensional trajectory and energy measurement of scattered electrons; and a gamma calorimeter (6) which is located between a field cage of the time projection chamber detector (5) and the inner wall of the high-gas-pressure tank (1) and is used for implementing position and energy measurement of Compton scattered gamma and electron leakage. The camera implements high-precision measurement of Compton scattered electrons and gamma, and accurate measurement of the gamma direction and energy, providing key technical support for applications such as astronomical observation and radiation therapy.

Description

A high-resolution Compton gamma camera Technical Field

[0001] The present invention relates to the technical field of gamma measurement, in particular to a high-resolution Compton gamma camera. Background Art

[0002] The 0.3-10 MeV gamma (γ) energy band encompasses the characteristic spectral lines of the major elements known to us, making precise measurements of it of crucial scientific and industrial application value. In existing astronomical observation instruments, the sensitivity of γ observations in the MeV energy band is 2-3 orders of magnitude lower than in other energy bands, making it a crucial observation window in urgent need of research breakthroughs. In novel radiotherapy applications, such as proton radiotherapy, high-precision measurement of the γ direction is crucial for precisely locating the proton beam's range. High-precision positioning and imaging of γ radiation sources is also a significant need in nuclear power safety applications.

[0003] However, gamma-ray detection technology for this energy range has long been slow to develop, primarily due to the short wavelengths of gamma rays in this energy range, making them difficult to focus using methods such as mirrors or lenses. Most incident photons deposit only a portion of their energy through Compton scattering, making accurate measurement of their incident direction and total energy challenging. Traditional Compton cameras measure only the Compton scattered gamma angle, yielding one of two angles representing the direction of the incident gamma ray. This lack of angular information about the recoil electrons makes it impossible to achieve high-sensitivity observation of gamma-ray sources under conditions of significant background gamma-ray contamination. Traditional Compton camera measurement methods, most of which still use solid-state detectors based on semiconductors or scintillators, measure the top and bottom of Compton scattering, failing to measure the initial trajectory of scattered electrons. The critical angular resolution of this measurement is only around 10°, far from meeting the requirements of scientific research and application. For example, in proton therapy, achieving millimeter-level localization accuracy for the Bragg peak of the proton range requires extremely close proximity to the body and a large number of event statistics, which cannot meet the requirements of rapid clinical imaging measurements.

[0004] Summary of the Invention

[0005] The purpose of the present invention is to provide a high-resolution Compton gamma camera to solve the problems existing in the above-mentioned prior art, realize high-precision measurement of Compton scattered electrons and gamma, and simultaneously realize accurate measurement of gamma direction and energy, providing key technical support for applications such as astronomical observation, radiation medicine, and source term detection.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The present invention provides a high-resolution Compton gamma camera, comprising a high-pressure tank body provided with a window sealed with a metal film, and a plurality of flange interfaces provided on the side wall or bottom of the high-pressure tank body; a time projection chamber detector disposed in the high-pressure tank body, and used for realizing Compton scattering conversion of gamma rays and three-dimensional track and energy measurement of scattered electrons; and a gamma calorimeter located between a field cage of the time projection chamber detector and the inner wall of the high-pressure tank body, and used for realizing position and energy measurement of Compton scattered gamma rays and electron leakage.

[0008] Optionally, the window is opened at one end of the high-pressure tank body, and the thickness of the metal film sealed at the window does not exceed 10 mm.

[0009] Optionally, the high-pressure tank body is provided with windows at both symmetrical ends, and the thickness of the metal film sealed at the windows does not exceed 10 mm.

[0010] Optionally, gas at a pressure of 1-15 bar can be introduced into the high-pressure tank; the high-pressure tank can adopt a closed air mode or a gas circulation mode.

[0011] Optionally, the time projection chamber detector includes a microstructure gas detector, which is arranged in the high-pressure tank body near the window. The end of the microstructure gas detector near the window is connected to the time projection chamber readout electronics, and the end of the microstructure gas detector away from the window is provided with the field cage.

[0012] Optionally, the microstructure gas detector can be suitable for high pressure environment, and the microstructure gas detector adopts gas electron multiplier (GEM / THGEM), micromegas, double-layer micromesh gas detector (DMM) or resistive microwell detector (μRWELL).

[0013] Optionally, the gamma calorimeter includes a pixel semiconductor detector arranged between the field cage and the inner wall of the high-pressure tank; the pixel semiconductor detector is made of cadmium zinc telluride, cadmium telluride or perovskite material, the pixel unit size of the pixel semiconductor detector is 0.1mm to 10mm, and the single layer thickness of the pixel semiconductor detector is 5mm to 30mm, and it can be arranged in multiple layers to improve detection efficiency.

[0014] Optionally, the gamma calorimeter includes a scintillation crystal array + a photoelectric readout detector arranged between the field cage and the inner wall of the high-pressure tank; the scintillation crystal array of the scintillation crystal array + the photoelectric readout detector is formed by splicing multiple crystal unit arrays, and the crystal units are cerium-activated lanthanum bromide crystals, lanthanum bromide crystals, sodium iodide crystals or cesium iodide crystals. The scintillation crystal array is coupled with a photomultiplier detector or a multi-anode photomultiplier tube as a photoelectric signal readout.

[0015] Optionally, the gas component is a single-component gas such as carbon tetrafluoride and methane.

[0016] Optionally, the gas component is a mixture of an inert gas and a polyatomic molecular gas, the inert gas is argon, neon, or xenon, and the polyatomic molecular gas is carbon dioxide, isobutane, carbon tetrafluoride, methane, or ethane.

[0017] Compared with the prior art, the present invention has achieved the following technical effects:

[0018] The present invention uses time projection chamber technology based on advanced gas detectors, combined with pixel-type semiconductor detectors or high-resolution scintillator calorimeters, to achieve high-precision measurement of Compton scattered electrons and gamma, while also achieving accurate measurement of gamma direction and energy. Specifically, compared to traditional solid Compton scatterers (such as scintillators and semiconductors), the present invention achieves high-precision measurement of the angle and energy of Compton scattered electrons, determines the Compton scattering plane, and uniquely locates the gamma incident direction. Compared to other time projection chamber solutions, the present invention uses a microstructured gas detector with high energy and high position resolution, combined with a new pixel-type semiconductor detector or high-resolution scintillator calorimeter, to achieve high-precision measurement of gamma energy and incident direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] FIG1 is a schematic structural diagram of a high-resolution Compton gamma camera according to the present invention;

[0021] FIG2 is a schematic diagram of the high-pressure tank structure of the present invention;

[0022] FIG3 is another structural schematic diagram of a high-pressure tank according to a different embodiment of the present invention;

[0023] FIG4 is a schematic diagram of a time projection chamber detector according to the present invention;

[0024] FIG5 is a schematic diagram of a pixel semiconductor detector according to the present invention;

[0025] FIG6 is a schematic diagram of a scintillation crystal array + photoelectric readout detector according to the present invention;

[0026] FIG7 is a schematic structural diagram of a scintillation crystal array + photoelectric readout detector in another embodiment of the present invention;

[0027] Explanation of the reference numerals: 1-high pressure tank, 2-window, 3-metal film, 4-flange interface, 5-time projection chamber detector, 501-microstructure gas detector, 502-time projection chamber readout electronics, 503-field cage, 6-gamma calorimeter. DETAILED DESCRIPTION

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] The purpose of the present invention is to provide a high-resolution Compton gamma camera to solve the problems existing in the above-mentioned prior art, realize high-precision measurement of Compton scattered electrons and gamma, and simultaneously realize accurate measurement of gamma direction and energy, providing key technical support for applications such as astronomical observation, radiation medicine, and source term detection.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] The present invention provides a high-resolution Compton gamma camera, as shown in Figures 1, 2, 3, 4, 5, 6 and 7, comprising a high-pressure tank 1, a window 2 being provided at one end of the high-pressure tank 1, a metal film 3 having a thickness not exceeding 10 mm being sealed at the window 2, the metal film 3 being made of, for example, stainless steel, titanium alloy, aluminum alloy, carbon fiber, etc., a plurality of flange interfaces 4 being provided on the side wall or bottom of the high-pressure tank 1 for leading out detector gas, high-voltage power supply, and electronic signal, and the high-pressure tank 1 having an internal energy storage device. The high-pressure tank 1 can be used to pass gas with a pressure of 1-15 bar, so that the high-pressure tank 1 can be used in a closed gas mode or a gas circulation mode. The gas component is a single-component gas such as carbon tetrafluoride and methane, or a mixture of an inert gas and a polyatomic molecular gas. The inert gas is argon, neon, or xenon, and the polyatomic molecular gas is carbon dioxide, isobutane, carbon tetrafluoride, methane or ethane. A time projection chamber detector 5 is fixedly provided in the high-pressure tank 1, which includes a microstructure gas detector 501. The microstructure gas detector 501 is arranged at the high pressure. On the side of the window 2 in the pressure tank 1, the signal of the microstructure gas detector 501 near the window 2 is connected to the time projection chamber readout electronics 502, and the end of the microstructure gas detector 501 away from the window 2 is provided with a field cage 503. The field cage 503 structure is composed of fine metal wires or metal strips, and usually adopts a double-layer structure to improve the uniformity of the electric field; the microstructure gas detector is used as the signal readout detector, and the selected microstructure gas detector 501 can be applied to high pressure environments, such as gas electron multipliers, microgrid gas detectors, Double-layer microgrid gas detectors, resistive microwell detectors, etc., combined with corresponding low-noise multi-channel readout electronics, achieve gamma-ray Compton scattering conversion and three-dimensional track and energy measurement of scattered electrons; the microstructured gas detector 501 adopts two-dimensional cross-bar readout or pixel readout, with the readout bar or pixel spacing generally being 0.1mm-10mm; a gamma calorimeter 6 is provided between the field cage 503 of the time projection chamber detector 5 and the inner wall of the high-pressure tank 1 to achieve position and energy measurement of Compton scattered gamma and electron leakage.

[0032] Further preferably, the gamma calorimeter 6 includes a pixel semiconductor detector disposed between the field cage 503 and the inner wall of the high-pressure tank 1; the pixel semiconductor detector is made of cadmium zinc telluride, cadmium telluride or perovskite material, the pixel unit size of the pixel semiconductor detector is 0.1 mm to 10 mm, and the thickness of a single layer of the pixel semiconductor detector is 5 mm to 30 mm. When in use, multiple units are usually spliced ​​to achieve a larger sensitive area, and then multiple layers are arranged to ensure sufficient detection efficiency. In addition to the aforementioned structure, the gamma calorimeter 6 can also utilize a scintillation crystal array combined with a photoelectric readout detector. The scintillation crystal array in this configuration is constructed by splicing together multiple crystal units. The crystal units are cerium-activated lanthanum bromide crystals, lanthanum bromide crystals, sodium iodide crystals, or cesium iodide crystals. The scintillation crystal array is coupled to a photomultiplier detector or a multi-anode photomultiplier tube for photoelectric signal readout. Pixel readout typically utilizes code-multiplexing to reduce readout size. Crystal unit widths typically range from 3 mm to 20 mm, with a single layer thickness of 5 to 30 mm. Multiple layers are typically deployed to ensure sufficient detection efficiency. Furthermore, in another embodiment, considering that some high-energy gamma rays cannot be fully absorbed by the gamma calorimeter 6, a larger scintillator detector is added to the bottom or exterior of the gamma calorimeter 6 to serve as a gamma residual energy absorption detector, while also functioning as an anti-coincidence detector.

[0033] In a different embodiment, windows 2 are provided at both symmetrical ends of the high-pressure tank 1. The thickness of the metal film 3 sealed at the windows 2 does not exceed 10 mm. Combining different high-pressure tank 1 structures, time projection chamber detectors 5, and gamma calorimeters 6 schemes can form the complete system of the present invention.

[0034] In the description of the present invention, it should be noted that the terms "center," "top," "bottom," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0035] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A high-resolution Compton gamma camera, characterized in that: It comprises a high-pressure tank body, which is provided with a window, a metal film is sealed at the window, and a plurality of flange interfaces are opened on the side wall or the bottom of the high-pressure tank body; A time projection chamber detector, which is arranged in the high-pressure tank and is used to realize the gamma-ray Compton scattering conversion and the three-dimensional track and energy measurement of scattered electrons; The gamma calorimeter is located between the field cage of the time projection chamber detector and the inner wall of the high-pressure tank, and is used to measure the position and energy of Compton scattered gamma and electron leakage.

2. The high-resolution Compton gamma camera according to claim 1, characterized in that: The window is provided at one end of the high-pressure tank body, and the thickness of the metal film sealed at the window does not exceed 10 mm.

3. The high-resolution Compton gamma camera according to claim 1, characterized in that: The high-pressure tank body is symmetrically provided with windows at both ends, and the thickness of the metal film sealed at the windows does not exceed 10 mm.

4. The high-resolution Compton gamma camera according to claim 1, characterized in that: The high-pressure tank body can be filled with gas at a pressure of 1-15 bar; the high-pressure tank body can adopt a gas sealing mode or a gas circulation mode.

5. The high-resolution Compton gamma camera according to claim 1, characterized in that: The time projection chamber detector comprises a microstructure gas detector, which is arranged in the high-pressure tank body near the window. The end of the microstructure gas detector near the window is connected to the time projection chamber readout electronics, and the end of the microstructure gas detector away from the window is provided with the field cage.

6. According to claim 5, the microstructure gas detector can be applied to high pressure environment, and the microstructure gas detector adopts a gas electron multiplier, a microgrid gas detector, a double-layer microgrid gas detector or a resistive micro-well detector.

7. The high-resolution Compton gamma camera according to claim 1, characterized in that: The gamma calorimeter includes a pixel semiconductor detector arranged between the field cage and the inner wall of the high-pressure tank; the pixel semiconductor detector is made of cadmium zinc telluride, cadmium telluride or perovskite material, the pixel unit size of the pixel semiconductor detector is 0.1mm~10mm, the single layer thickness of the pixel semiconductor detector is 5mm~30mm, and it can be arranged in multiple layers to improve the detection efficiency.

8. The high-resolution Compton gamma camera according to claim 1, characterized in that: The gamma calorimeter comprises a scintillation crystal array and a photoelectric readout detector arranged between a field cage and an inner wall of a high-pressure tank; the scintillation crystal array of the scintillation crystal array and the photoelectric readout detector is formed by splicing a plurality of crystal unit arrays, wherein the crystal units are cerium-activated lanthanum bromide crystals, lanthanum bromide crystals, sodium iodide crystals or cesium iodide crystals, and the scintillation crystal array is coupled with a photomultiplier detector or a multi-anode photomultiplier tube as a photoelectric signal readout.

9. The high-resolution Compton gamma camera according to claim 4, characterized in that: The gas components are single-component gases such as carbon tetrafluoride and methane.

10. The high-resolution Compton gamma camera according to claim 4, characterized in that: The gas component is a mixture of an inert gas and a polyatomic molecular gas, wherein the inert gas is argon, neon, or xenon, and the polyatomic molecular gas is carbon dioxide, isobutane, carbon tetrafluoride, methane, or ethane.

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