Charged particle computed tomography device

Abstract

The invention relates to the field of medical imaging, and discloses a charged particle computed tomography imaging device, which comprises a particle beam current limiter used for receiving and limiting the size and the intensity of a charged particle beam released by a beam current nozzle, so that the diameter and the intensity of the beam current meet set requirements to accurately hit a target area where an object to be measured is located; the four-axis coordinatograph is arranged at the lower part of the to-be-measured object and is used for driving the to-be-measured object to freely translate in the X, Y and Z directions and rotate around the Z axis to ensure that the particle beam can accurately cover a target area where the to-be-measured object is located; the energy measuring device is arranged at the rear part of the object to be measured and is used for measuring particle energy deposition, calculating a range and an RSP value and transmitting a calculation result to the data reading and device motion controller; and the data reading and device motion controller is used for controlling the motion of the four-axis coordinatograph.

Description

Technical Field

[0001] The present invention relates to the technical field of medical imaging, in particular to a charged particle computer tomography (CT) device. Background Art

[0002] Malignant tumors are one of the leading causes of death worldwide. Most existing radiotherapy technologies rely on image-guided solutions based on MeV-level X-rays. Although such technologies can provide certain tumor localization functions, healthy tissues will inevitably suffer additional radiation damage due to the interaction of photons in tissues. In addition, the range and energy distribution information of X-ray imaging cannot be directly applied to charged particle therapy, and information conversion is required, which introduces range uncertainty and affects the accuracy of radiotherapy. Summary of the invention

[0003] In view of the above problems, an object of the present invention is to provide a charged particle computer tomography device which can accurately locate the tumor and effectively reduce the radiation impact on healthy tissues.

[0004] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a charged particle computer tomography device, which includes: a particle beam limiter, which is used to limit the size and intensity of the charged particle beam released by the beam nozzle, so that the diameter and intensity of the beam meet the set requirements to accurately hit the target area where the object to be measured is located; a four-axis coordinate meter, which is arranged at the lower part of the object to be measured, and is used to drive the object to be measured to freely translate in the X, Y, and Z directions, and rotate around the Z axis, so as to ensure that the particle beam can accurately cover the target area where the object to be measured is located; a calorimeter, which is arranged at the rear of the object to be measured, and is used to measure the particle energy deposition and calculate the range and RSP value; and a device motion controller is used to control the movement of the four-axis coordinate meter.

[0005] In a preferred embodiment, the particle beam limiter adopts a single small hole structure; or, the particle beam limiter adopts a multiple small hole structure.

[0006] Furthermore, preferably, the particle beam limiter with a single small hole structure has a small hole diameter of 10μm to 2000μm; the particle beam limiter with multiple small hole structures has each small hole diameter of 10μm to 2000μm, and the multiple small holes are regularly arranged to hit multiple positions of the object to be tested at the same time.

[0007] Further, preferably, the particle beam limiter is used to adjust the size and intensity of the beam so that the particle beam accurately hits the target area.

[0008] Further, preferably, the contact area between the particle beam limiter and the beam is larger than the maximum cross-sectional area of ​​the object to be measured.

[0009] In a preferred embodiment, the four-axis coordinate system can accurately control the position of the object to be measured in three-dimensional space, including free translation in planes perpendicular and parallel to the particle beam direction and free rotation in a plane perpendicular to the particle beam direction, to ensure accurate alignment and positioning of the particle beam.

[0010] In a preferred embodiment, the calorimeter is a multi-layer structure, each layer of the structure is a detection layer; the detection layer uses a square silicon detector or a scintillator detector or a silicon pixel detector or a scintillating optical fiber.

[0011] Further, preferably, the thickness of the detection layer is:

[0012] The thickness of the square silicon detector is 100μm to 800μm;

[0013] The thickness of the scintillator detector is 1mm to 3mm;

[0014] The pixel size of silicon pixel detectors is 20μm to 100μm;

[0015] The diameter of the scintillating optical fiber is 0.5mm to 1mm.

[0016] Furthermore, preferably, each detection layer can measure the energy deposition of particles in the layer, and the energy deposition at the Bragg peak position is the largest, thereby determining the range and RSP value of the particles; by converting the RSP value, the water equivalent path of the particles in the patient's body is obtained.

[0017] In a preferred embodiment, the device motion controller is combined with computer software to adjust the motion trajectory of the four-axis coordinate measuring machine in real time, thereby achieving higher precision imaging scanning control.

[0018] The present invention adopts the above technical solution, which has the following advantages:

[0019] The present invention can effectively avoid the energy conversion error and additional radiation dose problems in the traditional X-ray IGRT scheme, and greatly reduce the range uncertainty and reduce the radiation damage to healthy tissues.

[0020] The present invention can be widely applied to accurate image-guided radiotherapy (IGRT) and tumor-targeted radiotherapy planning in tumor detection and treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 1 is a schematic diagram of the overall structure of a charged particle computer tomography device according to an embodiment of the present invention;

[0022] Figure 2 is a cross-sectional view of a particle beam current limiter and a beam vertical plane using a single pinhole structure in an embodiment of the present invention;

[0023] Figure 3 is a cross-sectional view of a particle beam current limiter and a beam vertical plane using a plurality of small hole structures in an embodiment of the present invention;

[0024] Figure 4 Schematic diagram of the structure of the four-axis coordinate machine and the stage in the embodiment of the present invention.

[0025] Figure 5 Schematic diagram of the structure of the calorimeter in the embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to overcome the limitations of the existing technology, charged particle imaging technology has gradually become a new solution in tumor radiotherapy. It uses the Bragg peak effect to more accurately locate tumors and reduce the radiation impact on healthy tissues. The present invention proposes a computer tomography device based on charged particles, which aims to improve the accuracy of image-guided radiotherapy (IGRT) in tumor radiotherapy. The device consists of a particle beam limiter 1, a four-axis coordinate machine 4 and a calorimeter 5, which can provide more accurate tumor positioning through charged particle imaging. Compared with traditional X-ray CT imaging, the present invention greatly reduces the range uncertainty and reduces the radiation damage to healthy tissues. The four-axis coordinate machine 4 can be flexibly moved or rotated in four directions of X, Y, Z, and R to adjust the imaging position and angle. Through the same particle imaging as the treatment beam, the energy conversion error and additional radiation dose problems in the traditional X-ray IGRT scheme are avoided.

[0027] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0028] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0029] In one embodiment of the present invention, a charged particle computer tomography apparatus is provided. In this embodiment, Figure 1 As shown, the device includes: a particle beam limiter 1, a four-axis coordinate machine 4, a calorimeter 5 and a device motion controller 6.

[0030] The particle beam limiter 1 is used to limit the size and intensity of the charged particle beam released by the beam nozzle 2, so that the diameter and intensity of the beam meet the set requirements to accurately hit the target area where the object to be tested 3 is located;

[0031] The position of the particle beam limiter 1 is relatively fixed relative to the position of the beam nozzle 2 .

[0032] The four-axis coordinate machine 4 is arranged at the lower part of the object to be tested 3, and is used to drive the object to be tested 3 to freely translate in the X, Y, and Z directions, and rotate around the Z axis, so as to ensure that the particle beam can accurately cover the target area where the object to be tested 3 is located. Specifically, when in use, the position of the beam nozzle 2 is fixed and cannot be moved, so the object to be tested 3 is fixed on the four-axis coordinate machine 4, and the four-axis coordinate machine 4 drives the object to be tested 3 to freely translate along the X, Y, and Z axis directions, and drives the object to be tested 3 to rotate around the Z axis at the same time; free translation in the X and Z axis directions can realize beam coverage of the area of ​​the object to be tested 3 perpendicular to the beam plane; free translation along the Y axis can adjust the distance of the object to be tested 3 from the beam nozzle 2; rotating around the Z axis can switch to the next plane to be tested of the object to be tested 3; after the above operations, the computer tomography scanning of the object to be tested 3 can be completed, and it can be ensured that the particle beam can accurately cover the target area where the object to be tested 3 is located.

[0033] The calorimeter 5 is arranged at the rear of the object to be tested, and is used to measure the particle energy deposition, calculate the range and RSP value, and transmit the calculation results to the device motion controller 6.

[0034] The device motion controller 6 is used to control the motion of the four-axis coordinate measuring machine 4 .

[0035] In the above embodiment, the particle beam limiter 1 is used to limit the size and intensity of the charged particle beam so as to generate a high-precision, narrow-band particle beam. The particle beam limiter 1 can be a single small hole structure (such as Figure 2 As shown), or, the particle beam limiter 1 adopts a plurality of small hole structures (such as Figure 3 As shown in the figure, the size and intensity of the beam can be controlled, so that the particle beam can accurately hit the target area and reduce the number of lateral scans.

[0036] Among them, the particle beam limiter 1 with a single small hole structure has a small hole diameter including but not limited to 10μm to 2000μm, which can be adjusted according to the actual beam parameters. The particle beam limiter 1 with multiple small holes has each small hole diameter including but not limited to 10μm to 2000μm, and the multiple small holes can be arranged regularly, including but not limited to a row arrangement, so as to hit multiple positions of the object to be tested 3 at the same time.

[0037] In this embodiment, the contact area between the particle beam limiter 1 and the beam is larger than the maximum cross-sectional area of ​​the object 3 to be measured. Figure 4As shown, the four-axis coordinate measuring machine 4 can freely translate in three axes: X-axis 7 (horizontally perpendicular to the particle beam direction), Y-axis 8 (parallel to the particle beam direction), and Z-axis 9 (vertically perpendicular to the particle beam direction), and can drive the stage 10 to move horizontally and vertically according to the measurement needs. The object to be measured 3 is placed on the stage 10, and the stage 10 can be rotated around the Z-axis 9 to switch the measurement plane, so as to realize scanning at different angles during CT imaging. The detector platform 11 is used to place the calorimeter 5 and realize the position adjustment in the direction of the Z-axis 9.

[0038] In this embodiment, the four-axis coordinate measuring machine 4 is controlled by the device motion controller 6 to ensure high-precision adjustment. The translation accuracy of the X, Y, and Z axes reaches 1 μm, and the Z-axis rotation accuracy is 0.01°, which is used to flexibly adjust the imaging position and angle to achieve multi-directional tumor area scanning.

[0039] In the above embodiment, if Figure 5 As shown, the calorimeter 5 is a multi-layer structure, and each layer is a detection layer 12 .

[0040] The detection layer 12 is a square silicon detector or a scintillator detector or a silicon pixel detector or a scintillating optical fiber;

[0041] Among them, the thickness of the square silicon detector includes but is not limited to 100μm~800μm, the thickness of the scintillator detector includes but is not limited to 1mm~3mm, the pixel size of the silicon pixel detector includes but is not limited to 20μm~100μm, and the diameter of the scintillating optical fiber includes but is not limited to 0.5mm~1mm.

[0042] Each detection layer 12 can measure the energy deposition of the particle in the layer, and the energy deposition at the Bragg peak position is the largest, thereby determining the range and RSP value of the particle in the object to be tested. By converting the RSP value, the water equivalent path (ΔWEPL) of the particle in the patient's body can be obtained.

[0043] In this embodiment, the RSP value is the relative stopping power, which is the stopping power of a substance relative to water, and its calculation formula is as follows:

[0044]

[0045] ρ e =ρ·N g

[0046] Among them, RSP m S is the stopping power of material m, which is used to describe the energy loss capability of material m relative to the reference substance (the reference substance in this embodiment is water); m is the energy loss of material m, S w Energy loss for water; is the number of electrons per unit mass of material m, is the number of electrons per unit mass of water; m e is the rest mass of the electron; c is the speed of light, β is the relative speed of the particle, (v is the velocity of the particle); I m , I w denote the average excitation and ionization energies of material m and water, respectively.

[0047] N g Indicates the number of electrons per unit mass; N A is Avogadro's constant, Z is the atomic number, A is the relative atomic mass; ρ e represents the electron density and ρ is the density of the material.

[0048] The RSP value is converted to obtain the water equivalent path ΔWEPL of the particles in the patient's body. The specific method includes the following steps:

[0049] (1) Calculate the RSP (Relative Stopping Power) value of each substance, RSP W and RSP m etc., and the total water equivalent thickness of the beam at a certain energy (Water Equivalent Thickness), denoted as WET;

[0050] Among them, various materials include materials used in the detection path of the device, such as tungsten (W), silicon (Si), etc.; RSP 钨 , RSP 硅 wait;

[0051] (2) The thickness of each detection layer 12 is L 探 , the relative blocking capability of the detection layer 12 is RSP 探 , let the range after tracking be N, then calculate the ΔWEPL of the object to be tested:

[0052] WET-N·L 探 ·RSP 探 ;

[0053] In the above embodiments, the device of the present invention can measure and generate high-precision tomographic images through accurate detection of ΔWEPL at multiple positions and angles. Combined with the imaging algorithm, it can effectively restore the position, shape and size of the tumor and assist clinicians in radiotherapy planning.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A charged particle computer tomography device, characterized in that: include: The particle beam limiter is used to limit the size and intensity of the charged particle beam released by the beam nozzle, so that the diameter and intensity of the beam meet the set requirements and accurately hit the target area where the object to be tested is located; The four-axis coordinate machine is set at the bottom of the object to be tested, which is used to drive the object to be tested to freely translate in the X, Y, and Z directions, and rotate around the Z axis to ensure that the particle beam can accurately cover the target area where the object is located; The calorimeter is set at the rear of the degrader, used to measure the particle energy deposition, calculate the range and RSP value, and transmit the calculation results to the data readout and device motion controller; The device motion controller is used to control the movement of the four-axis coordinate measuring machine.

2. The charged particle computer tomography apparatus according to claim 1, characterized in that: The particle beam limiter adopts a single small hole structure; or, the particle beam limiter adopts a multiple small hole structure.

3. The charged particle computer tomography apparatus according to claim 2, characterized in that: A particle beam limiter with a single small hole structure, the small hole diameter of which is 10μm to 2000μm; A particle beam current limiter with a structure of multiple small holes, each of which has a small hole diameter of 10 μm to 2000 μm, and the multiple small holes are arranged regularly to hit multiple positions of the object to be tested at the same time.

4. The charged particle computer tomography apparatus according to claim 2, characterized in that: Particle beam limiters are used to control the size and intensity of the beam so that the particle beam can accurately hit the target area.

5. The charged particle computer tomography apparatus according to claim 2, characterized in that: The contact surface area between the particle beam limiter and the beam is larger than the maximum cross-sectional area of ​​the object to be measured.

6. The charged particle computer tomography apparatus according to claim 1, characterized in that: The energy degrader is a cube made of material with an RSP value higher than a set value.

7. The charged particle computer tomography apparatus according to claim 1, characterized in that: The calorimeter is a multi-layer structure, each layer of which is a detection layer; The detection layer adopts square silicon detector, scintillator detector, silicon pixel detector or scintillating optical fiber.

8. The charged particle computer tomography apparatus according to claim 7, characterized in that: The thickness of the detection layer is: The thickness of the square silicon detector is 100μm to 800μm; The thickness of the scintillator detector is 1mm to 3mm; The pixel size of silicon pixel detectors is 20μm to 100μm; The diameter of the scintillating optical fiber is 0.5mm to 1mm.

9. The charged particle computer tomography apparatus according to claim 7, characterized in that: Each detection layer can measure the energy deposition of particles in that layer. The energy deposition at the Bragg peak position is the largest, thereby determining the range and RSP value of the particles. By converting the RSP value, the water equivalent path of the particles in the patient's body is obtained.

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