Dynamic adaptive range compensator imaging system and imaging method

Abstract

The invention provides a dynamic self-adaptive range compensator imaging system, which belongs to the technical field of particle imaging equipment, and comprises a particle track detection module used for screening particles directly penetrating through a detector, reconstructing the track and direction of particle motion, and obtaining the energy and position information when particles are incident; the self-adaptive range compensation module is used for realizing dynamic self-adaptive compensation of the particle residual range by adjusting the effective thickness of the compensator so as to receive the particle signal and obtain the residual range corresponding to the residual energy when the particle penetrates out of the imaged object; wherein the effective thickness of the compensator refers to the thickness of the compensator in the particle incidence range along the particle incidence direction; and the image processing module is used for calculating and outputting an image according to the residual range of the imaged object under the conditions of different positions and angles. Through the dynamic compensator, (quasi) continuous range compensation is realized, the precision is improved, and a better detection effect is realized while the cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of particle imaging equipment, and particularly relates to a dynamic self-adaptive range compensator imaging system and an imaging method. BACKGROUND

[0002] Proton / heavy ion therapy is the main development direction of current radiotherapy, and its treatment principle is to use the Bragg peak effect of protons or heavy ions to release a large amount of energy at the end of the range to kill tumor cells. Compared with conventional photon radiotherapy, proton / heavy ion therapy has the advantages of concentrated dose distribution, good protection of normal tissues, short treatment course, etc. In addition, protons / heavy ions have greater linear energy transfer (LET) than photons, and the relative biological effectiveness (RBE) is better than that of photons. However, if the energy is deposited in normal tissues, it will also cause stronger damage. Therefore, accurate estimation of the range of protons / heavy ions is particularly important. Therefore, the accuracy of proton / heavy ion therapy in treatment planning, estimation of proton / heavy ion range (also known as relative stopping power, RSP), and positioning verification is higher than that of photon radiotherapy.

[0003] Currently, the main method in clinical practice is to obtain the relative stopping power (RSP) of protons / heavy ions in tissues by converting the Hu (Hounsfield unit) value based on the CT (Computed Tomography) image of X-rays. Since the interaction between X-rays and matter is fundamentally different from the interaction between protons / heavy ions and matter, the range uncertainty will be introduced in the process of converting the Hu value to the RSP value. For head and neck tumors, the range uncertainty can even reach 10%. The deviation of particle range caused by this uncertainty may cause harm to healthy organs during radiotherapy. In order to fully exert the advantages of treatment, if direct imaging of protons / heavy ions (hereinafter referred to as "particles") can be used to obtain accurate estimation of the range of the lesion area, the range uncertainty caused by the conversion process can be effectively avoided, thereby solving the above problems.

[0004] However, there are many technical difficulties in direct imaging of particles. The most important one is that protons / heavy ions lose energy through interactions in the stopping medium, forming a nearly straight track, which is completely different from the single scattering or absorption of photons, so how to accurately determine the range of the straight object particle becomes the key. To solve the above problems, on the one hand, higher requirements are put forward for the position detection accuracy of the track detector, and on the other hand, better elimination of the negative effects of particle multiple scattering on the imaging results is needed. In the current common particle CT scheme at home and abroad, the detection system is usually divided into two parts, i.e. the tracking plane and the energy / range detector. For the tracking plane, the research focus in recent years at home and abroad is concentrated on the use of high position accuracy detectors to realize the detection of particle tracks and angles, so as to reconstruct the tracks of the incident and outgoing imaged objects.

[0005] For the energy / range detector, the current method is to use a scintillator detector, or to use a multi-layer detector system. The scintillator is limited by the processing method and volume, and is often used for energy detection, with a position resolution usually at the level of millimeters / sub-millimeters. The multi-layer structure is manufactured by using a silicon-based detector to realize accurate measurement of position. Each sensitive layer of the multi-layer detector system is mainly composed of an absorber and a position detector, which realizes fast energy dissipation of the particle and records its position. During the particle travel, in order to reduce the particle energy as soon as possible, an absorber is usually used as an energy dissipation layer. The absorber is usually made of a metal with high atomic number, so as to have a larger water equivalent path length WEPL. In the design process of the multi-layer detector imaging system, it is necessary to select appropriate absorber materials and thicknesses to balance the design cost, imaging effect and system application range.

[0006] The position resolution of the position detector has a great influence on the imaging accuracy and subsequent treatment effect. When the particle passes through the object, it does not pass straight through, but will scatter, so the position of the final arriving detector cannot directly represent its range. By setting multiple layers of position detectors, the position of the particle at each layer can be recorded to realize particle track reconstruction, and the particle stopping position obtained through particle track reconstruction can obtain a particle range closer to the true value. However, the current silicon pixel or silicon microstrip detector usually has a small detection area, and if it is to cover the imaged object, it usually needs to be spliced to realize it, which inevitably introduces a dead zone of detection. At the same time, due to the very large number of channels of the pixel chip, the cost of the required electronic supporting equipment is very high.

[0007] The fixed layer multi-layer detector imaging system collects particles through a multi-layer detector and a compensator. After the particles pass through a position detector and an imaged object, the WEPL corresponding to the energy lost by the particles in the imaged object can be calculated by the following formula: wherein, is the water equivalent path length corresponding to the total energy of the particles before being incident on the imaged object, is the sum of the water equivalent paths of the stopping layer (i layer) and the layers before it in the range detector. is the water equivalent path of the energy lost in the imaged object.

[0008] Since the range / energy detector designed with a fixed number of layers usually has a single layer thickness that is not adjustable, the detection result presents discrete results, and some particles may stop in the absorber or in the gap between layers and other undetectable areas, ultimately resulting in reduced accuracy of the detected range or energy. From a theoretical analysis, it can be known that the number of layers of the detector or the thickness of the compensator can be increased to improve the device to adapt to different sizes of the imaged object. However, in actual engineering applications, the customized detector is expensive, the electronic readout is complex, the splicing structure is precise and difficult to disassemble, and other factors make it difficult to reduce the cost of the entire system. Using a too thick compensator will reduce the measurement accuracy of a single layer, and the imaging result cannot meet the requirements.

[0009] For the problem of covering the lateral imaging area, it is generally necessary to achieve by splicing the detector chips. For a large-area detector, the splicing process and the integrated circuit readout process are difficult; on the other hand, increasing the area of the multi-chip splicing means that multiple channels of electronics need to be matched. In terms of processing, the solder joints between the circuit and the chip are very small and fragile, and the current splicing method results in poor stability of the entire system; in terms of data, too much data from multiple channels will result in a large amount of data transmission capacity, which requires higher stability of data transmission and storage space.

[0010] In summary, in the design idea of the existing particle imaging system, the number of layers of the detector required by the detection part is too large, and the splicing process is complex, resulting in problems such as high system cost, high processing difficulty, and high maintenance difficulty. SUMMARY

[0011] The present application aims to provide a dynamic adaptive range compensator imaging system and imaging method to solve at least one of the technical problems in the background art.

[0012] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0013] The present application provides a dynamic adaptive range compensator imaging system, comprising:

[0014] A particle track detection module is configured to screen particles that pass straight through the detector, reconstruct the track and direction of the particle movement, and obtain energy and position information of the particle at the time of incidence;

[0015] An adaptive range compensator module is configured to adjust the effective thickness of the compensator to achieve dynamic adaptive compensation of the residual range of the particle, receive the particle signal, and obtain the residual range corresponding to the residual energy of the particle when it passes out of the imaged object; wherein the effective thickness of the compensator refers to the thickness of the compensator in the range of particle incidence along the direction of particle incidence.

[0016] An image processing module is configured to calculate and output an image based on the residual range of the imaged object under different position and angle conditions.

[0017] As a further limitation of the first aspect of the application, in the particle track detection module, the particle passes through the first position detector, the imaged object, and the second position detector in sequence after being emitted by the particle source, and the second position detector records the energy and position information of the particle at the time of incidence.

[0018] As a further limitation of the first aspect of the application, the adaptive range compensator module includes an adaptive range compensator, a third position detector, and a control unit; the third position detector feeds back the particle receiving state to the control unit according to the received particle signal, and the control unit adjusts the effective thickness of the compensator; the control unit has a trigger input signal and an output signal, and forms a feedback adjustment between receiving the trigger signal from the third position detector; the input signal is used to adjust the effective thickness of the adaptive range compensator, and the output signal is used to give the state of the adaptive range compensator at the time and the current effective thickness of the compensation.

[0019] As a further limitation of the first aspect of the application, the adaptive range compensator includes: a plurality of adaptive range compensator blades are fixed on a lead screw one in parallel through keys and slots, the adaptive range compensator as a whole is fixed on a lead screw two, the lead screw two is driven by a motor two to make the adaptive range compensator as a whole move in one dimension, the lead screw one is driven by a motor one to adjust the position of each adaptive range compensator blade, so that the adaptive range compensator blades are in or out of the particle beam path, and finally the independent in-out motion of part of the blades is realized.

[0020] As a further limitation of the first aspect of the application, the adaptive range compensator includes: a pneumatic device adjusts the total thickness of the compensator block by adjusting the position of a plurality of adaptive range compensator blades in parallel on the motion mechanism in one dimension; the adaptive range compensator blades are fixed on a lead screw one through keys and connected in parallel through slots, and the adaptive range compensator blades are driven by a pneumatic actuator to make one-dimensional reciprocating motion on the guide rail or above, so that part of the adaptive range compensator blades are in the same position as the particle gun, and the other part of the adaptive range compensator blades are in different positions from the particle gun.

[0021] As a further limitation of the first aspect of the present invention, the adaptive range compensator includes: processing a metal block into a wedge-shaped block to obtain a wedge-shaped adaptive range compensator; fixing the wedge-shaped adaptive range compensator to a lead screw by a key; and having a motor drive the lead screw to move, thereby changing the position of the wedge-shaped adaptive range compensator and providing different effective thicknesses of the compensator.

[0022] As a further definition of the first aspect of the present invention, the adaptive range compensator includes: a disc-shaped adaptive range compensator instead of a wedge-shaped adaptive range compensator; the disc shape is designed as a non-uniform disc with thickness varying with the angle, a rotation center is set at the center position, and the position of each different thickness of the disc is precisely calibrated by the degree of a potentiometer coupled thereto.

[0023] In a second aspect, the present invention provides an imaging method for a dynamic adaptive range compensator, comprising:

[0024] By filtering out particles that pass directly through the detector, the trajectory and direction of the particle's motion are reconstructed to obtain the energy and position information of the particle at the time of incident.

[0025] Dynamic adaptive compensation of the particle's remaining range is achieved by adjusting the effective thickness of the compensator, so as to receive the particle signal and obtain the remaining range corresponding to the remaining energy when the particle passes through the imaged object; where the effective thickness of the compensator refers to the thickness of the compensator within the particle incident range along the particle incident direction.

[0026] The remaining range of the imaged object is calculated based on different positions and angles, and the resulting image is output.

[0027] The beneficial effects of this invention are as follows: It replaces a large number of detectors with mechanical modules, and with fewer detector layers, it reduces manufacturing difficulty and costs while achieving efficient continuous target detection. The entire system is divided into a detector module, an adaptive range compensation module, and an electronics module. The detector data acquisition process and the motion control of the adaptive range compensation module are integrated into the electronics module, and mutual adjustment is achieved through trigger control to realize the overall operation of the system. A dynamic compensator is used instead of the non-adjustable compensator in the original method. The biggest difference between the dynamic compensator and the existing non-adjustable compensator is that the compensator adjustment system is a self-contained module, integrated with other modules into the electronics module, and adjusts the mechanical motion state of the adaptive range compensator through feedback electrical signals. The adaptive range compensator module consists of an adjustable compensation block and a motion mechanism. The motion mechanism receives the electrical signals fed back from the electronics part and adjusts the adjustable compensation block to meet the detection requirements. By making the compensator dynamic, (quasi-)continuous range compensation can be achieved in principle. By using compensation blocks with different compensation thicknesses and fewer detector layers, higher accuracy than the original method can be achieved, reducing costs while achieving better detection results.

[0028] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and will become apparent from the description or may be learned by practice of the invention. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a functional framework diagram of the imaging system described in an embodiment of the present invention.

[0031] Figure 2 This is a structural diagram of the adaptive range compensator described in Embodiment 1 of the present invention.

[0032] Figure 3 This is a structural diagram of the adaptive range compensator described in Embodiment 2 of the present invention.

[0033] Figure 4 This is a structural diagram of the adaptive range compensator described in Embodiment 3 of the present invention.

[0034] Figure 5 This is a structural diagram of the adaptive range compensator described in Embodiment 4 of the present invention.

[0035] The components are: 1. Particle source; 2a. Position detector one; 2b. Position detector two; 2c. Position detector three; 3. Imaged object; 4. Adaptive range compensator; 5a. Motor one; 5b. Motor two; 6a. Data cable one; 6b. Data cable two; 6c. Data cable three; 7. Slot; 8. Key; 9a. Lead screw one; 9b. Lead screw two; 10. Pneumatic actuator; 11. Shaft. Detailed Implementation

[0036] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0037] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0038] It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as here.

[0039] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, and / or groups thereof.

[0040] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0041] In the description of this specification, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0042] In the description of this specification, the terms “center,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” and “outer,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this technology and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this technology.

[0043] Unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integral connection or setting. Those skilled in the art can understand the specific meaning of these terms in this art according to the specific circumstances.

[0044] To facilitate understanding of the present invention, the present invention will be further explained and described below with reference to the accompanying drawings and specific embodiments. However, the specific embodiments do not constitute a limitation on the embodiments of the present invention.

[0045] Those skilled in the art should understand that the accompanying drawings are merely schematic diagrams of embodiments, and the components in the drawings are not necessarily essential for implementing the present invention.

[0046] The basic principles employed in this invention can be described as follows.

[0047] The range of a particle varies in different materials. The ratio of a particle's range in a material to its range in water is the relative stopping power (RSP) of that material. Therefore, the RSP of water is 1.00. The material's RSP value is converted to WEPL for unified calculation. Thus, the following relationship exists:

[0048] ;

[0049] Among them, WEPL 总 For the particle's range in water, WEPL i RSP is the equivalent water path of a particle in a certain material. i This refers to the relative blocking ability of the material. The thickness is the material thickness.

[0050] The particle exits from the accelerator output window, passes through the position detector, the imaged object, and the compensator, and stops exactly on the detector and generates a response. At this time, the WEPL (hereinafter referred to as "remaining range") corresponding to the remaining energy when the particle exits the imaged object can be calculated by the number of layers compensated by the compensator.

[0051] like Figure 1 The system involved in the method of the present invention mainly consists of a particle source, a position detector, an adaptive range compensator, a compensator position control circuit, a data acquisition and image processing computer, and other equipment. The main steps and key design components of the system operation are described in detail below. This embodiment provides a dynamic adaptive range compensator imaging system, including: a particle track detection module, used to filter particles that pass directly through the detector, reconstruct the track and direction of particle motion, and obtain the energy and position information of the particles at the time of incident; an adaptive range compensation module, used to achieve dynamic adaptive compensation of the remaining range of the particles by adjusting the effective thickness of the compensator, so as to receive particle signals and obtain the remaining range corresponding to the remaining energy of the particles when they exit the imaged object; wherein, the effective thickness of the compensator refers to the thickness of the compensator within the particle incident range along the particle incident direction; and an image processing module, used to calculate and output images based on the remaining range of the imaged object under different position and angle conditions.

[0052] In the particle track detection module, after being emitted from the particle source, the particle sequentially passes through the first position detector, the imaged object, and the second position detector. The second position detector records the energy and position information of the particle upon incident. The adaptive range compensation module includes an adaptive range compensator, a third position detector, and a control unit. The third position detector feeds back the particle reception status to the control unit based on the received particle signal. The control unit adjusts the effective thickness of the compensator. The control unit has a trigger input signal and an output signal, forming a feedback adjustment between receiving the trigger signal from the third position detector. The input signal is used to adjust the effective thickness of the adaptive range compensator, and the output signal is used to provide the current state of the adaptive range compensator and the current effective compensation thickness.

[0053] Particle Track Detection Module: This module reconstructs the tracks and directions of particle motion. During particle transport, scattering may occur, causing the path to deviate from a straight line and affecting image reconstruction. Unlike common multi-layer detector imaging systems, analyzing the particle positions measured by each layer allows for fitting the particle track and obtaining an approximate particle range. However, this invention uses a significantly reduced number of detector layers. While it cannot completely reconstruct the particle track, it can be used to filter particles that pass directly through the detectors for image reconstruction. After being emitted from the particle source, the particle sequentially passes through position detector one, the imaged object, and position detector two. The position detectors record information such as the particle's energy and position upon incident. The number of detector layers before the adaptive range compensation module can be flexibly adjusted as needed. The more position detector layers, the more accurate the fitted particle track and the better the imaging result.

[0054] Adaptive Range Compensation Module: The core idea of ​​the adaptive range compensation module is to achieve dynamic adaptive compensation of the particle's remaining range through the mechanical movement of a variable-thickness compensation layer. Compared to the original method that uses a large number of detectors and compensators for detection, mechanical control has advantages such as simple structure, high compensation accuracy, simple output signal, and low cost, which is also the main innovation of this method. Due to the Bragg effect of particles, if the WEPL of position detector three is ignored, when the WEPL of the compensator is greater than the particle's remaining range, the particle will not pass through; when the WEPL of the compensator is less than the particle's remaining range, the particle will pass through the compensator and position detector three; when the WEPL of the compensator is equal to the particle's remaining range, position detector three just receives the particle. At this time, the WEPL of the imaged object at that position can be calculated based on the WEPL of the compensator for final imaging. The effective thickness of the compensator refers to the thickness of the compensator within the particle's incident range along the particle's incident direction. When the compensator material is constant, the effective thickness of the compensator is proportional to the WEPL. In actual operation, position detector three feeds back the particle receiving status to the position control circuit based on the received particle signal. The position control circuit then controls the position control element to adjust the effective thickness of the compensator. The compensation module has a trigger input signal and an output signal, forming a feedback adjustment between the trigger signal given by position detector three. The input signal is used to adjust the effective thickness of the compensator, and the output signal is used to indicate the current state of the compensator and the current effective thickness being compensated.

[0055] In one specific embodiment, the effective thickness adjustment of the adaptive range compensator is achieved by adjusting the blades via a motor-screw control system, such as... Figure 2As shown, the system includes: a particle source 1; position detector 1 2a; position detector 2b; position detector 3 2c; the object being imaged 3; an adaptive range compensator 4; a motor 1 5a; a motor 2 5b; a data cable 1 6a; a data cable 2 6b; a data cable 3 6c; a slot 7; a key 8; a lead screw 1 9a; and a lead screw 2 9b. Multiple adaptive range compensator blades made of metal are fixed to lead screw 1 in parallel via keys and slots. The entire adaptive range compensator is fixed to lead screw 2. Motor 2 drives lead screw 2, allowing the compensator to move in one dimension. Motor 1 drives lead screw 1, adjusting the position of each adaptive range compensator blade, enabling the blades to be in or out of the particle beam path, ultimately resulting in independent entry and exit movements of some blades. Only the adaptive range compensator blades located in the particle beam path are included in the effective thickness of the compensator. The motor receives electrical signals from the feedback circuit, enabling forward and reverse rotation, corresponding to the two directions of movement of the lead screw and its connected adaptive range compensator blades on the base. Initially, all blades of the adaptive range compensator block the beam path, resulting in no particle signal in the detector. At this point, the blades are moved out of the beam path layer by layer. When the detector module receives a particle signal, the motor stops via a trigger control circuit. The adaptive module outputs the number of compensation layers for each compensator at this moment through the motor's encoder reading. This, combined with the particle gun position and the detection results from position detectors one and two, determines the total thickness of the compensator. The entire system is placed on a one-dimensional motion platform capable of movement in one dimension. Through point-by-point scanning of the beam in one dimension, a one-dimensional projection of the scanning range distribution of the imaged object's cross-section at the current angle is formed. The advantages of screw adjustment are its simple structure, mature technology, stable operation, and low mechanical requirements, but it requires regular maintenance. The disadvantages are the slower required movement speed and longer imaging time.

[0056] In another specific embodiment, the effective thickness adjustment of the adaptive range compensator is controlled by a pneumatic actuator to adjust the blades, such as... Figure 3As shown, it includes: particle source 1; position detector 1 2a; position detector 2b; position detector 3 2c; imaged object 3; adaptive range compensator 4; pneumatic actuator 10; motor 2 5b; data cable 1 6a; data cable 2 6b; data cable 3 6c; slot 7; key 8; lead screw 1 9a; lead screw 2 9b. Similar to lead screw adjustment, the pneumatic device also increases or decreases the total thickness of the compensation block by adjusting the position of multiple adaptive range compensator blades connected in parallel on the motion mechanism in one dimension. The pneumatic actuator uses compressed gas as a medium, converting gas pressure into mechanical energy to drive the compensation block to reciprocate. Unlike lead screw adjustment where the compensator position changes continuously, when the pneumatic actuator adjusts the compensator position, there are generally only two extreme states. The method of adjusting the position is basically the same as that of lead screw adjustment. The adaptive range compensator blades are fixed to lead screw one by a key and connected in parallel by a slot. The pneumatic actuator drives the adaptive range compensator blades to perform one-dimensional reciprocating motion on the guide rail or surface, so that some adaptive range compensator blades are in the same position as the particle gun, and others are in a different position. When the system is in the initial state, all adaptive range compensator blades are in the same position as the particle gun, and position detector three has no signal. As the number of adaptive range compensator blades in the same position as the particle gun is gradually reduced until position detector three shows a signal, the status information of each pneumatic actuator is read, and the effective thickness of the adaptive range compensator can be obtained at this time. Motor two drives lead screw two and the compensator assembly fixed on lead screw two to move in one dimension. Combined with the point-by-point scanning of the beam in one dimension, a one-dimensional projection of the scanning range distribution of the imaged object cross-section at the current angle is formed. The advantage of pneumatic actuator adjustment is that it is responsive and simple to control; position adjustment can be achieved by controlling the cylinder valve. The disadvantage of pneumatic actuator adjustment is that the high-pressure air supply mechanism occupies a large volume and has low motion accuracy. However, this method only requires the compensator to switch between two extreme positions and does not require high position accuracy, so this point does not need to be considered.

[0057] In another specific embodiment, the effective thickness adjustment of the adaptive range compensator is achieved by adjusting the position of the wedge compensator, such as... Figure 4As shown, it includes: particle source 1; position detector 1 2a; position detector 2b; position detector 3 2c; imaged object 3; adaptive range compensator 4; motor 1 5a; motor 2 5b; data cable 1 6a; data cable 2 6b; data cable 3 6c; key 8; lead screw 1 9a; lead screw 2 9b. Both of the above adjustment methods require multiple compensator blades to work simultaneously and require multiple motors to control them. By machining the metal block into a wedge shape, a wedge-shaped adaptive range compensator can be obtained. The wedge-shaped adaptive range compensator is fixed to lead screw 1 by a key. Motor 1 drives lead screw 1 to move, changing the position of the wedge-shaped adaptive range compensator to provide different effective compensator thicknesses. Initially, the wedge-shaped adaptive range compensator is set at the maximum effective thickness position. As the movement continues, the effective thickness gradually decreases until position detector 3 sends a signal. The motor encoder reading at this point is read to obtain the effective thickness, and the range at that position is calculated. Motor 2 drives lead screw 2 and the compensator fixed on lead screw 2 to move in one dimension. Combined with point-by-point scanning of the beam in one dimension, a one-dimensional projection of the scanning range distribution of the imaged object's cross-section is formed at the current angle. The adjustment method is consistent with that of a multi-layer blade compensator, using a one-dimensional translational motion platform to drive the compensator's movement. Each stroke value corresponds to the compensator thickness. In this method, the compensator position is proportional to WEPL. High accuracy of the compensator position parameters is required during imaging, making pneumatic adjustment unsuitable; lead screw adjustment is preferred. Accurate reading of the lead screw position parameters is necessary during adjustment, and certain requirements are placed on the return signals from the moving parts.

[0058] In another specific embodiment, the effective thickness adjustment of the adaptive range compensator is adjusted via a rotary compensator, such as... Figure 5 As shown, it includes: particle source 1; position detector 1 2a; position detector 2b; position detector 3 2c; imaged object 3; adaptive range compensator 4; motor 1 5a; motor 2 5b; data cable 1 6a; data cable 2 6b; data cable 3 6c; shaft 11; lead screw 2 9b. The motion mode of the wedge compensator results in a longer imaging time. To address this drawback, a disc-type adaptive range compensator is used instead of the wedge-shaped adaptive range compensator. The disc shape is designed as a non-uniform disc with thickness varying with the angle, and a rotation center is set at the center position. The position of each different thickness of the disc can be precisely calibrated by the degree of the potentiometer coupled to it. Replacing one-dimensional linear motion with circular motion can also achieve the purpose of changing the effective thickness of the compensator. Figure 4This is a schematic diagram of the device used in this method. During the detection process, a disc-shaped adaptive range compensator is fixed on a shaft. Motor 1 drives the disc-shaped adaptive range compensator to rotate via the shaft, traversing every angle of the compensator, corresponding to various effective thicknesses of the compensator and different WEPL (Weighted Field Proportion). The rotation angle of the disc-shaped adaptive range compensator is correlated with the receiving state through the output signal of position detector 3. Motor 2 drives lead screw 2 and the compensator fixed on lead screw 2 to move in one dimension. Combined with the point-by-point scanning of the beam in one dimension, a one-dimensional projection of the scanning range distribution of the cross-section of the imaged object at the current angle is formed. The advantage of using a disc-shaped compensator for adjustment is that the disc rotation speed can be very fast, and the imaging time can be further shortened compared to the previous two methods.

[0059] The sheet-like compensator described in this embodiment of the invention is the most common type in currently used detection systems. By fabricating compensator blades from different materials, various compensator blades with different WEPLs can be obtained. Table 1 below provides the RSP reference values ​​for different materials.

[0060] Table 1 Reference RSP values ​​for different materials

[0061]

[0062] Based on the RSP values ​​in Table 1 above, different materials are selected to manufacture the compensator blades as needed. Multiple compensator blades are integrated into a single compensator system and uniformly controlled via electronic circuitry. Alternatively, multiple adaptive modules can be used to meet the needs of large imaging objects.

[0063] After passing through the compensator module, the particle reaches position detector three. Position detector three is used to detect the particle's range and feed it back to the electronics section. When the particle's range is large and it passes through position detector three, the electronics section adjusts the compensator module via electrical signals to increase the total thickness of the compensator. When a suitable thickness is reached, the electronics section outputs the state of the compensator blades at this time, which is used to calculate the WEPL at that moment.

[0064] Since the WEPL change inside the imaged object is theoretically continuous, in the design of the compensator adjustment method, the state of the compensator blade at the next position can inherit the state of the compensator blade at the previous position. Adjustment can be made in the previous state, which can save detection time.

[0065] The aforementioned device can rotate around the object being imaged, or scan at different angles by rotating the object. It ultimately outputs a WEPL two-dimensional projection distribution map of the object at different angles. A tomographic image reconstruction algorithm is then used by an image processing computer to output a tomographic image of the object.

[0066] In summary, the dynamic adaptive range compensator imaging system and method described in this invention can adjust the equivalent water thickness in real time according to the particle emission energy state, achieving precise control so that "the particle just stops on the detector." This closed-loop feedback mechanism is significantly superior to the internationally commonly used fixed-layer passive compensation structure, exhibiting clear advantages in measurement accuracy, cost, and integration. By implementing this method, the number of detector layers required for particle imaging can be effectively reduced, as can the use of high-precision position detectors and their multi-channel electronics, greatly saving material and manufacturing costs and simplifying the mechanical structure of the entire imaging system. The compact structure and the good stackability of the compensator and detector modules allow for the expansion of the range measurement range and the recording of particle response information at multiple positions, enabling the tracking of their tracks and compensating for image degradation caused by multiple scattering. This achieves the adjustment requirements for higher imaging accuracy under low-cost conditions. The particle imaging and dynamic range compensation technology of this invention can significantly improve the accuracy and safety of tumor particle radiotherapy, further reducing treatment errors and side effects, and improving patient treatment experience and prognosis.

[0067] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that, based on the technical solutions disclosed in the present invention, various modifications or variations that can be made by those skilled in the art without creative effort should be included within the scope of protection of the present invention.

Claims

1. A dynamic adaptive range compensator imaging system, characterized in that, include: The particle track detection module is used to filter particles that pass directly through the detector, reconstruct the track and direction of particle motion, and obtain the energy and position information of the particles when they are incident. The adaptive range compensation module is used to achieve dynamic adaptive compensation of the particle's remaining range by adjusting the effective thickness of the compensator, so as to receive the particle signal and obtain the remaining range corresponding to the remaining energy when the particle passes through the imaged object; where the effective thickness of the compensator refers to the thickness of the compensator within the particle incident range along the particle incident direction. The image processing module is used to calculate and output images based on the remaining range of the imaged object under different positions and angles.

2. The dynamic adaptive range compensator imaging system according to claim 1, characterized in that, In the particle track detection module, after the particle is emitted from the particle source, it passes through the first position detector, the imaged object and the second position detector in sequence. The second position detector records the energy and position information of the particle when it is incident.

3. The dynamic adaptive range compensator imaging system according to claim 1, characterized in that, The adaptive range compensation module includes an adaptive range compensator, a third position detector, and a control unit. The third position detector feeds back the particle receiving status to the control unit based on the received particle signal, and the control unit adjusts the effective thickness of the compensator. The control unit has a trigger input signal and an output signal, forming a feedback adjustment between receiving the trigger signal from the third position detector. The input signal is used to adjust the effective thickness of the adaptive range compensator, and the output signal is used to give the current state of the adaptive range compensator and the current effective thickness of the compensation.

4. The dynamic adaptive range compensator imaging system according to claim 3, characterized in that, The adaptive range compensator includes: multiple adaptive range compensator blades fixed in parallel on lead screw one via keys and slots; the adaptive range compensator as a whole fixed on lead screw two; the compensator as a whole moves in one dimension by driving lead screw two via motor two; the position of each adaptive range compensator blade can be adjusted by driving lead screw one via motor one, so that the adaptive range compensator blades are in or away from the particle beam path, and finally exhibit independent entry and exit movements of some blades.

5. The dynamic adaptive range compensator imaging system according to claim 3, characterized in that, The adaptive range compensator includes: a pneumatic device that adjusts the position of multiple adaptive range compensator blades connected in parallel on the motion mechanism to increase or decrease the total thickness of the compensation block in one dimension; the adaptive range compensator blades are fixed to the lead screw by a key, connected in parallel by slots, and driven by a pneumatic actuator to perform one-dimensional reciprocating motion on a guide rail or on a guide rail, so that a portion of the adaptive range compensator blades are in the same position as the particle gun, and another portion of the adaptive range compensator blades are in different positions from the particle gun.

6. The dynamic adaptive range compensator imaging system according to claim 3, characterized in that, The adaptive range compensator includes: machining a metal block into a wedge-shaped block to obtain a wedge-shaped adaptive range compensator; fixing the wedge-shaped adaptive range compensator to a lead screw by a key; and driving the lead screw to move by a motor to change the position of the wedge-shaped adaptive range compensator and provide different effective compensator thicknesses.

7. The dynamic adaptive range compensator imaging system according to claim 6, characterized in that, The adaptive range compensator includes: a disc-shaped adaptive range compensator instead of a wedge-shaped adaptive range compensator; the disc shape is designed as a non-uniform disc with thickness varying with the angle, and a rotation center is set at the center position. The position of each different thickness of the disc is precisely calibrated by the reading of a potentiometer coupled to it.

8. A dynamic adaptive range compensator imaging method, characterized in that, include: By filtering out particles that pass directly through the detector, the trajectory and direction of the particle's motion are reconstructed to obtain the energy and position information of the particle at the time of incident. Dynamic adaptive compensation of the particle's remaining range is achieved by adjusting the effective thickness of the compensator, so as to receive the particle signal and obtain the remaining range corresponding to the remaining energy when the particle passes through the imaged object; where the effective thickness of the compensator refers to the thickness of the compensator within the particle incident range along the particle incident direction. The remaining range of the imaged object is calculated based on different positions and angles, and the resulting image is output.

Images