Laser proton cancer treatment rotating support system based on chromatic aberration energy selection

Abstract

The invention discloses a laser proton cancer treatment rotating bracket system based on chromatic aberration energy selection, which adopts a laser proton cancer treatment rotating bracket scheme of a rotating light path, realizes efficient delivery of a proton beam driven by laser, and reduces the weight of Gantry.

Description

Technical Field

[0001] The invention relates to a laser proton accelerator, and in particular to a laser proton cancer treatment rotating bracket system based on chromatic aberration energy selection. Background Art

[0002] According to the World Health Organization, approximately 10 million cancer deaths occur worldwide each year, a number projected to reach 24 million in 20 years. Traditional photon radiotherapy, such as X-rays, has significant side effects and poor efficacy, leading to high recurrence rates. However, protons and heavy ions possess a significant advantage in human irradiation therapy due to their Bragg peak. Upon entering the body, they release most of their energy only where they land, effectively killing deep-seated tumors while minimizing damage to superficial normal tissue. By 2015, proton and heavy ion tumor treatments had exceeded 154,000 cases worldwide, with proton therapy accounting for over 130,000 of these cases. However, ion acceleration equipment, primarily based on radiofrequency accelerators, is bulky, expensive, and requires significant maintenance and operation, making it difficult to commercialize.

[0003] The laser-driven proton therapy device, currently being designed by Peking University, is a novel proton accelerator. It is the world's first laser-driven proton therapy accelerator. Protons will be generated by laser-plasma interaction, using a 2PW laser to achieve proton energies of 100 MeV. This laser accelerator, utilizing this novel principle, can achieve acceleration gradients exceeding 100 GV / m (at least three orders of magnitude higher than radiofrequency accelerators), significantly reducing the size and cost of the accelerator. Ultra-intense, ultra-short laser-driven accelerators, due to their high acceleration gradients, have become one of the most intriguing topics in the accelerator community in recent years.

[0004] Traditional proton therapy accelerator rotating gantry is a device used for radiotherapy, typically consisting of an accelerator, a rotating gantry, a control system, and a radiation device. The rotating gantry can rotate 360 ​​degrees around the patient's body to achieve precise radiotherapy. The rotating gantry can flexibly adjust the incident angle and direction of the particle beam, enabling personalized radiotherapy plans based on factors such as the location and shape of the tumor. A stable magnetic field and control system ensure the stability of the particle beam's trajectory and energy, improving the precision and effectiveness of radiotherapy. In contrast, in the laser proton therapy rotating gantry structure, the accelerator's magnet portion is replaced by the optical path, significantly reducing the weight of the rotating gantry and lowering the equipment's maintenance and operating costs. Summary of the Invention

[0005] In order to solve the technical problems existing in the above-mentioned prior art, the present invention provides a rotating bracket system for laser proton cancer therapy based on a rotatable optical path, which is characterized by comprising a rotatable optical path and a bracket system, wherein the rotatable optical path includes four reflectors, the first reflector is a deformable reflector; the second, third, and fourth reflectors are used to adjust the laser transmission angle.

[0006] In a possible implementation manner, the first reflector can correct the mirror deviation caused by gravity according to the rotation angle of the rotating frame.

[0007] In one possible implementation, an off-axis parabolic reflector is also included.

[0008] The present invention also proposes a beam transport device, including a beam chromatic aberration energy selection beam line and a rotating optical path laser proton cancer therapy rotating support system, characterized in that the rotating optical path laser proton cancer therapy rotating support system comprises: a rotatable optical path, a support system;

[0009] The beam chromatic aberration energy selection beamline includes: superconducting solenoid S1#, energy degrader, superconducting solenoid S2# and energy selection aperture;

[0010] The rotating optical path includes four reflectors, the first reflector is a deformable reflector; the second, third and fourth reflectors are used to adjust the laser transmission angle.

[0011] In one possible implementation, an off-axis parabolic reflector is also included.

[0012] In a possible implementation manner, the first reflector can correct the mirror deviation caused by gravity according to the rotation angle of the rotating frame.

[0013] In one possible implementation, the beam chromatic aberration energy selection beam line and the laser proton cancer therapy rotating support system with a rotating optical path can rotate together.

[0014] The medium-beam chromatic aberration energy-selective beamline of the present invention includes: a superconducting solenoid S1#, an energy degrader, a superconducting solenoid S2#, and an energy-selective aperture. The motion state of the beam passing through the superconducting solenoid and drift section is calculated based on beam dynamics, and the parameter changes of the beam before and after passing through the energy degrader are calculated using Monte Carlo simulation. Subsequently, the motion state of the beam after passing through the drift section, solenoid, and energy-selective slit is further calculated using beam dynamics. Finally, a laser proton beam with an energy spread of less than 6% is obtained, which is used for late scattering scheme to treat cancer. The present invention uses a beam chromatic aberration energy selection beam line to achieve beam screening and introduces the beam to the required position through a laser proton cancer treatment rotating bracket system with a rotating optical path. The device and method of the present invention abandon the complex transmission system used in traditional cancer treatment accelerators, and adopt a relatively simple chromatic aberration energy selection combination of solenoids, energy degraders and energy selection apertures. It uses a more miniaturized beam chromatic aberration energy selection beam line to complete the selection of target energy required for cancer treatment, and can control the beam transmission energy dispersion to facilitate Bragg peak superposition during the treatment process, ensuring that different depths of the irradiated lesions can receive uniform and controllable dose irradiation; and the bracket system is improved, so that the weight of the proton synchrotron gantry will be reduced by 10 times. The beam line system and proton transmission system can be placed in a 10×6×6m 3 The volume and weight of the proton therapy device are reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of an embodiment of a laser proton cancer therapy rotating stent system based on a rotatable optical path according to the present invention;

[0016] Figure 2 A schematic diagram of an embodiment of a laser-accelerated proton beam transport system based on a combination of chromatic energy selection and an energy degrader according to the present invention; DETAILED DESCRIPTION

[0017] To address the technical challenges of the existing technologies, a promising approach is to use a compact beam delivery structure. This new system accelerates laser protons at the target point and delivers the beam to the patient's lesion via a beam delivery line.

[0018] like Figure 1 As shown in Figure 2, this compact, rotatable laser beamline structure significantly reduces the size and weight of a proton laser therapy rotating gantry. It avoids the engineering challenges of using large electromagnets to bend a high-energy proton beam 180 degrees. The proton laser therapy rotating gantry system primarily consists of an optical transmission system and a beam delivery system.

[0019] After the laser is emitted from the laser system, it passes through four reflectors to calibrate the laser beam position. The first reflector is a deformable mirror. It can correct mirror deviation caused by gravity according to the rotation angle of the rotating frame to avoid affecting laser quality. The second, third, and fourth reflectors are used to adjust the laser transmission angle. Finally, the beam passes through the off-axis parabolic reflector to complete the laser target process.

[0020] The proton beam chromatically selected beamline consists of two solenoids, an energy decelerator, and a terminal energy aperture. The entire rotating bracket can rotate 0-180 degrees around the isocentric position of the laser outlet and the treatment bed.

[0021] During this process, the beam chromatic aberration energy selection beamline and the laser proton therapy rotating support system with rotating optical path can rotate together. The lightweight and compact laser gantry adopts a simple and compact structure. The weight of the gantry is expected to be controlled within 10 tons, and the weight of the proton synchrotron gantry will be reduced by 10 times. The beamline system and proton transport system can be placed in a 10×6×6m 3 The volume and weight of the proton therapy device are reduced.

[0022] The method of the present invention abandons the complex transmission system used in traditional cancer treatment accelerators and adopts a relatively simple chromatic energy selection combination of a solenoid, an energy degrader, and an energy selection aperture. It uses a more miniaturized beam chromatic energy selection beam line to complete the selection of the target energy required for cancer treatment. It can also control the energy dispersion of the beam transmission to facilitate Bragg peak superposition during the treatment process, ensuring that different depths of the irradiated lesion receive uniform and controllable irradiation doses.

[0023] One object of the present invention is to provide a beam transport device, including a beam chromatic aberration energy selection beam line and a rotating optical path laser proton cancer therapy rotating support system, characterized in that the rotating optical path laser proton cancer therapy rotating support system comprises: a rotatable optical path, a support system;

[0024] The beam chromatic aberration energy selection beamline includes: superconducting solenoid S1#, energy degrader, superconducting solenoid S2# and energy selection aperture;

[0025] The rotating optical path includes four reflectors, the first reflector is a deformable reflector; the second, third and fourth reflectors are used to adjust the laser transmission angle.

[0026] The medium-beam chromatic aberration energy-selective beamline of the present invention includes: a superconducting solenoid S1#, an energy degrader, a superconducting solenoid S2#, and an energy-selective aperture. The motion state of the beam passing through the superconducting solenoid and drift section is calculated based on beam dynamics, and the parameter changes of the beam before and after passing through the energy degrader are calculated using Monte Carlo simulation. Subsequently, the motion state of the beam after passing through the drift section, solenoid, and energy-selective slit is further calculated using beam dynamics. Finally, a laser proton beam with an energy spread of less than 6% is obtained, which is used for late scattering scheme to treat cancer. The present invention uses a beam chromatic aberration energy selection beam line to achieve beam screening and introduces the beam to the required position through a laser proton cancer treatment rotating bracket system with a rotating optical path. The device and method of the present invention abandon the complex transmission system used in traditional cancer treatment accelerators, and adopt a relatively simple chromatic aberration energy selection combination of solenoids, energy degraders and energy selection apertures. It uses a more miniaturized beam chromatic aberration energy selection beam line to complete the selection of target energy required for cancer treatment, and can control the beam transmission energy dispersion to facilitate Bragg peak superposition during the treatment process, ensuring that different depths of the irradiated lesions can receive uniform and controllable dose irradiation; and the bracket system is improved, so that the weight of the proton synchrotron gantry will be reduced by 10 times. The beam line system and proton transmission system can be placed in a 10×6×6m 3 The volume and weight of the proton therapy device are reduced.

[0027] The beamline for chromatic aberration energy selection consists of a first superconducting solenoid, an energy degrader, a second superconducting solenoid, and an energy selection aperture. During beam propagation, the beam parameters in one direction are expressed as a 2x1 matrix. The z-axis is the beam's motion direction, and two mutually perpendicular x and y directions are defined on a plane perpendicular to this axis. In subsequent calculations, the beam's motion is described using 2x1 matrices in each of these three directions. Forces that alter the beam's motion are described using 2x2 matrices.

[0028] The motion state of the beam entering the beam chromatic aberration selection process can be expressed by the following matrices:

[0029]

[0030] Among them, xyz represents the position of the beam in the three directions of xyz, and x′y′z′ represents the momentum in the three directions of xyz.

[0031] The beam drift section is also called the drift node. When the beam passes through the drift node, it is not affected by external forces and will continue its previous motion state. The transmission matrix is ​​as follows:

[0032]

[0033] Where Δs is the drift node length and γ is the relative velocity of the beam.

[0034] The motion state of the beam after passing through the drift node can be calculated as follows:

[0035]

[0036] The transmission of a quadrupole magnet can be approximated by the following parameters:

[0037]

[0038] in, is the focusing intensity of the beam in the x direction. Since the solenoid is symmetrically focused, k x =k y , Δs = ρΔα is the magnetic rigidity of the particle. In this calculation, the solenoid is treated as a thin lens, meaning a lens with no thickness. The beam tends to move toward the center of the beam as it passes through the solenoid, which is called focusing. The solenoid only provides a lateral force on the beam and does not affect its longitudinal motion. Therefore, the longitudinal transmission matrix is ​​a unit matrix. The motion of the beam after passing through the solenoid can be calculated as follows:

[0039]

[0040] The low-energy beam can be blocked when the beam passes through the degrader. The changes in various parameters of the beam after passing through the degrader can be calculated through Monte Carlo simulation.

[0041] The energy loss and exit angle of a proton in a material depend primarily on the proton's initial energy, the material's properties (such as atomic number and density), the length of the path it travels, and the interaction between the proton and the material's atoms. Energy loss occurs primarily through ionization loss and radiation loss. Ionization loss dE / dx can be calculated using the following formula:

[0042]

[0043] Among them, m e is the rest mass of the electron; c is the speed of light; z is the charge number of the incident charged particle (proton is 1); e is the charge of the electron; β is the ratio of the speed of the incident charged particle to the speed of light β = v / c; γ is the Lorentz factor; Z is the atomic number of the target; A is the atomic mass number of the target; T max is the maximum energy that a charged particle can transfer to a free electron; I is the average ionization energy of the target.

[0044] The proton's exit angle is mainly affected by multiple Coulomb scattering, and the multiple scattering angle can be estimated using the following formula:

[0045]

[0046] Where θ0 is the root mean square scattering angle; p is the momentum of the proton; z is the proton charge number; x is the thickness of the material the particle passes through; and X0 is the radiation length of the material, which represents the path length through which the charged particle's energy is reduced to 1 / e of its original energy.

[0047] Based on the above formula, we conclude that the energy degrader can effectively block the passage of low-energy beams without affecting the normal passage of high-energy beams. We will use the above characteristics and the chromatic aberration effect of different energies to achieve the selection of corresponding energies, and by controlling the aperture of the energy selection aperture, we can achieve the regulation of the terminal output energy dispersion. The specific operation process of the beam is as follows:

[0048] The beam is initially collected and lateralized by the first superconducting solenoid. After passing through the first drift section, it passes through the energy degrader to filter out low-energy particles. After passing through the second drift section, the beam enters the second superconducting solenoid for further collection. After passing through the third drift section, the beam passes through the energy selection aperture. The solenoids collect the beam, resulting in different focal lengths for beams of different energies. Controlling the solenoid's magnetic field determines the desired central energy, while controlling the energy selection aperture radius modifies the aperture's energy spread.

[0049] The method of the present invention abandons the complex transmission system used in traditional cancer treatment accelerators, and adopts a relatively simple chromatic energy selection combination of a solenoid, an energy degrader and an energy selection aperture. It uses a more miniaturized beam chromatic energy selection beam line to complete the selection of the target energy required for cancer treatment, and can control the beam transmission energy dispersion to facilitate Bragg peak superposition during the treatment process, ensuring that different depths of the irradiated lesions can receive uniform and controllable dose irradiation; the present invention will use a combination of chromatic energy selection and an energy degrader to complete the transmission and delivery of the laser-driven proton beam, and promote the laser-driven proton therapy device project.

[0050] We used TraceWin software to simulate the collection process of a laser-driven proton beam and studied the beam envelope of the laser-driven proton beam in the CS. The proton parameters obtained by laser acceleration were defined as input parameters. The particle source was located 340 mm upstream of the first superconducting solenoid, marked as the "entrance" in Figure 1. CLAPA-II can deliver proton beams with energies between 30 and 200 MeV, but at this stage of the project, we required a beam with a maximum energy of 100 MeV and an energy spread of less than 5%.

[0051] Figure 2 The envelope and structure diagram of the CS obtained by simulation under given parameters are shown in Figure 2. The energy selection process is realized by using a combination of solenoid and energy selection aperture.

[0052] The collection efficiency (ηT) of the light beam is expressed as the ratio of the number of particles passing through the energy hole (NT) to the total number of particles at the beginning (NTtotal). The 1% energy dispersion selection efficiency (η1%) of the light beam is defined as the ratio of the number of particles with energy dispersion less than 1% (N±1%) passing through the energy selection device to the number of transmitted particles (NT).

[0053]

[0054] This solution utilizes the chromatic aberration effect of the solenoid, and under the premise of energy dispersion of ±1%, ηT = 29.7%.

[0055] The collection efficiency (ηT) of the light beam is expressed as the ratio of the number of particles (NT) passing through the energy selection hole to the total number of particles at the beginning (NTtotal). The 1% energy dispersion selection efficiency (η1%) of the light beam is defined as the ratio of the number of particles with energy dispersion less than 1% (N±1%) passing through the energy selection device to the number of transmitted particles (NT).

[0056] This solution utilizes the chromatic aberration effect of the solenoid, and under the premise of energy dispersion of ±1%, ηT = 29.7%.

[0057] It should be noted that for the aforementioned product embodiments, for the sake of simplicity of description, they are all expressed as a series of action combinations, but those skilled in the art should know that the present invention is not limited by the order of the actions described, because according to the present invention, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by the present invention. In the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, please refer to the relevant description of other embodiments.

[0058] In the several embodiments provided herein, it should be understood that the disclosed devices can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the module division is merely a logical functional division. In actual implementation, other division methods may be used. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not implemented. In addition, the coupling or direct coupling or communication connection shown or discussed may be through some interface. The indirect coupling or communication connection of devices or modules may be electrical or other forms.

[0059] The modules described as separate components may or may not be physically separate, and the components shown as modules may or may not be physical modules, that is, they may be located in one place or distributed across multiple network modules. Some or all of the modules may be selected to achieve the purpose of the present embodiment according to actual needs.

[0060] In addition, the functional modules in various embodiments of the present invention may be integrated into a single processing module, or each module may exist physically separately, or two or more modules may be integrated into a single module. The aforementioned integrated modules may be implemented in the form of hardware or software functional modules.

[0061] The embodiments of the present invention are described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the products of the present invention and their core ideas. At the same time, for those skilled in the art, there may be changes in the specific implementation methods and application scopes based on the products of the present invention. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A laser proton cancer treatment rotating stent system based on a rotatable optical path, characterized in that: It includes a rotatable optical path and a bracket system, wherein the rotatable optical path includes 4 reflectors, the first reflector is a deformable reflector, and the second, third and fourth reflectors are used to adjust the laser transmission angle.

2. According to claim 1, a laser proton cancer treatment rotating stent system based on a rotatable optical path is characterized in that: The first reflector can correct the mirror deviation caused by gravity according to the rotation angle of the rotating frame.

3. A laser proton cancer treatment rotating stent system based on a rotatable optical path according to any one of claims 1-2, characterized in that: Also included is a beam off-axis parabolic reflector.

4. A beam transport device, including a beam chromatic aberration energy selection beam line and a rotating optical path laser proton cancer therapy rotating support system, characterized in that The laser proton cancer treatment rotating support system with rotating optical path includes: a rotatable optical path and a support system; The beam chromatic aberration energy selection beam line includes: superconducting solenoid S1#, energy degrader, superconducting solenoid S2# and energy selection aperture; The rotating optical path includes four reflectors, the first reflector is a deformable reflector, and the second, third and fourth reflectors are used to adjust the laser transmission angle.

5. A beam transport device according to claim 4, characterized in that: Also included is a beam off-axis parabolic reflector.

6. A beam transport device according to claim 4, characterized in that: The first reflector can correct the mirror deviation caused by gravity according to the rotation angle of the rotating frame.

7. A beam transport device according to claim 4, characterized in that: The beam chromatic aberration energy selection beam line and the laser proton cancer therapy rotating support system with a rotating optical path can rotate together.

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