CN117065231B - Dose optimizing device for high-energy electron radiotherapy - Google Patents
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Abstract
The invention belongs to the field of radiation therapy beam regulation and control, and in particular relates to a dosage optimizing device for high-energy electron radiation therapy, which comprises the following components: a defocusing magnetic lens group and a focusing magnetic lens group which are arranged at intervals; the defocusing magnetic lens group enables the beam current to have defocusing effect in the x and y transverse directions and is used for expanding the original collimated high-energy electron beam; the expanded electron beam further expands through a drift section positioned between the two magnetic lens groups and reaches a focusing magnetic lens group, and the focusing magnetic lens group enables the beam current to present mutually symmetrical focusing effects in the x and y transverse directions and is used for focusing the electron beam expanded by the drift section on a target; the structural parameters of the defocusing magnetic lens groups and the length of the drift section between the two magnetic lens groups enable the diameter D of the electron beam reaching the focusing magnetic lens groups after two expansion to be smaller than the electron beam incident window of the focusing magnetic lens groups. The invention can avoid the generation of quasi-uniform dose distribution of the high-energy electron beam on the incident path.
Description
Technical Field
The invention belongs to the field of radiation therapy beam regulation and control, and particularly relates to a dosage optimizing device for high-energy electron radiation therapy.
Background
Radiation therapy is an important treatment for malignant tumors, and about 70% of cancer patients require radiation therapy during the course of treatment. In 2000, high energy electrons (VHEE, very High Energy Electron) with energies in the range of 150 to 250MeV were first proposed for radiation therapy. The traditional low-energy electrons have shallow penetration depth and are only suitable for treating superficial tumors, such as breast cancer, skin cancer and the like. In contrast, the high-energy electrons have strong penetrability and can be used for treating deep tumors (15-30 cm).
Currently, high-energy electrons have great potential in cancer treatment. Compared with other particle radiotherapy modes, the high-energy electron radiotherapy has more advantages: first, the side scatter of the energetic electrons in air and human body is low; secondly, the sensitivity of the high-energy electrons to the areas with uneven density is extremely low, and the high-energy electrons are more suitable for highly uneven tissues and lesions which are easier to move, in particular lung cancer and the like; thirdly, the high-energy electron radiotherapy has low cost and small occupied area; fourth, the high energy electrons easily achieve high dose rate delivery and fast pencil scanning, effectively improving the effectiveness of the treatment, and can be used for advanced flash radiotherapy (Flash Radiotherapy).
The European nuclear research Center (CERN) linear electron accelerator can generate high-energy electrons, however, the collimated high-energy electron beam generates uniform dose distribution on an incident path, so that higher surface dose and emergent dose are caused, the protection of normal tissues around tumors is not facilitated, the clinical practical value is low, and higher-level conformal intensity modulated radiation therapy is difficult to realize.
Therefore, in order to realize practical clinical application of the high-energy electrons, the problem of quasi-uniform dose distribution of the high-energy electrons in a patient needs to be avoided.
Disclosure of Invention
In view of the drawbacks and the improvement of the prior art, the present invention provides a dose optimizing device for high-energy electron radiotherapy, which aims to avoid a quasi-uniform dose distribution of a high-energy electron beam on an incident path.
To achieve the above object, according to one aspect of the present invention, there is provided a dose optimizing apparatus for high-energy electron radiotherapy, comprising: a defocusing magnetic lens group and a focusing magnetic lens group which are arranged at intervals;
the defocusing magnetic lens group enables beam current to be defocused in the x and y transverse directions, so that the original collimated high-energy electron beam is expanded; the expanded electron beam further expands through a drift section positioned between the defocusing magnetic lens group and the focusing magnetic lens group and reaches the focusing magnetic lens group, and the focusing magnetic lens group enables the beam current to present focusing effects symmetrical to each other in the x and y transverse directions so as to be used for focusing the electron beam expanded by the drift section on a target; the structural parameters of the defocusing magnetic lens group and the length of a drift section between the defocusing magnetic lens group and the focusing magnetic lens group enable the diameter D of the electron beam reaching the focusing magnetic lens group after two expansions to be smaller than an electron beam incident window of the focusing magnetic lens group.
Further, the defocusing magnetic lens group enables the beam current to have a defocusing effect symmetrical to each other in the x and y transverse directions.
Further, the defocusing magnetic lens group and/or the focusing magnetic lens group are/is of a FODO structure composed of quadrupole magnets.
Further, the structural parameters of the defocusing magnetic lens group and the focusing magnetic lens group each include: the number of the quadrupole magnets, the length of a drift section between two adjacent quadrupole magnets, the thickness of each quadrupole magnet and the magnetic field gradient;
in practical application, the dose optimizing device has fixed values of all structural parameters of the defocusing magnetic lens group; the values of all structural parameters except the magnetic field gradient of the focusing magnetic lens group are fixed, and the magnetic field gradient of each quadrupole magnet in the focusing magnetic lens group is adjusted according to the actually required focusing strength.
Further, the values of the structural parameters of the defocusing magnetic lens group are as follows: the number of the quadrupole magnets is three; the thicknesses of the three quadrupole magnets arranged along the electron beam emission direction are 36cm, 36cm and 26cm respectively, the lengths of the drift sections between two adjacent quadrupole magnets are 36cm and 18cm respectively, and the magnetic field gradients of the three quadrupole magnets arranged along the electron beam emission direction are-20.78T/m, 10.22T/m and 2.42T/m respectively;
the values of all structural parameters except the magnetic field gradient of the focusing magnetic lens group are as follows: the number of the quadrupole magnets is three; the thicknesses of three quadrupole magnets arranged along the electron beam emission direction are 26cm, 26cm and 36cm respectively, and the lengths of drift sections between two adjacent quadrupole magnets are 18cm and 36cm respectively;
the length of the drift section between the defocusing magnetic lens group and the focusing magnetic lens group is 3m.
Further, the position of the focusing magnetic lens group from the target is determined according to the formula f=f/D, wherein F represents a focal length for determining the position of the focusing magnetic lens group from the target; f is a focusing factor, and represents the focusing intensity of the focusing magnetic lens group, wherein the smaller the focusing factor is, the larger the focusing intensity is.
Further, the value range of the focusing factor f is 1.2-9.0.
The invention also provides a beam current transmission system for high-energy electron radiotherapy, which is provided with the dose optimizing device for the high-energy electron radiotherapy.
In general, through the above technical solutions conceived by the present invention, the following beneficial effects can be obtained:
(1) The invention is equivalent to providing a magnetic focusing system device for optimizing the dosage of high-energy electron radiotherapy, namely, a defocusing magnetic lens group and a focusing magnetic lens group are adopted, and the defocusing magnetic lens group can: the beam current has defocusing effect in the x and y transverse directions and is used for expanding the original collimated high-energy electron beam; and the focusing magnetic lens group can: the focusing effect of the beam current in the x and y transverse directions is symmetrical, and the focusing effect is used for focusing the electron beam expanded by the drift section on a target, wherein the defocusing magnetic lens group and the focusing magnetic lens group are arranged at intervals so as to have the drift section, and the beam current output by the defocusing magnetic lens group is secondarily expanded. The thought of beam expanding and focusing firstly changes the almost uniform distribution characteristic of the original beam along the transmission path, thereby eliminating the problems of overhigh target area dose deposition, overhigh surface and emergent dose and overhigh normal tissue deposition dose caused by the quasi-uniform distribution of the original beam, optimizing the dose distribution effect and being capable of being used for realizing the high local dose deposition of the tumor target area.
(2) The invention utilizes the dose optimizing device designed by the mode of firstly expanding and then focusing, can focus high-energy electrons on the tiny target volume of a human body, obviously reduces the surface dose and the emergent dose on the premise of ensuring the consistent dose of a tumor target area, obviously reduces the damage to normal tissues around the tumor target area and improves the effect of radiotherapy.
(3) The dose optimizing device provided by the invention can fix the structural parameters of the defocusing magnetic lens group, the length of a drift section between the defocusing magnetic lens group and the focusing magnetic lens group and the structural parameters except for magnetic field gradients in the focusing magnetic lens group, flexibly realize the required focusing strength by adjusting the magnetic field gradients of all quadrupole magnets in the focusing magnetic lens group, and further determine the position of the focusing magnetic lens group away from a target by combining the formula f=f/D, wherein F represents a focal length and is used for determining the position of the focusing magnetic lens group away from the target; f is a focusing factor, and represents the focusing intensity of the focusing magnetic lens group, wherein the smaller the focusing factor f is, the larger the focusing intensity is. Based on the dose optimizing device, focusing beam flows with different focusing effects can be obtained by adjusting the distance between the focusing magnetic lens group and a target and the magnetic field intensity of each quadrupole magnet in the focusing magnetic lens group according to different tumor positions, tumor types and individual differences of people, so that longitudinal scanning can be realized, and the device is high in operability and practicability.
(4) The defocusing magnetic lens group has the defocusing effect symmetrical to each other in the x and y transverse directions, so that the structural parameter setting of the focusing magnetic lens group is facilitated, and the symmetrical focusing function of the focusing magnetic lens group is easy to realize.
Drawings
Fig. 1 is a schematic diagram of a dose optimizing device for high-energy electron radiotherapy according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a specific structure of a dose optimizing device according to an embodiment of the present invention;
FIG. 3 is a schematic view of another embodiment of a dose optimizing device according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a central axis percent depth dose curve provided by an embodiment of the present invention;
FIG. 5 is a schematic diagram of a two-dimensional dose deposition shape provided by an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
Example 1
A dose optimizing device for high energy electron radiotherapy, as shown in fig. 1, comprising: a defocusing magnetic lens group and a focusing magnetic lens group which are arranged at intervals;
the defocusing magnetic lens group enables the beam current to have defocusing effect in the x and y transverse directions so as to be used for expanding the original collimated high-energy electron beam; the expanded electron beam further expands through a drift section positioned between the defocusing magnetic lens group and the focusing magnetic lens group and reaches the focusing magnetic lens group, and the focusing magnetic lens group enables the beam current to present focusing effects symmetrical to each other in the x and y transverse directions so as to be used for focusing the electron beam expanded through the drift section on a target; the structural parameters of the defocusing magnetic lens group and the length of the drift section between the defocusing magnetic lens group and the focusing magnetic lens group enable the diameter D of the electron beam reaching the focusing magnetic lens group after two expansions to be smaller than the electron beam incident window of the focusing magnetic lens group.
In conventional high-energy electron radiotherapy, the radiotherapy dose distribution on the transmission path thereof shows almost uniform distribution, resulting in higher surface dose and exit dose. In the embodiment, the beam state on the transmission path is changed by designing the magnetic lens group structure, so that the defect is overcome, the original collimated high-energy electron beam is expanded by using the defocusing magnetic lens group, and is focused on the tiny target volume of the die body by using the focusing magnetic lens group, so that the high-energy electron beam can achieve the focusing effect in the horizontal and vertical transverse directions, namely, the focusing is symmetrical, and finally, the focused high-energy electron beam can be obtained.
That is, the specific idea of the optimizing device provided in this embodiment is how to use the existing high-energy electron beam to realize focusing the high-energy electron beam. In the embodiment, from the angles of beam optics design and radiotherapy dosage optimization, a dosage optimization device is designed, and the spatial distribution of high-energy electron beams is optimized, so that the dosage distribution characteristic of the high-energy electron beams in a human body is optimized, and therefore high local dosage deposition can be realized in practical application, namely, most of dosages are concentrated in a tumor target area, the surface absorption dosage and the emergent dosage of normal tissues around the target area are reduced, and the transverse dosage distribution is improved.
It should be noted that, because the magnetic lens group adopts the quadrupole magnet, the focusing intensity can be flexibly controlled, so the envelope shape of the beam can be flexibly controlled, and the dose transmitted by the beam can be flexibly controlled. In addition, the defocusing magnetic lens group enables the beam to have defocusing effects in the x and y lateral directions, namely, the structural parameters of the defocusing magnetic lens group are limited, namely, the structural parameters of the defocusing magnetic lens group enable the defocusing magnetic lens group to enable the beam to have defocusing effects in the x and y lateral directions. Similarly, the focusing magnetic lens group presents a focusing effect symmetrical to each other in the x and y lateral directions, which is equivalent to the limitation of the structural parameters of the focusing magnetic lens group, namely, the structural parameters of the focusing magnetic lens group cause the focusing magnetic lens group to present a focusing effect symmetrical to each other in the x and y lateral directions.
As a preferred embodiment, the defocusing magnetic lens group makes the beam current have the defocusing effect symmetrical to each other in the x and y transverse directions.
The defocusing magnetic lens group has the defocusing effect symmetrical to each other in the x and y transverse directions, so that the structural parameter setting of the focusing magnetic lens group is facilitated, and the symmetrical focusing function of the focusing magnetic lens group is easy to realize.
As a preferred embodiment, as shown in fig. 2, the defocusing magnetic lens group and/or the focusing magnetic lens group are FODO structures composed of quadrupole magnets.
Quadrupole magnets are focusing elements commonly used to control the lateral (x, y) motion of the beam, focusing the beam in one lateral direction and defocusing in the other lateral direction. In the present invention, functions to change the beam envelope of the high-energy electron beam.
In addition, regarding selection of the basic structure of the magnetic lens group, in order to achieve symmetrical focusing and in consideration of cost, it is preferable to use the FODO structure. The FODO structure is composed of triple quadrupole magnets and two drift sections, and when the two magnetic lens groups in the whole dose optimizing device are optimal FODO structure, the actual magnetic focusing structure is composed of two groups of triple quadrupole magnets and a plurality of drift sections. The first group of quadrupole magnets Q1-Q3 form a defocusing magnetic lens group for pre-expanding the diameter of the collimated high-energy electron beam, and the collimated high-energy electron beam is continuously expanded through a drift section positioned between the defocusing magnetic lens group and a focusing magnetic lens group, and the second group of quadrupole magnets Q4-Q6 form a focusing magnetic lens group for playing a role of focusing the beam.
As a preferred embodiment, the structural parameters of the defocusing magnetic lens group and the focusing magnetic lens group include: the number of the quadrupole magnets, the length of a drift section between two adjacent quadrupole magnets, the thickness of each quadrupole magnet and the magnetic field gradient; in practical application, the values of all structural parameters of the defocusing magnetic lens group are fixed; the values of all structural parameters except the magnetic field gradient of the focusing magnetic lens group are fixed, and the magnetic field gradient of each quadrupole magnet in the focusing magnetic lens group is adjusted according to the actually required focusing strength.
That is, in practical applications, different focus intensities are required according to different scenes. Under the condition, the values of all structural parameters of the defocusing magnetic lens group which can present defocusing effects in the x and y transverse directions can be fixed, and the values of all structural parameters of the focusing magnetic lens group which can present focusing effects which are symmetrical to each other in the x and y transverse directions except for the magnetic field gradient can be fixed, and according to the focusing strength actually required, only the magnetic field gradient of each quadrupole magnet of the focusing magnetic lens group is required to be adjusted, so that the dosage optimizing device is convenient to flexibly apply in practice.
As a preferred embodiment, the position of the focusing magnetic lens group from the target is determined according to the formula f=f/D, where F represents the focal length for determining the position of the focusing magnetic lens group from the target; f is a focusing factor, the focusing intensity of the focusing magnetic lens group is represented, the focusing factor f equivalently represents a focusing angle theta, the larger the focusing angle theta is, the smaller the focusing factor f is, the larger the represented focusing intensity is, the smaller the focusing factor is, and the larger the focusing intensity is; d is the diameter of the high-energy electron beam before focusing.
Deep tumors are generally about 15cm away from the surface of a human body, and different requirements are put on the performance of focused high-energy electron radiotherapy due to the positions and types of the tumors and the individual differences of different people. By adjusting magnetic focusing structure parameters, focusing high-energy electron beam flows with different focusing intensities are generated, the focusing point position, the maximum dose, the on-axis dose, the off-axis dose, the surface dose, the emergent dose and the like are changed, and the depth requirements of clinical actual tumor target areas are met.
For a better illustration of the invention, the following examples are given:
as shown in fig. 3, two groups of magnetic lens groups are designed, the collimated high-energy electron beam is expanded to the beam diameter of 2cm through the defocused magnetic lens groups, and the beam diameter of 20cm is reached through a Drift section Drift (3 m) between the focused magnetic lens groups and the defocused magnetic lens groups; and then expanded by focusing the magnetic lens group is focused to 30 x 30cm 3 The water mould body is 15cm deep.
Wherein Q1, Q2 and Q3 are quadrupolar magnets, which form a basic FODO structure, and correspond to the defocused magnetic lens group in FIG. 1, and have the beam expanding function, the thicknesses of the three quadrupolar magnets are 36cm, 36cm and 26cm respectively, and the lengths of drift sections between two adjacent quadrupolar magnets are 36cm and 18cm respectively.
Q4, Q5 and Q6 are quadrupole magnets, which form another group of basic FODO structure, and correspond to the focusing magnetic lens group in FIG. 1 to play a role in focusing, wherein the thicknesses of the three quadrupole magnets are respectively 26cm, 26cm and 36cm, and the lengths of drift sections between two adjacent quadrupole magnets are respectively 18cm and 36cm;
in addition, F is the distance between Q6 and the depth of the water mold body at 15cm, which is also called the focal length, and the focusing effect of the target in the water mold body can be adjusted by adjusting the length of the focal length F and the magnetic field intensity of the quadrupole iron. Specifically, the target can be fixed at the beam focusing point, the diameter D of the high-energy electron beam before focusing is kept unchanged, and only the magnetic field gradient of the quadrupole magnet in the focusing magnetic lens group is adjusted, so that the focusing strength at the focus is changed.
Taking the focusing capability of the actual quadrupolar iron and the length limit of the magnetic focusing structure into consideration, 9 groups of focusing intensities are selected, and the corresponding focusing factors are as follows: f=1.2, f=1.4, f=1.6, f=2.0, f=2.4, f=3.0, f=4.0, f=6.0, f=9.0.
As shown in table 1, the parameters are described for the 250MeV high energy electron magnetic focusing configuration at different focusing intensities. The quadrupole ferromagnetic field gradients were all less than 27T/m. The magnetic field gradients of the first set of quadrupolar irons are sequentially-20.78T/m, 10.22T/m, 2.42T/m, and the second set of quadrupolar iron magnetic field gradients are shown in Table 1.
TABLE 1 magnetic field gradients for the second set of quadrupolar irons at different focusing intensities
As shown in fig. 4, the central axis percentage depth dose curve for different radiotherapy modes is described, which characterizes the on-axis dose distribution of the beam after entering the human body. The invention uses Monte Carlo simulation to simulate the dose distribution of beam in the water mould body.
Photon radiation therapy, among other things, tends to achieve maximum dose deposition at 5cm from the surface, with the dose at the target tumor depth (15 cm) reduced to 70% of the maximum dose. Proton radiotherapy is the use of multiple streams of different energies to cover the target tumor, resulting in an extended Bragg peak (SOBP), but with a surface dose of 50% of the maximum dose. The collimated high energy electron beam produces a quasi-uniform dose distribution along the beam transport path, resulting in an increase in surface and exit dose. Compared with the collimated high-energy electron beam, under the condition that the target area is guaranteed to absorb the same dose (2 Gy), the focused high-energy electron beam achieves high-local dose deposition at a position of 15cm, the surface dose and the outlet dose are remarkably reduced, the surface dose and the outlet dose are reduced by about 3-4 orders of magnitude, and normal tissues and organs around the target area on an incident path are better protected.
As shown in table 2, the surface dose and the emergent dose of the high-energy electron radiotherapy under different focusing intensities. Compared with a collimated parallel VHEE beam, the 250MeV focused high-energy beam can reduce the surface dose to 1% -14%, the emergent dose to 1% -12%, and the focusing effect is obvious.
TABLE 2 surface dose and exit dose for high energy electron radiotherapy at different focus intensities
As shown in fig. 5, the two-dimensional dose deposition shape of the 250MeV high-energy electron radiotherapy at different focusing intensities is characterized by the transverse distribution characteristic of the beam current. As can be seen from the figure, the value range of the focusing factor f is preferably 1.2 to 9.0. Beyond this range, the focusing effect is significantly reduced.
Due to the symmetrical focusing, the dose curve exhibits symmetry with respect to the central axis. The high-energy electrons of different focus intensities are scattered differently and accordingly the peak dose depth is shifted to a different extent. As the focus intensity is reduced, the dose deposition shape is overextended in the beam penetration direction, resulting in more dose being deposited in surrounding normal tissue.
For a strongly focused high-energy electron beam, the transverse distribution of the central dose has an obvious peak value at the central axis of the beam, namely the transverse half width of the central depth is narrowest, and the focusing capacity is very strong. Due to scattering of electrons and secondary particles in the water phantom, the lateral distribution of the outlet dose is flatter than the surface dose, the lateral half-width is wider, the lateral diffusion of the dose deposition distribution is smaller, the surface and emergent doses are obviously reduced, and the damage to normal tissues and organs is obviously reduced.
The present invention relates generally to the design of magnetic focusing systems in which specific parameters such as state, characteristics of the electron beam current are taken into account, not just the statistics of the final dose deposition and the contrast of the radiotherapy effect. In addition, the invention also considers how to realize strong focusing of the actual high-energy electron beam through the magnetic focusing system, the adjusting mode provided by the invention is flexible, the position or focusing depth of the focusing point is controllable, the flexibility is high, the longitudinal or transverse scanning can be realized in future, the invention is suitable for tumor radiotherapy in different forms, and a closer connection with clinical treatment can be established, thereby having practicability.
Example two
A beam delivery system for high energy electron radiotherapy, provided with a dose optimizing device for high energy electron radiotherapy as described above.
The related technical solution is the same as the first embodiment, and will not be described herein.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (6)
1. A dose optimizing device for high energy electron radiotherapy, comprising: a defocusing magnetic lens group and a focusing magnetic lens group which are arranged at intervals;
the defocusing magnetic lens group enables beam current to be defocused in the x and y transverse directions, so that the original collimated high-energy electron beam is expanded; the expanded electron beam further expands through a drift section positioned between the defocusing magnetic lens group and the focusing magnetic lens group and reaches the focusing magnetic lens group, and the focusing magnetic lens group enables the beam current to present focusing effects symmetrical to each other in the x and y transverse directions so as to be used for focusing the electron beam expanded by the drift section on a target; the structural parameters of the defocusing magnetic lens group and the length of a drift section between the defocusing magnetic lens group and the focusing magnetic lens group enable the diameter D of an electron beam reaching the focusing magnetic lens group after two expansions to be smaller than an electron beam incident window of the focusing magnetic lens group;
wherein, the structural parameters of the defocusing magnetic lens group and the focusing magnetic lens group all comprise: the number of the quadrupole magnets, the length of a drift section between two adjacent quadrupole magnets, the thickness of each quadrupole magnet and the magnetic field gradient;
in practical application, the dose optimizing device is characterized in that the values of all structural parameters of the defocusing magnetic lens group are fixed, the values of all structural parameters of the focusing magnetic lens group except for the magnetic field gradient are fixed, and the magnetic field gradient of each quadrupole magnet in the focusing magnetic lens group is adjusted along with the focusing strength actually required;
the values of the structural parameters of the defocusing magnetic lens group are as follows: the number of the quadrupole magnets is three; the thicknesses of the three quadrupole magnets arranged along the electron beam emission direction are 36cm, 36cm and 26cm respectively, the lengths of the drift sections between two adjacent quadrupole magnets are 36cm and 18cm respectively, and the magnetic field gradients of the three quadrupole magnets arranged along the electron beam emission direction are-20.78T/m, 10.22T/m and 2.42T/m respectively;
the values of all structural parameters except the magnetic field gradient of the focusing magnetic lens group are as follows: the number of the quadrupole magnets is three; the thicknesses of three quadrupole magnets arranged along the electron beam emission direction are 26cm, 26cm and 36cm respectively, and the lengths of drift sections between two adjacent quadrupole magnets are 18cm and 36cm respectively;
the length of the drift section between the defocusing magnetic lens group and the focusing magnetic lens group is 3m.
2. Dose optimizing device according to claim 1, characterized in that the defocusing magnetic lens group makes the beam current have a defocusing effect symmetrical to each other in both x, y lateral directions.
3. Dose optimizing device according to claim 1, characterized in that the defocusing magnetic lens group and/or the focusing magnetic lens group is a FODO structure consisting of quadrupole magnets.
4. A dose optimizing device as claimed in any one of claims 1 to 3, wherein the position of the focusing magnetic lens group from the target is according to the formulaDetermining, in the formula, F tableA focal length for determining a position of the focusing magnetic lens group from the target;fand (3) representing the focusing intensity of the focusing magnetic lens group to obtain a focusing factor, wherein the smaller the focusing factor is, the larger the focusing intensity is.
5. Dose optimizing device according to claim 4, characterized in that the focusing factorfThe value range of (2) is 1.2-9.0.
6. A beam delivery system for high energy electron radiotherapy, characterized in that a dose optimizing device for high energy electron radiotherapy is provided as claimed in any of claims 1 to 5.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102008062971A1 (en) * | 2008-12-23 | 2010-07-01 | Ludwig-Maximilians-Universität | Undulator for use as x-ray source in table-top free-electron laser, has quadrupole lenses whose magnetic axis is arranged about preset distance to form undulator field that emits undulator radiation to charged particle beam |
| CN109413832A (en) * | 2018-10-30 | 2019-03-01 | 清华大学 | Interdigitated Longitudinal Magnetic Mode Drift Tube Linear Accelerator Using Permanent Magnet |
| CN109640508A (en) * | 2019-01-28 | 2019-04-16 | 清华大学 | A Separation-Focused Interdigitated Longitudinal Magnetic Mode Drift Tube Linear Accelerator |
| CN115952726A (en) * | 2022-11-24 | 2023-04-11 | 西安空间无线电技术研究所 | A design method and system for an electron beam expander magnet based on an intelligent algorithm |
| CN116407777A (en) * | 2021-12-30 | 2023-07-11 | 上海联影医疗科技股份有限公司 | Flash radiotherapy device and flash radiotherapy equipment |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7639785B2 (en) * | 2007-02-21 | 2009-12-29 | L-3 Communications Corporation | Compact scanned electron-beam x-ray source |
-
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102008062971A1 (en) * | 2008-12-23 | 2010-07-01 | Ludwig-Maximilians-Universität | Undulator for use as x-ray source in table-top free-electron laser, has quadrupole lenses whose magnetic axis is arranged about preset distance to form undulator field that emits undulator radiation to charged particle beam |
| CN109413832A (en) * | 2018-10-30 | 2019-03-01 | 清华大学 | Interdigitated Longitudinal Magnetic Mode Drift Tube Linear Accelerator Using Permanent Magnet |
| CN109640508A (en) * | 2019-01-28 | 2019-04-16 | 清华大学 | A Separation-Focused Interdigitated Longitudinal Magnetic Mode Drift Tube Linear Accelerator |
| CN116407777A (en) * | 2021-12-30 | 2023-07-11 | 上海联影医疗科技股份有限公司 | Flash radiotherapy device and flash radiotherapy equipment |
| CN115952726A (en) * | 2022-11-24 | 2023-04-11 | 西安空间无线电技术研究所 | A design method and system for an electron beam expander magnet based on an intelligent algorithm |
Non-Patent Citations (3)
| Title |
|---|
| An experimental study of focused very high energy electron beams for radiotherapy;Karolina Kokurewicz 等;《Communications Physics》;第1-8页 * |
| Design aspects for Very High Energy Electron (150 to 250 MeV) acceleration for use in radiation therapy: Beam shaping, electromagnetic scanning;Keith Stewart 等;《IEEE Nuclear Science Symposuim & Medical Imaging Conference》;第1622-1627页 * |
| 激光磁共振加速及其辐射;张耀;《中国优秀硕士学位论文全文数据库 基础科学辑》;第3章 * |
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