Radiotherapy device for treatment fraction-to-fraction angle adjustment in multi-fraction radiotherapy

Abstract

The application provides a radiotherapy device for angle adjustment between treatment fractions in multi-fraction radiotherapy, comprising: an angle selection unit for performing irradiation angle selection of an initial treatment fraction; an angle adjustment unit for performing angle adjustment in a subsequent treatment fraction based on the irradiation angle of the initial treatment fraction; and a monitoring adjustment unit for performing dose accumulation, monitoring and adjustment based on the irradiation angle of the initial treatment fraction and the adjusted angle in the subsequent treatment fraction.

Description

Technical Field

[0001] This invention relates to the field of medical devices, specifically to a radiotherapy device for adjusting the angle between treatment fractions during multi-fraction radiotherapy. It enables precise multi-angle irradiation by adjusting the irradiation angle between different treatment fractions on accelerator devices with a limited number of machine heads or fixed irradiation angles. Background Technology

[0002] Radiation therapy is a treatment method that uses radiation (such as alpha, beta, and gamma rays, X-rays, electron beams, proton beams, and other particle beams produced by radioactive isotopes) to treat tumors, and is generally used to treat malignant tumors. Radiation therapy is widely used in tumor treatment; it destroys the DNA of tumor cells through high-energy radiation, thereby inhibiting tumor growth and spread.

[0003] Intensity-modulated radiotherapy (IMRT) is a highly sophisticated tumor treatment technique. The development of its treatment plan is extremely complex, and the selection of the radiation field angle is one of the key factors in ensuring treatment effectiveness. IMRT uses a combination of multiple radiation fields at different angles to deliver radiation into the patient's body from multiple directions, creating a cross-coverage dose distribution. This concentrates radiation on the tumor while effectively avoiding critical organs. This multi-angle radiation field design not only improves the local control rate of the tumor but also significantly reduces the risk of side effects caused by radiotherapy.

[0004] In clinical practice, the selection of radiation field angles primarily depends on the tumor's anatomical location, shape, size, and its relative position to surrounding critical organs (such as the spinal cord, heart, lungs, and bladder). Typically, this selection process is a collaborative effort between experienced radiation physicists and clinicians, incorporating computer-aided dose distribution optimization algorithms to develop the optimal treatment plan. Studies have shown that among 8143 IMRT treatment plans conducted at the Department of Radiation Oncology, Cancer Hospital of the Chinese Academy of Medical Sciences between 2012 and 2022, most plans typically require 5 to 9 radiation field angles, while some complex plans even require as many as 11 to 13 angles to achieve optimal tumor coverage and protection of critical organs.

[0005] In traditional IMRT treatment, all treatment fractions typically employ the exact same irradiation angles. These field angles remain consistent throughout the treatment to create a stable, multi-angle dose distribution, thereby maximizing tumor coverage and protecting critical organs. This multi-field IMRT plan achieves precise dose control by repeating the same irradiation angles in each treatment fraction. However, this approach relies on accelerator flexibility and the number of heads to ensure that each treatment fraction can provide multiple irradiation angles to achieve optimal therapeutic effects.

[0006] For example, in the treatment of head and neck tumors, due to the complex anatomy of the region, a more complex multi-angle field combination is usually required to avoid high-dose radiation exposure to critical structures such as nerves and blood vessels. In the treatment of complex tumors such as lung cancer or rectal cancer, reasonable multi-angle field design not only improves the dose coverage of the tumor, but also reduces the radiation exposure to organs such as the heart, lung or bladder. Therefore, the selection of field angles in IMRT is not only a technical challenge, but also an important decision that affects the treatment effect and quality of life of patients. Every detail needs to be carefully weighed to ensure the best tumor treatment effect and minimize damage to normal tissues.

[0007] With the continuous development of radiotherapy technology, new accelerator devices such as FLASH accelerators have shown obvious advantages in certain clinical applications due to their efficient irradiation characteristics such as ultra-fast irradiation and extremely short treatment time. However, due to the limitations of mechanical design or irradiation conditions, these accelerators usually cannot provide more than 5 irradiation angles in a single treatment, which poses a challenge to the treatment of complex tumors. In addition to the limitations of these advanced devices, some accelerators are relatively outdated and cannot achieve flexible rotation of the gantry or multi-angle adjustment. The design of traditional accelerator devices is often limited by the fixed number of gantries or irradiation angles, and cannot provide multi-angle field combination functions similar to modern IMRT accelerators. This technical limitation makes it difficult for these accelerators to achieve the treatment effect of traditional IMRT when treating complex tumors.

[0008] In these cases, due to the limitation of the number of gantries or irradiation angles in a single treatment, these accelerators cannot optimize the dose distribution by flexibly adjusting the field angles, which to some extent affects the overall coverage of the tumor and the protection of critical organs. This not only increases the complexity of treatment, but also puts higher requirements on the treatment effect and quality of life of patients. Therefore, how to achieve a treatment effect comparable to traditional IMRT under the condition of limited irradiation angles has become a technical problem that needs to be solved. This not only involves optimization of existing hardware, but also requires the development of new treatment plans to gradually optimize the irradiation angle in multiple treatment fractions, thereby overcoming the limitations of single treatment.

[0009] The following several typical cases further demonstrate the limitations of existing technology:

[0010] Case 1: Head and neck cancer patient

[0011] The patient is a 60-year-old male diagnosed with left nasopharyngeal carcinoma, with the tumor close to the spinal cord. Traditional IMRT plans usually require the design of 9 field angles to ensure that the tumor is fully covered while exposing the spinal cord to the lowest radiation dose. This multi-angle field design can concentrate the dose in the tumor area through cross-ray paths without excessive radiation to the spinal cord.

[0012] However, when using FLASH accelerators for treatment, due to the fixed number of heads and the inability to adjust field angles, treatment plans can only use a few fixed field angles, resulting in higher radiation doses to the spinal cord and significantly increasing the risk of patients developing radiation myelitis. This case shows that fixed field angle designs have significant limitations in dealing with complex tumors near critical organs, which may affect patient safety and treatment effectiveness.

[0013] Case Two: Lung Cancer Patient

[0014] The patient is a 70-year-old female diagnosed with lung cancer in the left upper lobe, with the tumor located close to the heart. Traditional IMRT plans usually require 7 field angles to ensure dose coverage of the tumor while minimizing radiation to the heart. Through multi-angle field design, the treatment plan can avoid the heart while concentrating on the tumor area.

[0015] However, under the fixed field angle conditions of FLASH accelerators, treatment plans cannot be flexibly adjusted, resulting in some rays directly passing through the heart area, increasing the radiation exposure of the heart. This situation may lead to a higher risk of radiation-induced heart disease in patients after treatment, affecting the long-term health of patients.

[0016] Case Three: Rectal Cancer Patient

[0017] The patient is a 55-year-old male diagnosed with rectal cancer, with the tumor located in the pelvic cavity close to the bladder. Traditional IMRT plans designed 5 field angles to effectively cover the tumor while reducing the radiation dose to the bladder. Through this multi-angle field design, the treatment plan can concentrate most of the dose on the tumor while trying to avoid the bladder.

[0018] However, in the application of FLASH accelerators, due to the fixed field angles, treatment plans cannot be flexibly adjusted like traditional IMRT, resulting in higher radiation doses to the bladder. This not only increases the risk of radiation-induced cystitis in patients, but also may affect the quality of life of patients, even requiring additional medical intervention to manage side effects.

[0019] These cases show that although the fixed field angle design of FLASH accelerators simplifies the treatment process to some extent, there are significant limitations in the treatment of complex tumors, especially in cases with complex anatomical structures or special tumor locations. These limitations may result in poor treatment outcomes and even threaten the health of patients.

[0020] Therefore, the field of radiotherapy urgently needs a new technological solution that can overcome the limitations of fixed field angles in FLASH accelerators while maintaining their high-efficiency treatment characteristics, providing treatment effects comparable to or even better than traditional IMRT. This new technology should be able to flexibly adjust the combination of field angles in treatment fractions to optimize dose distribution, ensure adequate dose coverage for the tumor, and protect surrounding critical organs. Summary of the Invention

[0021] The technical problem to be solved by the present invention is to address the above-mentioned defects in the prior art by providing a radiotherapy device based on inter-fraction angle adjustment that can achieve better planning quality. This device can flexibly adjust the combination of field angles in the treatment fractions to optimize dose distribution, ensure that the tumor receives adequate dose coverage, and protect surrounding critical organs.

[0022] According to one aspect of the present invention, a radiotherapy device based on inter-fraction angle adjustment is provided, the device comprising:

[0023] Angle selection unit: used to select the irradiation angle for performing the initial treatment fractions;

[0024] Angle adjustment unit: used to perform angle adjustments in subsequent treatment fractions based on the irradiation angle of the initial treatment fraction;

[0025] Monitoring and Adjustment Unit: Used to perform dose accumulation, monitoring and adjustment based on the irradiation angle of the initial treatment fraction and the adjusted angle in subsequent treatment fractions.

[0026] Preferably, the angle adjustment unit includes a data input unit and a control unit; the data input unit is used to input the big data of IMRT treatment plan using a single irradiation head; the control unit retrieves the actual IMRT plan of the case closest to the subject to be treated from the big data of IMRT treatment plan, and optimizes it based on the retrieved actual IMRT plan to determine the number of irradiations of the irradiation head and the irradiation angle during each irradiation.

[0027] Preferably, the control unit is used to perform the following steps:

[0028] In the retrieved IMRT plan, a single irradiation head is used for multiple irradiations at N irradiation angles A1-AN. ​​The control unit adopts an adaptive simulated annealing method to calculate the following objective function value for the number of irradiations and the irradiation angle at each irradiation:

[0029] minf(β)

[0030] Wherein, β is the angle of the gantry relative to the irradiated area at the time of rotation, M is the number of machine heads, L is the number of rotations of the machine head, and B is the angle of the machine head relative to the gantry in each rotation.

[0031] Preferably, the number of machine heads is between 3-5.

[0032] Preferably, the number of rotations of the machine head is between 1-4.

[0033] Preferably, the IMRT treatment plan big data is the case big data related to hospital IMRT treatment plan.

[0034] Preferably, after rotation, the dose of each fraction and the total dose of the target area after synthesis meet the prescription dose requirements.

[0035] Preferably, the angle adjustment unit introduces new angle combinations by rotating the gantry or adjusting the irradiation angle in subsequent treatment fractions to supplement the tumor area not covered in the initial fraction and further reduce radiation exposure to normal tissues.

[0036] Preferably, the monitoring and adjustment unit monitors the dose distribution of each fraction in real time during the entire treatment process and accumulates the total radiation dose to the tumor and critical organs; wherein the dose delivered by each treatment fraction is converted to equivalent 2Gy fraction dose EQD2:

[0037]

[0038] Wherein, D represents the total dose (Gy), d is the fraction dose (Gy) in each treatment fraction, and α / β is the parameter of a specific tissue or tumor, representing the radio-biological response characteristics of the tissue. For tumors, the typical α / β value is usually about 10 Gy, while for normal tissues, especially late-responding tissues, the α / β value is usually between 2 and 4 Gy;

[0039] Moreover, after calculating the EQD2 of each treatment fraction, the monitoring and adjustment unit adds these values to obtain the total EQD2 of the entire treatment process, and then compares this cumulative EQD2 with the clinical prescription requirements to ensure that the combined dose of all treatment fractions meets the treatment target.

[0040] Preferably, the radiotherapy equipment based on fraction-to-fraction angle adjustment further comprises an evaluation unit for performing dose evaluation after treatment, which comprehensively evaluates the entire treatment process after all treatment fractions are completed, analyzes the dose coverage of the tumor and the protection of critical organs, and through comprehensive analysis of cumulative dose, ensures that the treatment achieves the expected effect, and provides reference for future treatment plans for similar cases, further optimizing the radiotherapy scheme.

[0041] Preferably, the radiotherapy device based on angle adjustment between fractions is a FLASH radiotherapy device.

[0042] The radiotherapy device based on angle adjustment between fractions provided by the present application can realize multi-angle precise irradiation by adjusting irradiation angles between different treatment fractions on a limited number of machine heads or an accelerator device with fixed irradiation angles, can flexibly adjust the field angle combination in the treatment fraction to optimize the dose distribution, and ensure that the tumor is fully covered by the dose while protecting the surrounding key organs. BRIEF DESCRIPTION OF DRAWINGS

[0043] The present application will be more fully understood and its attendant advantages and features will become apparent with reference to the following detailed description, taken in conjunction with the accompanying drawings, in which:

[0044] Figure 1 A general block diagram of a radiotherapy device for angle adjustment between treatment fractions in multi-fraction radiotherapy according to the first preferred embodiment of the present application is schematically shown.

[0045] Figure 2A A prior IMRT plan in a specific example is schematically shown.

[0046] Figure 2B An improved IMRT plan is schematically shown.

[0047] Figure 2C An improved IMRT plan is schematically shown.

[0048] Figure 2D An improved IMRT plan is schematically shown.

[0049] Figure 3A A prior IMRT plan in another specific example is schematically shown.

[0050] Figure 3B An improved IMRT plan is schematically shown.

[0051] Figure 3C An improved IMRT plan is schematically shown.

[0052] Figure 4 A general block diagram of a radiotherapy device for angle adjustment between treatment fractions in multi-fraction radiotherapy according to the second preferred embodiment of the present application is schematically shown.

[0053] It should be noted that the accompanying drawings are used to illustrate the present application, not to limit the present application. It should be noted that the drawings showing the structure can not be drawn in scale. And in the drawings, the same or similar elements are marked with the same or similar reference numerals. DETAILED DESCRIPTION

[0054] In order to make the content of the present application more clear and easy to understand, the content of the present application is described in detail below in combination with specific embodiments and drawings.

[0055] In order to solve the above problems, the present application provides a radiation therapy fraction angle adjustment irradiation method. By dynamically adjusting the irradiation angle between different treatment fractions, the limitations of insufficient irradiation angle in single treatment are compensated for, so as to achieve the same treatment effect as the combination of multiple fields in traditional IMRT. The method of the present application is suitable for various accelerator devices, and in particular in the case of limited number of gantry heads or irradiation angles, the accuracy and safety of treatment can be effectively improved.

[0056] The specific embodiments of the present application are described below.

[0057] <First embodiment>

[0058] Figure 1 The overall block diagram of a radiation therapy device for multi-fraction radiotherapy treatment fraction angle adjustment according to the first preferred embodiment of the present application is schematically shown. For example, the radiation therapy device for multi-fraction radiotherapy treatment fraction angle adjustment is a FLASH device.

[0059] As shown in Figure 1 The radiation therapy device for multi-fraction radiotherapy treatment fraction angle adjustment according to the preferred embodiment of the present application comprises a data input unit 100, a control unit 200 and a plurality of irradiation gantry heads 300 arranged on a gantry.

[0060] The data input unit 100 is used to input IMRT treatment plan big data using a single irradiation gantry head, such as case big data related to hospital IMRT treatment plans.

[0061] The control unit 200 retrieves the IMRT plan of the case closest to the object to be treated from the IMRT treatment plan big data according to the object to be treated, and optimizes based on the retrieved IMRT plan to control the number of rotations of the irradiation gantry head 300 and the irradiation angle at each rotation.

[0062] Specifically, for example, the optimization of the control unit 200 based on the retrieved IMRT plan includes:

[0063] In the retrieved IMRT plan, the single irradiation gantry head uses N irradiation angles A1-AN (generally 4≤N≤9) for multiple irradiations, and the control unit 200 uses an adaptive simulated annealing method (ASA) to calculate the following objective function value for the number of irradiations of the irradiation gantry head 300 and the irradiation angle at each irradiation:

[0064] minf(β)

[0065] Wherein,

[0066] Furthermore, β is the angle between the gantry and the area to be irradiated during rotation, M is the number of gantry heads (e.g., 3≤M≤5), L is the number of rotations of the gantry head, and B is the angle between the irradiation direction of the gantry head and the gantry in each rotation.

[0067] Therefore, the value of β should minimize the above formula. Thus, in practice, this invention achieves an irradiation range that is as consistent as possible with the retrieved IMRT plan using as few irradiation cycles as possible.

[0068] Preferably, the number of irradiation heads 300 is between 3 and 5.

[0069] Preferably, the number of irradiations of the irradiation head 300 is between 1 and 4.

[0070] This invention establishes a radiotherapy protocol for inter-fraction angle adjustment, where different gantry angles are used between different treatment fractions for the same patient, achieving multi-angle irradiation based on a fixed angle to achieve better treatment planning quality. In the irradiation protocol proposed in this invention, a further provision ensures that, through rotational irradiation, the fraction dose at different gantry angles and the final synthesized total target dose all meet the prescribed dose requirements.

[0071] <Example>

[0072] Example 1: For lung cancer cases, the original IMRT plan had field angles of 10°, 35°, 60°, 320°, and 345°, such as... Figure 2A As shown in the photo.

[0073] Therefore, the rotation plan for different numbers of aircraft noses is as follows:

[0074] Number of heads M Number of turns L Turn angle set 1 Turn angle set 2 3 2 50°、170°、270° 90°、210°、330° 4 2 10°、120°、160°、200° 40°、150°、200°、340° 5 1 0°、30°、160°、200°、330°

[0075] Specifically, such as Figure 2B (Three aircraft noses photographed twice) Figure 2C (Two rounds of photography of the four noses) Figure 2D The photo shown is from the sequence of five aircraft heads in a single rotation.

[0076] Example 2: For rectal cases, the original IMRT plan had seven fields evenly divided at 0°, 50°, 100°, 150°, 210°, 260°, and 310°. Figure 3A As shown in the photo.

[0077] Therefore, the rotation plan for different numbers of aircraft noses is as follows:

[0078] Number of heads M Number of turns L Turn angle set 1 Turn angle set 2 3 2 0°、120°、240° 50°、170°、290° 4 2 60°、110°、250°、310° 40°、150°、200°、340° 5 2 20°、50°、80°、210°、250° 110°、150°、280°、310°、340°

[0079] Specifically, such as Figure 3B(Four machine heads, two rotations) Figure 3C (Five machine heads, two rotations) as shown in the photographs.

[0080] The radiotherapy device based on fraction-to-fraction angle adjustment provided by the present application can achieve multi-angle precise irradiation by adjusting the irradiation angle between different treatment fractions on an accelerator device with limited machine heads or fixed irradiation angles, can flexibly adjust the field angle combination in the treatment fraction to optimize the dose distribution, and ensure that the tumor is fully covered with the dose while the surrounding key organs are protected.

[0081] <Second embodiment>

[0082] According to another aspect of the present application, the radiotherapy method of fraction-to-fraction angle adjustment can be realized by the following units in actual operation to ensure the same treatment effect as traditional IMRT on an accelerator device with limited machine heads or irradiation angles.

[0083] Figure 4 The overall block diagram of the radiotherapy device for fraction-to-fraction angle adjustment in multi-fraction radiotherapy according to the second preferred embodiment of the present application is schematically shown. For example, the radiotherapy device for fraction-to-fraction angle adjustment in multi-fraction radiotherapy is a FLASH device.

[0084] As Figure 4 shown, Figure 4 The radiotherapy device for fraction-to-fraction angle adjustment in multi-fraction radiotherapy according to the second preferred embodiment of the present application schematically includes:

[0085] The angle selection unit 101 is configured to perform irradiation angle selection of the initial treatment fraction.

[0086] Specifically, before the first treatment fraction, a set of optimal irradiation angle combinations is selected according to the patient's anatomical structure, the specific situation of the tumor, and the previous treatment experience. The set of angles should cover the main area of the tumor as much as possible and avoid key organs as much as possible. To ensure the rationality of the angle selection, it is usually necessary to combine the patient's imaging data (such as CT, MRI) and computer-aided dose distribution optimization algorithm for accurate calculation. The selection of irradiation angles also refers to a large number of IMRT treatment planning databases, and uses heuristic algorithms to preferentially select key angles to establish a preliminary field distribution framework. These selected angles remain fixed throughout the initial fraction to ensure effective dose delivery.

[0087] Embodiment: For a patient with lung cancer in the upper lobe of the left lung, the initial treatment fraction can select five field angles, such as 0°, 30°, 90°, 120°, and 150°, to cover the tumor and avoid the heart and spinal cord.

[0088] The angle adjustment unit 102 is configured to perform angle adjustment in the subsequent treatment fractions based on the irradiation angles of the initial treatment fractions.

[0089] The angle adjustment unit introduces new angle combinations in the subsequent treatment fractions by rotating the gantry or adjusting the irradiation angles to supplement the tumor regions not covered in the initial fractions and further reduce the radiation exposure to normal tissues. These new irradiation angles can be selected by heuristic algorithms aiming to cover the critical angles not included in the initial fractions, thus ensuring the overall coverage of the tumor. The rotation angles of each treatment fraction are determined according to the principle of optimizing the remaining irradiation angles, minimizing the radiation exposure to organs at risk (OARs), thus enhancing the conformity of the overall dose distribution and the treatment effect.

[0090] Embodiment: In the second treatment fraction, the field angles are adjusted to 15°, 45°, 75°, 135° and 165° to cover the tumor regions not fully covered in the previous fraction and reduce the dose exposure of the heart and spinal cord.

[0091] Furthermore, for example, the previously mentioned scheme can be employed. Specifically:

[0092] At this time, in the irradiation angle selection of the initial treatment fraction, the single irradiation head uses N irradiation angles A1-AN (generally 4≤N≤9) for multiple irradiations, and the angle adjustment unit uses the adaptive simulated annealing method (ASA) to calculate the following objective function value for the number of irradiations of the irradiation head and the irradiation angle at each irradiation:

[0093] minf(β)

[0094] Wherein,

[0095] And wherein β is the angle of the gantry relative to the irradiated region at the time of rotation, M is the number of heads (for example, 3≤M≤5), L is the number of rotations of the head, and B is the angle of the irradiation direction of the head relative to the gantry in each rotation.

[0096] It can be seen that the value of β should make the above formula minimum.

[0097] The monitoring adjustment unit 103 is configured to perform dose accumulation, monitoring and adjustment based on the irradiation angles of the initial treatment fractions and the adjusted angles in the subsequent treatment fractions.

[0098] The monitoring and adjustment unit monitors the dose distribution of each fraction in real-time throughout the entire treatment process and accumulates the total radiation dose to the tumor and critical organs. The key to cumulative dose monitoring is to convert the dose delivered by each treatment fraction into equivalent 2Gy fraction dose EQD2, so as to accurately synthesize the dose between all treatment fractions. The EQD2 model provides a standardized index to compare different treatment plans by adjusting the physical dose, considering the differences between fractions, so as to ensure the safety and effectiveness of the treatment. The EQD2 conversion formula is as follows:

[0099]

[0100] where D represents the total dose (Gy), d is the fraction dose in each treatment fraction (Gy), and α / β is the parameter of a specific tissue or tumor, representing the radio-biological response characteristics of the tissue. For tumors, the typical α / β value is usually about 10 Gy, while for normal tissues, especially late-responding tissues, the α / β value is usually between 2 and 4 Gy.

[0101] After the monitoring and adjustment unit calculates the EQD2 of each treatment fraction, it adds these values to obtain the total EQD2 of the entire treatment process. This cumulative EQD2 is then compared with the clinical prescription requirements to ensure that the combined dose of all treatment fractions meets the treatment goals while avoiding exceeding the safety threshold of critical organs.

[0102] If the cumulative dose of critical organs is found to approach or exceed the safety threshold during treatment, the radiotherapy physicist can adjust the irradiation angles and plans of subsequent fractions based on the dose accumulation data to ensure the safety and effectiveness of the treatment process.

[0103] Example: In the third treatment fraction, the radiotherapy physicist notices that the dose accumulation of the spinal cord approaches the safety threshold and decides to adjust the field angles to 20°, 60°, 100°, 140°, and 180° to reduce further radiation exposure to the spinal cord and enhance coverage of the tumor margin. Through this adjustment, the radiation exposure of the spinal cord is controlled within a safe range while still effectively covering the tumor area.

[0104] Evaluation unit 104: used to perform dose evaluation after treatment.

[0105] After all treatment fractions are completed, a comprehensive evaluation of the entire treatment process is performed to analyze the dose coverage of the tumor and the protection of critical organs. Through the comprehensive analysis of cumulative dose, it is ensured that the treatment achieves the expected effect, and reference is provided for the treatment plan of future similar cases to further optimize the radiotherapy plan.

[0106] Example: After the end of the entire treatment cycle in a lung cancer patient, the radiation team evaluates the total dose distribution and confirms that the tumor area is sufficiently covered while the radiation dose to the heart and spinal cord remains within safe limits.

[0107] This method is not only suitable for modern advanced FLASH accelerators, but also for conventional accelerator devices with relatively backward technology. For devices that cannot perform gantry rotation or multi-angle field combination, by adjusting the irradiation angle between different fractions, the effect of multi-angle coverage can also be achieved, ensuring effective treatment of complex tumors.

[0108] On a conventional accelerator, since the device cannot perform gantry rotation, angle adjustment between fractions becomes the key to optimizing treatment effect. In each treatment fraction, the device irradiates through a fixed field angle, but after each treatment, the irradiation angle of the next fraction is recalculated and adjusted, so as to gradually achieve multi-angle coverage and achieve the ideal treatment effect.

[0109] It should be noted that the radiotherapy device for angle adjustment between treatment fractions in multi-fraction radiotherapy according to the present application is preferably suitable for FLASH devices, but the present application can be applied to any suitable radiotherapy device; FLASH devices are only preferred examples.

[0110] It should be noted that, unless specifically indicated, the terms "first", "second", "third" and the like in the specification are merely used to distinguish the components, elements, steps and the like in the specification, and are not used to represent the logical relationship or sequence relationship between the components, elements, steps and the like.

[0111] It can be understood that, although the present application has been disclosed as above with preferred embodiments, the above embodiments are not intended to limit the present application. For any person skilled in the art, many possible changes and modifications or equivalent embodiments of the technical solutions of the present application can be made by using the technical content disclosed above without departing from the scope of the technical solutions of the present application. Therefore, any simple modification, equivalent change and modification of the above embodiments made according to the technical essence of the present application without departing from the content of the technical solutions of the present application shall still fall within the scope of protection of the technical solutions of the present application.

Claims

1. A radiotherapy device for angle adjustment between treatment fractions in multi-fraction radiotherapy, the device comprising: an angle selection unit for performing selection of irradiation angles for an initial treatment fraction; an angle adjustment unit for performing angle adjustment in a subsequent treatment fraction based on the irradiation angles of the initial treatment fraction; a monitoring adjustment unit for performing dose accumulation, monitoring and adjustment based on the irradiation angles of the initial treatment fraction and the adjusted angles in the subsequent treatment fraction; wherein the angle adjustment unit comprises a data input unit for inputting IMRT treatment plan big data using a single irradiation head, and a control unit for retrieving an IMRT plan actual of a case closest to the subject to be treated from the IMRT treatment plan big data according to the subject to be treated, and performing optimization based on the retrieved IMRT plan actual to determine the number of rotations of the irradiation head and the irradiation angles at each rotation.

2. The radiotherapy device for angle adjustment between treatment fractions in multi-fraction radiotherapy according to claim 1, wherein the control unit is configured to perform the following steps: in the retrieved IMRT plan, the single irradiation head uses N irradiation angles A1-AN for multiple irradiations, and the control unit uses an adaptive simulated annealing method to calculate the following objective function value for the number of irradiations of the irradiation head and the irradiation angles at each irradiation: ； wherein β is the angle of the gantry relative to the irradiation region at rotation, M is the number of heads, L is the number of rotations of the head, and B is the angle of the irradiation direction of the head relative to the gantry at each rotation.

3. The radiotherapy device for multi-fraction radiotherapy treatment fraction angle adjustment of claim 2, wherein, The number of heads is between 3 and 5.

4. The radiotherapy device for multi-fraction radiotherapy treatment fraction angle adjustment of claim 2, wherein, The number of rotations of the head is between 1 and 4.

5. The radiotherapy device for multi-fraction radiotherapy treatment fraction angle adjustment of claim 1, wherein, The IMRT treatment plan big data is case big data related to hospital IMRT treatment plans.

6. The radiotherapy device for multi-fraction radiotherapy treatment fraction angle adjustment of claim 1, wherein, Through rotation, the fraction dose at different gantry angles and the final total dose of the target region are all up to the prescription dose requirement.

7. The radiotherapy device for multi-fraction radiotherapy treatment fraction angle adjustment of claim 1, wherein, The angle adjustment unit introduces new angle combinations in subsequent treatment fractions by rotating the gantry or adjusting the irradiation angles to supplement the tumor regions not covered in the initial fraction and further reduce radiation exposure to normal tissues.

8. The radiotherapy device for multi-fraction radiotherapy treatment fraction angle adjustment of claim 1, wherein, The monitoring adjustment unit monitors the dose distribution of each fraction in real time during the entire treatment process and accumulatively calculates the total radiation dose to the tumor and critical organs; wherein the dose delivered by each treatment fraction is converted into equivalent 2 Gy fraction dose EQD2: ； wherein D represents the total dose (Gy), d is the fraction dose (Gy) in each treatment fraction, and a / β is the parameter of a specific tissue or tumor, representing the radio-biological response characteristics of the tissue; for tumors, the typical a / β value is usually 10 Gy, while for normal tissues, the a / β value is usually between 2 and 4 Gy; Moreover, after calculating the EQD2 of each treatment fraction, the monitoring adjustment unit adds these values to obtain the total EQD2 of the entire treatment process, and then compares this cumulative EQD2 with the clinical prescription requirement to ensure that the combined dose of all treatment fractions meets the treatment goal.

9. The radiotherapy device for multi-fraction radiotherapy treatment fraction angle adjustment of any of claims 1-3, wherein Also include: evaluation unit: for performing dose evaluation after treatment, comprehensive evaluation of the whole treatment process after all treatment fractions are completed, analysis of tumor dose coverage and protection of key organs, through comprehensive analysis of cumulative dose, ensure that the treatment achieves the expected effect, and provide reference for future similar cases of treatment planning according to these data, further optimize the radiotherapy scheme.

10. The radiotherapy device for multi-fraction radiotherapy treatment fraction angle adjustment of any of claims 1-3, wherein, The radiotherapy equipment for angle adjustment between treatment fractions in multi-fraction radiotherapy is a FLASH equipment.

Images