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CN-121971808-A - Method for selecting irradiation units for proton arc treatment planning and related apparatus

CN121971808ACN 121971808 ACN121971808 ACN 121971808ACN-121971808-A

Abstract

The invention discloses an irradiation unit selection method of a proton arc treatment plan and related equipment, and relates to the technical field of radiation treatment, wherein the method comprises the steps of constructing at least one arc-shaped radiation field based on a patient medical image and delineated target area and endangered organ information, and executing ray tracing aiming at each radiation field angle to generate an initial set comprising a plurality of irradiation units; generating and recording coverage relation information and additional item information in a ray tracing process, screening an irradiation unit subset for subsequent dose optimization from the initial set based on the coverage relation information and the additional item information, executing dose optimization based on the screened irradiation unit subset to generate a proton arc treatment plan, and finishing accurate screening of the irradiation units by introducing a target space unit concept and combining a double-target optimization model and a coverage constraint mechanism in advance without modifying the existing hardware and flow and reducing the manual dependency, thereby improving the plan generation efficiency, stability and clinical adaptation expansibility.

Inventors

  • TAO ZHEN
  • LI WANQING
  • WAN PENG
  • ZHENG YANHONG

Assignees

  • 华中科技大学同济医学院附属同济医院

Dates

Publication Date
20260505
Application Date
20260206

Claims (18)

  1. 1. A method of selecting an irradiation unit for a proton arc treatment plan, comprising: Constructing at least one arc-shaped radiation field based on the medical image of the patient and the delineated target area and the information of the organs at risk, and executing ray tracing on each irradiation angle of the radiation field to generate an initial set comprising a plurality of irradiation units; generating and recording coverage relation information and additional item information in the ray tracing process, wherein the coverage relation information is used for indicating the coverage state of each irradiation unit on a plurality of target space units, and the target space units are preset space areas with the scale being larger than or equal to voxels; Screening a subset of the irradiation units from the initial set based on the coverage relationship information and the additional item information, wherein the screening process is required to satisfy coverage constraints and the priority of the irradiation units is assessed by using the additional item information; and performing dose optimization based on the screened irradiation unit subset to generate a proton arc treatment plan.
  2. 2. The method of claim 1, wherein the irradiation unit is an energy layer, and one energy layer includes a plurality of beam spots having the same proton energy.
  3. 3. The irradiation unit selection method according to claim 1, wherein the irradiation unit is a beam spot.
  4. 4. The method of claim 1, wherein the target space cells are regions in a patient coordinate system obtained by meshing the target, the meshing dimensions of which are configured such that each target space cell can be covered by an illumination cell in at least one of the initial sets.
  5. 5. The irradiation unit selection method according to claim 1, wherein the coverage relation information is obtained by: And judging whether the Bragg peak of at least one beam spot contained in one irradiation unit falls in a certain target space unit or not, and if so, recording that the irradiation unit covers the target space unit in the coverage relation information.
  6. 6. The method of claim 1, wherein the coverage constraint comprises, for each target space cell, obtaining a coverage number not less than a preset minimum coverage number for the space cell, wherein the coverage number characterizes a number of coverage of the space cell by the irradiation cells in the selected subset of irradiation cells.
  7. 7. The method according to claim 6, wherein the preset minimum coverage number is set uniformly according to a global minimum coverage parameter or differently for spatial units at different positions in the target region.
  8. 8. The method of claim 7, wherein for any target space cell, the predetermined minimum coverage is not more than the coverage available for that space cell when all of the irradiation cells in the initial set are selected.
  9. 9. The illumination unit selection method according to claim 1, wherein the additional item information includes at least one of: A parameter related to a physical property of the illumination unit itself, and Parameters related to energy deposition contributions on the path of the illumination unit to the target volume space unit.
  10. 10. The irradiation unit selection method according to claim 9, wherein the parameter related to the physical characteristics of the irradiation unit itself includes a beam spot size of the beam spot; The parameter related to the contribution of energy deposition on the path includes a contribution value attributed to at least one of the target, the organ at risk, or the normal tissue from the irradiation start position to the cumulative water equivalent thickness of the target space unit.
  11. 11. The illumination unit selection method according to claim 1, wherein the evaluating the priority of the illumination unit using the additional item information includes: assigning weights to each physical contribution parameter; based on the weight, carrying out weighted calculation on multiple physical contribution parameters of each irradiation unit to obtain a comprehensive evaluation value of each irradiation unit; And sequencing or evaluating the irradiation units according to the comprehensive evaluation value.
  12. 12. The illumination unit selection method according to claim 1, wherein the screening process is implemented by solving a dual-objective optimization model, the objectives of which include minimizing the number of illumination units in the selected subset of illumination units and maximizing the overall priority rating of the selected subset of illumination units, and controlling the relative importance of the two objectives by weight parameters.
  13. 13. The illumination unit selection method according to claim 12, wherein the overall priority rating is measured by an index dice_a: Wherein EL_selected is the selected subset of illumination units, The method comprises the steps of arranging the irradiation units in the initial set in a weighted comprehensive evaluation value descending order, taking a subset formed by the first n irradiation units, wherein n is the number of the irradiation units screened currently.
  14. 14. The illumination unit selection method according to claim 12, wherein the solving the dual-objective optimization model employs a heuristic algorithm comprising the following phases: a greedy construction stage for iteratively adding the irradiation units to the candidate subset according to the comprehensive evaluation value of the current irradiation unit and the contribution to the coverage constraint; And a local adjustment stage, wherein the irradiation units in the current candidate subset are deleted or exchanged, so that the targets of the dual-target optimization model are further optimized on the premise of meeting coverage constraint.
  15. 15. The illumination unit selection method according to claim 1, wherein after performing dose optimization based on the screened subset of illumination units, the method further comprises: And processing and verifying the preliminary plan generated by optimization to generate a treatment plan which finally meets clinical requirements. The processing and verifying includes at least one of: Deleting the irradiation units with weights lower than a preset threshold value; removing the irradiation units contributing to the target dose distribution below a preset standard based on intermediate information generated by the dose optimization process; the final dose distribution is calculated and a clinical target compliance assessment is made.
  16. 16. An irradiation unit selection apparatus for proton arc treatment planning, comprising: at least one processor, and A memory communicatively coupled to the at least one processor; The memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method of any one of claims 1-15.
  17. 17. A radiation therapy system comprising a planning workstation having an irradiation unit selection module configured to perform the method of any one of claims 1-15.
  18. 18. A computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program which, when executed by at least one processor, implements the steps of the method of any of claims 1-15.

Description

Method for selecting irradiation units for proton arc treatment planning and related apparatus Technical Field The invention relates to the technical field of radiation therapy, in particular to a method for selecting an irradiation unit of a proton arc therapy plan and related equipment. Background In Proton radiotherapy, proton ARC therapy (Proton ARC THERAPY, commonly referred to as Proton ARC) improves dose distribution quality by multi-angle beam irradiation, which is an important technical direction for clinical treatment. However, proton beams corresponding to different irradiation angles generally comprise a large number of energy layers, if all the energy layers participate in subsequent dose optimization, the calculation scale is rapidly enlarged, the problems of excessively high resource occupation, slow optimization speed and the like are caused, the clinical popularization and application of the proton beams are seriously limited, meanwhile, the existing energy layer screening multi-dependence voxels are used as basic units for coverage constraint, the situation that part of target voxels are not covered by any energy layers easily occurs, and the integrity of target coverage is difficult to ensure. The prior related technical proposal has limitation, and is difficult to balance the calculation efficiency, the treatment plan quality and the plan execution efficiency. One type of scheme screens energy layers based on information such as gradients in the dose optimization process, but all the energy layers still need to participate in calculation in the initial stage of the optimization, so that the calculation efficiency in the initial stage is extremely low, the clinical requirement on timeliness cannot be met, and the other type of scheme filters part of the energy layers through a simple downsampling rule, but cannot establish effective association between the energy layers and the dose distribution contribution, cannot accurately distinguish the actual effects of different energy layers, and is easy to adversely affect the quality of a treatment plan (TREATMENT PLAN), namely a radiotherapy plan. And the existing coverage constraint mechanism lacks flexible adaptability, and generally adopts unified coverage standard, so that the balance problem between the plan quality and the execution efficiency is further aggravated. As the irradiation angle in proton ARC planning increases and the number of available energy layers increases, the initial candidate energy layers and their corresponding beam spot sizes expand rapidly. Even if the energy layer or beam spot participation condition is adjusted and screened in the optimization process, a large amount of calculation in the initial stage of optimization still causes huge problem scale, excessively high resource consumption and significantly increased calculation time consumption, and is difficult to adapt to the efficiency requirement of clinical application scenes. If the energy layers are preprocessed by means of geometric rules, equidistant sampling or fixed thresholds before dose optimization, the difference of physical contributions of different energy layers to actual dose distribution cannot be fully reflected, and the energy layers or beam spots critical to target coverage and dose regulation may be deleted by mistake, thereby damaging the dose quality of the final treatment plan. In addition, the prior art has strong dependence on cases and lacks a general and stable energy layer participation strategy. Whether the energy layer selection is explicitly controlled or the energy layer participating in calculation is implicitly reduced through weight optimization, sparsification, post-processing and other modes, the core parameter setting of the energy layer is highly dependent on specific cases. For example, the energy layer is optimized to participate in critical parameters such as scale, retention threshold, sparseness and the like, and often needs to be set and repeatedly debugged by relying on experience of operators. Because different disease types and different patients have obvious differences in the aspects of target area morphology, spatial distribution, organ-jeopardy position and the like, the participation range of the energy layer applicable to a certain case is difficult to be universal. The mode which depends on manual experience or fixed rules not only increases the uncertainty and operation complexity of treatment planning, but also is unfavorable for constructing a stable and reusable standardized clinical plan flow, and further restricts the clinical scale application of the proton ARC treatment technology. Disclosure of Invention Based on the above problems, the present invention aims to provide a method for selecting an irradiation unit of a proton arc treatment plan and related equipment, which introduces a target space unit concept, combines a dual-target optimization model and a coverage constraint mechanism to compl