Performance limitations in feedback control systems with application to radiotherapy

反馈控制系统在放射治疗中的性能限制

• 批准号: 238743-2006
• 负责人: Davison, Daniel
• 金额: $ 2.04万
• 依托单位: University of Waterloo
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2007
• 资助国家: 加拿大
• 起止时间: 2007-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=362087
• 关键词: Performance; limitations; feedback; control; systems

External radiotherapy is a cancer treatment process where external high-energy x-ray beams are used to eradicate tumor cells.  Recently, the applicant and other researchers have introduced feedback control into the radiotherapy process so that the x-ray beam tracks the position of the tumor as it moves; movement is caused by a number of processes, including breathing, heart beat, and changes in the gastrointestinal tract.  Advantages of the feedback scheme include a reduction in side effects, more accurate radiation dose delivery to the tumor, and a reduction in treatment time.  The radiotherapy research has revealed deficiencies in current control engineering knowledge, and has inspired research in several directions, including the direction of the proposed research.  The basic question that the proposed research seeks to answer is:  are there any limitations on what can be done using feedback control?  Understanding the existence and nature of such performance limitations is important because the knowledge helps engineers avoid trying to solve impossible problems, and aids engineers in modifying problems to overcome performance limitations that otherwise cannot be overcome.  The proposed research will focus on several aspects of controller performance.  First, the issue of "tracking" is addressed:  is there a limit to how well the x-ray beam can track the tumor?  Second, the issue of "disturbance rejection" is dealt with:  if the patient moves on the treatment table, is there any fundamental reason why the tumor tracking system should not be able to accommodate the movement?  Finally, the issue of "robustness" is studied:  how much knowledge about the patient's tumor dynamics must be known for treatment to be effective?   Several potential causes for the existence of performance limitations will be considered, including time delays, instabilities in the system, and controller structure.  Although motivated by and applied specifically to radiotherapy, the theoretical work in the proposed research is general; indeed, almost any system that uses feedback control (airplanes, automobiles, nuclear reactors, distillation columns, rockets, etc.) can potentially benefit from the work.

外部放疗是一种癌症治疗过程，外部高能X射线束用于放射疗法肿瘤细胞。最近，适用的和其他研究人员将反馈控制引入了放射疗法过程中，以便X射线梁在肿瘤移动时跟踪肿瘤的位置。运动是由许多过程引起的，包括呼吸，心跳以及胃肠道的变化。反馈方案的优点包括减少副作用，更准确的辐射剂量向肿瘤递送以及减少治疗时间。放疗研究揭示了当前控制工程知识的缺陷，并激发了多个方向的研究，包括拟议研究的方向。拟议的研究试图回答的基本问题是：使用反馈控制可以做什么？了解这种绩效限制的存在和性质很重要，因为知识可以帮助工程师避免试图解决不可能的问题，并帮助工程师修改问题以克服否则无法克服的绩效限制。拟议的研究将重点介绍控制器性能的几个方面。首先，解决了“跟踪”的问题：X射线梁可以跟踪肿瘤的状况是否有限？其次，处理“干扰拒绝”的问题：如果患者在治疗台上移动，是否有任何根本原因为什么肿瘤跟踪系统不应适应运动？最后，研究了“鲁棒性”的问题：对于患者的肿瘤动力学有多少知识才能有效？将考虑有几种绩效限制的潜在原因，包括时间延迟，系统中的不稳定性和控制器结构。尽管是受放射疗法专门用于放射疗法的动机，但拟议研究的理论工作是一般的。实际上，几乎所有使用反馈控制（飞机，汽车，核反应堆，蒸馏柱，火箭等）的系统都可以从工作中受益。