Treatment planning and verification tools for adaptive radiation therapy

放射治疗寻求通过向肿瘤提供致命剂量的电离辐射来摧毁癌细胞，同时将周围健康组织的辐射降至最低。一种典型的放射治疗方案是以一系列每日治疗部分的形式在几周内进行的。当前放射治疗技术不是最优的一个重要领域是，它们没有考虑到治疗过程中解剖结构的变化。具体地说，在治疗过程中，由于呼吸和消化等生理过程，内部解剖结构会移动和变形。肿瘤缩小，周围组织的形态可以从一个治疗部分改变到下一个治疗部分。没有考虑到这些变化的治疗计划可能无法在肿瘤控制和保留健康组织之间实现最佳平衡。*为了解决这个问题，目前正在研究适应性放射治疗技术，以补偿放射治疗过程中发生的解剖变化。然而，在适应性放射治疗的常规临床应用之前，有许多技术和科学挑战必须解决。这些挑战之一是，需要准确确定向肿瘤和周围组织传递的辐射剂量，以指导治疗适应。该剂量计算应考虑射束输送过程中的组织运动、治疗部分之间的组织收缩和/或扩张，以及治疗输送中的任何与机器有关的误差。*这项研究计划将通过开发一个软件和验证工具的框架来解决这一挑战，该框架用于重建考虑到放射治疗过程中的解剖变化的交付剂量。这项研究将建立在一种新的剂量重建方法的能力上，该方法是在以前资助的NSERC DG研究计划下开发的。具体目标是开发：(1)精确模拟内部器官运动的方法；(2)用于验证运动建模和剂量重建的新型可变形模体和剂量计；以及(3)在多个治疗分数上估计累积剂量的方法，考虑到肿瘤缩小和正常组织变化。申请者是这项计划中将使用的精确剂量累积方法开发的公认领导者。*拟议的研究将提供关键的技术工具，允许在放射治疗过程中验证患者的剂量传递。这些技术创新将为当前和未来适应性治疗战略的需要、开发和验证提供信息。这最终将提高放射治疗治疗癌症的有效性。

Radiation therapy seeks to destroy cancerous cells by delivering a lethal dose of ionizing radiation to the tumour while minimizing the irradiation of surrounding healthy tissue. A typical radiation treatment regimen is delivered over a period of weeks in a series of daily treatment fractions. One important area in which current radiation therapy techniques are not optimal is that they do not account for the changes in anatomy during therapy. Specifically, internal anatomy will move and deform during treatment delivery due to physiological processes such as respiration and digestion. Tumours shrink and the configuration of the surrounding tissue can change from one treatment fraction to the next. Treatment plans which do not account for these changes may not achieve an optimum balance between tumour control and sparing healthy tissue. ******To solve this problem, adaptive radiation therapy techniques are currently being investigated to compensate for the anatomical changes which occur over the course of a radiation treatment. However, there are a number of technical and scientific challenges which must be solved before routine clinical use of adaptive radiation therapy. One of these challenges is that an accurate determination of the radiation dose delivered to the tumour and surrounding tissues is required to guide the treatment adaptation. This dose calculation should account for tissue motion during beam delivery, tissue shrinkage and/or expansion between treatment fractions, as well as any machine-related errors in the treatment delivery. ******This research program will address this challenge by developing a framework of software and verification tools for reconstruction of delivered dose accounting for anatomical changes during a radiotherapy treatment course. The research will build upon the capabilities of a novel dose reconstruction method developed under a previously-funded NSERC DG research program. The specific objectives are to develop: (1) methods to accurately model internal organ motion; (2) novel deformable phantoms and dosimeters for validation of motion modelling and dose reconstruction; and (3) methods to estimate cumulative dose, over multiple treatment fractions, accounting for tumour shrinkage and normal tissue changes. The applicant is a recognized leader in the development of the accurate dose accumulation methods which will be used in this program.******The proposed research will provide key technical tools which will permit verification of patient dose delivery over a radiotherapy treatment course. These technical innovations will inform the need for, development of, and verification of current and future adaptive treatment strategies. This will ultimately improve the effectiveness of radiation therapy to treat cancer.