Treatment planning and verification tools for adaptive radiation therapy

放射治疗试图通过向肿瘤提供致命剂量的电离辐射来破坏癌细胞，同时最大限度地减少对周围健康组织的辐射。典型的放射治疗方案在一系列每日治疗部分中在数周的时间段内递送。当前放射治疗技术不是最佳的一个重要领域是它们没有考虑治疗期间解剖结构的变化。具体地，由于生理过程（诸如呼吸和消化），内部解剖结构将在治疗递送期间移动和变形。肿瘤缩小，周围组织的结构可以从一个治疗部分到下一个治疗部分发生变化。不考虑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，目前正在研究自适应放射治疗技术，以补偿在放射治疗过程中发生的解剖学变化。然而，在适应性放射治疗的常规临床使用之前，必须解决许多技术和科学挑战。这些挑战之一是需要准确确定递送到肿瘤和周围组织的辐射剂量以指导治疗适应。该剂量计算应考虑射束输送期间的组织运动、治疗分次之间的组织收缩和/或扩张以及治疗输送中的任何机器相关误差。** 本研究计划将通过开发一个软件框架和验证工具来解决这一挑战，用于重建放射治疗过程中的解剖学变化。这项研究将建立在一种新的剂量重建方法的能力，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体模和剂量计;以及（3）在多个治疗部分估计累积剂量的方法，考虑肿瘤收缩和正常组织变化。申请人是开发本计划中使用的准确剂量累积方法的公认领导者。**拟议的研究将提供关键的技术工具，这将允许验证病人的剂量输送超过放射治疗过程。这些技术创新将为当前和未来适应性治疗策略的需求、开发和验证提供信息。这将最终提高放射疗法治疗癌症的有效性。

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.