Salari Ehsan, Mazur Thomas, Sharp Gregory
Department of Industrial, Systems, and Manufacturing Engineering, Wichita State University, Wichita, KS, United States of America.
Washington University in St. Louis, St. Louis, MO, United States of America.
Phys Med Biol. 2023 Apr 10;68(8). doi: 10.1088/1361-6560/acc631.
The goal of this research is to demonstrate proof-of-principle for managing intrafraction motion via feedback control of delivered dose to achieve dosimetry comparable to respiratory gating without compromising delivery efficiency.. We develop a stochastic control approach for step-and-shoot intensity-modulated radiotherapy (IMRT) in which the cumulative delivered dose and future trajectory of intrafraction motion are dynamically estimated by combining pre-treatment four-dimensional computed tomography imaging and intrafraction respiratory-motion surrogates. The IMRT plan is then re-optimized in real time to ensure delivery of the planned dose in the presence of free-breathing motion. We compare the performance of the proposed approach against traditional motion-management techniques, namely, respiratory gating and internal target volume (ITV) planning, using the four-dimensional extended cardiac-torso computational phantom.We simulate the delivery of treatment plans for a lung tumor in the presence of variable breathing amplitude, tumor size, and location. Results show that the proposed method reduces irradiated tissue volume compared to ITV treatment. Additionally, it significantly reduces treatment time compared to traditional respiratory-gated treatment, without compromising the dosimetric quality.Respiratory gating is a common technique to manage intrafraction motion. While gating supports reduced treatment volumes, it also prolongs the treatment delivery time. The proposed stochastic control approach can help improve the delivery efficiency of respiratory gating without compromising the dose quality.
本研究的目标是通过对输送剂量的反馈控制来管理分次内运动，以证明其原理，从而在不影响输送效率的情况下实现与呼吸门控相当的剂量测定。我们为步进式调强放射治疗（IMRT）开发了一种随机控制方法，通过结合治疗前的四维计算机断层扫描成像和分次内呼吸运动替代指标，动态估计累积输送剂量和分次内运动的未来轨迹。然后实时重新优化IMRT计划，以确保在自由呼吸运动情况下输送计划剂量。我们使用四维扩展心脏体模，将所提出方法的性能与传统运动管理技术（即呼吸门控和内部靶区体积（ITV）规划）进行比较。我们模拟了在呼吸幅度、肿瘤大小和位置可变的情况下，肺部肿瘤治疗计划的输送。结果表明，与ITV治疗相比，所提出的方法减少了受照射组织体积。此外，与传统呼吸门控治疗相比，它显著缩短了治疗时间，同时不影响剂量质量。呼吸门控是管理分次内运动的常用技术。虽然门控有助于减小治疗体积，但也会延长治疗输送时间。所提出的随机控制方法有助于在不影响剂量质量的情况下提高呼吸门控的输送效率。
