Sharpening the edge in pencil-beam proton therapy: an aftermarket collimation system to better spare normal tissue during radiation treatment

项目摘要/摘要： 目前，铅笔束扫描(PBS)质子疗法存在一个技术空白，导致过量 将辐射剂量泄漏到预定目标组织之外。这种差距的存在代表着一个重要的 问题是，在开发出技术解决方案之前，接受PBS质子治疗的患者将 暴露于不需要的辐射剂量和正常组织并发症。长期目标是增加 治疗效果和降低与PBS质子治疗相关的副作用风险。整体而言 本项目的目标是翻译和验证一种新的准直器技术，称为动态准直 系统(分布式控制系统)，在临床环境中使用现有的商用PBS质子治疗输送系统，以限制 剂量泄漏。分布式控制系统使用四个独立控制的修剪机刀片，这些刀片被设计为可以移动 在PBS传送期间与扫描的质子束同步。通过在光束到达时将其拦截 肿瘤的侧界、剂量分布可被锐化，而周围剂量正常 结构可以大大减少。与其他建议的解决方案不同，分布式控制系统可以提供独特的 对于PBS质子治疗的每个能源层的准直和足够小的足迹 放置在靠近病人表面的位置。该项目的基本原理是，将分布式控制系统添加到 现有的PBS设备，成本仅为3000万美元质子治疗中心的一小部分，可以迅速 转化为更好的临床护理服务。在我们的硅内治疗的强大初步数据的指导下 规划研究和发展将通过追求三个具体目标来进行：1)设计、建造、 并验证了基于扩展建模的集散控制系统原型，2)最小化治疗时间损失 与分布式控制系统相关联，以及3)为中心使用分布式控制系统提供适当的方法。在特定项下 目标1，现有的计算机设计模型将推动集成原型的物理构造 系统和剂量学性能将根据系统的模型进行验证。在具体目标2下， 将开发并测试允许修剪器叶片动态运动的修剪器排序算法 与光束扫描同时进行。该算法的目的是使治疗时间惩罚最小化 与分散控制系统相关，目标治疗时间惩罚每一次治疗疗程少于2分钟。 在具体目标3下，将制定质量保证和调试方法，以促进安全和 放射肿瘤界对集散控制系统的有效临床应用。这项研究中提出的 应用程序是创新的，因为它代表了对当前准直性的新的实质性偏离 采用紧凑型动态运动准直器塑造个人铅笔的技术 一层接一层的梁。这一贡献预计将是巨大的，因为准直系统将减少 给靶子周围的健康组织提供剂量，从而改善患者的预后。最终，这样的设备 有可能减少接受PBS质子治疗的患者的正常组织并发症。

Project Summary/Abstract: There is currently a technological gap in pencil beam scanning (PBS) proton therapy that is resulting in excess spillage of radiation dose outside of the intended target tissue. Existence of this gap represents an important problem because, until a technological solution is developed, patients undergoing PBS proton therapy will be exposed to unwanted radiation dose and the normal tissue complications. The long-term goal is to increase therapeutic efficacy and reduce the risk of side effects associated with PBS proton therapy. The overall objective of this project is to translate and validate a new collimator technology, called the dynamic collimation system (DCS), with an existing commercial PBS proton therapy delivery system in a clinical setting to limit the dose spillage. The DCS makes use of four independently controlled trimmer blades that are designed to move in synchrony with the scanned proton beam during PBS delivery. By intercepting the beam as it arrives at the lateral boundaries of the tumor, the dose distribution can be sharpened and dose to surrounding normal structures can be substantially reduced. Unlike other proposed solutions, the DCS can provide unique collimation for each energy layer of a PBS proton therapy treatment and a footprint small enough to allow placement near the surface of the patient. The rationale for the project is that the addition of the DCS to existing PBS equipment, at only a small fraction of the cost of a $30M+ proton therapy center, can rapidly translate to improved clinical care delivery. Guided by strong preliminary data from our in-silico treatment planning studies, development of the DCS will be carried out by pursing three specific aims: 1) Design, build, and validate a DCS prototype based on our extensive modeling, 2) Minimize the treatment time penalty associated with the DCS, and 3) Provide appropriate methodologies for centers to use the DCS. Under specific aim 1, an existing computer designed model will drive the physical construction of an integrated prototype system and the dosimetric performance will be validated against a model of the system. Under specific aim 2, a trimmer sequencing algorithm will be developed and tested that allows dynamic motion of trimmer leaves simultaneously with beam scanning. The purpose of this algorithm is to minimize the treatment time penalty associated with the DCS, with a target treatment time penalty of less than 2 minutes per treatment session. Under specific aim 3, a quality assurance and commissioning approach will be developed to facilitate safe and effective clinical use of the DCS by the radiation oncology community. The research proposed in this application is innovative because it represents a new and substantial departure from current collimation technologies with the introduction of a compact collimator with dynamic motion for shaping individual pencil beams layer-by-layer. This contribution is expected to be significant as the collimation system will decrease the dose to healthy tissue surrounding the target, leading to improved patient outcomes. Ultimately, such a device has the potential to reduce normal tissue complications for patients undergoing PBS proton therapy.