MR-Compatible Linac Gun for Robotic Linac Adaptation

描述（由申请人提供）：放射治疗中的图像引导有三个目标：1.以减少剂量分布的几何不确定性，2.改善健康组织的保留，以及3.以便于对肉眼可见的肿瘤进行额外的加强治疗。一个理想 用于图像引导的成像系统将提供每秒3-5帧的实时成像、用于肿瘤可视化的优良软组织对比度以及2 mm的几何保真度，所有这些都具有对患者的额外非治疗辐射剂量。我们假设，实时磁共振图像引导提供了必要的图像质量的各种肿瘤类型和位置的身体。为了支持这一假设，我们与多机构合作计划保持一致，以研究，开发和评估将MR引导带入放射治疗世界所需的技术的各个方面。在本提案中，我们将我们在电子光学和X射线管开发方面的经验应用于研究和构建MR兼容直线加速器的挑战，该加速器用于“在线MR直线加速器”系统，以及用于我们的机器人直线加速器适应或“RLA MRI直线加速器”的新概念。我们的假设是，被设计用于在线磁场中的最佳操作的电子枪可以像当前的电子枪设计在非磁场条件下一样有效且高效地起作用。该项目的具体目标是：1。发展一个最佳化的电子枪设计，可在强度达0.2 T和2.构建并验证该电子枪在串联MRI-直线加速器和/或RLA MRI-直线加速器中平行放置在高达0.2 T边缘磁场下时的使用。第一个目标将使用有限元建模来完善我们的新的MR兼容电子枪设计，以包括栅极控制以及确保枪和加速波导之间的兼容性。第二个目标将通过与电子枪制造商合作来构建我们的优化设计，然后通过使用法拉第杯测量装置测量和验证电子枪在各种外场中的性能来实现。我们解决的一般问题是在治疗过程中肿瘤的解剖学和生理学变化时将辐射束聚焦在肿瘤上。我们相信，这个MRI直线加速器项目的成功完成可能会在不久的将来对癌症患者的治疗和生活产生直接影响。

DESCRIPTION (provided by applicant): Image guidance in radiation therapy has three goals: 1. to decrease the geometric uncertainties of the dose distribution, 2. to improve the sparing of healthy tissue, and 3. to facilitate additional boost treatment to the macroscopic tumour. An ideal imaging system for image guidance would provide real-time imaging at 3-5 frames per second, excellent soft tissue contrast for tumour visualization, and geometric fidelity of 2 mm, all with n additional non-therapeutic radiation dose to the patient. We hypothesize that real-time magnetic resonance image guidance provides the requisite image quality for a wide variety of tumour types and locations in the body. In support of this hypothesis, we have aligned with a multi-institution collaborative program to research, develop and evaluate all aspects of the technology required to bring MR guidance into the radiation therapy world. In this proposal, we bring our experience with electron optics and x-ray tube development to bear on the challenge of researching and building an MR-compatible linear accelerator for use with the 'in-line MR-Linac' system, as well as for use with our new concept of Robotic Linac Adaptation or 'RLA MRI-Linac'. Our hypothesis is that an electron gun designed for optimal operation in an in-line magnetic field can function as effectively and efficiently as current electron gun designs in non- magnetic field conditions. The specific aims of this project are: 1. to develop an optimized electron gun design for use within a parallel fringe field with strengths up to 0.2 T and 2. to build and verify the us of this gun when placed in parallel at up to 0.2 T fringe magnetic field in the In-Line MRI-Linac and/or the RLA MRI- Linac. The first aim will be accomplished using Finite Element modeling to refine our new, MR-compatible electron gun design to include grid control as well as to ensure compatibility between the gun and the accelerating waveguide. The second aim will be accomplished by working with an electron gun manufacturer to build our optimized design, and then by measuring and verifying the performance of the gun in various external fields using a Faraday cup measurement apparatus. The general problem we address is the focusing of radiation beams on tumors as their anatomy and physiology changes during treatment. We believe that successful completion of this MRI-Linac program could have a direct impact on the treatment and lives of cancer patients in the near future.