MR-Compatible Linac Gun for Robotic Linac Adaptation

描述(申请人提供)：放射治疗中的图像引导有三个目标：1.减少剂量分布的几何不确定性；2.改善健康组织的节约性；3.促进对宏观肿瘤的额外促进治疗。一种理想 影像引导成像系统将提供每秒3-5帧的实时成像，良好的软组织对比度，用于肿瘤可视化，几何保真度为2 mm，所有这些都将为患者提供额外的非治疗性辐射剂量。我们假设，实时磁共振图像引导为体内各种肿瘤类型和位置提供了所需的图像质量。为了支持这一假设，我们已经与一个多机构合作计划保持一致，以研究、开发和评估将磁共振指导引入放射治疗世界所需的技术的所有方面。在这份提案中，我们将利用我们在电子光学和X射线管开发方面的经验，迎接研究和建造与‘直插式MR-直线加速器’系统以及我们的机器人直线加速器适应新概念或‘RLA MRI-直线加速器’一起使用的MR兼容直线加速器的挑战。我们的假设是，为在线磁场中的最佳操作而设计的电子枪可以像当前的电子枪在非磁场条件下设计的那样有效和高效地工作。该项目的具体目标是：1.开发一种优化的电子枪设计，用于强度高达0.2T的平行条纹磁场中；2.在串联MRI-直线加速器和/或RLA MRI-直线加速器中，当平行放置在高达0.2T的边缘磁场时，建立和验证该电子枪的US。第一个目标将通过有限元建模来实现，以改进我们新的、与MR兼容的电子枪设计，包括栅格控制以及确保电子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仪器测量和验证电子枪在各种外部领域的性能来实现。我们解决的一般问题是，当肿瘤在治疗过程中发生解剖和生理变化时，辐射束聚焦在肿瘤上。我们相信，成功完成这一核磁共振-直线加速器计划可能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.