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MAGNETIC RESONANCE GUIDED ENHANCED RADIOTHERAPY

磁共振引导增强放射治疗

基本信息

批准号：
6394697
负责人：
BRUCE E HAMMER
金额：
$ 11.14万
依托单位：
UNIVERSITY OF MINNESOTA
依托单位国家：
美国
项目类别：
财政年份：
2000
资助国家：
美国
起止时间：
2000-09-30 至 2004-06-30
项目状态：
已结题

项目摘要

The proposed research will integrate a state-of-the-art linear accelerator with a 1.5 T MRI system to yield a first generation diagnostic-therapeutic modality. Combining a magnetic resonance scanner with a radiation therapy unit yields a synergy and forms the foundation for Magnetic Resonance Guided Enhanced Radiation Therapy (MR-GERT). MR-GERT has the capability of imaging a turr and surrounding tissue while simultaneously visualizing the path of an ionizing particulate radiation beam, e.g., electron, proton, heavy ion. The proposed research is highly innovative in that it will create a new methodology that combines radiation treatment with diagnostic imaging in the same physical space. The NMR relaxation properties of tissue will alter in the presence of an intense particulate ionizing radiation beam. This occurs for the following reasons: (1) ionizing radiation such as e-beams, p+beams, etc., generate charged particles in matter through which they pass. In aqueous systems, free radicals form during exposure to ionizing radiation. This creates susceptibility differences along the radiation path that will affect regional magnetic field homogeneity. T2 (i.e. apparent spin-spin relaxation due to magnetic field non-uniformity) should be affected and measurable; (2) Unpaired electrons from free radicals, especially the hydrated electron, interact with neighboring proton spins of water and will reduce T1 (spin- lattice) and T2 (spin-spin) relaxation times; (3) The electron beam will create a small pertubation of the local magnetic field resulting in a phase shift or loss of phase coherence of the NMR signal. Visualization of a radiation beam during radiation treatment should be possible by obtaining T1, T2 and T2* weighted MR images. This allows accurate determination of radiation dose to tumor and healthy tissue in-situ. No modality exists that can do this. Real time imaging of the radiation field opens the way to dynamic tumor targeting in regions of the body where organ displacement is a problem.

这项拟议的研究将把最先进的直线加速器与1.5T磁共振系统相结合，以产生第一代诊断-治疗模式。磁共振扫描仪与放射治疗单元的结合产生了协同作用，并形成了磁共振引导的增强放射治疗(MR-GERT)的基础。MR-GERT具有成像TURR和周围组织的能力，同时可视化电离粒子辐射束的路径，例如电子、质子、重离子。这项拟议的研究具有很高的创新性，因为它将创造一种新的方法，将放射治疗与诊断成像在同一物理空间中结合起来。在强粒子电离辐射束存在的情况下，组织的核磁共振弛豫特性会发生变化。发生这种情况的原因如下：(1)电子束、p+束等电离辐射在它们通过的物质中产生带电粒子。在水体系中，自由基会在暴露于电离辐射时形成。这在辐射路径上产生了磁化率差异，这将影响区域磁场的均匀性。(2)来自自由基团的未成对电子，特别是水合电子，与邻近的水中质子自旋相互作用，并将减少T1(自旋晶格)和T2(自旋-自旋)弛豫时间；(3)电子束将产生局部磁场的微小扰动，导致核磁共振信号的相移或相干性损失。通过获得T1、T2和T2*加权MR图像，应该可以在放射治疗期间显示辐射束。这使得能够在原位准确地确定肿瘤和健康组织的辐射剂量。没有一种医疗方式可以做到这一点。辐射场的实时成像为在器官移位存在问题的身体区域进行动态肿瘤靶向开辟了道路。