MgB2 0.5-T/800-mm Whole-Body MRI Magnet: Phase I

描述(申请人提供)：医学成像对于高质量的医疗保健、疾病和损伤的早期发现和有效治疗至关重要。20世纪70年代，当MRI成为一种临床工具时，它受到了医院的热烈欢迎。这些医院已经从0.5T系统转移到1-1.5T系统，现在的目标是3T。然而，目前在全球范围内投入使用的约20,000个MRI设备只造福于约10%的人类，主要是在发达国家的城市地区。要纠正这种医疗机会上的明显差距和不公平，一个直接而快捷的方法是开发低成本和易于操作的核磁共振系统。对于大多数人来说，低成本的0.5-T超导磁共振成像设备将是有益的，也应该有助于降低美国的医疗成本。与NbTi(~10K)和Nb 3SN(~18K)的临界温度(TC)相比，MgB_2的TC~40K具有明显的优势。由于高温超导磁体具有较高的T_c，它的稳定性将大大提高，低温系统也将大大简化。在原项目开发技术的基础上，我们计划在第二阶段结束时完成0.5T的全身全功能磁共振磁体。在这个第一阶段项目中，我们将解决原始项目中没有研究的问题。在第一阶段，我们的重点将是制造将在持续模式下运行的主线圈。我们将解决导线(特别是长长度时的性能一致性)、保护和时间稳定性问题。在第二阶段，我们将加入一套校正线圈，将第一阶段系统转变为全功能磁共振模型磁体。利用原项目中演示的低温冷却器-SN2方法，并由第一阶段系统重新确认，磁体可以在没有液氦的情况下连续运行。该计划的意义在于高温超导磁体在以下设计/操作问题上的进一步进步：1)使用镁合金2，以保持高温超导磁体的低成本；2)在10-15 K左右工作以增强稳定性；3)无液体制冷剂的“干燥”环境；4)持续模式操作，以获得良好的时间稳定性和操作简易性；5)防止猝灭损坏。此外，低温方法将使该系统容易受到电力中断的影响，预计美国和欠发达国家的许多农村社区都会出现这种情况。我们坚信，二期MRI磁体将成为适合农村和欠发达地区的低成本、易操作的MRI磁体的典范。该项目所积累的技术还将促进在与目前最先进的NbTi磁体相比具有更高磁场竞争力的磁共振磁体中应用MGB 2，但成本大大降低，稳定性增强，而且不依赖液氦供应。 与公共卫生相关：这个分两个阶段的更新项目的具体目标是在第二阶段结束时完成一个全身全功能磁共振磁体，它将成为小医院、农村社区和欠发达国家低成本和无液氦商业单位的典范。这些核磁共振磁铁应该有助于在大量人类中早期发现和有效治疗疾病和损伤。它们还将有助于降低美国的医疗保健成本。

DESCRIPTION (provided by applicant): Medical imaging is critical for quality health care for early detection and efficient treatment of disease and injury. In 1970s, when MRI became a clinic tool, it was enthusiastically embraced by the hospitals. These hospitals, having since moved from systems of 0.5 T to 1-1.5 T, now target 3 T. However, ~20,000 MRI units now in service worldwide benefit only ~10 % of the total humanity, chiefly in the urban areas of the developed nations. One direct and quick way to redress this glaring disparity and unfairness in medical treatment opportunities is to develop low-cost and easy-to- operate MRI systems. For a vast majority of humanity, low-cost 0.5-T superconducting MRI units would be beneficial and should also help to reduce health care costs in the U.S. Compared with the critical temperatures ( Tc ) of NbTi (~10 K) and Nb 3Sn (~18 K), Tc ~40 K of MgB2 promises obvious advantages. Owing to a higher Tc, an MgB 2 magnet will have its stability considerably enhanced and cryogenic system substantially simplified. Based on the technologies developed in the original project, we propose to complete, at the conclusion of Phase II, a whole- body fully functional MRI magnet of 0.5 T. In this Phase I project, we will address issues, which were not investigated in the original project. In Phase I, our focus will be on the fabrication of MAIN COIL that will be operated in persistent mode. We will address the issues of conductor (particularly performance consistency in long lengths), protection, and temporal stability. In Phase II, we will incorporate a set of correction coils to transform the Phase I system to a fully functional MRI model magnet. With the cryocooler-SN 2 approach demonstrated in the original project and to be reconfirmed by the Phase I system, the magnet can operate continuously without liquid helium. Significance of the program is further advancement in the following design/operation issues for HTS magnets: 1) using MgB 2, to keep the HTS magnet low-cost; 2) operating at around 10--15 K for enhanced stability; 3) liquid cryogen free "dry'' environment; 4) persistent-mode operation for good temporal stability and ease of operation; 5) protection from quench damages. In addition, the cryogenic approach will allow the system susceptible to power disruptions, expected in many rural communities in the U.S. and underdeveloped nations. We strongly believe that Phase II MRI magnet will become a model of low-cost, easy-to-operate MRI magnets suitable for rural and underdeveloped region. The technologies accumulated in the project will also promote the application of MgB 2 for MRI magnets of even higher field competitive to the current state-of-the-art NbTi magnets, but with substantially lower costs, enhanced stability, and without reliance on liquid helium supply. PUBLIC HEALTH RELEVANCE: The specific aim of this 2-phase renewal project is to complete, at the conclusion of Phase II, a whole-body fully functional MRI magnet that will become a model for low-cost and liquid-helium-free commercial units for small hospitals, rural communities, and underdeveloped nations. These MRI magnets should contribute to early detection and efficient treatment of disease and injury among a large mass of humanity. They would also contribute to reduced health care costs in the U.S.