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

描述（由申请人提供）：医学成像对于早期发现和有效治疗疾病和损伤的优质医疗保健至关重要。20世纪70年代，当MRI成为临床工具时，它受到了医院的热情欢迎。这些医院已经从0.5 T的系统转移到1-1.5 T，现在的目标是3 T。然而，目前在全球范围内使用的约20，000台MRI设备仅使约10%的人类受益，主要是在发达国家的城市地区。一个直接和快速的方法来纠正这种明显的差距和不公平的医疗机会是开发低成本和易于操作的MRI系统。对于绝大多数人类来说，低成本的0.5 T超导MRI设备将是有益的，并且还应有助于降低美国的医疗保健成本。与NbTi（~10 K）和Nb 3Sn（~18 K）的临界温度（Tc）相比，MgB 2的Tc ~40 K具有明显的优势。由于具有较高的Tc，MgB 2磁体的稳定性将大大提高，低温系统将大大简化。基于原项目中开发的技术，我们建议在第二阶段结束时完成0.5 T的全身全功能MRI磁体。在这个第一阶段项目中，我们将解决原始项目中没有调查的问题。在第一阶段，我们的重点将是制造主线圈，将在持久模式下运行。我们将讨论导体（特别是长长度的性能一致性），保护和时间稳定性的问题。在第二阶段，我们将采用一组校正线圈，将第一阶段系统转换为功能齐全的MRI模型磁体。在最初的项目中展示了低温冷却器-SN 2方法，并将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。 该计划的意义在于进一步推进了以下HTS磁体的设计/操作问题：1）使用MgB 2，以保持HTS磁体的低成本; 2）在约10- 15 K下操作，以增强稳定性; 3）无液体制冷剂的“干燥”环境; 4）持久模式操作，以获得良好的时间稳定性和易于操作; 5）防止失超损坏。此外，低温方法将使系统容易受到电力中断的影响，预计在美国和欠发达国家的许多农村社区。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MRI磁体的典范。该项目中积累的技术也将促进MgB 2在MRI磁体中的应用，其磁场甚至比目前最先进的NbTi磁体更高，但成本更低，稳定性更高，并且不依赖液氦供应。 公共卫生相关性：这个2阶段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MRI磁体，该磁体将成为小型医院，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MRI磁体应该有助于早期发现和有效治疗大量人类的疾病和损伤。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.