Development of low-cost MgB2/solid N2 MRI magnets

描述(由申请人提供)： 该计划的具体目标是展示低成本、即商业上可行的超导磁共振成像(MRI)磁体系统的可行性和实用性，该系统专门针对小医院、农村社区和欠发达国家使用。核磁共振系统采用了二硼化镁(MgB2)复合导体和创新的低温设计/操作概念。我们通过建造和运营0.5特斯拉(T)/80厘米口径演示磁体来实现这一特定目标，该演示磁体除了缺乏核磁共振级别的空间均匀性外，还满足0.5T/80厘米核磁共振磁体系统的关键操作要求。我们相信，商业核磁共振磁体制造商将基于本文提出的演示系统来设计此类核磁共振磁体。该演示系统为核磁共振超导磁体技术引入了两个重要的第一，均有利于下一代低成本核磁共振磁体系统的运行：1)引领下一代核磁共振磁体趋势的镁B2磁体；2)在磁体外壳中引入大量固体氮的创新低温设计/操作概念。系统中固体氮的存在由制冷机维持，极大地提高了磁体的热容量，使磁体即使在制冷机关闭的情况下也能在有限的时间内保持其作业场，这在农村社区和欠发达国家并不少见。只有在关闭期间，磁体和固体氮气才会在一天的时间内升温到15K的设计极限温度，否则，磁体和固体氮气将通过其制冷机保持在10K的标称工作温度。这些特定温度和关闭持续时间用于建议的演示磁体和全尺寸磁共振磁体，其参考设计包含在应用程序中。这个拟议的示范磁体系统的意义在于，它的成功运行有望刺激低成本的以镁为基础的磁共振成像系统的商业生产(和需求)。与这种低成本磁体相结合的创新低温设计/操作概念使MRI系统即使在比标准MRI系统更不可靠的工作条件下也能可靠地运行。

DESCRIPTION (provided by applicant): The specific aim of this program is to demonstrate the feasibility and practicality of a low-cost, i.e., commercially viable, superconducting magnetic resonance imaging (MRI) magnet system specifically targeted for use in small hospitals, rural communities, and underdeveloped nations. The MRI system incorporates Magnesium Diboride (MgB2) composite conductor and an innovative cryogenic design/operation concept. We achieve this specific aim by building and operating a 0.5 Tesla (T)/80 cm bore demonstration magnet that, except for its lack of an MRI-grade spatial homogeneity, satisfies key operational requirements of 0.5 T/80 cm MRI magnet systems. We are confident that commercial MRI magnet manufacturers will base their design for such MRI magnets on the demonstration system proposed herein. The demonstration system introduces two important firsts to MRI superconducting magnet technology, both benefiting the operation of the next generation low-cost MRI magnet systems: 1) a trend-setting MgB2 magnet for the next-generation of MRI magnets; and 2) an innovative cryogenic design/operation concept that introduces a volume of solid nitrogen in the magnet housing. The presence of solid nitrogen in the system, maintained by a cryocooler, enhances the magnet's heat capacity enormously, enabling the magnet to maintain its operating field over a limited time period even with its cryocooler shut off as would be in case of a power outage, an event not rare in rural communities and underdeveloped nations. Only during this shut off period, the magnet and the solid nitrogen, otherwise kept at a nominal operating temperature of 10 K by its cryocooler, will warm up to a design limit of 15 K over a period of one day. These specific temperatures and shut off duration are for the proposed demonstration magnet and a full-scale MRI magnet, a reference design of which is included in the application. The significance of this proposed demonstration magnet system is that its successful operation is expected to spur commercial production (and demand) of low-cost MgB2-based MRI systems. The innovative cryogenic design/operation concept coupled to this low-cost magnet enables the MRI system to perform reliably even under working conditions much less reliable than those tacitly assumed for standard MRI systems.