Conductors, Joints, and Coils for Cryogen Free Whole Body 3 T MRI systems (Renewal)

总结 目前安装的大多数全身MRI系统都是基于1.5 T液态He- 冷却NbTi磁体，但3.0 T系统的安装率正在迅速增加。 然而，氦的成本增加是有据可查的，这导致了 MRI系统的生命周期成本，这可能会限制传统的 患者群体，并限制了将可用性扩展到传统上不太好的患者群体的能力 服务于患者群体。问题的根本原因是氦气日益短缺 国际吧主要的MRI磁体制造商（西门子、通用电气和菲利普斯） 有开发计划，重点是转换1.5吨螺线管线圈从液体 氦浴冷却到干（无冷冻剂）传导冷却。事实上， 需要液氦冷却（即无致冷剂、传导冷却、运行）， 变得越来越重要虽然NbTi设计已被探索用于1.5 T 然而，3 T系统的更高要求使得这条路线站不住脚。越大 MgB 2的热裕度和经济性使得基于MgB 2的3 T系统成为 可行 即使在MRI的液体制冷剂问题之外，低温冷却MRI的发展 磁铁可以允许新的几何形状和MRI应用，开辟新的治疗方法， 可能性但是，我们必须关注行业可以在哪些方面过渡到这一新的 技术商业化。因此，拟议方案的重点是开发 技术使无冷冻剂3 T系统能够使用低温冷却模式。我们建议 通过（1）在适合于3 T MRI的范围内继续增加MgB 2 Je（4-10 K，0-6 T），但重点是可保护导体，在长时间内保证n > 30 长度，（2）优化我们目前的磁体模型（FEM/数值）， - 减小导线上的峰值场，以减小所需的导体长度， 结构支持（使目前的原理证明具有竞争力， 吸引人），（3）也展示了可靠和更高性能的持久接头 作为一个持久的开关，两者都与全尺寸分段线圈一起工作，（4） 展示了一个具有3 T设计性能的反作用和缠绕线圈段， 具有高可靠性的集成主动保护方案（如实验所示， 线圈在持续模式下运行），（5）开发替代磁性/机械 用于特殊应用的设计，包括图像引导应用。 1

Summary Most presently installed full-body MRI systems are based on 1.5 T liquid-He- cooled NbTi magnets, but the rate of installation of 3.0 T systems is rapidly increasing. However, the increasing cost of helium is well documented, and this leads to increases in the life cycle cost of MRI systems, which could limit ready access for traditional patient groups, and limit the ability to expand availability to traditionally less well served patient groups. The root cause of the problem is the growing shortage of helium worldwide. The major MRI magnet manufacturers (Siemens, GE, and Phillips) each have development programs focused on converting the 1.5T solenoid coils from liquid helium bath cooling to dry (cryogen free) conduction cooling. Indeed, freedom from the need for liquid-helium cooling (i.e. cryogen free, conduction-cooled, operation) is becoming more and more important. While NbTi designs have been explored for 1.5 T systems, the much higher demands of 3 T systems makes that route untenable. The larger thermal margin of MgB2 and affordability makes MgB2 based 3 T systems the most feasible. Even beyond the liquid cryogen issues for MRI, the development of cryocooled MRI magnets could allow for new geometries and MRI applications, opening up new treatment possibilities. However, we must focus where the industry can transition this new technology commercially. Accordingly, the proposed program focuses on developing the technology to enable cryogen free 3 T systems using a cryocooled mode. We proposed to do this by (1) Continuing to increase MgB2 Je in ranges appropriate to 3 T MRI (4-10 K, 0-6 T), but focus on a protectable conductor with n > 30 guaranteed over long lengths, (2) Optimizing our present magnet models (FEM/numerical) targeting reduced peak fields on the wire in order to reduce required conductor length and structural support (making present proof-of principle competitive and highly attractive), (3) Demonstrating reliable and higher performance persistent joints as well as a persistent switch, both working in conjunction with a full size segment coil, (4) Demonstrating a react and wind coil segment with 3 T design performance and an integrated active protection scheme with high reliability (as shown experimentally with coil operating in persistent mode), (5) Developing alternative magnetic/mechanical designs for specialty applications including image guided applications. 1