Conductors, joints, and Coils for Cryogen Free Whole Body 3 T MRI systems

描述（由申请人提供）：目前安装的大多数全身MRI系统基于1.5 T液氦冷却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MRI系统的生命周期成本增加，这可能会限制传统患者群体的可用性，并限制将可用性扩展到传统上服务不太好的患者群体的能力。问题的根本原因是全球氦气日益短缺。主要的MRI磁体制造商（Siemens、GE和菲利普斯）都有专注于将1.5 T螺线管线圈从液氦浴冷却转换为干式（无冷冻剂）传导冷却的开发计划。事实上，不需要液氦冷却（即无冷冻剂、传导冷却的操作）变得越来越重要。目前，MRI系统（2000-3000升）在装运之前在工厂填充有液态He氦，在美国的成本约为20-30 K。考虑到从2006年到2011年，液氦的成本增加了两倍，并且预计将继续增加，可以预期液氦MRI装置的成本也会相应增加。在世界上的某些地方，液体He的成本约为每升9 -13美元，而在其他地方约为每升25 - 70美元，导致根据MRI的尺寸和位置，再填充成本为18，000 - 210，000美元。因此，预计对不依赖于液态He冷却的MRI磁体的需求将不断增长。 即使超出了MRI的液体冷冻剂问题，低温冷却MRI磁体的发展也可以允许新的几何形状和MRI应用，开辟新的治疗可能性。然而，我们必须关注该行业可以将这项新技术商业化的地方。因此，拟议的计划侧重于开发技术，使无制冷剂的3 T系统使用低温冷却模式。我们建议这样做，（1）在适合于3 T MRI的场和温度范围内，将实际MgB 2工程电流密度Je比目前开发的1G线增加一个数量级（4-10 K，0-4 T），（2）开发足够用于持续模式磁体操作的n值（3）开发具有足够细节的磁体模型，以开发导体规格/目标，以及冷却、线圈段上的温度梯度之间的权衡，和导体性能，（4）确定通道内导线MgB 2/Cu的适当Cu/SC比，并证明其长长度制造，（5）使用项目（4）的WIC，证明具有所需电流、n值、温度梯度和失超性能的总线圈的一个段，（6）在磁体工程友好的反作用和风力模式下，开发用于MgB 2导体的坚固持久接头。

DESCRIPTION (provided by applicant): 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 patint 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. Presently, MRI systems (2000-3000 liters) are filled with liquid He helium at the factory prior to shipping at a cost in the U.S. of about 20-30 K. Given that from 2006 to 2011 the cost of LHe has tripled, and it is expected to continue to increase, corresponding increases in the cost of liquid-He MRI units can be expected. In some parts of the world liquid He costs about $9-13 per liter and in others about $25 to $70 per liter leading to re-filling costs of $18,000-$210,000 depending on the MRI's size and location. Thus a growing demand is predicted for MRI magnets that do not depend on liquid He for cooling. 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) Increases practical MgB2 engineering current density, Je, by one order of magnitude over presently developed 1 G wire, in the fields and temperature ranges appropriate to 3 T MRI (4-10 K, 0-4 T), (2) Developing n-values sufficient for persistent mode magnet operation (30 or more in the relevant field range) in the multifilament 2 G wires of (1), (3) Developing a magnet model with sufficient detail to develop the conductor specification/targets, and the tradeoffs between cooling, temperature gradients across a coil segment, and conductor performance, (4) Determining the proper Cu/SC ratio for wire-in-channel MgB2/Cu, and demonstrate its long-length manufacture, (5) Demonstrating one segment of the total coil, using the WIC of item (4), with the needed current, n-value, temperature gradient, and quench performance, and (6) Developing a robust persistent joint for MgB2 conductors in a magnet engineering friendly react & wind mode.