超极化129Xe自动收集-升华装置研究

因其较高的核自旋极化度所提供的探测灵敏度，超极化¹²⁹Xe气体已被成功应用于动物和人体磁共振成像（MRI）.但是，在超极化¹²⁹Xe的收集-升华过程中，多种因素会导致¹²⁹Xe核自旋弛豫，进而限制其应用范围.本文通过理论模型分析和实验测量，验证了温度、磁场、螺旋冷阱材质等对冷冻恢复过程中超极化¹²⁹Xe弛豫的影响；同时，测量了自动收集-升华装置的稳定性.研究结果表明，升华方式和冷阱材质对¹²⁹Xe极化度损耗的影响显著；自制收集-升华装置的自动化程度高、长时间稳定，¹²⁹Xe极化度的恢复率可达到85.6% ± 4.7%.本研究非常有助于提升超极化¹²⁹Xe在动物和人体MRI中的使用效率.

Study on the Automatic Accumulation-thawing Device of Hyperpolarized 129Xe

Due to the detection sensitivity provided by the high nuclear spin polarization, hyperpolarized ¹²⁹Xe has been employed in animal and human magnetic resonance imaging (MRI). However, during the accumulation-thawing process of hyperpolarized ¹²⁹Xe, multiple factors lead to the relaxation of spin polarization and would hinder the wider application of ¹²⁹Xe. In this research, the spin relaxation mechanism of hyperpolarized ¹²⁹Xe during the accumulation-thawing process is investigated by both theoretical model analysis and experimental measurements. Meanwhile, the stability of the homebuilt device for the accumulation-thawing is measured. Our results demonstrate that the thawing mode and the cold trap material significantly affect the polarization loss; the automatic device is very stable during long-term operation and shows a high degree of automation, resulting in a polarization recovery ratio of 85.6% ± 4.7%. This research greatly helps to improve the efficiency of hyperpolarized ¹²⁹Xe in animal and human MRI.