| Polarized helium-3 has been proved to be useful in low-field magnetic resonance(LMR),and can be used as an imaging medium to achieve low-field pulmonary MR imaging.This project completed the polarization ~3He cell design,completed the alkali metal filling and implements a~3He hyperpolarization,designed the main magnet and the gradient coil for LMR,obtained water cavity image under 6.6 m T and obtained hyperpolarization cavity image under 8.7 m T.This project provides a research basis for the human lung imaging.The main work contents of this project are as follows:(1)Designed the the ~3He cell which can exit the hyperpolarized gas.Completed the inflationsystem design and RB-K mixing chamber.(2)The laser modulation platform of ~3He hyperpolarization had been completed and built.Finally,the polarization signal of polarized ~3He waobtained by using RB-K mixing cavity.(3)In this project,a novel coil system for Ultra-Low Field Polarized 3He PulmonaryMagnetic Resonance Imaging is presented by using the series expansion design method with the coil spacing and maximum diameter as constraints.After optimization,the planar octagonal main magnetic field coil,spacing of 70 cm,had been designed.The magnetic field within the range of 40 cm DSV center uniformity is less than 100 ppm,and processing and debugging successfully completed.(4)The design of X/Y/Z gradient coils for low field is completed by using the target fieldmethod under biplanar constraints.The distance between the coils is 70cm,and the maximum radius is 120 cm.The gradient performance is better than 5%in 40cm DSV,and the processing of the gradient coils is completed.(5)The low-field equipment installation was completed,and the solenoid coil was used asthe RF coil.The cylinder water model image with a diameter of 20 cm was successfully obtained under 6.6m T,and the image resolution was less than or equal to 2mm.On this basis,the magnetic field intensity was adjusted to 8.7m T,and the polarized ~3He cell image was successfully obtained. |
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