Speaker
Description
A significant milestone in India’s scientific and technological advancement has been achieved with the successful development of India’s first indigenously designed 1.5T whole-body Magnet Resonance Imaging (MRI) magnet. The cryogenics and applied superconductivity lab at the Inter-University Accelerator Centre (IUAC), New Delhi has recently developed an actively shielded whole-body 1.5T superconducting magnet for a clinical scanner. The superconducting magnet system is the heart of any MRI scanner, the performance of which directly affects the quality of imaging. The design process of the magnet was focused on achieving optimal magnetic field homogeneity, and stability and minimizing operational costs while maintaining international standards. The multi-coil MRI magnet not only poses many challenges in achieving homogeneity at unshimmed conditions but also increases the inter-coil forces, number of superconducting joints etc.
An extensive FEA simulations on electromagnetic, thermal, cryogenics, mechanical, and electrical have been done during the design of the 1.5T MRI magnet. We performed extensive prototyping, and developed various associated technologies; superconducting joints, superconducting switches, quench protection systems, and performed component characterization, endurance testing, validation etc. The superconducting MRI magnet needs the development of various complex technologies to achieve high homogeneity ((±5ppm) and high temporal stability ( 0.1ppm/hr or 6Hz/hr) and zero-boil-off condition of the magnet system. The whole-body MRI magnet developed at IUAC has recently been tested. The magnet was parked at 1.5T field. The unshimmed homogeneity is achieved 615 ppm in the imaging volume. The field stability is measured to be ~ 0.02 ppm/hr. The performance of the passive quench protection system of the MRI has been tested during a quench of the MRI magnet.
This paper briefly discusses the design, optimization and development, experimental studies of various critical components of the 1.5T whole-body actively shield MRI magnet system. Such development involved overcoming challenges related to superconducting coils, quench protection systems, superconducting switches, integrating magnets and the cryostat, cryogenic cooling etc. This paper briefly discusses the challenges faced during the development of such a whole-body magnet in an R&D laboratory in India
Acknowledgement
The authors would like to thank the Ministry of Electronics and Information Technology (MeitY), Govt of India for funding this research under the IMRI project. The authors would also thank members of the cryogenic group for providing technical support in development of the test rigs.
