Speaker
Description
Low-field (<10mT) Magnetic Resonance Imaging (MRI) opens the possibility to perform medical imaging at a fraction of the cost of conventional MRI. As signal vanishes with lower applied magnetic field, it becomes necessary to use an ultra-sensitive and ultra-low noise detector to acquire medically relevant images in a reasonable time. Thanks to their exceptional noise performances, Superconducting Quantum Interference Device (SQUID) detectors are particularly well-suited for this application. To preserve signal integrity it is however necessary to reduce noise, which is dominated by the Johnson noise generated in the MRI detection coil. It is therefore primordial to cool down the whole detection chain. Previous designs [1] made use of a SQUID detector connected to a low-temperature superconducting coil hosted in a non-metallic liquid helium cryostat. Such a design however has high running costs and lacks geometric flexibility to perform imaging of body parts, mainly due to the technical choice of using a Nb detection coil placed on the 4K stage of the cryostat.
At Chipiron, we are making a 1mT MRI machine built around SQUID detectors. We report on the realization of a dry 4K cryostat by a collaboration between Chipiron and MyCryoFirm, a division of Pasqal. This cryostat is compatible with the stringent requirements of SQUID-MRI that is capable of hosting SQUID sensors at 4K and a deported cryogenic detection setup predicted to work at 45K. By reducing both the temperature and the resistance of the detection chain, this cryostat will significantly improve the signal-to-noise ratio of SQUID-MRI experiments. In addition, superconducting materials with transition temperatures in the few tens of Kelvin such as MgB2 wires are under investigations to realize a fully superconducting detection chain thus achieving ultimate imaging performances.
[1] Seton et al., Cryogenics 45 (2005)
| Submitters Country | France |
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