Magnets, Gradients, and RF Coils of MR Scanners

The topic of this paper is the parts modern MR devices, which contain magnet coils. scanner magnets are made four types electromagnetic coils: 1) Main magnet, superconducting material. main an (Magnetic Resonance Imaging) creates a strong and uniform magnetic field around patient being scanned. This typically in range 0.5 to 3 Tesla used align moments hydrogen atoms patient's body. superconductors, create field, should be cooled with liquid helium nitrogen. superconductors use cryostat, cooling vessels nitrogen, thermal insulation, other protective elements system. 2) gradient three x-coils, y-coils, z-coils. X coil, resistive material, variable horizontally, from left right, across scanning tube; 3) Y coil vertically, bottom top; 4) Z longitudinally, head toe, inside tube. RF coils generate pulses excite protons (spins) body detect signals emitted by when they return their equilibrium state after excitation turned off. resulting interaction between aligned produces signal that images seen MRI scan. what allows imaging produce detailed anatomical functional information non-invasively. structure complex. resonant frequency changes at each point controlled manner. Inside copper core embedded windings material form microfibers. A non-linear created conductive It adds field. Thus obtained. exist basic configurations scanners analyzed. Scanners closed cylindrical cavity fields passing current through solenoid, maintained temperature superconductor. Exclusively niobium-titanium (NbTi), niobium-tin (Nb3Sn), vanadium-gallium (V3Ga), magnesium-diboride (MgB2). Only magnesium diboride high-temperature superconductor, critical Tc = 390K. remaining low temperatures. New have been discovered, as well room temperature. Newly discovered materials not scanners.