Gradient Coil replacement Introduction

Description - This describes the removal and replacement of the combined RF and gradient body coils in the various Signa Horizon systems without Cx Magnets. If you have a Cx magnet, please use procedure for Cx magnets, Gradient Coil Replacement.

The procedure includes moving the RF body coil from the failed gradient coil to the replacement gradient coil. It also deals with making the replacement in the limited space of mobile MRI vans.

The Epoxy-filled Gradient Coil is a field-replaceable unit (FRU). The coil is available in 1.0T and 1.5T versions. It consists of an inner and outer gradient coil, and each of these consists of an x, y, and z gradient winding. The windings are sealed in a strong adhesive. The inner gradient coil includes hose fittings that connect via 1/2-inch I.D. hoses to a heat exchanger, used to cool the entire assembly.

During manufacture, the inner coil is placed inside the outer coil, and the combination is then filled with an epoxy resin. This epoxy holds the inner and outer coils together, forming the Epoxy-filled Gradient Coil Assembly.

The RF body coil mounts inside the combined gradient coil. If the RF body coil is still operational, it will be necessary to move it from the failed gradient coil to its replacement.

While some of the following procedure can be accomplished by one person (connecting/disconnecting various cables, etc.), replacing a failed coil assembly is not a job for one person. The coil assembly weighs 2300 lbs (1045 kg), and the special cart and cradle weigh almost 1000 lbs (~450 kg); a minimum of four people should be available for moving this equipment.