[Development of Magnetic Stimulator].

Transcranial magnetic stimulation (TMS) has been used in research into brain function. Recently, TMS has also become an option in treating brain dysfunction. The equipment consists of a coil and a driving circuit. The most widely used coil is a figure-8 coil because of its good resolution, and the most widely used circuit generates a biphasic pulse for repetitive stimulation. To assess the induced electric field distribution in the brain, we conducted simulations using a coil and constructed a brain model from a MR image. Finally, we introduce the coils we have developed for treatment in the home. These include an eccentric figure-8 coil and a dome-shaped coil. Reducing the size of the equipment is one of the chief technical challenges of using rTMS therapeutically in the home. An eccentric figure-8 coil can be driven with a lower current than a conventional figure-8 coil because of its good efficiency, which results in a smaller driving circuit. Conventional figure-8 coils stimulate a highly localized area, therefore making it difficult to ensure that a particular area receives stimulation without the assistance of an infrared camera support system, which is large and expensive. A dome-shaped coil is capable of stimulating a larger area and is robust against errors of positioning caused by the simple navigation system used in the home.