Magnetic navigation system for home use of repetitive transcranial magnetic stimulation (rTMS)

We are developing stimulation coil navigation systems for home use of repetitive transcranial magnetic stimulation (rTMS). rTMS is effective for intractable diseases of the nervous system. However, the effects of rTMS last only for several hours, requiring a continuing daily rTMS therapies in a nearby clinic. A magnetic navigation system, the present system for fulfilling such needs, uses downsized, lightweight, low-cost magnetic sensors with datasets relating the magnetic field to the 3D position of the stimulation coil instead of the complicated handling and operation of large-scale and expensive devices or systems like a 3D position-measurement device. This system has been modified for home use and is easily available to non-medical staff. However, in a hospital, a large number of datasets, at least 500, is required, so collecting datasets might be a burden for the physician. To solve this problem, this paper proposes a method for extracting the necessary datasets for navigation. In the proposed method, many more datasets, which can handle any shape of a patient´s head, are prepared in advance. The physician then collects only a few samples in the hospital. The system extracts the remaining datasets necessary for navigation by applying geometric model approximations like Delaunay triangulation or the ellipsoid model to the data for these samples. We evaluate the efficiency of the proposed method by a simulation of extracting datasets and navigating using a head model. The proposed method reduces the number of datasets collected by physicians from 500 to 10, thus reducing physicians´ burdens.