Eccentric figure-eight coils for transcranial magnetic stimulation.

Previously we proposed an eccentric figure-eight coil that can cause threshold stimulation in the brain at lower driving currents. In this study, we performed numerical simulations and magnetic stimulations to healthy subjects for evaluating the advantages of the eccentric coil. The simulations were performed using a simplified spherical brain model and a realistic human brain model. We found that the eccentric coil required a driving current intensity of approximately 18% less than that required by the concentric coil to cause comparable eddy current densities within the brain. The eddy current localization of the eccentric coil was slightly higher than that of the concentric coil. A prototype eccentric coil was designed and fabricated. Instead of winding a wire around a bobbin, we cut eccentric-spiral slits on the insulator cases, and a wire was woven through the slits. The coils were used to deliver magnetic stimulation to healthy subjects; among our results, we found that the current slew rate corresponding to motor threshold values for the concentric and eccentric coils were 86 and 78 A/µs, respectively. The results indicate that the eccentric coil consistently requires a lower driving current to reach the motor threshold than the concentric coil. Future development of compact magnetic stimulators will enable the treatment of some intractable neurological diseases at home.

Coil positioning system for repetitive transcranial magnetic stimulation treatment by ToF camera ego-motion.

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive method for treating various neurological and psychiatric disorders. With the growing demands of neuropathic pain patients and their increasing numbers, rTMS treatment tools are becoming more necessary. rTMS uses electromagnetic induction to induce weak electric currents by rapidly changing the magnetic field. Targeting the electric current to a specific part of the brain is one treatment for pain relief. This paper focuses on treatment for neuropathic pain caused by a lesion or disease of the central or peripheral nervous system, including stroke, trauma, or surgery. However, the current style of rTMS treatment is still developing and is so technically specialized that only a limited number of hospitals and only a handful of specialists can provide this therapy. The existing rTMS systems use an optical markerbased 3D sensing technique that positions the stimulation coil to target the small region of interest in the brain through coregistration with pre-scanned MRI data. This system requires the patient to be immobilized on a bed. The optical markers for 3D sensing are placed on the patient's head to maintain accurate positioning. We propose a constraints-free, markerless rTMS system, which employs ego-motion, a computation technique to estimate relative 3D motion of a camera to what the camera sees. We use a ToF sensor as a camera, which is capable of capturing shape information from a single viewpoint instantly. The markerless target spot is based on the shape features of the patient's face. This paper shows the process of a prototype system and its potential for achieving an easy-to-handle system framework.

Embedded ubiquitous services on hospital information systems.

A Hospital Information Systems (HIS) have turned a hospital into a gigantic computer with huge computational power, huge storage and wired/wireless local area network. On the other hand, a modern medical device, such as echograph, is a computer system with several functional units connected by an internal network named a bus. Therefore, we can embed such a medical device into the HIS by simply replacing the bus with the local area network. This paper designed and developed two embedded systems, a ubiquitous echograph system and a networked digital camera. Evaluations of the developed systems clearly show that the proposed approach, embedding existing clinical systems into HIS, drastically changes productivity in the clinical field. Once a clinical system becomes a pluggable unit for a gigantic computer system, HIS, the combination of multiple embedded systems with application software designed under deep consideration about clinical processes may lead to the emergence of disruptive innovation in the clinical field.