The emergence of transcranial magnetic stimulation (TMS) as a tool for investigating the brain has been remarkable over the past decade. While many centers are now using TMS, little has been done to automate the delivery of planned TMS stimulation for research and/or clinical use. We report on an image-guided robotically positioned TMS system (irTMS) developed for this purpose. Stimulation sites are selected from functional images overlaid onto anatomical MR images, and the system calculates a treatment plan and robotically positions the TMS coil following that plan. A new theory, stating that cortical response to TMS is highest when the induced E-field is oriented parallel to cortical columns, is used by the irTMS system for planning the position and orientation of the TMS coil. This automated approach to TMS planning and delivery provides a consistent and optimized method for TMS stimulation of cortical regions of the brain. We evaluated the positional accuracy and utility of the irTMS system with a B-shaped TMS coil. Treatment plans were evaluated for sites widely distributed about a head phantom with well-defined landmarks. The overall accuracy in positioning the planned site of the TMS coil was approximately 2 mm, similar to that reported for the robot alone. The estimated maximum range of error in planned vs. delivered E-field strength was +4%, suggesting a high degree of accuracy and reproducibility in the planned use of the irTMS system.
An image processing system is described for use in micromechanics research on materials, such as for determining the displacements and strains surrounding crack tips. This vision system is a machine implementation of the stereoimaging technique that was developed for making submicron measurements of displacements under high resolution conditions. It uses a Cognex 2000 image processing system, cameras to obtain digital images from analog photographs, a graphics display terminal and track ball for operator interaction with the system, and a video display monitor for display of the measured displacements. Displacements are sent directly to an associated VAX that computes strains and permits their graphical display. The system is described in detail and examples of its use in micromechanics research are given.
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