Introduction - Robotized Transcranial Magnetic Stimulation - page 18

application or treatment results in inaccuracies for coil placement and target
localization. For direct head tracking on the contrary, no additional marker and
therefore no marker registration is required. The tracking system directly tracks
the shape of the head or anatomical landmarks on the head which can be
matched to three-dimensional head scans of the patient. We describe different
approaches for direct head tracking and test them for use in the robotized TMS
system. We present some first results and discuss future trends and ideas for
direct head tracking.
With these improvements and further developments, the robotized TMS system
becomes a safe robotic system that can be used fail-safe on the patient. The
dramatically improved usability ensures the easy and unproblematic clinical
application of the robotized TMS system. The development of the robotized TMS
system, from its not yet mature state to a safe and clinically applicable system, is
described stepwise in the following section.
1.4.1 Structure of this Work
Beside introducing the basic principles of TMS and discussing the current
developments in this chapter from neuro-navigated systems towards robotized
TMS, this work is divided into three parts: Part I presents a systematic analysis
and practical evaluation of the robotized TMS system in its present state. Part II
describes the implementation and development of the safe and clinically appli-
cable robotized TMS system. Part III discusses the developed system and presents
some closing remarks.
Thus, Chap. 2 outlines the main challenge for precise targeting: the naturally
occurring, unavoidable head motion of the patient's head. Therefore, the impact of
head motion on the induced electric field is systematically presented. The realistic
measurements demonstrate that robotized TMS with active motion compensation
avoids the impact of head motion.
Subsequently, Chap. 3 evaluates the robotized TMS system in two recent
studies. These studies show that robotized TMS facilitates precise positioning, and
that even small changes in the coil position and/or the coil orientation can be
explicitly measured in the stimulation result. Beside the clear advantages of
robotized TMS, the chapter also demonstrates the deficits of the system in its
current setup.
Solving these deficits, Part II therefore describes the further development of the
robotized TMS system to a safe and clinically applicable system.
Starting to overcome the deficits, Chap. 4 characterizes an improvement of the
system setup: A robust real-time calibration method between robot and tracking
system supersedes the need of a time-consuming calibration step before system
start. Furthermore, a comparison between the standard techniques and the robust