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Prof. Dr.-Ing. Dr. h.c. Heinz Wörn

Professor im Ruhestand
Tel.: +49 721 608-44006
Fax: +49 721 608-47141
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Professor Wörn studierte Elektrotechnik an der Universität Stuttgart und promovierte dort am Institut für Werkzeugmaschinen mit seiner Arbeit zu dem Thema "Mehrprozessorsteuerungssystem für Werkzeugmaschinen mit standartisierten Schnittstellen". Im Anschluss arbeitete er bei KUKA Schweißanlagen und Roboter GmbH, wo er eine leitende Stellung in Forschung und Entwicklung inne hatte. Professor Wörn ist ein international anerkannter Experte für Roboter und Automation. Seine Erfahrung umfasst Roboteranwendungen, Robotersteuerungen und Sensoren für Roboter, sowie deren Programmmierung und Simulation. Seit 1997 leitet er das Institut für Prozessrechentechnik, Automation und Robotik der Universität Karlsruhe als Professor für "Komplexe Systeme in Automation und Robotik".

Forschungsgebiete

  • Planung, Programmierung, Steuerung, Diagnose und Sensorsysteme für Industrieroboter
  • Autonome, mobile Roboter, Mikroroboter, Serviceroboter, Teleroboter, Autonome Fahrzeuge
  • Planung und Simulation von Anlagen und Fabriken
  • Roboter- und sensorgestützte Chirurgie
  • Mikromontage
  • Modellierung komplexer Systeme in Produktion und Medizin

Bringing laser for osteotomy into the operation theatre

AutorH. Peters, H. Knoop, W. Korb, S. Ghanai, J. Raczkowsky, M. Werner, M. Klasing, M. Ivanenko, S. Hassfeld, P. Hering, H. Wörn
Jahr2005
Veröffentlicht inCARS 2005, Proceedings of the 19th International Congress and Exhibition
EditorH.U. Lemke, K. Inamura, K. Doi, M.W. Vannier, A.G. Farman
KurzfassungPurpose Machining of bone by means of trephine, driller or saw is a common treatment in today’s surgery. Especially in craniofacial surgery it is essential to detect the inner side of the scull in order not to hurt any inner parts such as the dura mater or the brain. This problem, also occurs, when using the surgical robot system “RobaCKa”[1][2] that has performed the first milling of a complex trajectory on a patient’s scull worldwide in April 2003[3]. Furthermore, the heat produced by the milling can lead to necroses and the impressed forces may move the patient and invalidate its registration. Yet the system proved that it is feaseable to use a robot in OR with respect to safety and usability. Stepping further, the authors wanted to try a new technology for cutting the bone faster, better and more securely with respect to the mentioned border between the scull and the dura mater. LASER is a technology well known for processing a variety of materials in the industrial environment. Nowaday it is also used in medical fields such as ophthalmology, dermatology and neurosurgery. It has also become common for treating teeth or bone tissue[Siebert96]. Applied on bone, LASER accomplishes finer cuts whilst causing less damage to the surrounding material than milling does[4][5][6]. Yet it has not been possible to produce long and complicated cuts into 3-dimensional objects like a scull, which are necessary in cranio facial surgery or similar applications. Methods The “RobaCKa”-system has been developed within the scope of the collaborative research center (SFB) 414 “Computer and Sensor Based Surgery”. Its main hardware consists of a robot with six degrees of freedom (Stäubli RX90 modified by orto Maquet[7]) and an industrial PC collecting and processing sensor information. A force torque sensor serves as input device and increases, together with a mechanical collision protection, the system’s safety. Moreover, an infrared navigation system monitors the robot’s and the patient’s movements and also facilitates patient registration. There is also operation planning software for this system (KasOp[8]) and a tool for finding the optimum setup of robot and patient within the operating room[2]. The robot’s end-effector – a milling cutter in the original “RobaCKa”-setup – has been replaced by a laser focusing head and a 3-D beam scanning head respectively. The beam was guided from the laser to the head over an articulated mirror arm. After a dissatisfactory trial with an Er:YAG laser a short-pulsed CO2 laser, developed at the center of advanced european studies and research (caesar) in Bonn, Germany, was used to cut some trajectories into a porcal scull. Here the ablation of material occurs due to an explosionlike evaporation of the liquid in the bone tissue, and it is performed at temperatures low enough to avoid melting the mineral components or carbonizing the proteins[4][6][9]. The cut trajectory had been planned with KasOp on a surface model based on CT-Images. The pig was registered using titanium marker screws. The beam scanning head was moved to a desired position by the robot. Then the laser beam was projected onto the pig’s scull. Its exact positions and movements were controlled by the scanning head. Results A very fine notch of 0.2 mm in width and 100 mm in length was cut into the bone, shaping the contours of jigsaw piece edges. The cutting process produces an unpleasant smell. A characteristic sound gives significant indication on whether the laser is cutting bone or not. Due to the specific ablation principle there was no traumatic vibration, bone dust or metal abrasion. Conclusion The LASER technology used in this experiment offers several benefits to osteotomy, especially on the scull. It minimizes necroses and it can be controlled in depth in steps of few µm. The sound produced whilst cutting could be used for detecting the end of the scull and the beginning of the dura mater. Since the LASER protrudes into the scull relatively slowly only (100 µm/pulse[9]), it would be possible to stop it in time, just before doing any harm to the dura mater. To avoid local heating in single points, the LASER has to be moved very quickly, thus periodically, across the area to be cut. The accuracy needed for this movement in order to hit the same points again and again is most easily achieved utilizing a 3-D beam scanning head. This does also allow the robot to move slowly, avoiding any danger to people in the operating room. The scanning head is big and heavy, though, demanding for further optimization. Since the LASER beam emits from one single point on the robots end effector, it is not possible to cut any arbitrary trajectory on a scull without moving the robot arm. A way how to synchronize LASER and robot movement has yet to be developed. Some configurable parameters may have to be built into the operation planning software. Anyway, the use of LASER for osteotomy cannot be realized without the help of a robot, holding the LASER optics very exactly and rigidly. [1] Dirk Engel, Arno Pernozzoli, Oliver Schorr, Jakob Brief, Thorsten Heurich, Joerg Raczkowsky, Stefan Hassfeld, Heinz Woern, Joachim Muehling: "Evaluation of a Computer Aided Planning and Surgical Robot System for Craniofacial Surgery",Published in CARS 2002: Computer Assisted Radiology and Surgery, p. 1080, Paris, France, 2002. [2] D. Engel, W. Korb, J. Raczkowsky, S. Hassfeld, H. Woern: "Location Decision for a robot milling complex trajectories in craniofacial surgery", Published in CARS 2003: Computer Assisted Radiology and Surgery, p. 760-765, London, England, 2003. [3] Korb W, Engel D, Boesecke R, Eggers R, Kotrikova B, Marmulla R, Raczkowsky J, Wörn H, Mühling J, Hassfeld S. Development and First Patient Trial of a Surgical Robot for Complex Trajectory Milling. Comp Aid Surg 8:248-257, 2003. [4] Peter Hering, Mikhail Ivanenko, Martin Hartmann: “3-D Beam Scanning Head Improves Bone Surgery”, europhotonics, april/may 2002, pp 32-33, 2002 [5] M. M. Ivanenko, S. Fahimi-Weber, T. Mitra, W. Wierich, P. Hering. Bone Tissue Ablation with sub-µs Pulses of a Q-switch CO2 Laser: Histological Examination of Thermal Side-Effects. Lasers in Medical Science 17 (2002) 258-264 [6] M. Frentzen, W. Götz, M. Ivanenko, S. Afilal, M. Werner, P. Hering. Osteotomy with 80-μs CO2 laser pulses - histological results. Lasers in Medical Science 18 / 2 (2003) 119 – 124 [7] Meister, D., Pokrandt, P., Both, A.: "Milling Accuracy in Robot Assisted Orthopaedic Surgery", Published in IECON '98: Proceedings of the 24th IEEE Annual Conference of the Industrial Electronics Society, p. 2502-2505, vol. 4 , 1998. [8] O. Schorr, J. Münchenberg, J. Raczkowsky, H. Wörn: “KasOp - A Generic System for Pre- and Intraoperative Surgical Assistance and Guidance”, Published in Proceedings of the 15th International Congress and Exhibition of Computer Assisted Radiology and Surgery (CARS), p. 1161, 2001 [9] S. Afilal, M. Ivanenko, M. Werner, P. Hering. Osteotomie mit 80 µs CO2-Laserpulsen. In: Fortschritt-Berichte VDI 17: Biotechnik / Medizintechnik 231 (2003) 164-169, VDI Verlag, Düsseldorf
Bibtex@article{ ipr_1127223421, author = "{H. Peters and H. Knoop and W. Korb and S. Ghanai and J. Raczkowsky and M. Werner and M. Klasing and M. Ivanenko and S. Hassfeld and P. Hering and H. W{{\"o}}rn}", title = "{Bringing laser for osteotomy into the operation theatre}", year = "2005", journal = "{CARS 2005, Proceedings of the 19th International Congress and Exhibition}", pages = "1364", }
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