Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

Filters

11
11
Reset filters

Settings
Now showing 1 - 10 of 11
No Thumbnail Available
Publication

Overlay visualization in endoscopic ENT surgery

2011 , Winne, Christian , Khan, Martin , Stopp, Fabian , Jank, Emanuel , Keeve, Erwin

Purpose In endoscopic ENT surgery, the identification and localization of target structures is challenging-depth information is missing, relevant tissues could be hidden behind opaque material and image distortion affects the instrument handling. In this paper, a novel overlay visualization is presented that supports the surgeon by superimposing planning and navigation information on the endoscopic image. Method Target regions, which have been identified in preoperative CT data, are superimposed on the endoscopic image, allowing the use of guiding lines for distance visualization. To match the overlay information with the geometrically distorted endoscopic images, a new intraoperative calibration procedure has been developed. Results The accuracy of this new method has been verified by cadaver studies. Clinical evaluation in three paranasal sinus interventions was performed to show the intraoperative assistance and practicability with promising results. Conclusion The new techniques safely support the surgeon in locating target structures in the paranasal sinuses with little change in the actual workflow.

View
No Thumbnail Available
Publication

An accuracy study on navigated freehand-milling along a cutting path for craniofacial reconstruction surgery

2010 , Liu, W. , Keeve, E.

View
No Thumbnail Available
Publication

Konzept und Prinzip eines Unterstützungssystems für die einzeitige, alloplastische Tumortherapie in der kraniofazialen Chirurgie

2008 , Rose, A. , Klein, M. , Krüger, T. , Tiesenhausen, C. von , Jank, E. , Krüger, J. , Keeve, E.

Dieser Artikel beschreibt Konzepte und Prinzipien eines Unterstützungssystems für die einzeitige alloplastische Therapie von Tumoren im Schädelknochen. Ziel ist es den behandelnden Arzt sowohl bei der Implantatplanung und -rekonstruktion als auch bei der anschließenden exakten umsetzung der Planung zu unterstützen. Es wird ein Arbeitsablauf für die Planung und Rekonstruktion entwickelt und vorgestellt, der die anatomische Symmetrie ausnutzt und somit weitgehende Automatisierung erlaubt. Bei der Behandlung soll durch wesentliche Zusatzinformationen über die Lage des Instruments bezüglich des Patienten und der Resektiopnslinien eine Unterstützung erreicht werden, die auwendige Nacharbeiten der Passgenauigkeit vermeidet. Anhand von drei Fällen wurde die Funktionsfähigkeit des Planungs- und Rekonstruktionsprinzips nachgewiesen. Zukünftige Arbeiten umfassen die Fertigstellung des Behandlungsteils und die Erbringung des Nachweises der Gesamtgenauigkeit für eine Zulassung nach MPG.

View
No Thumbnail Available
Publication

Automatisierte motorische Rehabilitation nach Schlaganfall

2006 , Hesse, S. , Werner, C. , Schmidt, H. , Bardeleben, A.

Der Artikel bietet einen Überblick über die junge Forschungsrichtung der automatisierten motorischen Rehabilitation nach Schlaganfall. Der Einsatz intelligenter Maschinen zielt auf eine Steigerung der Therapieintensität, eine Entlastung der Therapeuten und die Gewährung einer nachvollziehbaren und auf die individuellen Bedürfnisse abgestimmten Therapie. Beispiele im Bereich der oberen Extremität sind der "MIT-Manus" und der "MIME"-Roboter für eine ungehinderte Schulter-Ellenbogenbewegung in der Horizontalen, der "Bi-Manu-Track" für das bilaterale, passive und aktive Üben einer Unterarmdreh- und Handgelenkscharnierbewegung, und das "Nudelholz" für die Eigentherapie einer dreidimensionalen Bewegung in der Klinik oder zu Hause. In der Gangrehabilitation werden der "Lokomat®" als angetriebenes Exoskeleton in Verbindung mit dem Laufband sowie der elektromechanische Gangtrainer "GT I" als Modell mit angetriebenen Fußplatten verwandt. Klinische Studien zu den einzelnen Geräten werden mit aufgeführt.

View
No Thumbnail Available
Publication

Robot-assisted motor activation monitored by time-domain optical brain imaging

2011 , Steinkellner, O. , Wabnitz, H. , Schmid, S. , Steingräber, R. , Schmidt, H. , Krüger, J. , Macdonald, R.

Robot-assisted motor rehabilitation proved to be an effective supplement to conventional hand-to-hand therapy in stroke patients. In order to analyze and understand motor learning and performance during rehabilitation it is desirable to develop a monitor to provide objective measures of the corresponding brain activity at the rehabilitation progress. We used a portable time-domain near-infrared reflectometer to monitor the hemodynamic brain response to distal upper extremity activities. Four healthy volunteers performed two different robot-assisted wrist/forearm movements, flexion-extension and pronation-supination in comparison with an unassisted squeeze ball exercise. A special headgear with four optical measurement positions to include parts of the pre- and postcentral gyrus provided a good overlap with the expected activation areas. Data analysis based on variance of time-of-flight distributions of photons through tissue was chosen to provide a suitable representati on of intracerebral signals. In all subjects several of the four detection channels showed a response. In some cases indications were found of differences in localization of the activated areas for the various tasks.

View
No Thumbnail Available
Publication

Computer-aided manufacturing technologies for guided implant placement

2010 , Neugebauer, J. , Stachulla, G. , Ritter, L. , Dreiseidler, T. , Mischkowski, R. , Keeve, E. , Zöller, J.

Implant treatment increasingly focuses on the reduction of treatment time and postoperative impairment. The improvement of 3D dental diagnosis by ConeBeam computed tomography allows detailed preparation for the surgical placement of dental implants under prosthetic considerations. While the first generation of implant planning software used high-contrast multislice computed tomography, software that has been specifically designed for ConeBeam computed tomography is now available. Implant placement can be performed using surgical guides or under the control of optical tracking systems. Surgical guides are more commonly used in private office owing to their availability. The accuracy for both techniques is clinically acceptable for achieving implant placement in critical anatomical indicatio ns. When using prefabricated superstructures and in flapless surgery, special abutments or an adjusted workflow are still necessary to compensate misfits of between 150 and 600 microm. The proposition to ensure proper implant placement by dentists with limited surgical experience through the use of surgical guides is unlikely to be successful, because there is also a specific learning curve for guided implant placement. Current and future development will continue to decrease the classical laboratory-technician work and will integrate the fabrication of superstructures with virtual treatment planning from the start.

View
No Thumbnail Available
Publication

Intraoperative bone modelling for autologous bone grafting

2007 , Tiesenhausen, C.V. , Klein, M.

For the reconstruction of a mandibular defect after tumour or trauma, a vascularized bone graft is taken from the iliac crest. In order to facilitate the healing process and to achieve a functional and aesthetic outcome, the geometry of the transplant has to be similar to the defect. We present a system that uses intraoperative tactile scanning to acquire the geometry of defect and donor site. If the tumour had been resected in a previous operation, its geometry has to be reconstructed by interpolating the remaining pieces of the mandible. The presented system uses the definition of two cut surfaces and the connecting path in order to construct a smooth interpolation. The accuracy of this interpolation was measured using a plastic replica of a human mandible where a piece had been cut out and bridged with a bone plate. The resected piece was scanned for reference using a laser surface scanner. The mean distance between the reconstructed cut surface and the reference was -2.17 mm. This distance includes the gap that is introduced by the saw (blade thickness 0.7 mm). The system was integrated into a navigation system and certified according to the European medical device directive. A patient with a large defect in the left mandible could be treated successfully using this device. The defect was reconstructed without the need for an additional adjustment of the bone graft.

View
No Thumbnail Available
Publication

MAR-SART: Metal artifact reduction for simultaneous algebraic reconstruction technique

2010 , Käseberg, M. , Winne, C. , Keeve, E.

In X-ray computed tomography metallic objects, located in the scanned area, lead to streak artifacts in the reconstructed image data. The use of less absorbing materials (like titanium) for implants is often not an option, so the common solution is a modification of the existing 3D reconstruction algorithms. Usually these methods are based on complete scans of the affected area with many projection images. However, some applications like intraoperativ 3D imaging can implicate a limited scan angle and a reduced number of images to reduce the radiation exposure. In this article a new approach for metal artifact reduction using a simultaneous algebraic reconstruction technique is proposed. Metallic components in the projection images are detected and replaced with synthetic projection data t o improve the 3D reconstruction quality. First results from simulations with a computer generated phantom are presented.

View
No Thumbnail Available
Publication

Assumption for improving intraoperative 3D X-ray scanners

2008 , Jank, E.

View
No Thumbnail Available
Publication

Intraoperative and experimental evaluation of an optical tactile surface scanning system for autologous bone grafting

2006 , Tiesenhausen, C.V. , Klein, M. , Lueth, T.C. , Bier, J.

We present a system that enables a surgeon to acquire precise information about the shape of a bone part intraoperatively and without the use of 3D imaging Using a navigation system, we track the position of the bone part and the position of a spatula with a known geometry. After initially creating a binary voxel-volume around the bone piece, we remove all voxel where the spatula was moved through. When the spatula is moved along the surface of the bone, we can iteratively create a model of the bone surface from the remaining voxels. This is done interactively with visual feedback to the user. We used three plastic bone replicas in order to access the system's accuracy. We compared the carved model with a high precision laser scanner model. The mean distance of 4.2 Mio measured surface points was 0.57 mm, standard deviation 0.39 mm, the maximum distance was 3.03 mm, 95% of all measured points were closer than 1.34 mm to the reference surface. We tested the applicability of the system during an intervention showing that the system can be used in clinical routine. In future work, the intraoperatively acquired models will be used to determine an optimal position for the bone graft donor site.

View