Jochen Neuhaus

Soft tissue navigation using needle-shaped markers: Evaluation of navigation aid tracking accuracy and CT registration

We evaluate two core modules of a novel soft tissue navigation system. The system estimates the position of a hidden target (e.g. a tumor) during a minimally invasive intervention from the location of a set of optically tracked needle-shaped navigation aids which are placed in the vicinity of the target. The initial position of the target relative to the navigation aids is obtained from a CT scan. The accuracy of the entire system depends on (a) the accuracy for locating a set of navigation aids in a CT image, (b) the accuracy for determining the positions of the navigation aids during the intervention by means of optical tracking, (c) the accuracy for tracking the applicator (e.g. the biopsy needle), and (d) the accuracy of the real-time deformation model which continuously computes the location of the initially determined target point from the current positions of the navigation aids. In this paper, we focus on the first two aspects. We introduce the navigation aids we constructed for our system and show that the needle tips can be tracked with submillimeter accuracy. Furthermore, we present and evaluate three methods for registering a set of navigation aid models with a given CT image. The fully-automatic algorithm outperforms both the manual method and the semi-automatic algorithm, yielding an average distance of 0.27 ± 0.08 mm between the estimated needle tip position and the reference position.

Simplified development of image-guided therapy software with MITK-IGT

Due to rapid developments in the research areas of medical imaging, medical image processing and robotics, computer assistance is no longer restricted to diagnostics and surgical planning but has been expanded to surgical and radiological interventions. From a software engineering point of view, the systems for image-guided therapy (IGT) are highly complex. To address this issue, we presented an open source extension to the well-known Medical Imaging Interaction Toolkit (MITK) for developing IGT systems, called MITK-IGT. The contribution of this paper is two-fold: Firstly, we extended MITK-IGT such that it (1) facilitates the handling of navigation tools, (2) provides reusable graphical user interface (UI) components, and (3) features standardized exception handling. Secondly, we developed a software prototype for computer-assisted needle insertions, using the new features, and tested it with a new Tabletop field generator (FG) for the electromagnetic tracking system NDI Aurora ®. To our knowledge, we are the first to have integrated this new FG into a complete navigation system and have conducted tests under clinical conditions. In conclusion, we enabled simplified development of imageguided therapy software and demonstrated the utilizability of applications developed with MITK-IGT in the clinical workflow.

A quality-refinement process for medical imaging applications.

OBJECTIVES To introduce and evaluate a process for refinement of software quality that is suitable to research groups. In order to avoid constraining researchers too much, the quality improvement process has to be designed carefully. The scope of this paper is to present and evaluate a process to advance quality aspects of existing research prototypes in order to make them ready for initial clinical studies. The proposed process is tailored for research environments and therefore more lightweight than traditional quality management processes. METHODS Focus on quality criteria that are important at the given stage of the software life cycle. Usage of tools that automate aspects of the process is emphasized. To evaluate the additional effort that comes along with the process, it was exemplarily applied for eight prototypical software modules for medical image processing. RESULTS The introduced process has been applied to improve the quality of all prototypes so that they could be successfully used in clinical studies. The quality refinement yielded an average of 13 person days of additional effort per project. Overall, 107 bugs were found and resolved by applying the process. CONCLUSIONS Careful selection of quality criteria and the usage of automated process tools lead to a lightweight quality refinement process suitable for scientific research groups that can be applied to ensure a successful transfer of technical software prototypes into clinical research workflows.

The MITK image guided therapy toolkit and its application for augmented reality in laparoscopic prostate surgery

Image Guided Therapy (IGT) faces researchers with high demands and efforts in system design, prototype implementation, and evaluation. The lack of standardized software tools, like algorithm implementations, tracking device and tool setups, and data processing methods escalate the labor for system development and sustainable system evaluation. In this paper, a new toolkit component of the Medical Imaging and Interaction Toolkit (MITK), the MITK-IGT, and its exemplary application for computer-assisted prostate surgery are presented. MITK-IGT aims at integrating software tools, algorithms and tracking device interfaces into the MITK toolkit to provide a comprehensive software framework for computer aided diagnosis support, therapy planning, treatment support, and radiological follow-up. An exemplary application of the MITK-IGT framework is introduced with a surgical navigation system for laparos-copic prostate surgery. It illustrates the broad range of application possibilities provided by the framework, as well as its simple extensibility with custom algorithms and other software modules.

The MITK image guided therapy toolkit and its exemplary application for augmented reality guided prostate surgery

Image Guided Therapy (IGT) faces researchers with high demands and efforts in system design, prototype implementation, and evaluation. The lack of standardized software tools, like algorithm implementations, tracking device and tool setups, and data processing methods escalate the labor for system development and sustainable system evaluation.

MITK-IGT: Eine Navigationskomponente für das Medical Imaging Interaction Toolkit

MITK-IGT ist eine Erweiterung des Medical Imaging Interaction Toolkits, die es ermoglicht Softwareprogramme im Bereich bildgestutzte Therapie zu erstellen. Dieser Beitrag stellt die Architektur und Designprinzipien von MITK-IGT vor und vergleicht sie mit anderen Open Source Losungen. Neben der Ansteuerung von Trackingsystemen und Visualisierungsmodulen liegt der Fokus von MITK-IGT auf einer Filterarchitektur, die das schrittweise Verarbeiten von Trackingdaten erlaubt. Zur BVM 2009 wird die erste Version von MITK-IGT als Open Source veroffentlicht.

Entwicklung eines Navigationssystems für die telemanipulatorgestützte Oesophagektomie

Pipeline restraining device including a loop-shaped holding member surrounding a pipe of the pipeline and being of such dimensions as to be plastically deformed under the action of the force with which the pipe is held, which includes a further holding member disposed substantially parallel to the direction of application of the holding force and being longer than the plastically deformable holding member, the further holding member being of such dimension as to be elastically deformed under the action of the holding force.

Bounding-object Segmentation

The paper presents a new method for the semiautomatic segmentation of anatomical or pathological structures in MRI, CT or ultrasound images. The concept of bounding-object segmentation is based on an efficient combination of a new interactive approach with well known automatic segmentation algorithms. The efficiency of this new method is based on the transparent interaction between a 3D scene as well arbitrary 2D views of the scene. Bounding-object segmentation can also be described as a combination of interactive 3D segmentation with region-based, level-set-based, and/or texture based 3D-segmentation algorithms.

Der Telemanipulator daVinci als mechanisches Trackingsystem

Der Telemanipulator daVinci (Intuitive Surgical, Sunnyvale, Kalifornien) ist ein M aster-Slave System fur roboterassistierte minimalinvasive Chirurgie. Da er uber integrierte Gelenksensoren verfugt, kann er unter Verwendung der daVinci-API als mechanisches Trackingsystem verwendet werden. In dieser Arbeit evaluieren wir die Prazision und Genauigkeit eines daVinci mit Hilfe eines Genauigkeitsphantoms mit bekannten Masen. Der ermittelte Positionierungsfehler liegt in der Grosenordnung von 6 mm und ist somit fur einen Grosteil der medizinischen Fragestellungen zu hoch. Zur Reduktion des Fehlers schlagen wir daher eine Kalibrierung der Gelenksensoren vor.

Qualitätszentrierte Softwareentwicklung in wissenschaftlichen Arbeitsgruppen Auf dem Weg vom Prototypen zum Produkt

Neue Bildverarbeitungsmethoden werden haufig hauptsachlich fur Publikationszwecke entwickelt. DieWeiterentwicklung bis zur Verwendbarkeit fur klinische Anwender erfordert zusatzlichen Aufwand und wird daher oft nicht weiter verfolgt. In dieser Arbeit wurden mehrere Bildanalyseverfahren unserer Abteilung konsequent zu einem stabilen und benutzbaren Softwareprodukt weiter entwickelt, so dass es fur den Einsatz bei klinischen Partnern und als Demonstrationssoftware auf Messen verwendbar ist. Wir beschreiben das Vorgehen bei der Weiterentwicklung, welche Erfahrungen gemacht wurden und welcher zusatzliche Aufwand damit verbunden ist.