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Diese Arbeit stellt ein neuartiges Trainingskonzept fur die Felsenbeinchirurgie auf der Basis von Gips-Kunstoff-Modellen mit optoelektrischer Detektion von Risikostrukturen vor und evaluiert es prototypisch. Grundlage der Trainingsmodelle sind hochauflosende CT-Datensatze eines humanen Schadels. Der Datensatz wird an einem 3D-Drucker ausgedruckt. Aus Gipspulver und einem Bindemittel wird das dreidimensionale Phantom erstellt. Als Risikostrukturen wurden der N. facialis, der Labyrinthblock, die Ossikelkette, der Sinus sigmoideus, die Dura und die A. carotis interna definiert. Als Detektionsmaterialien fur die Risikostrukturen werden eine elektrisch leitfahige Metalllegierung und ein Lichtwellenleiter verwendet. 8 unerfahrene und 8 efahrene Ohrchirurgen trainierten an den optoelektrischen Trainingssystemen (Gruppe A) und auserdem an humanen Felsenbeinpraparaten (Gruppe B). Bei Verletzungen werden Anzahl, Zeitpunkt, Grad (N. facialis) und verletzte Struktur, auserdem die benotigte Gesamtzeit werden wahrend des Trainings am Modell protokolliert. Die Auswertung der anatomischen Detailtreue der Felsenbeinmodelle zeigte Ergebnisse zwischen 49,5% und 90% Ubereinstimmung. Die Fehlerdetektion wurde mit Werten zwischen 79% und 100% Ubereinstimmung mit der Wahrnehmung eines erfahrenen Chirurgen bewertet. Das Op.-Setting wurde besser gegenuber dem Frasen am humanen Felsenbeinpraparat eingeschatzt. Die Probanden bejahten die Moglichkeit, die bisherige Trainingsmethode am humanen Felsenbeinpraparat vollstandig durch das Training am untersuchten Modell zu ersetzen. Die vorliegenden Daten belegen die Eignung des hier untersuchten neuartigen Trainingssystems fur die Felsenbeinchirurgie. Das System verbindet die Vorarbeiten mit gedruckten und gesinterten Modellen mit den Moglichkeiten der Mikrosystemtechnik. Daruber hinaus ist eine vollstandige virtuelle Darstellung des Modells mit den entsprechenden weiterfuhrenden Anwendungen („look behind the wall“, virtuelle Endoskopie) moglich.

Hintergrund Die „Funktionelle Endoskopische Nasennebenhohlenoperation“ (FESS) ist durch eine einhandige Praparation und die Fuhrung des Endoskops mit der nichtdominanten Hand gekennzeichnet. Daraus ergeben sich eine Verlangerung der Operationszeit von bis zu 15% und ergonomische Defizite fur den Chirurgen. Das Ziel der vorliegenden Arbeit ist die Fortfuhrung der Konzeption eines automatisierten Assistenzsystems fur die Endoskopfuhrung bei der FESS. Dabei stehen folgende Fragen im Mittelpunkt: 1. Welches Design ist fur eine teilautomatisierte Endoskopfuhrung bei der FESS geeignet? 2. Wie sind die technischen Systemeigenschaften (Planung, Zeitaufwand, Genauigkeit, Prazision) des gewahlten Systems? 3. Bietet das System Potenzial fur eine klinische Anwendung?

Background The aim of this study was to evaluate the Navibase navigation system for ear, nose, and throat (ENT) surgery. A new methodology for evaluating surgical and human factors is developed. Patients and methods The evaluation is based on 102 ENT surgical applications, including 89 cases of functional endoscopic sinus surgery (FESS). The evaluation of surgical and human factors was performed by seven ENT surgeons. To evaluate surgical performance, level of quality (LOQ) in the 89 cases of FESS was determined, comparing the surgeon's own impressions with those of the navigation system on a scale from 0 to 100 and further comparing them with clinical results. Intraoperative changes in surgical strategy were documented. The human factors of total confidence (trust), situation awareness, skill set requirement and workload shift were recorded as level of reliance (LOR). Results The maximum deviation amounted to 1.93 mm. Averaging the quality of information resulted in an LOQ of 63.59. Every second application of the navigation system (47.9%) led to a change in surgical strategy. Total confidence showed a positive evaluation of 3.35 points in LOR. Conclusion Application-relevant information relevant to the application beyond only technical details permits comparison with other assisting systems.

Die Genauigkeit von Navigationssystemen stellt das herausragende Kriterium fur die Evaluation von Navigationssystemen dar. Die Angaben zur Genauigkeit variieren erheblich, und es besteht eine Diskrepanz zwischen Literaturangaben und der intraoperativen Genauigkeit. Es existiert kein einheitliches Verstandnis fur die Begriffe Genauigkeit und Prazision von Navigationssystemen, falschlicherweise werden diese auch gleichbedeutend verwendet. Daruber hinaus ist die klinische Genauigkeit nicht mit der technischen Bestimmung gleichzusetzen. Die vorliegende Arbeit hat das Ziel, den Begriff Genauigkeit und verwandte Begriffe grundlegend zu definieren, den Begriff der Prazision abzugrenzen, den Begriff chirurgische Genauigkeit abzuleiten, einen Vorschlag fur die Anwendung des Begriffs der chirurgischen Genauigkeit eines Navigationssystems zu unterbreiten, die vorhandenen Literaturangaben entsprechend einzuordnen. Dafur kamen die Normen nach der International Standardisation Organisation-ISO und dem Deutschen Institut fur Normung e.V.-DIN zur Anwendung.

This work presents a new training concept for surgery of the temporal bone. It is based on a model of gypsum plastic with optoelectric detection of risk structures. A prototypical evaluation is given.The training models are based on high-resolution computed tomographic data of a human skull. The resulting data set was printed by a three-dimensional (3D) printer. A 3D phantom is created from gypsum powder and a bonding agent. Risks structures are the facial nerve, semicircular canal, cochlea, ossicular chain, sigmoid sinus, dura, and internal carotid artery. An electrically conductive metal (Wood's metal) and a fiber-optic cable were used as detection materials for the risk structures. For evaluating the training system, a study was done with eight inexperienced and eight experienced ear surgeons. They were asked to perform temporal bone surgery using two identical training models (group A). In group B, the same surgeons underwent surgical training with human cadavers. In the case of injuries, the number, point in time, degree (facial nerve), and injured structure were documented during the training on the model. In addition, the total time needed was noted.The training systems could be used in all cases. Evaluation of the anatomic accuracy of the models showed results that were between 49.5% and 90% agreement with the anatomic origin. Error detection was evaluated with values between 79% and 100% agreement with the perception of an experienced surgeon. The operating setting was estimated to be better than the previous"gold standard." The possibility of completely replacing the previous training method, which uses cadavers, with the examined training model was affirmed.This study shows that the examined system fulfills the conditions for a new training concept for temporal bone surgery. The system connects the preliminary work with printed and sintered models with the possibilities of microsystem engineering. In addition, the model's digital database permits a complete virtual representation of the model with appropriate further applications ("look behind the wall," virtual endoscopy).

Functional endoscopic sinus surgery (FESS) is characterized by single-handed preparation and guidance of the endoscope by the nondominant hand. This results in an additional extension of operation time by up to 15% and ergonomic deficits. The aim of this study is the conception of an automated assistance system for FESS in view of the following questions: (1) Which degree of surgical automation is suitable for FESS? (2) Which design is suitable? (3) What are the properties of the technical system (planning, time, accuracy, precision) of the selected system? (4) Does the system offer potential for a clinical application?In all 49 FESS were analyzed for surgical workflows. Measurement of the maximum forces within FESS was performed with 40 trials on an anatomical model. Three different mechanical systems were used in ten FESS and evaluated using the ICCAS Human-Machine Evaluation Scale. For realization of automated endoscope guidance an engine-driven and -braked manipulator (PA10-6c, Mitsubishi, Japan) was used. The technical parameters determined were expenditure of time for the preoperative planning of workspace, surgical accuracy and precision of the intraoperative endoscope positioning, maximal forces, and time.Concept-conditioned instrument changes amount to an average of 41.1 and 18.9% (5.21 min) time requirement for each FESS side. Maximum forces on the mucous membrane during a conventional FESS were measured at 9.8 N (5.9-9.8). Usability of the mechanical endoscope holder was estimated in 18 of 20 cases to be inferior to the standard procedure. The time needed for segmenting the intranasal workspace was 15.2 min (10.0-23.0). The maximum deviation of the automatically driven endoscope from a planned position amounted to 0.85 mm (manually 4.64 mm). The maximum force was measured with 1.1 N in the z direction (manually 9.8 N). Automated guidance of the endoscope to an intranasal position needed 7.25 s (6.4-7.9); manually 12.64 s (5.9-43.0).Guidance of the endoscope for FESS by an automated motor-driven system is possible. The conception which is based on workflow analysis favors a system with automatic definition of the workspace and a manual movement of the endoscope. The examined system offers a potential for clinical application. Definition of the automation level and development of a man-machine interface is more important than selection or reconstruction of a special manipulator for endoscope guidance in FESS from a surgical point of view.

The aim of this study was to evaluate the Navibase navigation system for ear, nose, and throat (ENT) surgery. A new methodology for evaluating surgical and human factors is developed.The evaluation is based on 102 ENT surgical applications, including 89 cases of functional endoscopic sinus surgery (FESS). The evaluation of surgical and human factors was performed by seven ENT surgeons. To evaluate surgical performance, level of quality (LOQ) in the 89 cases of FESS was determined, comparing the surgeon's own impressions with those of the navigation system on a scale from 0 to 100 and further comparing them with clinical results. Intraoperative changes in surgical strategy were documented. The human factors of total confidence (trust), situation awareness, skill set requirement and workload shift were recorded as level of reliance (LOR).The maximum deviation amounted to 1.93 mm. Averaging the quality of information resulted in an LOQ of 63.59. Every second application of the navigation system (47.9%) led to a change in surgical strategy. Total confidence showed a positive evaluation of 3.35 points in LOR.Application-relevant information relevant to the application beyond only technical details permits comparison with other assisting systems.

Accuracy represents the outstanding criterion for navigation systems. Surgeons have noticed a great discrepancy between the values from the literature and system specifications on one hand, and intraoperative accuracy on the other. A unitary understanding for the term accuracy does not exist in clinical practice. Furthermore, an incorrect equality for the terms precision and accuracy can be found in the literature. On top of this, clinical accuracy differs from mechanical (technical) accuracy. From a clinical point of view, we had to deal with remarkably many different terms all describing accuracy. This study has the goals of: 1. Defining "accuracy" and related terms, 2. Differentiating between "precision" and "accuracy", 3. Deriving the term "surgical accuracy", 4. Recommending use of the the term "surgical accuracy" for a navigation system. To a great extent, definitions were applied from the International Standardisation Organisation-ISO and the norm from the Deutsches Institut für Normung e.V.-DIN (the German Institute for Standardization). For defining surgical accuracy, the terms reference value, expectation, accuracy and precision are of major interest. Surgical accuracy should indicate the maximum values for the deviation between test results and the reference value (true value) A(max), and additionally indicate precision P(surg). As a basis for measurements, a standardized technical model was used. Coordinates of the model were acquired by CT. To determine statistically and reality relevant results for head surgery, 50 measurements with an accuracy of 50, 75, 100 and 150 mm from the centre of the registration geometry are adequate. In the future, we recommend labeling the system's overall performance with the following specifications: maximum accuracy deviation A(max), precision P and information on the measurement method. This could be displayed on a seal of quality.