The subject of this dissertation is the calculation and visualization of intraoperative measurement uncertainty in computer-assisted surgical procedures. Error is the difference between the observed or measured value and the true value (called ground-truth) of a quantity. Uncertainty is the unknown difference between the measured and true values, and exists in the absence of knowledge of ground truth. If one has an algorithm for computing the ground truth then one can get an accurate estimate of error. However, in computer-assisted surgery, the ground truth is often unknown. The introduction of error to surgical procedures is inevitable: it cannot be avoided by simply taking very careful measurements, providing more accurate algorithms, or by improving instrument calibration. One can only reduce errors as much as reasonably possible, calculate a reliable estimate of the uncertainty, and provide a meaningful way to convey this uncertainty information to clinicians. In this dissertation, I demonstrate that the visualization of registration uncertainty improves surgical navigation and that real-time computation of intraoperative measurement uncertainty is possible. In an extensive user study of surgeons and surgical residents, I compare methods of visualizing intraoperative uncertainty and determine that there are several methods of effectively conveying uncertainty in surgical navigation. / Thesis (Ph.D, Computing) -- Queen's University, 2010-01-25 16:33:26.755

O objetivo desta revisão foi avaliar sistematicamente a literatura atual comparando a precisão da cirurgia de implantes assistida por computador, de acordo com os diferentes tecidos de suporte (dente, mucosa ou osso). Foi feita a busca nas bases de dados do PubMed (1972 a janeiro de 2015) e do Cochrane (de 2002 a janeiro de 2015). Para avaliar a precisão da cirurgia guiada, foram incluídos os estudos que tinham os seguintes desfechos: 1) desvio angular; 2) desvio no ponto de entrada; e 3) desvio no ápice. Foram oito estudos clínicos dos 1602 artigos inicialmente identificados que preencheram os critérios de inclusão para a análise qualitativa. Porém, só quatro estudos (n = 599 implantes) foram avaliados quantitativamente por meio de meta análise. Os guias ósseo-suportados demonstraram um maior desvio estatisticamente significativo no ângulo (p <0.001), ponto de entrada (p = 0.01), e o ápice (p = 0.001), quando comparado com os guias dento suportados. Inversamente, quando apenas estudos retrospectivos foram analisados, não se observaram diferenças significativas no desvio do ponto de entrada e ápice. Os guias mucoso-suportados revelaram uma redução estatisticamente significativa no desvio do ângulo (p = 0.02), no ponto de entrada (p = 0.002) e no ápice (p = 0.04) quando comparados com as guias apoiados em osso. Não houve diferenças estatisticamente significativas em nenhuma das variáveis para o grupo de guias apoiados em mucosa e dentes. Concluiu-se que o tipo de tecido de suporte dos guias cirúrgicos influencia a acurácia da cirurgia assistida por computador. / The main objective of this review was to systematically assess the current dental literature comparing the accuracy of computer-aided implant surgery when using different supporting tissues (tooth, mucosa, or bone). Two reviewers searched PubMed (1972 to January 2015) and the Cochrane Central Register of Controlled Trials (Central) (2002 to January 2015). For the assessment of accuracy, studies were included with the following outcome measures: 1) angle deviation, 2) deviation at the entry point, and 3) deviation at the apex. Eight clinical studies from the 1,602 articles initially identified met the inclusion criteria for the qualitative analysis. Four studies (n= 599 implants) were evaluated using meta-analysis. The bone-supported guides showed a statistically significant greater deviation in angle (p<0.001), entry point (p=0.01), and the apex (p=0.001) when compared to the tooth-supported guides. Conversely, when only retrospective studies were analyzed not significant differences is revealed in the deviation of the entry point and apex. The mucosa-supported guides indicated a statistically significant greater reduction in angle deviation (p=0.02), deviation at the entry point (p=0.002) and deviation at the apex (p=0.04) when compared to the bone-supported guides. Between mucosa- and tooth-supported guides, there were no statistically significant differences for any of the outcome measures. It can be concluded that the tissue of the guide support influences the accuracy of computer-aided implant surgery.

O objetivo desta revisão foi avaliar sistematicamente a literatura atual comparando a precisão da cirurgia de implantes assistida por computador, de acordo com os diferentes tecidos de suporte (dente, mucosa ou osso). Foi feita a busca nas bases de dados do PubMed (1972 a janeiro de 2015) e do Cochrane (de 2002 a janeiro de 2015). Para avaliar a precisão da cirurgia guiada, foram incluídos os estudos que tinham os seguintes desfechos: 1) desvio angular; 2) desvio no ponto de entrada; e 3) desvio no ápice. Foram oito estudos clínicos dos 1602 artigos inicialmente identificados que preencheram os critérios de inclusão para a análise qualitativa. Porém, só quatro estudos (n = 599 implantes) foram avaliados quantitativamente por meio de meta análise. Os guias ósseo-suportados demonstraram um maior desvio estatisticamente significativo no ângulo (p <0.001), ponto de entrada (p = 0.01), e o ápice (p = 0.001), quando comparado com os guias dento suportados. Inversamente, quando apenas estudos retrospectivos foram analisados, não se observaram diferenças significativas no desvio do ponto de entrada e ápice. Os guias mucoso-suportados revelaram uma redução estatisticamente significativa no desvio do ângulo (p = 0.02), no ponto de entrada (p = 0.002) e no ápice (p = 0.04) quando comparados com as guias apoiados em osso. Não houve diferenças estatisticamente significativas em nenhuma das variáveis para o grupo de guias apoiados em mucosa e dentes. Concluiu-se que o tipo de tecido de suporte dos guias cirúrgicos influencia a acurácia da cirurgia assistida por computador. / The main objective of this review was to systematically assess the current dental literature comparing the accuracy of computer-aided implant surgery when using different supporting tissues (tooth, mucosa, or bone). Two reviewers searched PubMed (1972 to January 2015) and the Cochrane Central Register of Controlled Trials (Central) (2002 to January 2015). For the assessment of accuracy, studies were included with the following outcome measures: 1) angle deviation, 2) deviation at the entry point, and 3) deviation at the apex. Eight clinical studies from the 1,602 articles initially identified met the inclusion criteria for the qualitative analysis. Four studies (n= 599 implants) were evaluated using meta-analysis. The bone-supported guides showed a statistically significant greater deviation in angle (p<0.001), entry point (p=0.01), and the apex (p=0.001) when compared to the tooth-supported guides. Conversely, when only retrospective studies were analyzed not significant differences is revealed in the deviation of the entry point and apex. The mucosa-supported guides indicated a statistically significant greater reduction in angle deviation (p=0.02), deviation at the entry point (p=0.002) and deviation at the apex (p=0.04) when compared to the bone-supported guides. Between mucosa- and tooth-supported guides, there were no statistically significant differences for any of the outcome measures. It can be concluded that the tissue of the guide support influences the accuracy of computer-aided implant surgery.

Im Rahmen einer experimentellen Vergleichsstudie zweier bildwandlergestützter Navigationssysteme wurde die 3D-bildwandlergestützte Navigation mit der 2D-bildwandlergestützten Navigation zur Pedikelschraubenplatzierung am Modell getestet. Neben der Präzision der Bohrungen in einem postoperativen CT wurden Bildqualität, Genauigkeit des 3D-Scans, Planbarkeit und Umsetzung der Bohrungen bewertet und verglichen. Mit der 3D- Bildwandler- Navigation wurden 38 der 40 Bohrungen exakt platziert (95%). Eine Planung wurde durch einen Softwarefehler der Alpha-Version auf dem Monitor falsch wiedergegeben. Bei einer weiteren Bohrung wurde der Bohrer verkantet, wodurch Bildschirmdarstellung und Realität voneinander abwichen. Daher kam es in einem Fall zu einer lateralen Perforation der Kortikalis im Bereich des Pedikels, im anderen zu einer kaudalen Perforation. Mit der 2D- Bildwandler- Navigation konnten alle 40 Schrauben ohne Pedikelperforation platziert werden. Zwei dieser Schrauben wurden durch die ventrale Kortikalis gebohrt. Beide Verfahren überzeugten durch hohe Präzision und Zuverlässigkeit. 3 der 4 Fehlplatzierungen waren Anwender einer Software bedingt. Eine optimierte Software und verbesserte Instrumente werden diese Fehlerquote weiter reduzieren. Voraussetzung für die 2D-bildwandlergestützten Navigation sind eine gute Bildqualität sowie normale anatomische Gegebenheiten für standardisierte Projektionen. Die neue 3D-bildwandlergestützter Navigation kombiniert die Vorteile der 2D-bildwandlergestützter Navigation und der CT- basierten Navigation mit einer Verringerung der Strahlenbelastung durch den Wegfall des präoperativen CT`s und somit der Einsatzmöglichkeit im akuten Notfall sowie nach intraoperativen Repositionsmanövern. Da kein Matching erforderlich ist, wird insbesondere bei traumatischer Verletzung oder tumorbedingter Veränderung der dorsalen Wirbelstrukturen ein großer Vorteil zur CT- basierten Navigation erwartet. Aufgrund der universellen Einsatzmöglichkeiten eines Bildwandlers wird für diese neue Technologie ein breites Indikationsspektrum angenommen. / An experimental study to compare 2D- and 3D- Computer-Assisted Fluoroscopic Navigation for pedicle screw placement. Each system was evaluated by a post-operative CT and included the comparison of the palpation of the pedicular canal, the image quality and the accuracy of planning and performance. For this purpose 40 screws have been set to 9 models of lumbar spine. Using the 3D-flouroscopy based navigation 38 from 40 (95%) drillings were placed correctly. One mistake was caused by an error of the navigation-software. The second mistake was due to a drilling mistake, the drill was not shown correctly on the monitor because the drill has been canted. Using the 2D-flouroscopy based navigation all screws could be placed correctly at the pedicle, but two times the corpus has been perforated to ventral. Both techniques are precise and reliable. 3 out of 4 mistakes were caused by incorrect handling the instrument. The other mistake happened because of a software-error. If the software and the instruments will be optimised, the amount of mistakes will be reduced in the future. In case of the 2D-flouroscopy based navigation sufficient image quality, normal anatomical structures and defined projections are required. The new 3D-flouroscopy based navigation combines the benefit of 2D-flouroscopy based navigation and CT-based navigation by reducing the radiation exposure and the preoperative planning time. Therefore, this technique is suitable for use in an emergency or intraoperative repositions. Because no matching-procedure is necessary for CT-based navigation, we expect advantages especially in therapy of traumatic injuries or changes at the dorsal structures of spine caused by tumour. Furthermore, the use of fluoroscopic based navigation extends the range of applications/the spectrum of indication for this new technology.