Multi-stereo camera system to enhance the position accuracy of image-guided surgery markers

The development of Image-guided Surgery (IGS) system as an assistant tool in medical navigation has led to new challenges for researchers to enhance the accuracy of the medical surgery. In IGS, a stereo camera is used to find the position of medical markers and visualize it on the screen of the surgeon. However, the line of sight (LOS) between the camera and the markers causes the stoppage of the tracking system if it cut during the operation. This paper presents a multi-stereo camera system to overcome the LOS problem, and to improve the accuracy of the IGS system. A pair of stereo cameras has been used to recognize and detect the reference markers and visualize a patient's body part and a surgical needle. A multi-stereo camera has generated a very good accuracy of 3D visualization with (2.88 mm) of root mean square error (RMSE). Image filtering techniques have been used to process the captured images. Thus, IGS system based on multi-stereo camera, contributes promising results of medical navigation and enhances the capabilities of IGS system

Multicamera Optical Tracker Assessment for Computer Aided Surgery Applications

Image-guided interventions enable the surgeon to display the position of instruments and devices with respect to the patient's imaging studies during surgery by means of a tracker device. Optical trackers are commonly chosen for many surgical applications when high accuracy and robustness are required. OptiTrack is a multicamera optical tracker whose number of sensors and their spatial configuration can be adapted to the application requirements, making it suitable for surgical settings. Nonetheless, no extensive studies of its accuracy are available. The purpose of this paper was to evaluate an eight-camera optical tracker in terms of accuracy, miscalibration sensitivity, camera occlusions, and tool detection in a feasible clinical setup. We studied the tracking accuracy of the system using a robotic arm (~μm precision) as the gold standard, a single reflective marker, and various tracked objects while the system was installed in an operating room. Miscalibration sensitivity was 0.16°. Mean target error was 0.24 mm for a single marker, decreasing to 0.05 mm for tracked tools. Single-marker error increased up to 1.65 mm when five cameras where occluded although 75% of the working volume showed an error lower than 0.23 mm. The accuracy was sufficient for navigating the collimator in intraoperative electron radiation therapy, improving redundancy and allowing large-working volumes. The tracker assessment we present and the validated miscalibration protocol are important contributions to image-guided surgery, where the choice of the tracker is critical and the knowledge of the accuracy in situations of camera occlusion is mandatory during surgical navigation

Desarrollo de un nuevo sistema de navegación en Implantología basado en unidades de medición inercial

La colocación de implantes dentales mediante cirugía guiada por ordenador tiene numerosas ventajas frente a la realizada a mano alzada, especialmente mayor precisión, mayor seguridad y menor invasividad. Pero también, tanto los sistemas estáticos o férulas, como los dinámicos o navegación, presentan dificultades de uso y un mayor coste, por lo que su utilización actual es limitada. Se elabora una revisión de los distintos sistemas de guiado de la cirugía de colocación de implantes, de su uso, precisión y fuentes de error. Describimos la unidad de medición inercial o IMU y sus primeras aplicaciones en cirugía general, como una alternativa versátil, simple y económica a las tecnologías existentes. Por medio de un prototipo que integra los sensores IMU en una interfaz computerizada, se colocan implantes guiados por estos sensores, y también por férulas CAD-CAM. Los resultados medios comparados que obtenemos entre ambos sistemas de guiado, son similares estadísticamente. Las desviaciones medias han sido en coronal 1.48 ± 0.2 (SD 0.58; 95% CI 1.27 - 1.69) y 1.42 ± 0.2 (SD 0.61; 95% CI 1.2 - 1.64) mm, en apical 2.00 ± 0.33 (SD 0.93; 95% CI 1.67 - 2.33) y 2.07 ± 0.35 (SD 0.97; 95% CI 1.72 - 2.42) mm, y las angulares 7.13º ± 1.47º (SD 4.1; 95% CI 5.66 - 8.6) y 5.63º ± 1.41º (SD 3.94; 95% CI 4.22 - 7.04), para IMU y Férulas Estereolitográficas (FE) respectivamente. Estos resultados son consistentes con la precisión reportada en la literatura para la cirugía guiada, tanto estática como dinámica. Se valora igualmente la percepción del operador y su comodidad de uso, encontrando que el manejo del sistema requiere un entrenamiento previo y que se facilitaría al mejorar la interfaz gráfica. Se abre así una vía de investigación para adaptar este nuevo sistema de navegación al uso clínico rutinario. Para ello, es necesaria la mejora in vitro de sus condiciones de manejo, así como ulteriores estudios sobre pacientes.Computer-guided dental implant placement is considered to be safer, more accurate and less invasive compared to freehand implant surgery. Currently two types of surgical guiding systems are available, static templates and dynamic navigation. Both make intervention more complex and costly and this could be the reason why their current use remains limited. A "state of the art" of the different implant placement guiding systems, their use, precision and sources of error has been conducted. The Inertial Measurement Unit (IMU) and its early applications in general surgery are described. The IMU was shown to be a versatile, simple and economical alternative to existing surgical guidance technologies. A prototype surgical handpiece was assembled with IMU sensors integrated with a computerized interface to guide implant placement. Implants were placed in models using this prototype and the standard CAD-CAM splints. Similar statistical average results were obtained using either of the two systems. The mean deviations were 1.48 ± 0.2 (SD 0.58; 95% CI 1.27 - 1.69) and 1.42 ± 0.2 (SD 0.61; 95% CI 1.2 - 1.64) mm coronal, 2.00 ± 0.33 (SD 0.93; 95% CI 1.67 - 2.33) and 2.07 ± 0.35 (SD 0.97; 95% CI 1.72 - 2.42) mm apical, and 7.13º ± 1.47º (SD 4.1; 95% CI 5.66 - 8.6) y 5.63º ± 1.41º (SD 3.94; 95% CI 4.22 - 7.04) angular, for IMU’s and splints respectively. These results are consistent with the precision reported in the literature for guided surgery, both current static and dynamic modalities. When operator’s perceptions and comfort of use were addressed, it was found that the system’s handling requires going through a learning curve and that it would be facilitated by improving the graphic interface. The present study opens a path of investigation to adapt this new surgical navigation system to routine clinical use. To this end, the system has to be improved to make the operator’s control easier before further studies on patients can be carried out