Development of an image guidance research system for bronchoscopy
MetadataShow full item record
This project has been carried out as collaboration between the Department of Thoracic Medicine at St. Olavs Hospital and the Department of Medical Technology at SINTEF, both in Trondheim, Norway. The team at SINTEF has been developing CustusX, a research and development platform for ultrasound-based navigation and image-guided therapy for more than 15 years. Their main focus has been abdominal laparoscopic surgery, neurosurgery and endovascular surgery. This PhD thesis covers the initial steps in the development of a navigation system for bronchoscopy. Bronchoscopy is the endoscopic examination of the lungs and airways, a cornerstone in the investigation of lung cancer and other diseases of the lung. The bronchoscope, a flexible instrument with a camera and a work channel, is passed through the nose or mouth, into the windpipe and the lung lobes. Instruments can be passed through the work channel to take tissue samples for diagnosis. One of the main obstacles for an accurate diagnosis is the complexity of the airways. The airways divide immensely, each more than 20 times, before reaching the 500 million alveoli, the 0.2 mm respiratory units. The bronchoscope is comparatively large, approximately 5 mm in diameter, so it can only traverse the more central parts of the airways. The target location is usually known from a radiology examination, but it is often difficult, and at times impossible, to navigate the diagnostic instruments through the correct airway divisions to reach the target of interest. In image-guided navigation and intervention, a tracking device is mounted on the tip of the instrument, giving the exact location of the instrument within the body. This position is shown to the investigator in the patient’s radiology exams, usually a CT or MRI. In this project we started with feasibility testing of the existing navigation system platform on pigs (1st paper). The tests were performed in an operating room containing specialized radiology equipment, a Cone Beam CT capable of acquiring 3D x-ray volumes of the swine lungs. For position tracking, we used an electromagnetic position system. The navigation system seemed to function to our purpose, but we experienced some troubling disturbances on the electromagnetic tracking field, which we believed were caused by the presences of the Cone Beam CT close to the navigation field. Large electrical and ferromagnetic structures are known to interfere with electromagnetic fields, and in our 2nd and 3rd paper we examined the influence of the Cone Beam CT on our tracking system. We found that it indeed caused major disturbances, mainly due to the electrical currents running in the radiology devices.