碩士 / 國立中央大學 / 生物醫學工程研究所 / 100 / C-arm guidance system is developed by integrating image processing, coordinate transformation and projection model estimation. Only two C-arm images are required to compute the orientations and positions of the targets. The locations of surgical instruments are also real-time shown on the computer displayed C-arm images, which enable the surgeon to move surgical tools accurately and safely to the target for following treatment. It also reduces radiation exposure during the operation.
The system automatically detects coordinates of the marker on the C-arm image by image processing techniques. Those markers are used in image distortion and registration. If the number of being recognized markers could not exceed the system requirements, an additional image is required. Therefore, the level of the recognition rate will affect the ease of use of the guidance system.
To improve the successfully recognition rate we analysis 98 C-arm images obtained from clinical try. The overall recognition rate of large marker is increased from 62% to 98%. As for small marker, the quantity of images which recognition rate above 75% is increased from 35 to 80. And recognition rate of all the images are higher than 60%.
Due to patient’s breathing, the relative position between C-arm image calibrator and patient is changed during the process of image capture. Using non-synchronized images and coordinate data will cause an incorrect estimation of projection model. We develop a kind of X-ray images synchronized registration method used in surgical guidance system, the method includes four steps: 1. Estimate the latency of fluoroscopic imaging. 2. Continuously obtain relative position between C-arm image calibrator and patient. 3. Measuring image similarity. 4. Reconstruct the relation between images and coordinate transformation. When the C-arm image is refreshed, software would automatically choose a transformation that has a timestamp prior to pre-measured latency. It solves the problem that image and coordinate are non-synchronized.
| Identifer | oai:union.ndltd.org:TW/100NCU05114004 |
| Date | January 2012 |
| Creators | Alex Tse, 謝仁懋 |
| Contributors | Ching-Shiow Tseng, 曾清秀 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 70 |
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