Study On The System For Identification Of Structures On The Sectional Images Based On 3D Model

With the rapid development of CT, MRI, PETS imaging technology, the three dimensional models of human body, reconstructed from sectional images, has played a more and more important role in medical research and diagnosis of clinical diseases. How to obtain the focal structure and related information from these medical images effectively becomes one of the hot spot in the medical research fields at present.Visualization in scientific computation is a technology to transform the two-dimensional data to three-dimensional graphics or images in the computer graphics and image processing methods, which facilitates the observation and scientific research. In this paper, a classic software in the scientific visualization field, named as Visualization Toolkit, was introduced. In particular, the principles of the reconstruction methods including the surface rendering and volume rendering reconstruction, their advantages and disadvantages were presented. Then the human brain was reconstructed by using VTK in Visual C++ 6.0 environment.Following that, the method of needle puncturing for points was introduced, and the problems of interactive operation in the VTK three-dimensional model scene were investigated, with the trigger obstacles solved by adding a callback function. A pick-up mechanism based on parallel perspective was used to realize the special characteristic points picking on the brain model, so that the design of three-dimensional interaction was completed. This work provided a basis to realize the extracting the structures on the three-dimensional model and marking the structures on the sectional images.The relationship between the characteristic points in every situation on the three-dimensional model was studied to derive formulas for sampling points. The conversion relation between the three-dimensional coordinates on the 3D VTK model and two-dimensional pixel coordinates on the sectional images in BMP format was investigated in details. By the use of this conversion relation to transform the three-dimensional structures coordinates to cross-section structures coordinates, the mapping function was realized.Finally, a digital system, based on object-oriented software programming method in Visual C++ 6.0 environment, was developed for extracting the three-dimensional structure and marking the structure on the sectional image. This system allows for setting the visualization attributes, extracting three-dimensional structures, transforming three-dimensional coordinate, marking cross-section structures and other functions. The preliminary results obtained by using this system to identify the sulcus and gyrus are encouraging for further development.