The Study Of CT Image Fusion And Reconstruction Based On Graded Variable Voltage

Computed Tomography(CT) is an advanced nondestructive detection technology, which has been widely applied in industry, medicine and other fields. But in practice, because of constraint factors such as scanning equipment, the shape of object and the dose of radiation, it is different to get the complete projection data.Iterative reconstruction algorithm is often used in the reconstruction of the incomplete projection data.The image matrix and projection matrix of CT are usually in large scale, and each iteration has a lot amount of calculation, therefore, to obtain a good reconstruction effect,multiple iterations is a need. Using TV- ART reconstruction can effectively improve the convergence speed of iterative algorithm and the quality of the image reconstructed.For the projection data in conventional imaging mode of fixation voltage easily appears the phenomenon of overexposed and underexposed. We put forward the theory of variable voltage CT fusion imaging. The methods fuses the effective information extracted by the best gray zone and obtains a complete, high dynamic projection data of complicated structural component. Experiment shows that the result using TV- ART algorithm is superior to the fixed voltage CT imaging. And the virtual experiment has proved that the method is feasible.In the iterative procedure of alternating voltage projection sequence, this paper advances linear fused CT reconstruction algorithm based on variable voltage, in accordance with the principle of variable voltage projection sequence converged. The algorithm firstly fuse the incomplete effective projection sequence into a highly dynamic complete projection data,with linear relation between effective projection sequences of different voltages, reconstruct the complete structure of the object using TV – ART algorithm. Experiment shows that the proposed algorithm get better reconstructed image and more stable pixel value, comparing with that is added directly. However, the pixel value is not stable enough for the coefficientsof the algorithm may be error.To solve this problem, the paper put forward the X-ray images fusion based on principle component analysis(PCA), reconstruct the complete structure of the object using TV-ART algorithm. Experiments show that this algorithm is more applicable. The fusion image artifacts information in the form of image sequence processing by this algorithm is relatively intact, the image grayscale range has also been extended.