3D Alignment of Projections in Electron Tomography
Permanent address of the item is
The goal of this thesis is to analyze the effect of projection angle errors on reconstructing 3D electron tomography. Noise, missing wedge and miss alignment are three main problems in electron tomography. This thesis focuses on how miss alignment affects the 3D reconstruction relative to the noise and missing wedge effects. Fourier-based iterative method (FIRM) is the main reconstruction method in this work. Instead of projecting the volume and back-projecting the tilt series in the image domain, FIRM conducts those operations in Frequency domain. By using non-uniform fast Fourier transform, FIRM avoids interpolation problem. Besides, the conjugate gradient method is used as the iterative reconstruction process to ﬁnd the optimal solution. With the simulations, the impacts of noise, missing wedge and miss alignment are studied quantitatively. Missing wedge is the most inﬂuential factor among those three factors, the lack of enough information causes the reconstruction volume to be highly burred. Miss alignment has a similar effect as Gaussian noise. However, miss alignment also introduces artifacts in the reconstruction. Normalized mean-square error (NMSE) decreases and resolution increases when decreasing the level of miss alignment. After the level of 0.2-degree variance of projection angle error, the results does not show signiﬁcant differences.