Distance driven represents a state of art method that used for reconstruction for x-ray techniques. C-arm
tomography is an x-ray imaging technique that provides three dimensional information of the object by
moving the C-shaped gantry around the patient. With limited view angle, C-arm system was investigated to
generate volumetric data of the object with low radiation dosage and examination time. This paper is a new
simulation study with two reconstruction methods based on distance driven including: simultaneous algebraic
reconstruction technique (SART) and Maximum Likelihood expectation maximization (MLEM). Distance
driven is an efficient method that has low computation cost and free artifacts compared with other methods
such as ray driven and pixel driven methods. Projection images of spherical objects were simulated with a
virtual C-arm system with a total view angle of 40 degrees. Results show the ability of limited angle C-arm
technique to generate three dimensional images with distance driven reconstruction.
C-arm tomosynthesis is a three dimensional imaging technique. Both x-ray source and the detector are mounted on a C-arm wheeled structure to provide wide variety of movement around the object. In this paper, C-arm tomosynthesis was introduced to provide three dimensional information over a limited view angle (less than 180o) to reduce radiation exposure and examination time. Reconstruction algorithms based on ray tracing method such as ray tracing back projection (BP), simultaneous algebraic reconstruction technique (SART) and maximum likelihood expectation maximization (MLEM) were developed for C-arm tomosynthesis. C-arm tomosynthesis projection images of simulated spherical object were simulated with a virtual geometric configuration with a total view angle of 40 degrees. This study demonstrated the sharpness of in-plane reconstructed structure and effectiveness of removing out-of-plane blur for each reconstruction algorithms. Results showed the ability of ray tracing based reconstruction algorithms to provide three dimensional information with limited angle C-arm tomosynthesis.
In this paper, distance driven (DD) back projection image reconstruction was investigated for digital tomosysthesis. Digital tomosysthesis is an imaging technique to produce three dimensional information of the object with low radiation dosage. This paper is our new study of DD back projection for image reconstruction in digital tomosysthesis. Since DD considers that the image pixel and detector cell have width, the convolution operation is used to calculate DD coefficients. The approximation characteristics of some other methods such as ray driven method (RD) can be avoided. A computer simulation result of DD with Maximum Likelihood Expectation Maximization (MLEM) of tomosysthesis reconstruction algorithm was studied. The sequence of projection images were simulated with 25 projections and a total view angle of 48 degrees. DD with MLEM reconstruction results were demonstrated. Line profile along x direction was used to evaluate DD and RD methods. Compared with RD, the computation time in DD with MLEM to provide the reconstruction results was shorter, since the main loop of DD is over x-y plane intercepts, not over the image pixels or detectors cells. In clinical applications, both the accuracy and computation speed of implementation condition are necessary requirements. DD back projection may satisfy the required conditions.
In this paper, C-arm tomosynthesis with digital detector was investigated as a novel three dimensional (3D) imaging technique. Digital tomosythses is an imaging technique to provide 3D information of the object by reconstructing slices passing through the object, based on a series of angular projection views with respect to the object. C-arm tomosynthesis provides two dimensional (2D) X-ray projection images with rotation (∓20 angular range) of both X-ray source and detector. In this paper, four representative reconstruction algorithms including point by point back projection (BP), filtered back projection (FBP), simultaneous algebraic reconstruction technique (SART) and maximum likelihood expectation maximization (MLEM) were investigated. Dataset of 25 projection views of 3D spherical object that located at center of C-arm imaging space was simulated from 25 angular locations over a total view angle of 40 degrees. With reconstructed images, 3D mesh plot and 2D line profile of normalized pixel intensities on focus reconstruction plane crossing the center of the object were studied with each reconstruction algorithm. Results demonstrated the capability to generate 3D information from limited angle C-arm tomosynthesis. Since C-arm tomosynthesis is relatively compact, portable and can avoid moving patients, it has been investigated for different clinical applications ranging from tumor surgery to interventional radiology. It is very important to evaluate C-arm tomosynthesis for valuable applications.