Cone-beam multislice spiral computed tomography: Novel reconstruction and applications.

摘要

A new family of cone-beam reconstruction algorithm, the General Surface Reconstruction (GSR), is proposed and formulated in this thesis for multi-slice spiral CT reconstructions. It provides a general framework to allow the reconstruction of planar or nor-planar surfaces using 2D filtered backprojection on a set of rebinned short-scan parallel beam projection data. Several different surface formation methods are proposed based upon various criteria and methods to minimize the adverse effect between the collected cone-beam projection data and the reconstruction surfaces. The superiority of the non-planar surfaces over planar surfaces in the 2D approximate cone-beam reconstructions is mathematically proved and demonstrated using numerical simulations.; The physical performances of the proposed algorithm have been evaluated according to its image artifacts, the center and off-center slice sensitivity profiles (SSP), the in-plane modulation transfer function (MTF), radiation dose utilization and the noise properties using computer simulations. The evaluation results show that the GSR algorithm generates much better image qualities compared to conventional multi-slice reconstruction algorithms. For a table speed up to 80 mm per rotation at beam width of 128 x 1 mm, GSR does not show obvious artifact in the low-contrast ball phantom and thorax phantom. All other performance parameters are comparable to the single-slice 180° LI algorithm, which is considered the “gold standard”. GSR also achieves high computing efficiency and good temporal resolution, which makes it a very promising cone-beam reconstruction algorithm for next generation multi-slice spiral CT with large number of detector rings.; Cone-beam multi-slice spiral CT with specially designed reconstruction algorithms leads to many possible new clinical applications. A modified GSR algorithm was proposed for cardiac reconstruction in cone-beam spiral CT to achieve high temporal resolution and capture all cardiac phases. Based on this cardiac reconstruction algorithm, a new cardiac imaging protocol was proposed which involves a single contrast enhanced spiral CT scan to simultaneously measure the coronary artery stenosis and the left ventricular function. The feasibility of this protocol has been verified using several preliminary clinical trials. The GSR algorithm has also been generalized for flat-panel micro-CT reconstructions.