Helical-scan computed tomography using cone-beam projections

A fast data-acquisition method for 3-D X-ray computed tomography is proposed. The method continuously rotates a cone-beam X-ray source and a 2-D detector constructed by stacking 1-D circular detector arrays for the fan-beam computed tomography. Simultaneously, a patient is translated in the field of view of the X-ray source. This method is called helical-san, because it provides cone-beam projections measured by moving an X-ray source on a helix surrounding the patient. An approximate convolution backprojection image reconstruction algorithm for the helical-scan is developed by extending L.A. Feldkamp's (1984) cone-beam reconstruction algorithm, for the circular-scan. How one should choose geometrical parameters of the data-acquisition system is discussed. Furthermore, the performance of the proposed method is analyzed by evaluating the point spread function of the reconstruction algorithm.<
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