An improved PI-method for reconstruction from helical cone-beam projections

Aiming for a more coherent 1D-filtering, the authors propose an improvement of the original PI-method. A PI-surface is defined by the object points which enter and exit over detector edges simultaneously. In between these to events the PI-surface is projected onto the detector, not quite along a perfect line, but nevertheless with most of the points concentrated along a certain non-horizontal line. The authors show that one-dimensional filtering along these slanted lines improves the image quality considerably