  Low-dose X-ray CT technology is one of important directions of current
research and development of medical imaging equipment. A fast algorithm of
blockwise sinogram filtering is presented for realtime low-dose CT imaging. A
nonstationary Gaussian noise model of low-dose sinogram data is proposed in the
low-mA (tube current) CT protocol. Then, according to the linear minimum mean
square error principle, an adaptive blockwise algorithm is built to filter
contaminated sinogram data caused by photon starvation. A moving sum technique
is used to speed the algorithm into a linear time one, regardless of the block
size and thedata range. The proposedfast filtering givesa better performance in
noise reduction and detail preservation in the reconstructed images,which is
verified in experiments on simulated and real data compared with some related
filtering methods.
