Helical cone-beam CT is widely used nowadays because of its rapid scan speed and efficient utilization of x-ray dose.
HCT-FDK is an effective reconstruction algorithm on Helical CT. However, like other 3D reconstruction algorithms,
HCT-FDK is time consuming because of its large amount of data processing including the convolution and 3D-3D back
projection. Recently, GPU is widely used to parallel many reconstruction algorithms. The latest GPU has some nice
features, such as large memory, lots of processors, fast 3D texture mapping, and flexible frame buffer object. All these
features help reconstruction a lot. In this paper, we present a solution to this problem with GPU. First, we bring a lookup
table into HCT-FDK. Then, both convolution and back projection are implemented on GPU. At last, the reconstruction
result is directly smoothed and visualized by GPU. Experimental results are given to compare among CPU and two
generations of GPU: Geforce 6800GT and Geforce 8800GTX. The comparison was applied both on simulation data and
real data. We show that, GPU-accelerated HCT-FDK gets result with similar levels of noise and clarity but gains a speed
increase of about 10-100 times faster than using CPU only. With its newer feature, Geforce 8800GTX can get a similar
quality like Geforce 6800GT and about 20 times faster.