Affiliations: ICT Research Center, Key Laboratory of Optoelectronic
Technology and System of the Education Ministry of China, Chongqing University,
Chongqing, China | College of Optoelectronic Engineering, Chongqing
University, Chongqing, China | College of Mathematics and Statistics, Chongqing
University, Chongqing, China | Department of Computer Science, Chongqing Education
College, Chongqing, China
Abstract: Traditional helical cone-beam Computed Tomography (CT) is based on
the assumption that the entire cross-section of the scanned object is covered
by x-rays at each view angle. Because of the size limitation of planar
detector, the traditional helical cone-beam CT scanning is restricted when the
cross-section of the object is larger than the field of view (FOV) of the CT
system. The helical cone-beam CT scanning based on FOV half-covered can almost
double the FOV, whose mechanism is simple and the scanning efficiency is the
same as that of traditional helical cone-beam CT. During reconstruction, the
extended helical cone-beam FDK algorithm (called half-covered helical FDK for
short) is developed, and the computational efficiency of this algorithm is
high. But the reconstruction image has truncation error. Regarding this
problem, this paper extends the idea of 2D local reconstruction to 3D
half-covered helical cone-beam CT, and develops an improved half-covered
helical cone-beam CT reconstruction algorithm based on localized reconstruction
filter. Experimental results indicate that the presented algorithm well solves
the truncation error of the half-covered helical FDK algorithm, improves the
quality of the reconstruction image. And for the noise projection data, the
presented algorithm can suppress noise and get better results. Moreover, the
reconstruction time is much less.
