  Upright position CT scans make it possible for full-length-body imaging at
conditions more relevant to daily situations, but the substantial weight of the
upright CT scanners increases the risks to floor's stability and
patients'safety. Robotic-arm CBCT systems are supposed to be a better solution
for this task, but such systems still face challenges including long scanning
time and low reconstruction quality. To address the above challenges, this
paper proposes a novel method to calculate optimal scanning pitch based on data
completeness analysis, which can complete the whole-body scan in the shortest
time without a significant decline in image quality. Besides, an FDK-style
reconstruction method based on normalized projections is proposed to obtain
fast image reconstruction. Extensive experiments prove the effectiveness of the
proposed optimal scanning trajectory. Qualitative and quantitative comparisons
with FDK and iterative algorithms show that the proposed reconstruction method
can obtain high imaging quality with reasonable computation costs. The method
proposed in this paper is expected to promote the application of robotic-arm
CBCT systems in orthopedic functional analysis.
