一种指数型动态螺距螺旋轨道的三维精确重建

寻求新型轨道,以适应形态各异的感兴趣区域的三维精确重建.基于动态螺距螺旋轨道精确重建的充分条件,提出一种指数型动态螺距的螺旋轨道.理论分析表明,该新型轨道完全满足这一充分条件,可实现锥形束CT的精确重建,并具有在物理上易于实现的优点及易于变形的特性.仿真1采用多个参数下的指数型螺旋轨道与标准螺旋轨道,对钟表模型实现重建;仿真2采用线性组合的指数型螺旋轨道与标准螺旋轨道,对简化的腹部模型感兴趣区域进行实验重建.对钟表模型的重建,各参数下的指数型螺旋轨道与标准螺旋轨道具有相似的重建效果;对简化的腹部模型中感兴趣区域重建,指数型螺旋轨道可同时降低整体与局部剂量,与标准螺旋轨道的重建结果相似.指数型动态螺距螺旋轨道可依据感兴趣区域的形态而灵活变换形态,并实现精确重建,可较好地逼近多种扫描轨道,且重建的效果相似.

3D Exact Reconstruction Based on Exponential Dynamic Pitch Helical Trajectories

This study is aimed to search for new kinds of scanning trajectories to reconstruct region of interest(ROI) of anomalous shapes.Methods: We presented a novel dynamic pitch helical trajectory named exp-helical trajectory, based on the sufficient condition for dynamic pitch helical cone beam CT.Theoretically, the new kind of trajectories satisfies the condition well and has the advantages of the simplicity in implementation and the flexibility in shaping.In one simulation, exp-helical trajectories with different parameters and standard helical trajectory were used to reconstruct a clock phantom.In the other simulation, a linear combined exp-helical trajectory and a standard helical trajectory were tested to reconstruct a simplified abdomen phantom.In the clock phantom reconstruction, exp-helical trajectories performed similar reconstruction results as that of the standard helical case, and as to the simplified abdomen phantom the linear combined exp-helical trajectory not only reduced integral and local dose but also showed similar reconstruction results as that of the standard helical case.Exp-helical trajectories could be shaped flexibly and easily according to the shapes of ROI, and exact reconstruction could be realized.Meanwhile, exp-helical trajectories could approach to various scanning trajectories quite well with similar reconstruction results.