研究了X射线发光断层成像(XLCT)的激发性能, 对笔束XLCT和锥束XLCT等两种主要的成像系统在不同激发方式下的扫描时间、重建精度、分辨率及重建时间等性能指标进行了对比研究。设计的对比实验中, 笔束XLCT系统的扫描时间为436 s, 锥束XLCT系统的扫描时间仅为10 s。目标实验中, 笔束XLCT系统的重建时间为82.57 s, 重建误差为0.47 mm; 锥束XLCT系统的重建时间为172.63 s, 重建误差为1.59 mm。在边距分别为1 mm和0.5 mm的两组双目标实验中, 笔束XLCT系统均能准确分辨, 重建误差均在0.8 mm以内, 而锥束XLCT系统对边距为1 mm的双目标重建误差均达到了1.7 mm左右; 当目标边距缩小到0.5 mm时, 其已无法进行全域分辨。实验结果表明: 相比于锥束XLCT, 笔束XLCT利用自身的“激发先验”优势具有较短的重建时间、较高的定位能力和分辨率, 但是其系统扫描时间要明显大于锥束XLCT。本文的工作为选择合适的XLCT成像系统提供了参考。

The excitation characteristics of X-ray Luminescence Computed Tomography (XLCT) was researched. Two kinds of imaging systems for pencil-beam XLCT and cone-beam XLCT were introduced and their respective performance indexes such as the excitation schemes, scanning costs, reconstruction efficiency, spatial resolving capacity and reconstruction costs were compared and analyzed in detail. The comparison experiment shows that the scanning time of pencil-beam XLCT is 436 s but that of the cone-beam XLCT is only 10 s. In the experiment for a single target, the reconstruction time and location error of pencil-beam XLCT are 82.57 s and 0.47 mm, and those of the cone-beam XLCT are 172.63 s and 1.59 mm, respectively. In the two group experiments for double targets with edge distances of 1 mm and 0.5 mm respectively, the pencil-beam XLCT can accurately distinguish all targets with a reconstruction error less than 0.8 mm; however, the reconstruction error of the cone-beam XLCT reaches to 1.7 mm for the double targets with the edge distance of 1 mm and can not distinguish the targets at the edge distance to be reduced to 0.5 mm. Experimental results demonstrate that compared with the cone-beam XLCT, the pencil-beam XLCT has better performance in reconstruction time, location accuracy and spatial resolving due to its “excitation priors”, but has obviously poor capability on the system scanning. This paper provides a valuable reference for researchers on the selection of appropriate XLCT systems.