Multiple pinhole collimator based X-ray luminescence computed tomography.
Multiple pinhole collimator based X-ray luminescence computed tomography.
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DOI：
10.1364/boe.7.002506
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发表时间：
2016-07
影响因子：
3.4
通讯作者：
Wei Zhang-;Dianwen Zhu;Michael C. Lun;Changqing Li
中科院分区：
文献类型：
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作者：
Wei Zhang-;Dianwen Zhu;Michael C. Lun;Changqing Li
X射线发光计算机层析成像(XLCT)是一种新兴的混合成像方式，它可以利用超细X射线铅笔束将深部目标的光学成像的空间分辨率提高到数百微米。然而，基于XLCT的单针孔准直器X射线光子利用率较低，测量数据采集时间较长。在这里，我们提出了一种基于多针孔准直器的XLCT，其中产生多个X射线束来同时在多个位置扫描样品。与基于单针孔的XLCT相比，多束X射线扫描方法所需的测量时间要短得多。数值模拟和体模实验验证了多束X射线扫描方法的可行性。在一次数值模拟中，我们使用四束X射线扫描了一个圆柱形物体，其中有六个深度嵌入的目标。通过6个角度投影的测量，6个目标均已成功重建。在体模实验中，我们用自制的准直器产生了两束X射线铅笔束。成功地重建了镶嵌在圆柱体模中的两个边缘间距为0.6 mm的毛细目标。采用双波束扫描，数据采集时间缩短了50%。从重建的XLCT图像中，我们发现目标之间的Dice相似度为85.11%，两个目标之间的距离误差小于3%。我们测量了XLCT扫描过程中的辐射剂量，发现辐射剂量为1.475 mSv，处于典型CT扫描的范围内。测量了准直器不同距离处准直X射线束大小和强度的变化。我们还研究了光束大小和强度对XLCT重建的影响。
X-ray luminescence computed tomography (XLCT) is an emerging hybrid imaging modality, which is able to improve the spatial resolution of optical imaging to hundreds of micrometers for deep targets by using superfine X-ray pencil beams. However, due to the low X-ray photon utilization efficiency in a single pinhole collimator based XLCT, it takes a long time to acquire measurement data. Herein, we propose a multiple pinhole collimator based XLCT, in which multiple X-ray beams are generated to scan a sample at multiple positions simultaneously. Compared with the single pinhole based XLCT, the multiple X-ray beam scanning method requires much less measurement time. Numerical simulations and phantom experiments have been performed to demonstrate the feasibility of the multiple X-ray beam scanning method. In one numerical simulation, we used four X-ray beams to scan a cylindrical object with 6 deeply embedded targets. With measurements from 6 angular projections, all 6 targets have been reconstructed successfully. In the phantom experiment, we generated two X-ray pencil beams with a collimator manufactured in-house. Two capillary targets with 0.6 mm edge-to-edge distance embedded in a cylindrical phantom have been reconstructed successfully. With the two beam scanning, we reduced the data acquisition time by 50%. From the reconstructed XLCT images, we found that the Dice similarity of targets is 85.11% and the distance error between two targets is less than 3%. We have measured the radiation dose during XLCT scan and found that the radiation dose, 1.475 mSv, is in the range of a typical CT scan. We have measured the changes of the collimated X-ray beam size and intensity at different distances from the collimator. We have also studied the effects of beam size and intensity in the reconstruction of XLCT.