High-resolution extremity cone-beam CT with a CMOS detector: Task-based optimization of scintillator thickness.
High-resolution extremity cone-beam CT with a CMOS detector: Task-based optimization of scintillator thickness.
复制标题
带有 CMOS 探测器的高分辨率四肢锥束 CT：基于任务的闪烁体厚度优化。
DOI：
10.1117/12.2255695
复制
发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Zbijewski,W
中科院分区：
文献类型：
--
作者：
Cao,Q;Brehler,M;Sisniega,A;Stayman,JW;Yorkston,J;Siewerdsen,JH;Zbijewski,W
目的CMOS X射线探测器具有小像素尺寸和低电子噪声特性，可支持锥束CT（CBCT）的新型高分辨率成像应用的开发。我们研究了CsI闪烁体厚度对高分辨率成像任务中CMOS探测器性能的影响，特别是在肢体CBCT中骨微结构的定量成像中。方法建立了与闪烁体厚度相关的CMOS X射线探测器级联系统模型。利用理论模型研究了低、高和超高分辨率成像任务（高斯型，半高宽分别为~250 μm、~80 μm和~40 μm）中闪烁体厚度对探测能力的影响。在CBCT测试台上进行了实验研究，该测试台配备了DALSA Xineos 3030 CMOS探测器（99 μm像素），CsI闪烁体厚度为400 μm和700 μm，以及0.3 FS紧凑型旋转阳极X射线源。该评价涉及放射学分辨率测量仪（0.6-5.0 lp/mm）、用于评估3D分辨率的127 μm钨丝、具有组织模拟插入物的造影剂体模和用于视觉评估精细骨小梁细节的人类胫骨切除片段。结果实验研究表明，与标准标称CsI厚度700 μm相比，使用400 μm闪烁体时50%MTF调制频率提高约35%。尽管两种探测器的高频DQE相当，但理论研究表明，与700 μ m CsI相比，400 μm CsI探测器的高分辨率和高分辨率任务的可探测性指数（d′2）分别增加了14%至28%。实验证实了理论研究结果，表明采用400 μm的面板在射线照相图案的可见性方面有所改善（在4.6 lp/mm时峰-通过距离提高了2倍），并且钨丝的半高宽降低了12.5%。胫骨平台的重建显示，使用CMOS探测器（400 μm闪烁器）增强了骨小梁结构的可见性。结论使用比常规X线摄影标准更薄的闪烁体将有利于CMOS探测器在骨小梁高分辨率CBCT成像中的应用。结果支持将400 μm CsI的CMOS传感器转化为基于CMOS的肢体CBCT的临床原型。
Purpose CMOS x-ray detectors offer small pixel sizes and low electronic noise that may support the development of novel high-resolution imaging applications of cone-beam CT (CBCT). We investigate the effects of CsI scintillator thickness on the performance of CMOS detectors in high resolution imaging tasks, in particular in quantitative imaging of bone microstructure in extremity CBCT. Methods A scintillator thickness-dependent cascaded systems model of CMOS x-ray detectors was developed. Detectability in low-, high- and ultra-high resolution imaging tasks (Gaussian with FWHM of ~250 μm, ~80 μm and ~40 μm, respectively) was studied as a function of scintillator thickness using the theoretical model. Experimental studies were performed on a CBCT test bench equipped with DALSA Xineos3030 CMOS detectors (99 μm pixels) with CsI scintillator thicknesses of 400 μm and 700 μm, and a 0.3 FS compact rotating anode x-ray source. The evaluation involved a radiographic resolution gauge (0.6–5.0 lp/mm), a 127 μm tungsten wire for assessment of 3D resolution, a contrast phantom with tissue-mimicking inserts, and an excised fragment of human tibia for visual assessment of fine trabecular detail. Results Experimental studies show ~35% improvement in the frequency of 50% MTF modulation when using the 400 μm scintillator compared to the standard nominal CsI thickness of 700 μm. Even though the high-frequency DQE of the two detectors is comparable, theoretical studies show a 14% to 28% increase in detectability index (d′2) of high- and ultrahigh resolution tasks, respectively, for the detector with 400 μm CsI compared to 700 μm CsI. Experiments confirm the theoretical findings, showing improvements with the adoption of 400 μm panel in the visibility of the radiographic pattern (2× improvement in peak-to-through distance at 4.6 lp/mm) and a 12.5% decrease in the FWHM of the tungsten wire. Reconstructions of the tibial plateau reveal enhanced visibility of trabecular structures with the CMOS detector with 400 μm scinitllator. Conclusion Applications on CMOS detectors in high resolution CBCT imaging of trabecular bone will benefit from using a thinner scintillator than the current standard in general radiography. The results support the translation of the CMOS sensor with 400 μm CsI onto the clinical prototype of CMOS-based extremity CBCT.