Cao Q, Brehler M, Sisniega A, Tilley S, Shiraz Bhruwani M M, Stayman J W, Yorkston J, Siewerdsen J H, Zbijewski W
Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD USA 21205.
Carestream Health, Rochester, NY USA.
Proc SPIE Int Soc Opt Eng. 2018 Feb;10573. doi: 10.1117/12.2293810. Epub 2018 Mar 9.
A prototype high-resolution extremity cone-beam CT (CBCT) system based on a CMOS detector was developed to support quantitative assessment of bone microarchitecture. We compare the performance of CMOS CBCT to an amorphous silicon (a-Si:H) FPD extremity CBCT in imaging of trabecular bone.
The prototype CMOS-based CBCT involves a DALSA Xineos3030 detector (99 m pixels) with 400 m-thick CsI scintillator and a compact 0.3 FS rotating anode x-ray source. We compare the performance of CMOS CBCT to an a-Si:H FPD scanner built on a similar gantry, but using a Varian PaxScan2530 detector with 0.137 mm pixels and a 0.5 FS stationary anode x-ray source. Experimental studies include measurements of Modulation Transfer Function (MTF) for the detectors and in 3D image reconstructions. Image quality in clinical scenarios is evaluated in scans of a cadaver ankle. Metrics of trabecular microarchitecture (BV/TV, Bone Volume/Total Volume, TbSp, Trabecular Spacing, and TbTh, trabecular thickness) are obtained in a human ulna using CMOS CBCT and a-Si:H FPD CBCT and compared to gold standard CT.
The CMOS detector achieves ~40% increase in the f20 value (frequency at which MTF reduces to 0.20) compared to the a-Si:H FPD. In the reconstruction domain, the FWHM of a 127 μm tungsten wire is also improved by ~40%. Reconstructions of a cadaveric ankle reveal enhanced modulation of trabecular structures with the CMOS detector and soft-tissue visibility that is similar to that of the a-Si:H FPD system. Correlations of the metrics of bone microarchitecture with gold-standard CT are improved with CMOS CBCT: from 0.93 to 0.98 for BV/TV, from 0.49 to 0.74 for TbTh, and from 0.9 to 0.96 for TbSp.
Adoption of a CMOS detector in extremity CBCT improved spatial resolution and enhanced performance in metrics of bone microarchitecture compared to a conventional a-Si:H FPD. The results support development of clinical applications of CMOS CBCT in quantitative imaging of bone health.
开发一种基于互补金属氧化物半导体（CMOS）探测器的原型高分辨率四肢锥形束CT（CBCT）系统，以支持对骨微结构进行定量评估。我们将CMOS CBCT与非晶硅（a-Si:H）平板探测器（FPD）四肢CBCT在小梁骨成像方面的性能进行比较。
基于CMOS的原型CBCT包括一个DALSA Xineos3030探测器（9900万像素），带有400μm厚的碘化铯闪烁体，以及一个紧凑型0.3FS旋转阳极X射线源。我们将CMOS CBCT的性能与基于类似机架构建的a-Si:H FPD扫描仪进行比较，但后者使用的是Varian PaxScan2530探测器，像素为0.137mm，以及一个0.5FS固定阳极X射线源。实验研究包括测量探测器的调制传递函数（MTF）以及进行三维图像重建。在尸体脚踝扫描中评估临床场景下的图像质量。使用CMOS CBCT和a-Si:H FPD CBCT在人体尺骨中获取小梁微结构指标（骨体积分数、骨体积/总体积、小梁间距和小梁厚度），并与金标准CT进行比较。
与a-Si:H FPD相比，CMOS探测器在f20值（MTF降至0.20时的频率）上提高了约40%。在重建领域，127μm钨丝的半高宽（FWHM）也提高了约40%。尸体脚踝的重建显示，CMOS探测器对小梁结构的调制增强，软组织可见性与a-Si:H FPD系统相似。CMOS CBCT提高了骨微结构指标与金标准CT的相关性：骨体积分数从0.93提高到0.98，小梁厚度从0.49提高到0.74，小梁间距从0.9提高到0.96。
与传统的a-Si:H FPD相比，在四肢CBCT中采用CMOS探测器提高了空间分辨率，并增强了骨微结构指标的性能。这些结果支持了CMOS CBCT在骨健康定量成像临床应用方面的开发。
