Jang Sun Young, Kim Ho Kyung, Youn Hanbean, Cho Seungryong, Cunningham Ian A
IEEE Trans Biomed Eng. 2017 Jan;64(1):173-183. doi: 10.1109/TBME.2016.2552496. Epub 2016 Apr 11.
We investigate the signal and noise performance of an x-ray microtomography system that incorporates a complementary metal-oxide-semiconductor flat-panel detector as a projection image receptor.
Signal and noise performance is analyzed in the Fourier domain using modulation-transfer function (MTF), noise-power spectrum (NPS), and noise-equivalent number of quanta (NEQ) with respect to magnification and different convolution kernels for image reconstruction.
Higher magnification provides lower NPS, and thus, higher NEQ performance in the transaxial planes from microtomography. A window function capable of smoothing the ramp filter edge to below one-half of the Nyquist limit results in better performance in terms of NPS and NEQ. The characteristics of convolution kernels do not affect signal and noise performance in longitudinal planes; hence, MTF performance mainly dominates the NEQ performance. The signal and noise performances investigated in this study are demonstrated with images obtained from the contrast phantom and postmortem mouse.
The results of our study could be helpful in developing x-ray microtomography systems based on flat-panel detectors.
我们研究了一种X射线显微断层扫描系统的信号和噪声性能，该系统采用互补金属氧化物半导体平板探测器作为投影图像接收器。
在傅里叶域中，使用调制传递函数（MTF）、噪声功率谱（NPS）和噪声等效量子数（NEQ），针对放大倍数和用于图像重建的不同卷积核，分析信号和噪声性能。
更高的放大倍数在显微断层扫描的横断面中提供更低的NPS，从而具有更高的NEQ性能。一种能够将斜坡滤波器边缘平滑至奈奎斯特极限一半以下的窗函数，在NPS和NEQ方面具有更好的性能。卷积核的特性不影响纵向平面中的信号和噪声性能；因此，MTF性能主要主导NEQ性能。本研究中所研究的信号和噪声性能通过从对比体模和死后小鼠获得的图像得以展示。
我们的研究结果可能有助于开发基于平板探测器的X射线显微断层扫描系统。
