Department of Imaging Sciences, University of Rochester Medical Center, Rochester, NY, USA.
J Xray Sci Technol. 2009;17(4):279-93. doi: 10.3233/XST-2009-0234.
The physical performance of two Flat Panel Detectors has been evaluated. The first Flat Panel Detector is for Fluoroscopic applications, Varian PaxScan 2520, and the second is for Cone Beam Computer Tomography applications, Varian PaxScan 4030CB. First, the spectrum of the X-ray source was measured. Second, the linearity of the detectors was investigated by using an ionization chamber and the average ADU values of the detectors. Third, the temporal resolution was characterized by evaluating their image lag. Fourth, their spatial resolution was characterized by the pre-sampling Modulation Transfer Function. Fifth, the Normalized Noise Power Spectrum was calculated for various exposures levels. Finally, the Detective Quantum Efficiency was obtained as a function of spatial frequency and entrance exposure. The results illustrate that the physical performance in Detective Quantum Efficiency and Normalized Noise Power Spectrum of the Cone Beam Computer Tomography detector is superior to that of the fluoroscopic detector whereas the latter detector has a higher spatial resolution as demonstrated by larger values of its Modulation Transfer Function at large spatial frequencies.
评估了两款平板探测器的物理性能。第一款平板探测器用于透视应用，是瓦里安（Varian）的 PaxScan 2520，第二款用于锥形束计算机断层扫描（Cone Beam Computer Tomography）应用，是瓦里安的 PaxScan 4030CB。首先，测量了 X 射线源的光谱。其次，使用电离室和探测器的平均 ADU 值研究了探测器的线性度。第三，通过评估图像滞后来描述时间分辨率。第四，通过预采样调制传递函数（MTF）来描述空间分辨率。第五，针对不同曝光水平计算归一化噪声功率谱（NPS）。最后，作为空间频率和入射曝光的函数获得探测量子效率（DQE）。结果表明，锥形束计算机断层扫描探测器在探测量子效率和归一化噪声功率谱方面的物理性能优于透视探测器，而后者的调制传递函数在大空间频率处具有较大的值，表明其具有更高的空间分辨率。
