Schaeffer Colin, Ghammraoui Bahaa, Taguchi Katsuyuki, Glick Stephen J
University of Florida, Department of Radiology, Gainesville, Florida, United States.
FDA, Office of Science and Engineering Laboratories (OSEL), Division of Imaging, Diagnostics and Software Reliability (DIDSR), Silver Spring, Maryland, United States.
J Med Imaging (Bellingham). 2023 Feb;10(Suppl 2):S22406. doi: 10.1117/1.JMI.10.S2.S22406. Epub 2023 Apr 11.
Most photon-counting detectors (PCDs) being developed use cadmium telluride (CdTe), which has nonoptimal characteristic x-ray emission with energies in the range used for breast imaging. New PCD using a gallium arsenide (GaAs) has been developed. Since GaAs has characteristic x-rays lower in energy than those of CdTe, it is hypothesized that this new PCD might be beneficial for spectral x-ray breast imaging.
We performed simulations using realistic mammography x-ray spectra with both CdTe and GaAs PCDs. Five different experiments were conducted, each comparing the performance of CdTe and GaAs: (1) sensitivity of iodine quantification to charge cloud size and electronic noise, (2) effect of photon spectrum on iodine quantification, (3) effect of varying the number of energy bins, (4) a dose analysis to assess any possible dose reduction from using either detector, and (5) spectral performance of ideal CdTe and GaAs PCDs. For each study, 3 sets of 5000 noise realizations were used to calculate the Cramer-Rao lower bound (CRLB) of iodine quantification.
For all spectra studied, GaAs gave a lower CRLB for iodine quantification, with 10 of the 12 spectra showing a statistically significant difference ( ). The photon energy spectrum that optimized iodine detection for both detector materials was the 40 kVp beam with 2-mm Al filtration, which produced CRLBs of and for CdTe and GaAs, respectively, when using five energy bins.
GaAs is a promising detector material for contrast-enhanced spectral mammography that offers better spectral performance than CdTe.
目前正在研发的大多数光子计数探测器（PCD）都使用碲化镉（CdTe），但在用于乳腺成像的能量范围内，其特征X射线发射并不理想。现已研发出一种使用砷化镓（GaAs）的新型PCD。由于GaAs的特征X射线能量低于CdTe，因此推测这种新型PCD可能对乳腺光谱X射线成像有益。
我们使用实际的乳腺X射线光谱对CdTe和GaAs PCD进行了模拟。进行了五个不同的实验，每个实验都比较了CdTe和GaAs的性能：（1）碘定量对电荷云大小和电子噪声的敏感度；（2）光子光谱对碘定量的影响；（3）改变能量区间数量的影响；（4）剂量分析，以评估使用任何一种探测器是否可能降低剂量；（5）理想的CdTe和GaAs PCD的光谱性能。对于每项研究，使用3组5000次噪声实现来计算碘定量的克莱姆 - 拉奥下界（CRLB）。
对于所有研究的光谱，GaAs在碘定量方面的CRLB较低，12种光谱中有10种显示出统计学上的显著差异（ ）。对于两种探测器材料，优化碘检测的光子能谱是经过2毫米铝过滤的40 kVp光束，使用五个能量区间时，CdTe和GaAs的CRLB分别为 和 。
GaAs是一种有前景的探测器材料，用于对比增强光谱乳腺摄影，其光谱性能优于CdTe。
