Department of Physics, Toronto Metropolitan University (formerly Ryerson University), Toronto, Canada.
Med Phys. 2023 Dec;50(12):7400-7414. doi: 10.1002/mp.16800. Epub 2023 Oct 25.
Dual-energy (DE) x-ray angiography with photon-counting detectors (PCDs) may enable single-exposure DE imaging of coronary vasculature.
To compare the iodine signal-difference-to-noise ratio (SDNR) of single-exposure DE angiography with digital subtraction angiography (DSA) and kV-switching DE angiography for matched patient x-ray exposure.
In a phantom study, we determined the technique parameters that maximized the iodine SDNR per root entrance air kerma for DSA, kV-switching DE angiography and single-exposure DE angiography. We measured SDNR from images of a phantom consisting of an iodine step-wedge immersed in a water tank of either 20 or 30 cm in thickness. We also imaged a phantom with simulated vessels embedded in background clutter and measured vessel SDNR. For this second phantom, we also applied anti-correlated noise reduction (ACNR) and calculated the resulting iodine SDNR. All images were acquired using a cadmium telluride PCD with two energy bins and analog charge summing for charge sharing suppression. The energy-discrimination capabilities were only used for the single-exposure DE approach. Optimized techniques were compared in terms of SDNR per root air kerma for two levels of x-ray scatter.
For the same patient x-ray exposure, the SDNR of single-exposure DE imaging without ACNR was 75% to 85% of that of kV-switching DE imaging (also without ACNR) and DSA, the latter two of which had nearly equal SDNR. The single-exposure DE approach required ∼50% of the tube load of the kV-switching approach to achieve the same SDNR. For matched patient air kermas, the single exposure approach required only ∼25% of the tube load of the kV-switching approach. ACNR increased SDNR by 2.4 and 3.0 for kV-switching and single-exposure DE imaging, respectively.
Photon-counting, single-exposure DE angiography can suppress soft tissues and provide iodine SDNR levels comparable to DSA and kV-switching DE angiography for matched patient radiation exposures. When ACNR is used to reduce DE image noise, the SDNR of single-exposure DE imaging and kV-switching DE imaging exceed that of DSA by more than a factor of two. Compared to kV-switching DE imaging, single-exposure DE imaging requires substantially lower tube loading to achieve the same SDNR.
基于光子计数探测器（PCD）的双能（DE）X 射线血管造影术可能实现冠状动脉血管的单次曝光 DE 成像。
比较单次曝光 DE 血管造影术与数字减影血管造影术（DSA）和千伏切换 DE 血管造影术在匹配的患者 X 射线照射下的碘信号差异噪声比（SDNR）。
在体模研究中，我们确定了最大程度提高 DSA、千伏切换 DE 血管造影术和单次曝光 DE 血管造影术每个根入口空气比释动能碘 SDNR 的技术参数。我们从浸没在 20cm 或 30cm 厚水箱中的碘阶跃体模的图像中测量 SDNR。我们还对模拟血管嵌入背景杂波的体模进行了成像，并测量了血管 SDNR。对于第二个体模，我们还应用了相关噪声降低（ACNR）并计算了由此产生的碘 SDNR。所有图像均使用具有两个能量-bin 的碲化镉 PCD 和模拟电荷求和进行采集，以抑制电荷共享。仅对单次曝光 DE 方法使用能量分辨能力。在两种 X 射线散射水平下，根据每个根空气比释动能的 SDNR 比较优化技术。
对于相同的患者 X 射线照射，单次曝光 DE 成像的 SDNR 没有 ACNR 时为千伏切换 DE 成像（也没有 ACNR）和 DSA 的 75%至 85%，后两者的 SDNR 几乎相等。单次曝光 DE 方法需要千伏切换方法的管负载的约 50%，以实现相同的 SDNR。对于匹配的患者空气比释动能，单次曝光方法仅需要千伏切换方法的管负载的约 25%。ACNR 分别将千伏切换和单次曝光 DE 成像的 SDNR 提高了 2.4 和 3.0。
基于光子计数的单次曝光 DE 血管造影术可以抑制软组织，并提供与 DSA 和千伏切换 DE 血管造影术相匹配的患者辐射暴露的碘 SDNR 水平。当使用 ACNR 降低 DE 图像噪声时，单次曝光 DE 成像和千伏切换 DE 成像的 SDNR 比 DSA 高两倍以上。与千伏切换 DE 成像相比，单次曝光 DE 成像需要大大降低管负载以达到相同的 SDNR。
