Effective DQE (eDQE) and speed of digital radiographic systems: an experimental methodology.
Effective DQE (eDQE) and speed of digital radiographic systems: an experimental methodology.
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数字射线照相系统的有效 DQE (eDQE) 和速度：一种实验方法。
DOI：
10.1118/1.3171690
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发表时间：
2009
期刊：
影响因子：
3.8
通讯作者：
Ravin,CarlE
中科院分区：
文献类型：
--
作者：
Samei,Ehsan;Ranger,NicoleT;MacKenzie,Alistair;Honey,IanD;Dobbins3rd,JamesT;Ravin,CarlE
先前对数字射线照相系统性能评估的研究主要集中于探测器性能的评估。然而，此类系统的临床性能也受到放大倍数、焦点模糊、散射辐射的存在以及抗散射网格的存在的显着影响。本研究的目的是评估一种实验方法，以评估数字放射线照相系统的性能（包括这些属性），并提出一种新的指标：有效检测量子效率（eDQE），这是定义数字放射线照相成像系统的效率或速度的候选指标。该研究采用了模拟成人胸部的衰减和散射特性的几何体模以及具有代表性的基于间接平板的临床数字放射成像系统。噪声功率谱 (NPS) 源自在跨越临床系统操作范围的三个暴露水平下采集的体模图像。使用位于体模表面、面向 X 射线源的边缘设备测量调制传递函数 (MTF)。使用光束停止技术进行散射测量。然后根据这些测量值以及体模衰减和 X 射线通量的测量值计算 eDQE。 MTF 结果显示了焦点模糊的显着影响，而 NPS 则描述了由于使用抗散射网格而产生的结构噪声的很大一部分。发现 eDQE 比传统 DQE 低一个数量级。在 时，eDQE(0) 在 8%–9% 范围内，比相同技术的 DQE(0) 低五倍。 eDQE 方法通过量化系统的固有速度，即在临床操作条件下测量的实际信噪比，在临床相关环境中产生系统性能的可重复估计。
Prior studies on performance evaluation of digital radiographic systems have primarily focused on the assessment of the detector performance alone. However, the clinical performance of such systems is also substantially impacted by magnification, focal spot blur, the presence of scattered radiation, and the presence of an antiscatter grid. The purpose of this study is to evaluate an experimental methodology to assess the performance of a digital radiographic system, including those attributes, and to propose a new metric,effectivedetective quantum efficiency (eDQE), a candidate for defining the efficiency orspeedof digital radiographic imaging systems. The study employed a geometric phantom simulating the attenuation and scatter properties of the adult human thorax and a representative indirect flat‐panel‐based clinical digital radiographic imaging system. The noise power spectrum (NPS) was derived from images of the phantom acquired at three exposure levels spanning the operating range of the clinical system. The modulation transfer function (MTF) was measured using an edge device positioned at the surface of the phantom, facing the x‐ray source. Scatter measurements were made using a beam stop technique. The eDQE was then computed from these measurements, along with measures of phantom attenuation and x‐ray flux. The MTF results showed notable impact from the focal spot blur, while the NPS depicted a large component of structured noise resulting from use of an antiscatter grid. The eDQE was found to be an order of magnitude lower than the conventional DQE. At , eDQE(0) was in the 8%–9% range, fivefold lower than DQE(0) at the same technique. The eDQE method yielded reproducible estimates of the system performance in a clinically relevant context by quantifying the inherent speed of the system, that is, the actual signal to noise ratio that would be measured under clinical operating conditions.