光子计数X射线探测器的探测量子效率

Detective quantum efficiency of photon-counting x-ray detectors.

作者信息

Tanguay Jesse, Yun Seungman, Kim Ho Kyung, Cunningham Ian A

机构信息

Robarts Research Institute, Western University, London, Ontario N6A 5C1, Canadaand Department of Medical Biophysics, Western University, London, Ontario, N6A 3K7, Canada.

Biomedical Engineering Program, Western University, London, Ontario, N6A 3K7, Canadaand School of Mechanical Engineering, Pusan National University, Jangjeon-dong, Geumjeong-gu, Busan 609-73, South Korea.

出版信息

Med Phys. 2015 Jan;42(1):491-509. doi: 10.1118/1.4903503.

DOI:10.1118/1.4903503

PMID:25563288

Abstract

PURPOSE

Single-photon-counting (SPC) x-ray imaging has the potential to improve image quality and enable novel energy-dependent imaging methods. Similar to conventional detectors, optimizing image SPC quality will require systems that produce the highest possible detective quantum efficiency (DQE). This paper builds on the cascaded-systems analysis (CSA) framework to develop a comprehensive description of the DQE of SPC detectors that implement adaptive binning.

METHODS

The DQE of SPC systems can be described using the CSA approach by propagating the probability density function (PDF) of the number of image-forming quanta through simple quantum processes. New relationships are developed to describe PDF transfer through serial and parallel cascades to accommodate scatter reabsorption. Results are applied to hypothetical silicon and selenium-based flat-panel SPC detectors including the effects of reabsorption of characteristic/scatter photons from photoelectric and Compton interactions, stochastic conversion of x-ray energy to secondary quanta, depth-dependent charge collection, and electronic noise. Results are compared with a Monte Carlo study.

RESULTS

Depth-dependent collection efficiency can result in substantial broadening of photopeaks that in turn may result in reduced DQE at lower x-ray energies (20-45 keV). Double-counting interaction events caused by reabsorption of characteristic/scatter photons may result in falsely inflated image signal-to-noise ratio and potential overestimation of the DQE.

CONCLUSIONS

The CSA approach is extended to describe signal and noise propagation through photoelectric and Compton interactions in SPC detectors, including the effects of escape and reabsorption of emission/scatter photons. High-performance SPC systems can be achieved but only for certain combinations of secondary conversion gain, depth-dependent collection efficiency, electronic noise, and reabsorption characteristics.

摘要

目的

单光子计数（SPC）X射线成像有潜力提高图像质量并实现新型能量依赖成像方法。与传统探测器类似，优化图像SPC质量将需要能产生尽可能高的探测量子效率（DQE）的系统。本文基于级联系统分析（CSA）框架，对实现自适应合并的SPC探测器的DQE进行全面描述。

方法

SPC系统的DQE可通过CSA方法描述，即通过简单量子过程传播成像量子数的概率密度函数（PDF）。建立了新的关系来描述PDF通过串联和并联级联的传递，以适应散射再吸收。结果应用于基于硅和硒的平板SPC探测器的假设情况，包括光电和康普顿相互作用中特征/散射光子的再吸收、X射线能量到二次量子的随机转换、深度依赖电荷收集以及电子噪声的影响。结果与蒙特卡罗研究进行比较。