Performance of in-pixel circuits for photon counting arrays (PCAs) based on polycrystalline silicon TFTs.
Performance of in-pixel circuits for photon counting arrays (PCAs) based on polycrystalline silicon TFTs.
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DOI：
10.1088/0031-9155/61/5/1968
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发表时间：
2016-03-07
影响因子：
3.5
通讯作者：
Lu JP
中科院分区：
文献类型：
--
作者：
Liang AK;Koniczek M;Antonuk LE;El-Mohri Y;Zhao Q;Street RA;Lu JP
光子计数阵列 (PCA) 被定义为像素化成像仪，可单独测量 X 射线光子的吸收能量并以数字方式记录此信息，越来越受到临床关注。最近采用多晶硅 (poly-Si) 制造了许多像素间距为 1 毫米的 PCA 原型，多晶硅是一种薄膜技术，能够创建尺寸与人体解剖结构相称的单片成像器。在这项研究中，开发了模拟和数字模拟框架，以深入了解单个多晶硅晶体管对像素电路性能的影响——这些信息无法通过经验手段轻易获得。仿真框架用于表征原型中采用的电路设计。模拟框架确定各个晶体管产生的噪声，用于估计能量分辨率，以及识别哪些晶体管贡献最大的噪声。该数字框架分析电路在晶体管特性存在显着变化的情况下的运行情况，用于估计电路产生输出的速度（称为输出计数率）。此外，还开发了一种算法并用于估计当前原型的像素电路可以实现的最小像素间距。仿真框架预测 PCA 原型的模拟组件在 70 keV 时的能量分辨率可低至 8.9% FWHM；即使存在显着的 TFT 变化，数字组件也应能正常工作，最快的组件具有高达 3 MHz 的输出计数率。最后，基于底层制造工艺的可想象的改进，该算法预测当前 PCA 原型的 1 mm 间距可能会显着减小，有可能减小到约 240 至 290 μm 之间。
Photon counting arrays (PCAs), defined as pixelated imagers which measure the absorbed energy of x-ray photons individually and record this information digitally, are of increasing clinical interest. A number of PCA prototypes with a 1 mm pixel-to-pixel pitch have recently been fabricated with polycrystalline silicon (poly-Si) — a thin-film technology capable of creating monolithic imagers of a size commensurate with human anatomy. In this study, analog and digital simulation frameworks were developed to provide insight into the influence of individual poly-Si transistors on pixel circuit performance — information that is not readily available through empirical means. The simulation frameworks were used to characterize the circuit designs employed in the prototypes. The analog framework, which determines the noise produced by individual transistors, was used to estimate energy resolution, as well as to identify which transistors contribute the most noise. The digital framework, which analyzes how well circuits function in the presence of significant variations in transistor properties, was used to estimate how fast a circuit can produce an output (referred to as output count rate). In addition, an algorithm was developed and used to estimate the minimum pixel pitch that could be achieved for the pixel circuits of the current prototypes. The simulation frameworks predict that the analog component of the PCA prototypes could have energy resolution as low as 8.9% FWHM at 70 keV; and the digital components should work well even in the presence of significant TFT variations, with the fastest component having output count rates as high as 3 MHz. Finally, based on conceivable improvements in the underlying fabrication process, the algorithm predicts that the 1 mm pitch of the current PCA prototypes could be reduced significantly, potentially to between ~240 and 290 μm.
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影响因子：
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