Cascaded systems analysis of a-Se/a-Si and a-InGaZnO TFT passive and active pixel sensors for tomosynthesis

Abstract

Today the most commonly used imager (The term 'imager' is used to describe the entire x-ray detection system including the x-ray detector and back-plane electronics.) technology in digital breast tomosynthesis (DBT) systems is based on direct x-ray detectors. Direct conversion detectors (The term 'detector' in this work pertains to the x-ray converting material like a-Se or CsI:Tl.) using x-ray absorbing materials like amorphous selenium

Computational models of direct and indirect X‐ray breast imaging detectors for in silico trials

“…Other approaches that model detector performances such as cascaded systems modeling 3,10–12 have been shown to achieve much better fits to measured MTF, NNPS as well as DQE data. However, cascaded systems modeling is a completely different approach that often relies on arbitrary fitting functions to match simulated resolution properties to the measured data 10,12 . These fitting functions are not derived from first principles and were not used in this work, except when proprietary information could not be obtained and released for systems such as DIR$$_{\text{CT}}$$.…”

“…Other approaches that model detector performances such as cascaded systems modeling 3,10–12 have been shown to achieve much better fits to measured MTF, NNPS as well as DQE data. However, cascaded systems modeling is a completely different approach that often relies on arbitrary fitting functions to match simulated resolution properties to the measured data 10,12 .…”

“…Some analytical models derive the detector statistics and image quality metrics in the spatial domain, 8,9 while others harness the powers of Fourier space. [10][11][12] The latter is called cascaded systems modeling, and is as a relatively simple way of predicting imaging performance of x-ray detectors. These models, however, cannot be directly used for generating mammograms and tomosynthesis images and need to be combined with ray tracing and scatter generation algorithms.…”

“…These models study the propagation of the signal and noise through x‐ray detectors as series of blurring and gain stages. Some analytical models derive the detector statistics and image quality metrics in the spatial domain, 8,9 while others harness the powers of Fourier space 10–12 . The latter is called cascaded systems modeling, and is as a relatively simple way of predicting imaging performance of x‐ray detectors.…”

Organic photoconductive film–stacked active pixel sensor pixel circuits using indium–tin–zinc-oxide thin-film transistors

“…To overcome this obstacle, it is necessary to introduce an active pixel sensor (APS) architecture, 15,16) which has three TFTs in each pixel and can perform in-pixel signal amplification. Although TFT-based APS circuits using amorphous Si 17,18) and IGZO [19][20][21][22][23][24] have been proposed to date, the TFTs were large because their field-effect mobilities (<1 and ∼10 cm 2 V −1 s −1 ) were not high enough to perform the APS operation, resulting in an increase in pixel size and/or a decrease in the pixel aperture ratio. On the other hand, it has also been reported based on simulation that ITZO TFTs with higher field-effect mobilities of >20 cm 2 V −1 s −1 can be of potential use in APSs.…”