Three-dimensional cascaded system analysis of a 50µm pixel pitch wafer-scale CMOS active pixel sensor x-ray detector for digital breast tomosynthesis

Abstract

Abstract. High-resolution, low-noise x-ray detectors based on the complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) technology have been developed and proposed for digital breast tomosynthesis (DBT). In this study, we evaluated the three-dimensional (3D) imaging performance of a 50 μm pixel pitch CMOS APS x-ray detector named DynAMITe (Dynamic Range Adjustable for Medical Imaging Technology). The two-dimensional (2D) angle-dependent modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE) were experimentally characterized and modeled using the cascaded system analysis at oblique incident angles up to 30°. The cascaded system model was extended to the 3D spatial frequency space in combination with the filtered back-projection (FBP) reconstruction method to calculate the 3D and in-plane MTF, NNPS and DQE parameters. The results demonstrate that the beam obliquity blurs the 2D MTF and DQE in the high spatial frequency range. However, this effect can be eliminated after FBP image reconstruction. In addition, impacts of the image acquisition geometry and detector parameters were evaluated using the 3D cascaded system analysis for DBT. The result shows that a wider projection angle range (e.g. ±30°) improves the low spatial frequency (below 5 mm -1 ) performance of the CMOS APS detector. In addition, to maintain a high spatial resolution for DBT, a focal spot size of smaller than 0.3 mm should be used.Theoretical analysis suggests that a pixelated scintillator in combination with the 50 μm pixel pitch CMOS APS detector could further improve the 3D image resolution. Finally, the 3D imaging performance of the CMOS APS and an indirect amorphous silicon (a-Si:H) thin-film A c c e p t e d M a n u s c r i p t transistor (TFT) passive pixel sensor (PPS) detector was simulated and compared.Keywords: CMOS active pixel sensor, x-ray detector, digital breast tomosynthesis, three-dimensional, cascaded system analysis, pixelated scintillator, detective quantum efficiency IntroductionHigh performance x-ray detectors based on the complementary metal-oxide-semiconductor ( Up to now, most studies focus on CMOS APS detector evaluation by measuring the one-dimensional (1D) or 2D modulation transfer function (MTF), noise power spectrum (NPS) and detective quantum efficiency (DQE) using a single x-ray projection at the zero-degree incident angle (perpendicular to the detector). Nevertheless, since DBT is a quasi-three-dimensional (3D) imaging technology, the DBT image quality is influenced by the system geometry and reconstruction algorithms (Sechopoulos 2013a(Sechopoulos , 2013b. Therefore, the 3D imaging performance should be evaluated for the CMOS APS detectors. However, it is difficult to empirically investigate the 3D image quality. To deal with this issue, the 3D cascaded system analysis for CMOS APS detectors was developed and is presented in this study.Cascaded system analysis can accurately model the signal and noise propagation and blurring within ...

Performance evaluation of digital breast tomosynthesis systems: physical methods and experimental data

“…Mainprize et al (2006) measured reductions in MTF of approximately 5% and 15% for angular incidences of 20°and 30°, respectively for a CsI detector at 4 mm −1 . Similar figures were found by Zhao et al (2017) for a CMOS active pixel sensor with a 50 μm pixel pitch (DynAMITe) coupled to a CsI scintillator.…”

“…While the simulations of system MTF and NPS calculated using cascaded systems analysis for the Siemens Mammomat Novation TOMO unit (Zhao and Zhao 2008b) were experimentally validated (Zhao et al 2009) experimental, measured DQE results were not given. Zhao et al (2017) measured the MTF, NPS and DQE as a function of oblique angle incidence for a CMOS active pixel sensor detector (DynAMITe) with 50 μm pixels and combined these data with the cascaded systems theory of (Zhao and Zhao 2008b) to model the impact of angular range, dose and focal spot size for a theoretical step and shoot system. They found that oblique entry of ±30°did not greatly influence inplane DQE but did improve the low frequency sampling in Fourier space and thus improved DQE below 2 mm −1 .…”

“…Tward and Siewerdsen (2008) focus solely on the noise transfer for CBCT systems while Zhao and Zhao include the additional stage of focal spot blur that is needed when modelling flying focus DBT systems (Zhao and Zhao 2008b). Chumin Zhao et al (2017) included the impact of oblique blurring in the x-ray detector. Such analysis can be complex and readers are referred to these papers for an in-depth description of this topic; an overview is given here as this offers some insight into the interpretation of MTF and NPS in the reconstructed planes.…”

Energy Transfer Assisted Fast X‐ray Detection in Direct/Indirect Hybrid Perovskite Wafer

“…However, one big obstacle faced for perovskite semiconductors is the serious ion migration effect of perovskite ions, especially under a large electric field to extract the charges induced by X-rays, thus impairing the device signal-to-noise ratio (SNR) and accelerating the degradation of perovskite-based electronic devices. [17,18] Indirect-type X-ray detectors based on scintillation crystals first convert X-rays into UV-vis photons, and followed by photodetector detection through image sensors, such as complementary metal-oxide semiconductor (CMOS), charge-coupled devices (CCDs), thin-film phototransistor (TFT) arrays, and so on, [19,20] which avoids applying large bias and ions migration effect. The development of indirect-type X-ray detection is relatively mature, and now dominating the markets of CT products.…”

“…Indirect‐type X‐ray detectors based on scintillation crystals first convert X‐rays into UV–vis photons, and followed by photodetector detection through image sensors, such as complementary metal‐oxide semiconductor (CMOS), charge‐coupled devices (CCDs), thin‐film phototransistor (TFT) arrays, and so on, [ 19 , 20 ] which avoids applying large bias and ions migration effect. The development of indirect‐type X‐ray detection is relatively mature, and now dominating the markets of CT products.…”