Large area CMOS active pixel sensor x‐ray imager for digital breast tomosynthesis: Analysis, modeling, and characterization

Zhao, Chumin; Kanicki, Jerzy; Konstantinidis, Anastasios; Patel, Tushita

doi:10.1118/1.4932368

Cited by 46 publications

(62 citation statements)

References 73 publications

(143 reference statements)

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“…Many of these image quality limitations are remedied by systems employing a flat‐panel detector (FPD) — for example, mobile systems such as the O‐arm (Medtronic, Littleton MA) and Vision 3D C‐arm (Ziehm, Nuremberg, Germany). Recent advances incorporate a complementary metal oxide semiconductor (CMOS) FPD to reduce electronic noise and improve spatial resolution …”

Section: Introductionmentioning

confidence: 99%

A mobile isocentric C‐arm for intraoperative cone‐beam CT: Technical assessment of dose and 3D imaging performance

et al. 2020

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Purpose To characterize the radiation dose and three‐dimensional (3D) imaging performance of a recently developed mobile, isocentric C‐arm equipped with a flat‐panel detector (FPD) for intraoperative cone‐beam computed tomography (CBCT) (Cios Spin 3D, Siemens Healthineers) and to identify potential improvements in 3D imaging protocols for pertinent imaging tasks. Methods The C‐arm features a 30 × 30 cm2 FPD and isocentric gantry with computer‐controlled motorization of rotation (0–195°), angulation (±220°), and height (0–45 cm). Geometric calibration was assessed in terms of 9 degrees of freedom of the x‐ray source and detector in CBCT scans, and the reproducibility of geometric calibration was evaluated. Standard and custom scan protocols were evaluated, with variation in the number of projections (100–400) and mAs per view (0.05–1.65 mAs). Image reconstruction was based on 3D filtered backprojection using “smooth,” “normal,” and “sharp” reconstruction filters as well as a custom, two‐dimensional 2D isotropic filter. Imaging performance was evaluated in terms of uniformity, gray value correspondence with Hounsfield units (HU), contrast, noise (noise‐power spectrum, NPS), spatial resolution (modulation transfer function, MTF), and noise‐equivalent quanta (NEQ). Performance tradeoffs among protocols were visualized in anthropomorphic phantoms for various anatomical sites and imaging tasks. Results Geometric calibration showed a high degree of reproducibility despite ~19 mm gantry flex over a nominal semicircular orbit. The dose for a CBCT scan varied from ~0.8–4.7 mGy for head protocols to ~6–38 mGy for body protocols. The MTF was consistent with sub‐mm spatial resolution, with f10 (frequency at which MTF = 10%) equal to 0.64 mm−1, 1.0 mm−1, and 1.5 mm−1 for smooth, standard, and sharp filters respectively. Implementation of a custom 2D isotropic filter improved CNR ~ 50–60% for both head and body protocols and provided more isotropic resolution and noise characteristics. The NPS and NEQ quantified the 3D noise performance and provided a guide to protocol selection, confirmed in images of anthropomorphic phantoms. Alternative scan protocols were identified according to body site and task — for example, lower‐dose body protocols (<3 mGy) sufficient for visualization of bone structures. Conclusion The studies provided objective assessment of the dose and 3D imaging performance of a new C‐arm, offering an important basis for clinical deployment and a benchmark for quality assurance. Modifications to standard 3D imaging protocols were identified that may improve performance or reduce radiation dose for pertinent imaging tasks.

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Section: Introductionmentioning

confidence: 99%

A mobile isocentric C‐arm for intraoperative cone‐beam CT: Technical assessment of dose and 3D imaging performance

et al. 2020

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“…An early implementation of such in‐pixel amplification was demonstrated in image sensors based on crystalline silicon (c‐Si) CMOS technology . These devices, referred to as active pixel sensors (APSs), are widely used in consumer products (e.g., cameras, cell phones, and tablets) and, more recently, are being introduced into medical imaging applications . The pixels in these devices generally incorporate a three‐transistor design which provides amplification through a source‐follower circuit and offers the advantage of multiple‐sampling readout for noise reduction – since, unlike for AMFPI pixel designs, readout does not reset the pixel signal.…”

Section: Introductionmentioning

confidence: 99%

Theoretical investigation of the noise performance of active pixel imaging arrays based on polycrystalline silicon thin film transistors

et al. 2017

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Purpose Active matrix flat-panel imagers, which typically incorporate a pixelated array with one a-Si:H thin-film transistor (TFT) per pixel, have become ubiquitous by virtue of many advantages, including large monolithic construction, radiation tolerance and high DQE. However, at low exposures such as those encountered in fluoroscopy, digital breast tomosynthesis and breast computed tomography, DQE is degraded due to the modest average signal generated per interacting x-ray relative to electronic additive noise levels of ~1000 e, or greater. A promising strategy for overcoming this limitation is to introduce an amplifier into each pixel, referred to as the active pixel (AP) concept. Such circuits provide in-pixel amplification prior to readout as well as facilitate correlated multiple sampling, enhancing signal-to-noise and restoring DQE at low exposures. In this study, a methodology for theoretically investigating the signal and noise performance of imaging array designs is introduced and applied to the case of AP circuits based on low-temperature polycrystalline silicon (poly-Si), a semiconductor suited to manufacture of large area, radiation tolerant arrays. Methods Computer simulations employing an analog circuit simulator and performed in the temporal domain were used to investigate signal characteristics and major sources of electronic additive noise for various pixel amplifier designs. The noise sources include photodiode shot noise and resistor thermal noise, as well as TFT thermal and flicker noise. TFT signal behavior and flicker noise were parameterized from fits to measurements performed on individual poly-Si test TFTs. The performance of three single-stage and three two-stage pixel amplifier designs were investigated under conditions relevant to fluoroscopy. The study assumes a 20×20 cm2, 150 µm pitch array operated at 30 fps and coupled to a CsI:Tl x-ray converter. Noise simulations were performed as a function of operating conditions, including sampling mode, of the designs. The total electronic additive noise included noise contributions from each circuit component. Results The total noise results were found to exhibit a strong dependence on circuit design and operating conditions, with TFT flicker noise generally found to be the dominant noise contributor. For the single-stage designs, significantly increasing the size of the source-follower TFT substantially reduced flicker noise – with the lowest total noise found to be ~574 e [rms]. For the two-stage designs, in addition to tuning TFT sizes and introducing a low-pass filter, replacing a p-type TFT with a resistor (under the assumption in the study that resistors make no flicker noise contribution) resulted in significant noise reduction – with the lowest total noise found to be ~336 e [rms]. Conclusions A methodology based on circuit simulations which facilitates comprehensive explorations of signal and noise characteristics has been developed and applied to the case of poly-Si AP arrays. The encouraging results suggest that the elect...

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“…The  opt •E• esc (z) represents the light output in number of escaped optical photons per absorbed x-ray quanta of energy E at position z in the scintillator (Vedantham et al 2004, Zhao et al 2015a, 2015b. The calculated g 2 ̅ (θ i = 0) is around 580.…”

Section: Three-dimensional Cascaded System Analysismentioning

confidence: 99%

“…Cascaded system analysis can be used to describe the signal and noise performance of an x-ray imaging system (Siewerdsen et al 1997, Vedantham et al 2004, Zhao and Kanicki 2014, Zhao et al 2015a. The system signal and noise is cascaded separately through a series of gain and blurring stages.…”

Section: Three-dimensional Cascaded System Analysismentioning

confidence: 99%

“…If a 4.5 cm breast tissue with 50% glandularity is considered, this will lead to an entrance surface air kerma (ESAK) of 0.24 mGy and a MGD of 1.5 mGy for 21 projection views. The MGD calculation was described previously elsewhere (Zhao et al 2015a(Zhao et al , 2015b. The impact of focal spot size is not currently included, but it will be discussed in section 3.5.…”

Section: Three-dimensional Imaging Performance Of the Dynamite Detectormentioning

confidence: 99%

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

et al. 2017

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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 ...

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Large area CMOS active pixel sensor x‐ray imager for digital breast tomosynthesis: Analysis, modeling, and characterization

Cited by 46 publications

References 73 publications

A mobile isocentric C‐arm for intraoperative cone‐beam CT: Technical assessment of dose and 3D imaging performance

A mobile isocentric C‐arm for intraoperative cone‐beam CT: Technical assessment of dose and 3D imaging performance

Theoretical investigation of the noise performance of active pixel imaging arrays based on polycrystalline silicon thin film transistors

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

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