Amorphous selenium direct detection CMOS digital x-ray imager with 25 micron pixel pitch

Scott, Christopher C.; Abbaszadeh, Shiva; Ghanbarzadeh, Sina; Allan, G.; Farrier, Michael G.; Cunningham, Ian; Karim, Karim S.

doi:10.1117/12.2043770

Cited by 10 publications

(21 citation statements)

References 5 publications

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“…Also a DBT system based on the CMOS APS detector will allow radiologists to better visualize the shape of microcalcifications with the image information contained in the high spatial frequency range for observer studies. Another suggested approach to improve the spatial resolution is to use the direct conversion amorphous selenium (a-Se) photodetector in combination with the CMOS APS backplane (Scott et al 2014, Parsafar et al 2015.…”

Section: Impact Of Pixelated Scintillatormentioning

confidence: 99%

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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Section: Impact Of Pixelated Scintillatormentioning

confidence: 99%

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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“…Measured MTF performance is reduced compared to an ideal 5.6-µm aperture due to edge imperfections and source-imager misalignment. To the best of our knowledge, this is the best MTF reported for a direct-conversion X-ray imager to date [5] [11]. X-ray images of a loop of 50-µm-diameter copper wire (imaged at a 40-kVp tube voltage) and a stainless steel syringe tip (imaged at 70 kVp) are shown in Figs.…”

Section: Resultsmentioning

confidence: 97%

“…Previous work on amorphous-silicon transistor based a-Se direct-conversion X-ray imagers demonstrated pixel pitch values that are two orders of magnitude larger than our current device [4] while the best previously reported CMOS-based direct conversion X-ray imagers had a pixel pitch at least 4× greater [5].…”

Section: Introductionmentioning

confidence: 93%

Direct-Conversion CMOS X-Ray Imager With <inline-formula> <tex-math notation="LaTeX">$5.6 ~\mu \text{m} \times 6.25~\mu \text{m}$ </tex-math></inline-formula> Pixels

Parsafar

Scott

El-Falou

et al. 2015

IEEE Electron Device Lett.

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“…Using these characteristics and other physical blurring phenomena, a point spread function was calculated and the Fourier transform was taken to obtain the detector MTF 2 , as shown in Figure 1. Using an electronic noise level of 300 electrons rms, the DQE was calculated for ROD analysis 2,3 .…”

Section: Methodsmentioning

confidence: 99%

“…Current flat panel detector technology provides pixel sizes on the order of 200 microns, falling short of the resolution necessary to accurately resolve vascular device detail. A novel amorphous selenium (a-Se) detector has been proposed 2,3 that will have incomparably high resolution if achieved. The new detector will feature 25 μ m pixel size, 1000 μ m active a-Se layer, and a 10 V/ μ m bias field.…”

Section: Introductionmentioning

confidence: 99%

Quantitative comparison using generalized relative object detectability (G-ROD) metrics of an amorphous selenium detector with high resolution microangiographic fluoroscopes (MAF) and standard flat panel detectors (FPD)

et al. 2016

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A novel amorphous selenium (a-Se) direct detector with CMOS readout has been designed, and relative detector performance investigated. The detector features include a 25μm pixel pitch, and 1000μm thick a-Se layer operating at 10V/μm bias field. A simulated detector DQE was determined, and used in comparative calculations of the Relative Object Detectability (ROD) family of prewhitening matched-filter (PWMF) observer and non-prewhitening matched filter (NPWMF) observer model metrics to gauge a-Se detector performance against existing high resolution micro-angiographic fluoroscopic (MAF) detectors and a standard flat panel detector (FPD). The PWMF-ROD or ROD metric compares two x-ray imaging detectors in their relative abilities in imaging a given object by taking the integral over spatial frequencies of the Fourier transform of the detector DQE weighted by an object function, divided by the comparable integral for a different detector. The generalized-ROD (G-ROD) metric incorporates clinically relevant parameters (focal-spot size, magnification, and scatter) to show the degradation in imaging performance for detectors that are part of an imaging chain. Preliminary ROD calculations using simulated spheres as the object predicted superior imaging performance by the a-Se detector as compared to existing detectors. New PWMF-G-ROD and NPWMF-G-ROD results still indicate better performance by the a-Se detector in an imaging chain over all sphere sizes for various focal spot sizes and magnifications, although a-Se performance advantages were degraded by focal spot blurring. Nevertheless, the a-Se technology has great potential to provide breakthrough abilities such as visualization of fine details including of neuro-vascular perforator vessels and of small vascular devices.

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Amorphous selenium direct detection CMOS digital x-ray imager with 25 micron pixel pitch

Cited by 10 publications

References 5 publications

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

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

Direct-Conversion CMOS X-Ray Imager With <inline-formula> <tex-math notation="LaTeX">$5.6 ~\mu \text{m} \times 6.25~\mu \text{m}$ </tex-math></inline-formula> Pixels

Quantitative comparison using generalized relative object detectability (G-ROD) metrics of an amorphous selenium detector with high resolution microangiographic fluoroscopes (MAF) and standard flat panel detectors (FPD)

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