Amorphous silicon pixel radiation detectors and associated thin film transistor electronics readout

Perez‐Mendez, V.; Cho, G.; Drewey, J.; Tao, Jinhui; Kaplan, S.N.; Mireshghi, A.; Wildermuth, D.; Goodman, C.A.; Fujieda, Ichiro

doi:10.1016/0920-5632(93)90036-6

Cited by 11 publications

(5 citation statements)

References 13 publications

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“…Holl et al [11] measured that 52,000 optical photons were emitted per 1-MeV absorbed and Jing et al [12,13] reported that 64,000 optical photons were emitted per 1-MeV absorbed. Hence, we assumed that 58 optical photons were emitted per keV absorbed (a mean value between the two reported values).…”

Section: Methodsmentioning

confidence: 98%

Monte Carlo simulation of a CsI-based flat-panel imager for mammography

2004

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The development of new digital mammography techniques such as dual-energy imaging, tomosynthesis and CT mammography often requires investigating optimal camera design parameters and imaging techniques. One tool that is useful for this purpose is Monte Carlo simulation. This paper presents a methodology for generating simulated images from a CsI-based, flat-panel imager by using the Geant 3 Monte Carlo code to model x-ray transport and absorption within the CsI scintillator, and the DETECT-II code to track optical photon spread within a columnar model of the CsI scintillator. The Monte Carlo modeling of x-ray transport and absorption within the CsI was validated by comparing to previously published values for the probability of a K-shell interaction, the fluorescent yield, the probability of a Kfluorescent emission, and the escape fraction describing the probability of a K x-ray escaping the scintillator. To validate the combined (Geant coupled with DETECT-II) Monte Carlo approach to form simulated images, comparison of modulation transfer functions (MTFs) and system sensitivity (electrons/mR/pixel) obtained from simulations were compared to empirical measurements obtained with different x-ray spectra and imagers with varying CsI thicknesses. By varying the absorption and reflective properties of the columnar CsI used in the DETECT-II code, good agreement between simulated MTFs and system sensitivity and empirically measured values were observed.

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Section: Methodsmentioning

confidence: 98%

Monte Carlo simulation of a CsI-based flat-panel imager for mammography

2004

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“…Backward diffusion can therefore occm over a distance, XD, of approximately 23 (2.16) where E is the electric field. The estimated value of xD is in the range of 35nm -90 nm [8,9].…”

Section: Back Diffusion Effectmentioning

confidence: 99%

“…These intrinsic defects produce defect states between the valence type and conducted type states ( Fig.l.2b). The most prominent intrinsic defect is the unsaturated bond, called the dangling bond, which is a paramagnetic center contributing an uncompensated spin to the electron spin resonance (ESR) signal [8,9]. Depending on the particular amorphous material considered, the defects may have different contributions to the electronic energy structure such as dangling bonds and voids which act as trapping and recombination centers for electrons and holes.…”

Section: The Disordered Structurementioning

confidence: 99%

“…The thermal expansion coefficients of Si (1.9~10-6 K-1) and of the suitable substrate material, fused quartz contrast, secondary photocurrent structures, such as n-i-n diodes, exhibit high optical photoconductive gain determined by the ratio of the electron lifetime to transit time, low light to dark sensitivity, and slow response times (of the order of milliseconds) [7,8,9]. To make a better sensor one would like to combine the gain associated with secondary photocurrents with the low dark currents and fast response times of the solar cell structures.…”

Section: A-simentioning

confidence: 99%

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High spatial resolution radiation detectors based on hydrogenated amorphous silicon and scintillator

Tao

1995

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“…These properties, which are essential for good image quality, arise from the columnar structure of CsI:Tl layers, when grown by evaporated deposition at high temperature. Jing et al [45] and Perez-Mendez et al [46] have shown that a 75-mm-thick CsI:Tl layer provides a spatial resolution of 12 c mm -1 . The X-ray quantum detection efficiency of the screen can be adjusted by varying the phosphor thickness without exacerbating unsharpness.…”

Section: Amorphous Silicon Tft Flat-panel Image Readoutmentioning

confidence: 99%

Direct digital mammography image acquisition

1997

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Mammography is a branch of radiology which could benefit greatly from the assimilation of digital imaging technologies. Computerized enhancement techniques could be used to ensure optimum presentation of all clinical images. Beyond this it will facilitate powerful new clinical resources such as computer-assisted diagnosis, tele-mammography, plus digital image management and archiving. An essential precursor to all these advances is the availability of appropriate direct digital mammography (DDM) image-acquisition system(s) to capture high-quality breast X-ray image data at the outset. The only practical DDM image-acquisition system currently available is (photo-stimulable phosphor) computed radiography. Modern computed mammography (CM) uses similar radiation doses to the patient and produces equivalent, albeit different, image quality to screen-film mammography. Computed mammography offers superior rendition of the skin edge and sub-cutaneous tissue and dense parenchyma, while ensuring equivalent micro-calcification detectability. Meanwhile, a variety of new technical approaches to DDM are under active investigation and/or development which promise to supercede film-based mammography. These new (second generation) DDM technologies promise the radiologist superior image quality combined with significant dose savings compared with contemporary imaging systems. In this review we describe and compare the physical and clinical characteristics of CM and the various emerging DDM image-acquisition technologies.

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Amorphous silicon pixel radiation detectors and associated thin film transistor electronics readout

Cited by 11 publications

References 13 publications

Monte Carlo simulation of a CsI-based flat-panel imager for mammography

Monte Carlo simulation of a CsI-based flat-panel imager for mammography

High spatial resolution radiation detectors based on hydrogenated amorphous silicon and scintillator

Direct digital mammography image acquisition

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