Amorphous silicon X-ray detectors

Hoheisel, M.; Arques, M.; Chabbal, Jean; Chaussat, C.; Ducourant, Thierry; Hahm, Gerhard; Horbaschek, Heinz; Schulz, R.; Spahn, M.

doi:10.1016/s0022-3093(98)00316-0

Cited by 26 publications

(8 citation statements)

References 8 publications

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“…Pixilated amorphous silicon (a-Si) photodiodes (PDs) are used to convert the optical photons to electron hole pairs (EHP). 8 The a-Si PDs are usually built side-by-side with the TFT, which limits the pixel fill-factor. The PD can also be built on top 9 of the TFT to achieve the largest fill factor 10 (Fig.…”

Section: 1) Existing Amfpi and Proposed Amfpi With Avalanche Gainmentioning

confidence: 99%

Low dose digital X-ray imaging with avalanche amorphous selenium

et al. 2015

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Active Matrix Flat Panel Imagers (AMFPI) based on an array of thin film transistors (TFT) have become the dominant technology for digital x-ray imaging. In low dose applications, the performance of both direct and indirect conversion detectors are limited by the electronic noise associated with the TFT array. New concepts of direct and indirect detectors have been proposed using avalanche amorphous selenium (a-Se), referred to as high gain avalanche rushing photoconductor (HARP). The indirect detector utilizes a planar layer of HARP to detect light from an x-ray scintillator and amplify the photogenerated charge. The direct detector utilizes separate interaction (non-avalanche) and amplification (avalanche) regions within the a-Se to achieve depthindependent signal gain. Both detectors require the development of large area, solid state HARP. We have previously reported the first avalanche gain in a-Se with deposition techniques scalable to large area detectors. The goal of the present work is to demonstrate the feasibility of large area HARP fabrication in an a-Se deposition facility established for commercial large area AMFPI. We also examine the effect of alternative pixel electrode materials on avalanche gain. The results show that avalanche gain > 50 is achievable in the HARP layers developed in large area coaters, which is sufficient to achieve x-ray quantum noise limited performance down to a single x-ray photon per pixel. Both chromium (Cr) and indium tin oxide (ITO) have been successfully tested as pixel electrodes.

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Section: 1) Existing Amfpi and Proposed Amfpi With Avalanche Gainmentioning

confidence: 99%

Low dose digital X-ray imaging with avalanche amorphous selenium

et al. 2015

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“…Instead of photochemical reactions, these matrix sensors usually use photoexcitation of the semiconductor. Among the numerous possible materials, amorphous silicon (often denoted a-Si) is considered to be the best material for digital X-radiation detection available today [64,65].…”

Section: General Overviewmentioning

confidence: 99%

A review of imaging methods in analysis of works of art: Thermographic imaging method in art analysis

2014

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This article discusses a number of modern techniques used for the analysis of works of art. The most widely used approaches as well as lesser known ones are outlined in terms of their applications and the kind of information on the condition of artworks that can be extracted. Special attention is paid to the method of thermographic analysis of works of pictorial art. The principles of the technique, various computational approaches, and safety concerns are discussed. A set of examples is provided for the demonstration of the capabilities of thermographic assessment, including a range of real canvas and panel paintings exhibited in museums and in private collections. PACS Nos.: 87.63.Hg, 78.20.nb, 81.70.Pg, 07.20.-n. Résumé : Nous discutons ici de techniques modernes utilisées pour analyser les oeuvres d'art. Nous présentons les méthodes les plus connues comme les moins connues, selon leurs applications et la sorte d'information qu'on peut extraire sur les conditions de l'oeuvre d'art. Nous portons une attention spéciale à l'analyse thermographique d'oeuvres picturales. Nous discutons les principes de la technique, des différentes approches informatiques et des soucis de sécurité. Nous présentons un ensemble d'exemples pour illustrer les capacités de l'évaluation thermographique, incluant plusieurs véritables tableaux et panneaux peints exposés dans des musées et des collections privées. [Traduit par la Rédaction]

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“…These detectors operate by converting x-ray energy into visible light in the scintillating material (usually Cesium Iodide) and the conversion photons then travel into the semiconductor to produce electron-hole pairs. As in the direct semiconductor detectors, the semiconductor is embedded with TFTs or a PIN photodiode for charge collection and read out purposes 17 . Indirect detectors have evolved to essentially eliminate the disadvantages associated with scintillator use and can now produce high-resolution images over large energy ranges.…”

Section: Detectorsmentioning

confidence: 99%

Applying high frame-rate digital radiography and dual-energy distributed-sources for advanced tomosynthesis

Travish¹,

Rangel

Evans

et al. 2013

SPIE Proceedings

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Conventional radiography uses a single point x-ray source with a fan or cone beam to visualize various areas of the human body. An imager records the transmitted photons-historically film and now increasingly digital radiography (DR) flat panel detectors-followed by optional image post-processing. Some post-processing techniques of particular interest are tomosynthesis, and dual energy subtraction. Tomosynthesis adds the ability to recreate quasi-3D images from a series of 2D projections. These exposures are typically taken along an arc or other path; and, tomosynthesis reconstruction is used to form a three-dimensional representation of the area of interest. Dual-energy radiography adds the ability to enhance or "eliminate" structures based on their different attenuation of well-separated end-point energies in two exposures. These advanced capabilities come at a high cost in terms of complexity, imaging time, capital equipment, space, and potentially reduced image quality due to motion blur if acquired sequentially. Recently, the prospect of creating x-ray sources, which are composed of arrays of micro-emitters, has been put forward. These arrays offer a flat-panel geometry and may afford advantages in fabrication methodology, size and cost. They also facilitate the use of the dual energy technology. Here we examine the possibility of using such an array of x-ray sources combined with high frame-rate (~kHz) DR detectors to produce advanced medical images without the need for moving gantries or other complex motion systems. Combining the advantages of dual energy imaging with the ability to determine the relative depth location of anatomical structures or pathological findings from imaging procedures should prove to be a powerful diagnostic tool. We also present use cases that would benefit from the capabilities of this modality.

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Amorphous silicon X-ray detectors

Cited by 26 publications

References 8 publications

Low dose digital X-ray imaging with avalanche amorphous selenium

Low dose digital X-ray imaging with avalanche amorphous selenium

A review of imaging methods in analysis of works of art: Thermographic imaging method in art analysis

Applying high frame-rate digital radiography and dual-energy distributed-sources for advanced tomosynthesis

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