Monolithically Integrated X-Ray Detector Arrays for Computed Tomography

1997 ◽  
Vol 487 ◽  
Author(s):  
R. Sudharsanan ◽  
M. Yoganathan ◽  
G. Vakerlis ◽  
C. S. Ferekides ◽  
B. McCandless ◽  
...  
Keyword(s):  
Computed Tomography ◽  
High Sensitivity ◽  
Signal Strength ◽  
Ct Scanner ◽  
Temporal Response ◽  
Detector Arrays ◽  
X Ray ◽  
Monolithically Integrated ◽  
And Performance ◽  
Sublimation Technique

AbstractThe design and performance of a high sensitivity monolithic X-ray detector array fabricated by depositing CdTe photodiodes on CdWO4 scintillators for computed tomography (CT) are presented. CdTe photodiodes offer improved sensitivity due to the better match to the CdWO4 scintillator emission spectrum than the Si photodiodes used in current CT scanners. A CdTe photodiode fabricated on glass mechanically stacked to a CdWO4 scintillator showed 30% improvement in signal strength over Si photodiodes stacked to CdWO4-. Monolithic X-ray detector arrays were fabricated by depositing a CdTe photodiode structure on CdWO4 using close-spaced sublimation technique. Preliminary results on the detector's X-ray response, signalto- noise ratio and the X-ray temporal response show that monolithic CdTe X-ray detectors are suitable for practical CT scanner applications.

scholarly journals High-sensitivity high-resolution X-ray imaging with soft-sintered metal halide perovskites

2021 ◽  
Vol 4 (9) ◽  
pp. 681-688
Author(s):  
Sarah Deumel ◽  
Albert van Breemen ◽  
Gerwin Gelinck ◽  
Bart Peeters ◽  
Joris Maas ◽  
...  
Keyword(s):  
High Sensitivity ◽  
Metal Halide ◽  
Detector Arrays ◽  
X Ray ◽  
Carrier Lifetimes ◽  
Sintered Metal ◽  
X Ray Imaging ◽  
Imaging Detector ◽  
High Carrier ◽  
Halide Perovskites

AbstractTo realize the potential of artificial intelligence in medical imaging, improvements in imaging capabilities are required, as well as advances in computing power and algorithms. Hybrid inorganic–organic metal halide perovskites, such as methylammonium lead triiodide (MAPbI3), offer strong X-ray absorption, high carrier mobilities (µ) and long carrier lifetimes (τ), and they are promising materials for use in X-ray imaging. However, their incorporation into pixelated sensing arrays remains challenging. Here we show that X-ray flat-panel detector arrays based on microcrystalline MAPbI3 can be created using a two-step manufacturing process. Our approach is based on the mechanical soft sintering of a freestanding absorber layer and the subsequent integration of this layer on a pixelated backplane. Freestanding microcrystalline MAPbI3 wafers exhibit a sensitivity of 9,300 µC Gyair–1 cm–2 with a μτ product of 4 × 10–4 cm2 V–1, and the resulting X-ray imaging detector, which has 508 pixels per inch, combines a high spatial resolution of 6 line pairs per millimetre with a low detection limit of 0.22 nGyair per frame.

scholarly journals Quantitative Evaluation of Soil Structure and Strain in Three Dimensions under Shear Using X-ray Computed Tomography Image Analysis

2021 ◽  
Vol 7 (11) ◽  
pp. 230
Author(s):  
Shintaro Nohara ◽  
Toshifumi Mukunoki
Keyword(s):  
Computed Tomography ◽  
Image Analysis ◽  
Shear Zone ◽  
Soil Structure ◽  
Three Dimensions ◽  
Image Correlation ◽  
Ct Scanner ◽  
Zone Formation ◽  
X Ray ◽  
X Ray Computed

The objective of this study is to quantitatively evaluate the soil structure behavior when under shear stress to understand the mechanism of shear zone formation using a micro-focus X-ray computed tomography (CT) scanner to visualize the internal samples without causing disturbance. A new image-analysis method was proposed to systematically evaluate the particle length and direction by fitting the particle as an ellipsoid. Subsequently, a direct shear experiment was conducted on soil materials, and shear band was scanned using a micro-focus X-ray CT scanner. After validating the proposed method, the soil structure was evaluated in the shear zone via image analysis on the CT images. Furthermore, the strain inside the specimen was evaluated using digital image correlation. The results showed that a partial change in the particle direction occurred when the volume expansion inside the shear zone exceeded the peak. In addition, the width of the shear zone was ~7.1 times the median grain size of the sand used; however, the region exhibiting a change in the direction of the particles was narrow and confined to the vicinity of the shear plane.

scholarly journals INSTRUMENTATION OF FOUR-POINT BENDING TEST DURING 4D COMPUTED TOMOGRAPHY

2018 ◽  
Vol 18 ◽  
pp. 20 ◽  
Author(s):  
Daniel Kytýř ◽  
Tomáš Fíla ◽  
Petr Koudelka ◽  
Ivana Kumpová ◽  
Michal Vopálenský ◽  
...  
Keyword(s):  
Computed Tomography ◽  
High Resolution ◽  
Process Zone ◽  
Brittle Materials ◽  
Time Lapse ◽  
Bending Test ◽  
Ct Scanner ◽  
X Ray ◽  
Four Point Bending ◽  
4D Computed Tomography

High-resolution time-lapse micro-focus X-ray computed tomography is an effective method for investigation of deformation processes on volumetric basis including fracture propagation characteristics of non-homogeneous materials subjected to mechanical loading. This experimental method requires implementation of specifically designed loading devices to X-ray imaging setups. In case of bending tests, our background research showed that no commercial solution allowing for reliable investigation of so called fracture process zone in quasi-brittle materials is currently available. Thus, this paper is focused on description of recently developed in-situ four-point bending loading device and its instrumentation for testing of quasi-brittle materials. Proof of concept together with the pilot experiments were successfully performed in a CT scanner TORATOM. Based on results of the pilot experiments, we demonstrate that crack development and propagation in a quasi-brittle material can be successfully observed in 3D using high resolution 4D micro-CT under loading.

Sample Treatment for TXRF - Requirements and Prospects

1988 ◽  
Vol 32 ◽  
pp. 211-220 ◽  
Author(s):  
Andreas Prange ◽  
Heinrich Schwenke
Keyword(s):  
Water Quality ◽  
Air Pollution ◽  
Dynamic Range ◽  
Water Quality Management ◽  
High Sensitivity ◽  
Total Reflection ◽  
Sample Treatment ◽  
Wide Dynamic Range ◽  
X Ray ◽  
And Performance

Total-reflection X-ray fluorescence spectrometry, abbreviated as TXRF, is known for its high sensitivity down to the low pg-level or sub-ppb level, respectively, and its wide dynamic range of about three to four orders of magnitude (Yoneda and Horiuchi, 1971, Wobrauschek and Aiginger, 1980; Knoth and Schwenke, 1978 and 1980, Aiginger and Wobrausohek, 1985, Michaelis et al., 1985, Prange, 1987). Meanwhile several laboratories have purchased commercially available TXRF spectrometers and have started to report favourable about this technique. Applications have been reported from various disciplines: These are estuarine and marine water quality management and research, air pollution studies, mineralogical investigations, biology and medicine (Prange, 1987, Prange et al, 1985; Prange and Kremling, 1985, Prange et al., 1987, Stöβel and Prange, 1985, Michaelis, 1986, Ketelsen and Knöchel, 1985, Leland et al., 1987, von Bohlen et al., 1987, Junge et al., 1983, Hentschke et al., 1985, Hentschke et al., 1985, Gerwinski and Goetz, 1987, von Bohlen et al., 1987), In spite of its close kinship to conventional EDXRF , TXRF is quite different with respect to operation and performance and provides complementary capabilities.

On the use of X-ray computed tomography for determining wood properties: a review1This article is a contribution to the series The Role of Sensors in the New Forest Products Industry and Bioeconomy.

2011 ◽  
Vol 41 (11) ◽  
pp. 2120-2140 ◽  
Author(s):  
Qiang Wei ◽  
Brigitte Leblon ◽  
Armand La Rocque
Keyword(s):  
Computed Tomography ◽  
Growth Ring ◽  
Back Propagation ◽  
Forest Products ◽  
Ct Images ◽  
Ct Scanner ◽  
Forest Products Industry ◽  
X Ray ◽  
Feed Forward Back Propagation ◽  
X Ray Computed

In several processes of the forest products industry, an in-depth knowledge of log and board internal features is required and their determination needs fast scanning systems. One of the possible technologies is X-ray computed tomography (CT) technology. Our paper reviews applications of this technology in wood density measurements, in wood moisture content monitoring, and in locating internal log features that include pith, sapwood, heartwood, knots, and other defects. Annual growth ring measurements are more problematic to be detected on CT images because of the low spatial resolution of the images used. For log feature identification, our review shows that the feed-forward back-propagation artificial neural network is the most efficient CT image processing method. There are also some studies attempting to reconstruct three-dimensional log or board images from two-dimensional CT images. Several industrial prototypes have been developed because medical CT scanners were shown to be inappropriate for the wood industry. Because of the high cost of X-ray CT scanner equipment, other types of inexpensive sensors should also be investigated, such as electric resistivity tomography and microwaves. It also appears that the best approach uses various different sensors, each of them having its own strengths and weaknesses.

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