DEVELOPMENT OF PHANTOM FOR PERFORMANCE EVALUATION OF MICRO-CT

2008 ◽  
Vol 20 (03) ◽  
pp. 177-184 ◽  
Author(s):  
Kevin Wen-Kai Tsai ◽  
Ho-Shiang Chueh ◽  
Jyh-Cheng Chen
Keyword(s):  
Performance Evaluation ◽  
Spatial Resolution ◽  
Evaluation Method ◽  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Research Field ◽  
High Signal ◽  
Micro Ct ◽  
Analytic Methods ◽  
American Society

Micro-X-ray computed tomography (micro-CT) has several characters such as non-invasive, high spatial resolution, high signal-to-noise ratio, providing three-dimensional volume information. Because micro-CT was utilized in many kinds of research field such as preclinical biomedical study, designing a performance phantom and developing analytic methods to objectively evaluate the performance of micro-CT are very important. In this study, the performance phantom and the analytic methods were developed for performance evaluation of micro-CT. The performance parameters extracted from different CT images including noise, linearity, spatial resolution, and hardware alignment were defined in the American Association of Physicists in Medicine (AAPM) Report No. 1 and the American Society for Testing and Materials (ASTM) E1695-95. Standard deviation, Pearson's correlation coefficient, edge response function, and visualization method were utilized to evaluate noise, linearity, spatial resolution, and hardware alignment, respectively. A digital uniform disk image was utilized to evaluate the accuracy of spatial resolution evaluation method. The physical phantom study was performed to evaluate a home-made micro-CT and a commercial micro-CT (Skyscan 1076). According to these results, the performance phantom and the analytic methods developed in this study have demonstrated their capability to evaluate performance of any micro-CT.

scholarly journals Three dimensional microelectrodes enable high signal and spatial resolution for neural seizure recordings in brain slices and freely behaving animals

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
P. Wijdenes ◽  
K. Haider ◽  
C. Gavrilovici ◽  
B. Gunning ◽  
M. D. Wolff ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
Signal To Noise Ratio ◽  
Brain Activity ◽  
Three Dimensional ◽  
Brain Slices ◽  
High Signal ◽  
Diagnostic Potential ◽  
Freely Behaving

AbstractNeural recordings made to date through various approaches—both in-vitro or in-vivo—lack high spatial resolution and a high signal-to-noise ratio (SNR) required for detailed understanding of brain function, synaptic plasticity, and dysfunction. These shortcomings in turn deter the ability to further design diagnostic, therapeutic strategies and the fabrication of neuro-modulatory devices with various feedback loop systems. We report here on the simulation and fabrication of fully configurable neural micro-electrodes that can be used for both in vitro and in vivo applications, with three-dimensional semi-insulated structures patterned onto custom, fine-pitch, high density arrays. These microelectrodes were interfaced with isolated brain slices as well as implanted in brains of freely behaving rats to demonstrate their ability to maintain a high SNR. Moreover, the electrodes enabled the detection of epileptiform events and high frequency oscillations in an epilepsy model thus offering a diagnostic potential for neurological disorders such as epilepsy. These microelectrodes provide unique opportunities to study brain activity under normal and various pathological conditions, both in-vivo and in in-vitro, thus furthering the ability to develop drug screening and neuromodulation systems that could accurately record and map the activity of large neural networks over an extended time period.

scholarly journals Ab initiostructure determination of nanocrystals of organic pharmaceutical compounds by electron diffraction at room temperature using a Timepix quantum area direct electron detector

2016 ◽  
Vol 72 (2) ◽  
pp. 236-242 ◽  
Author(s):  
E. van Genderen ◽  
M. T. B. Clabbers ◽  
P. P. Das ◽  
A. Stewart ◽  
I. Nederlof ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Room Temperature ◽  
Dynamic Range ◽  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Direct Methods ◽  
Liquid Nitrogen Temperature ◽  
High Dynamic Range ◽  
Electron Diffraction Data ◽  
High Signal

Until recently, structure determination by transmission electron microscopy of beam-sensitive three-dimensional nanocrystals required electron diffraction tomography data collection at liquid-nitrogen temperature, in order to reduce radiation damage. Here it is shown that the novel Timepix detector combines a high dynamic range with a very high signal-to-noise ratio and single-electron sensitivity, enablingab initiophasing of beam-sensitive organic compounds. Low-dose electron diffraction data (∼0.013 e− Å−2 s−1) were collected at room temperature with the rotation method. It was ascertained that the data were of sufficient quality for structure solution using direct methods using software developed for X-ray crystallography (XDS,SHELX) and for electron crystallography (ADT3D/PETS,SIR2014).

scholarly journals Studies of the ISM in the LMC using SN1987A

1991 ◽  
Vol 148 ◽  
pp. 431-431
Author(s):  
Max Pettini
Keyword(s):  
High Resolution ◽  
Interstellar Medium ◽  
Large Scale ◽  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Large Magellanic Cloud ◽  
Absorption Lines ◽  
High Signal ◽  
Hii Region ◽  
Sn 1987A

The exceptional brightness of SN1987A provided a wealth of opportunities for probing not only the interstellar medium in our Galaxy and in the Large Magellanic Cloud (LMC), but also any intergalactic matter between the two. Spectroscopic work has been directed both towards searches for very weak absorption lines, which require data of exceptionally high signal-to-noise ratio, and towards recording spectra of known features at unprecedentedly high resolution. Both approaches have yielded exciting and unexpected results. The first detection of [FeX] absorption has revealed the presence of million-degree gas in the interstellar medium of the LMC, possibly resulting from the explosions of previous supernovae in the 30-Doradus HII region. The ultra-high-resolution observations have been successful in resolving the hyperfine structure of the sodium D lines in several interstellar clouds along the line of sight to the supernova. This implies that the clouds are at temperatures of, at most, 170 K and have internal turbulent velocities of not more than 0.2 km s−1; large-scale motions thus appear to be mainly subsonic in these clouds. Radio observations of HI emission at 21-cm with the Parkes telescope have been combined with measurements of a variety of ultraviolet absorption lines, obtained with the International Ultraviolet Explorer satellite, to give the most detailed picture yet of the chemical composition of the gas between the Galaxy and the LMC. Finally, photographic monitoring of the light echo of SN 1987A over the last two years has provided a three-dimensional view of the interstellar environment in which SN 1987A exploded, complementing vividly the information deduced from the spectroscopic results.

scholarly journals 3D MPRAGE improves classification of cortical lesions in multiple sclerosis

2008 ◽  
Vol 14 (9) ◽  
pp. 1214-1219 ◽  
Author(s):  
F Nelson ◽  
A Poonawalla ◽  
P Hou ◽  
JS Wolinsky ◽  
PA Narayana
Keyword(s):  
Multiple Sclerosis ◽  
White Matter ◽  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Inversion Recovery ◽  
High Signal ◽  
Cortical Lesions ◽  
Rapid Acquisition ◽  
Lesion Morphology

Background Gray matter lesions are known to be common in multiple sclerosis (MS) and are suspected to play an important role in disease progression and clinical disability. A combination of magnetic resonance imaging (MRI) techniques, double-inversion recovery (DIR), and phase-sensitive inversion recovery (PSIR), has been used for detection and classification of cortical lesions. This study shows that high-resolution three-dimensional (3D) magnetization-prepared rapid acquisition with gradient echo (MPRAGE) improves the classification of cortical lesions by allowing more accurate anatomic localization of lesion morphology. Methods 11 patients with MS with previously identified cortical lesions were scanned using DIR, PSIR, and 3D MPRAGE. Lesions were identified on DIR and PSIR and classified as purely intracortical or mixed. MPRAGE images were then examined, and lesions were re-classified based on the new information. Results The high signal-to-noise ratio, fine anatomic detail, and clear gray-white matter tissue contrast seen in the MPRAGE images provided superior delineation of lesion borders and surrounding gray-white matter junction, improving classification accuracy. 119 lesions were identified as either intracortical or mixed on DIR/PSIR. In 89 cases, MPRAGE confirmed the classification by DIR/PSIR. In 30 cases, MPRAGE overturned the original classification. Conclusion Improved classification of cortical lesions was realized by inclusion of high-spatial resolution 3D MPRAGE. This sequence provides unique detail on lesion morphology that is necessary for accurate classification.

AAT Observations of the Interstellar Medium towards SN 1987A

1988 ◽  
Vol 7 (4) ◽  
pp. 527-534 ◽  
Author(s):  
M. Pettini
Keyword(s):  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Large Magellanic Cloud ◽  
High Spectral Resolution ◽  
High Signal ◽  
Interstellar Matter ◽  
Interstellar Clouds ◽  
Sn 1987A ◽  
Light Echoes ◽  
Dimensional Distribution

AbstractThe exceptional brightness of SN 1987A has provided a unique opportunity to probe intervening gas clouds in the disk and halo of our Galaxy and in the Large Magellanic Cloud, as well as intergalactic matter between the two. At the AAO we have exploited this opportunity in two ways: in searches for very weak interstellar features requiring exceptionally high signal-to-noise ratio spectra, and in recording known interstellar lines with unprecedentedly high spectral resolution. We are also monitoring photographically the evolution of the light-echoes to map the three-dimensional distribution of interstellar matter near the supernova. Surprisingly high column densities of million-degree gas have been found in the LMC through the first detection of [Fe X] in absorption. The hot gas may fill the interior of a ‘superbubble’, created by the combined effects of previous supernovae in this active region of star-formation; this cavity may be related to the shells of interstellar matter giving rise to the light-echoes. The ultra-high resolution observations, which required the rapid construction of a dedicated new spectrograph, were successful in resolving the hyperfine structure of the sodium D lines in several interstellar clouds. This implies that the clouds are at temperatures of at most 170 K and have internal turbulent velocities of no more than 0.3 km s−1, even though some are moving with high velocities relative to the Sun.

Three-Dimensional Optical Bit Memory in Sm(DBM)3Phen-Doped and Un-Doped Poly(methyl methacrylate)

2011 ◽  
Vol 284-286 ◽  
pp. 2251-2254
Author(s):  
Zhao Gang Nie ◽  
Xin Zhong Li ◽  
Yu Ping Tai ◽  
Ki Soo Lim ◽  
Myeongkyu Lee
Keyword(s):  
Refractive Index ◽  
Methyl Methacrylate ◽  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Pulsed Laser ◽  
High Signal ◽  
Signal To Noise ◽  
Fluorescent Signal ◽  
Poly Methyl Methacrylate ◽  
Noise Ratio

The feasibility of three-dimensional optical bit memory is demonstrated by using the change of fluorescence and refractive index in Sm(DBM)3Phen-doped and un-doped Poly(methyl methacrylate). After a femtosecond pulsed laser irradiation, a refractive-index bit and a fluorescent bit can be formed at the same position inside the bulk sample. Multilayer patterns recorded by tightly focusing the pulsed laser beam were read out by a reflection-type fluorescent confocal microscope, which can detect the reflection signal and also the fluorescent signal of the stored bits. The signal-to-noise ratio via the two retrieval modes was compared as a function of recording depth. The stored bits were retrieved with a high signal-to-noise ratio in the absence of any crosstalk and the detection of the fluorescent signal enables retrieval of the stored bits with a higher S/N ratio.

scholarly journals Chemical Imaging of Microstructure of Chickpea Seed Tissue within a Cellular Dimension using Synchrotron Infrared Microspectroscopy: A Preliminary Study

2020 ◽  
Author(s):  
Xin Feng ◽  
Na Liu ◽  
Peiqiang Yu
Keyword(s):  
Spatial Resolution ◽  
Cross Sections ◽  
Signal To Noise Ratio ◽  
Chemical Imaging ◽  
Cellular Level ◽  
High Signal ◽  
Chemical Information ◽  
Signal To Noise ◽  
Infrared Microspectroscopy ◽  
Chemical Distribution

Abstract Background: Synchrotron radiation-based infrared microspectroscopy (SR-IMS) is a non-destructive bioanalytical technique with a high signal to noise ratio and high ultra-spatial resolution (3-10µm). It is capable to explore the microstructures of plant tissues in a chemical sense and provide information on the composition, structure, and distribution of chemical compounds/ functional groups. The objective of this study was to illustrate how the SR-IMS can be used to image the internal microstructures of chickpea seed tissue on a cellular level.Methods: Chickpea seeds (CDC Cory) were collected from the Crop Development Center (University of Saskatchewan, Saskatoon, SK). The seed samples were frozen at -20ºC on the object disks in a cryostatic microtome and then were cut into thin cross sections (ca. 8 μm thick). The experiment was carried out on the Mid-Infrared beamline (01B1-1) at the Canadian Light Source (Saskatoon, SK). Results: We obtained the ultra-spatial images of chickpea tissue with pixel-sized increments of imaging steps. The results showed that with the extremely bright synchrotron light, spectra with high signal to noise ratios can be obtained from area as small as 3.3 µm allowing us to observe the seed tissue within a cellular level. Chemical distribution of chickpea such as lipids, protein, and carbohydrates could be mapped, revealing the chemical information of chickpea internal microstructure.Conclusions: In conclusion, SR-IMS can rapidly characterize molecular structure of protein, carbohydrates, and lipids at ultra-spatial resolution.

A Spherically Bent Crystal X-Ray Specteometer with Variable Curvature

1973 ◽  
Vol 17 ◽  
pp. 521-530
Author(s):  
Donald L. Parker
Keyword(s):  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
High Signal ◽  
X Rays ◽  
X Ray ◽  
Bent Crystal ◽  
Variable Curvature ◽  
The Face ◽  
Low Levels ◽  
And Performance

AbstractThe design and performance of a spherically bent crystal x-ray spectrometer with variable curvature are given. A thin crystal with the diffracting planes parallel to the face is mounted on a vacuum chuck consisting of an O-ring in a brass mounting. A controlled partial vacuum is applied behind the crystal to cause spherical deformation of the lattice. Thus, rays from a point source on the focusing circle are diffracted to a line image also on the focusing circle. The differential pressure is automatically varied such that the source-to-crystal and crystal-to-image distances are equal and constant for all Bragg angles and hence the simple θ-2θ motion of a one flat crystal spectrometer is used.The data are accumulated by a scanning proportional counter tube placed behind a vertical slit (perpendicular to the scattering plane) located at the image line. The fixed chord length is 22 cm and the instrument is designed to scan from zero up to 120° 2θ. Crystals are easily interchanged and the automatic vacuum regulator has sufficient flexibility to allow tailoring the spherical bending to crystals of materials of various thicknesses. The resolution is easily adjusted by either the size of the x-ray source or the width of the detector slit. The performance of the spectrometer has been evaluated by characteristic x-rays produced by various samples placed in a demountable x-ray tube. The main advantages of this three-dimensional focusing instrument are the very high signal-to-noise ratio and the very low levels of x-ray flux required.

Broadside wide-angle seismic studies and three-dimensional structure of the crust in the southeast Canadian Cordillera

1997 ◽  
Vol 34 (8) ◽  
pp. 1156-1166 ◽  
Author(s):  
M. J. A. Burianyk ◽  
E. R. Kanasewich ◽  
N. Udey
Keyword(s):  
Signal To Noise Ratio ◽  
Seismic Refraction ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
High Signal ◽  
Canadian Cordillera ◽  
Wide Angle ◽  
Low Velocity ◽  
Seismic Properties ◽  
High Degree

Broadside, or fan, recordings of a Lithoprobe seismic refraction – wide-angle reflection experiment in the southeastern Canadian Cordillera show several features further illuminating the crustal structure beyond that previously derived from SCoRE '90 (Southern Cordillera Refraction Experiment of 1990) in-line data. Analysis of a nearly in-line profile centred on Castlegar, British Columbia, shows lower velocities in the upper crust associated with the Purcell Anticlinorium as well as velocity variations that may have some association with the Purcell fault zone. The depth to Moho is almost 38 km, somewhat deeper and on trend with the structure that has been established farther north. The broadside records show high signal-to-noise ratio PmP arrivals (i.e., reflections from the bottom of the crust). These PmP fan picks were analysed in regions away from in-line profiles, providing further measurements of the depth to Moho in the southeastern Cordillera. The analysis of the broadside records combined with the earlier in-line interpretations as well as older crustal seismic measurements make up a relatively high resolution database, compared with most other regions in Canada, from which we have generated maps of depth to Moho and average crustal velocity in the southeastern Cordillera of Canada. The maps show thin, low-velocity crust over much of the region and indicate a high degree of correlation between current crustal seismic properties and regional isotherms.

Using micro-MRI to watch development live and in 3-D

1995 ◽  
Vol 53 ◽  
pp. 90-91
Author(s):  
R. E. Jacobs ◽  
J. Allman ◽  
A. Barr ◽  
S. E. Fraser ◽  
T. Meade
Keyword(s):  
Spatial Resolution ◽  
Temporal Resolution ◽  
Biological Samples ◽  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Clinical Tool ◽  
Signal To Noise ◽  
Mr Image ◽  
Contrast Mechanisms ◽  
Physical Effects

The ability of MRI to provide three dimensional images of thick opaque samples in a noninvasive manner has made it an extremely important clinical tool. In addition, the large number of types of contrast mechanisms in a MR experiment offer the clinician and research scientist the possibility of adapting the image contrast to fit the problem of interest. While typical resolutions employed clinically are on the order of a millimeter, the notion of using MRI at microscopic resolutions arose early in the development of this technique. Spatial resolution in biological samples is typically limited by a number of physical effects as well as signal-to-noise ratio (S/N) considerations. Estimates of the theoretical limits of resolution in the MR image arising from these phenomena range from 2 to 0.5 micron. The practical spatial resolution is currently determined by the S/N which is often limited by the amount of time available to actually acquire the image (i.e. the temporal resolution).

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