The effect of storage time and repeated measurements on the elastic properties of isolated porcine aortas using high resolution x-ray CT

1998 ◽  
Vol 76 (4) ◽  
pp. 451-456 ◽  
Author(s):  
Andrew O Medynsky ◽  
David W Holdsworth ◽  
Marvin H Sherebrin ◽  
Richard N Rankin ◽  
Margot R Roach
Keyword(s):  
Elastic Modulus ◽  
Storage Time ◽  
Repeated Measurements ◽  
Ct Scanner ◽  
Imaging Studies ◽  
X Ray ◽  
X Ray Computed ◽  
Significant Change ◽  
Humidified Air ◽  
Ct Measurement

A Laboratory CT scanner with a resolution of (0.1 mm)3 wasused to determine if storage up to 7 days in saline at 4°C and (or) repeated measurementswould alter the compliance, C, and incremental elastic modulus, Einc,of isolated porcine aortas. All specimens were obtained fresh, made pressure-tight, and thenmounted in the scanner, with humidified air used to produce adequate x-ray contrast. Thespecimens were imaged at pressures of 4, 8, 12, 16, 20, and 24 kPa, and vessel measurementswere then obtained with a computerized technique and analyzed. Seven thoracic aortas werestudied on days 0, 3, 5, and 7, with a significant change (p < 0.05) in compliance firstoccurring after three imaging studies (i.e., day 5). Compliance of the fresh thoracic aortas (mean± SD) was 0.90 ± 0.28 mm/kPa at 14.4 kPa and 0.85 ± 0.31 mm/kPa at 22.5 kPa.Six thoracic aortas were studied only on days 0 and 6 with no intermediate measurements. Theyshowed no change in either compliance (0.88 ± 0.07 mm/kPa at 14.4 kPa and 0.64 ±0.09 mm/kPa at 22.5 kPa) or Einc (0.46 ± 0.05 MPa at14.4 kPa and 0.88 ± 0.15 MPa at 22.5 kPa) from day 0 to day 6. Thus, number ofmeasurements rather than time appears to be the important factor. Six abdominal aortas werestudied similarly but on days 0, 3, and 6. No significant change occurred in compliance (0.15 ±0.06 mm/kPa at 14.4 kPa and 0.032 ± 0.026 mm/kPa at 22.5 kPa) butEinc showed a change, possibly due to their viscoelastic properties. Weconclude that this nondestructive CT measurement method is suitable for repeated studies onporcine thoracic aortas, but not abdominal aortas, if the measurement involves two consecutiveimaging sessions separated by no more than 6 days.Key words: compliance, incremental elastic modulus, porcine aorta,x-ray computed tomography.

scholarly journals The use of sodium polytungstate as an X-ray contrast agent to reduce the beam hardening artifact in hydrological laboratory experiments

2013 ◽  
Vol 61 (4) ◽  
pp. 347-352 ◽  
Author(s):  
Yoshito Nakashima
Keyword(s):  
Contrast Agent ◽  
Laboratory Experiments ◽  
Source Spectrum ◽  
Ct Scanner ◽  
Beam Hardening ◽  
Two Phase ◽  
X Ray ◽  
X Ray Computed ◽  
Element Bearing ◽  
Sodium Polytungstate

Abstract Iodine is conventionally used as a contrast agent in hydrological laboratory experiments using polychromatic X-ray computed tomography (CT) to monitor two-phase Darcy flow in porous geological media. Undesirable beam hardening artifacts, however, render the quantitative analysis of the obtained CT images difficult. CT imaging of porous sand/bead packs saturated with iodine and tungsten-bearing aqueous solutions, respectively, was performed using a medical CT scanner. We found that sodium polytungstate (Na6H2W12O40) significantly reduced the beam hardening compared with potassium iodide (KI). This result is attributable to the location of the K absorption edge of tungsten, which is nearer to the peak of the polychromatic X-ray source spectrum than that of iodine. As sodium polytungstate is chemically stable and less toxic than other heavy element bearing compounds, we recommend it as a promising contrast agent for hydrological CT experiments.

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.

Experimental Flow Measurements of a Spouted Bed Using Pressure Transducer and X-Ray CT Scanner

2011 ◽  
Vol 9 (1) ◽  
Author(s):  
Bangyou Wu ◽  
Ana Orta ◽  
Apostolos Kantzas
Keyword(s):  
Pressure Fluctuation ◽  
Ct Scanning ◽  
Ct Scanner ◽  
Gas Velocity ◽  
Spouted Bed ◽  
Flow Measurements ◽  
X Ray ◽  
Wall Pressure Fluctuation ◽  
Column Wall ◽  
X Ray Computed

Flow behaviour of an air-glass bead spouted bed (20 cm diameter, 1.31 m high) was investigated using wall pressure fluctuation measurements and X-ray Computed Tomography (CT) scanning. Spout shape, spout dimension, fountain shape and fountain height were visualized from CT images. Statistical and spectral analyses were applied to pressure fluctuation series measured along the column wall. Local and global gas-solids flow dynamics were compared. Gas velocity greatly affects hydrodynamics of the spout bed. A stable spouting regime was identified. This study enhances the understanding of gas-solid flow patterns and provides detail hydrodynamics for further modelling work.

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.

scholarly journals Computer Based X-Ray Computed Tomography Training System for Engineering Education

2017 ◽  
Vol 9 (3-2) ◽  
Author(s):  
Muhammad Hanif Ramlee ◽  
Jasmy Yunus ◽  
Eko Supriyanto
Keyword(s):  
Computed Tomography ◽  
Imaging Modality ◽  
Training System ◽  
Radiation Hazard ◽  
Ct Scanner ◽  
Virtual Instrumentation ◽  
X Ray ◽  
Computer Based ◽  
X Ray Computed ◽  
Working Principle

X-ray computed tomography (called CT) scanner is a powerful and widely used medical imaging modality in the hospital. The CT machine is very expensive and it can produce dangerous radiation when a person operates the machine. This makes it difficult for biomedical engineers and radiographer students to learn its working principles. In order to overcome this problem, a computer based CT scanner trainer system has been developed. The system is implemented using National Instrument’s Laboratory Virtual Instrumentation Engineering Workbench (LabVIEW). At the beginning, it was started with the studying of existing CT scan machine. After gathering information, development process continued to develop generator component, x-ray tube subsystem, detector subsystem, imaging subsystem, and finally is reconstruction subsystem. The trainer system that has been developed is able to be used to train students on how to use CT scanner especially to get high quality images with lowest possible radiation. This will help biomedical engineers and radiographer students to have a better understanding of CT scanner in term of its working principle and to prevent radiation hazard during the learning process.

scholarly journals PET-CT: Radiological signs in Sarcoidosis-Lymphoma Syndrome

2020 ◽  
pp. 45-50
Author(s):  
Brunela Ronchi ◽  
Gustavo Peña ◽  
Muriel Henriquez
Keyword(s):  
Computed Tomography ◽  
Positron Emission Tomography ◽  
Clinical Case ◽  
Emission Tomography ◽  
Ct Scanner ◽  
X Ray ◽  
Positron Emission ◽  
Pet Ct ◽  
X Ray Computed ◽  
Complex Cases

Sarcoidosis-lymphoma syndrome is a clinical entity that can be diagnosed in different ways. Some of them are atypical. For these complex cases, positron emission tomography (PET) combined with an X-ray computed tomography (CT) scanner (PET-CT) is definitive for subsequent biopsy. A clinical case of our group is presented, which leads to the corresponding revision / update.

scholarly journals Building a 3D Computed Tomography Scanner From Surplus Parts

2014 ◽  
Vol 48 (2) ◽  
pp. 142-151 ◽  
Author(s):  
Mark A. Haidekker
Keyword(s):  
Computed Tomography ◽  
Cost Savings ◽  
Ct Scanner ◽  
Research Groups ◽  
Biomedical Sciences ◽  
Imaging Studies ◽  
X Ray ◽  
Ct Technology ◽  
Surplus Parts

Computed tomography (CT) scanners are expensive imaging devices, often out of reach for small research groups. Designing and building a CT scanner from modular components is possible, and this article demonstrates that realization of a CT scanner from components is surprisingly easy. However, the high costs of a modular X-ray source and detector limit the overall cost savings. In this article, the possibility of building a CT scanner with available surplus X-ray parts is discussed, and a practical device is described that incurred costs of less than $16,000. The image quality of this device is comparable with commercial devices. The disadvantage is that design constraints imposed by the available components lead to slow scan speeds and a resolution of 0.5 mm. Despite these limitations, a device such as this is attractive for imaging studies in the biological and biomedical sciences, as well as for advancing CT technology itself.

scholarly journals Elucidating the Effect of Accelerated Carbonation on Porosity and Mechanical Properties of Hydrated Portland Cement Paste Using X-Ray Tomography and Advanced Micromechanical Testing

Micromachines ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 471 ◽  
Author(s):  
Hongzhi Zhang ◽  
Claudia Romero Rodriguez ◽  
Hua Dong ◽  
Yidong Gan ◽  
Erik Schlangen ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Cement Paste ◽  
Total Porosity ◽  
Correlation Study ◽  
Accelerated Carbonation ◽  
X Ray ◽  
Micromechanical Properties ◽  
Hydrated Cement Paste ◽  
X Ray Computed ◽  
Beam Bending

Carbonation of hydrated cement paste (HCP) causes numerous chemo–mechanical changes in the microstructure, e.g., porosity, strength, elastic modulus, and permeability, which have a significant influence on the durability of concrete structures. Due to its complexity, much is still not understood about the process of carbonation of HCP. The current study aims to reveal the changes in porosity and micromechanical properties caused by carbonation using micro-beam specimens with a cross-section of 500 μm × 500 μm. X-ray computed tomography and micro-beam bending tests were performed on both noncarbonated and carbonated HCP micro-beams for porosity characterization and micromechanical property measurements, respectively. The experimental results show that the carbonation decreases the total porosity and increases micromechanical properties of the HCP micro-beams under the accelerated carbonation. The correlation study revealed that both the flexural strength and elastic modulus increase linearly with decreasing porosity.

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