Numerical modelling based saturation conductivity estimation uncertainty – influence of the quality of the pore space geometry representation based on X-ray CT images

2020 ◽  
Author(s):  
Krzysztof Lamorski ◽  
Bartłomiej Gackiewicz ◽  
Cezary Sławiński ◽  
Shao-Yiu Hsu ◽  
Liang-Cheng Chang
Keyword(s):  
Ct Scan ◽  
Cell Size ◽  
Stokes Equations ◽  
Pore Space ◽  
Ct Scanning ◽  
Ct Images ◽  
X Ray ◽  
Space Geometry ◽  
The Impact ◽  
Mesh Cell

<p>X-ray computational tomography (CT) is becoming more and more popular research tool in geosciences. Estimation of the saturated conductivity of the porous media based on X-ray CT images is an example of its application. In case of simulations for the pore media, which are approximated by the very complicated meshes, problems might arise when mesh does not follow the shape of pore-space ideally, which may happen due to limitations imposed (e.g. due to some technical constraints) on minimum mesh cell size which usually is bigger than CT scan resolution used for determination of the pore space. If this is the case, the mesh can’t be generated properly in the narrow regions of the pore-space.</p><p>The work tries to quantify the impact of the limited mesh quality on estimation of the saturated conductivity coefficient. Four mesh generation parameters, resulting in different sizes of the minimum mesh cell size, were compared. For comparison five different pore media (three sandpacks prepared from different sand fractions and two types of sandstones) were used, all of them were used in two repetitions which resulted in 10 studied samples in total. First samples were X-ray CT scanned with resolution 2um. Than images were thresholded to obtain information about pore-space. In the next step, for all of 10 3D images of pore-space, mesh was generated in four repetitions differing with minimum mesh cell size: 2.56, 3.41, 5.12 and 10.25 times greater than voxel size used for CT scanning.</p><p>Saturated conductivity was simulated based on prepared meshes using finite volume based solver of the Navier-Stokes equations. Estimated for each sample saturated conductivity differed from 12% for coarse media to 200% for fine grain media for different numerical meshes representing with different accuracy pore space geometry.</p><p>Based on samples studied, one may conclude that for optimal results of saturated conductivity numerical estimation, the smallest numerical mesh’s cell size should be of the level of pore media CT scan resolution.  </p><p> </p><p>Acknowledgments:</p><p>This work was partially supported by a grant from the Polish National Centre for Research and Development within the contract no.: PL-TW/IV/5/2017.</p>

scholarly journals The impact of tumour regression in locally advanced carcinoma cervix during external beam radiotherapy and the need for adaptive planning

2016 ◽  
Keyword(s):  
Ct Scan ◽  
Locally Advanced ◽  
Target Volume ◽  
Ct Images ◽  
Tumour Regression ◽  
Target Coverage ◽  
Carcinoma Cervix ◽  
Advanced Carcinoma ◽  
The Impact ◽  
Planning Ct

Aim: To study the impact of tumour regression occurring during IMRT for locally advanced carcinoma cervix and study dose distribution to target volume and OARs and hence the need for any replanning. Materials and Methods: 40 patients undergoing IM-IGRT and weekly chemotherapy were included in the study. After 36 Gy, a second planning CT-scan was done and target volume and OARs were recontoured. First plan (non-adaptive) was compared with second plan (adaptive plan) to evaluate whether it would still offer sufficient target coverage to the CTV and spare the OARs after having delivered 36 Gy. Finally new plan was created based on CT-images to investigate whether creating a new treatment plan would optimize target coverage and critical organ sparing. To measure the response of the primary tumour and pathologic nodes to EBRT, the differences in the volumes of the primary GTV and nodal GTV between the pretreatment and intratreatment CT images was calculated. Second intratreatment IMRT plans was generated, using the delineations of the intratreatment CT images. The first IMRT plan (based on the first CT-scan or non adaptive plan) was compared with second IMRT plan (based on the second CT-scan or adaptive plan). Results: 35% patients had regression in GTV in the range of 4.1% to 5%, 20% in the range of 1.1%-2%, 15% in the range of 2.1%-3% and 20% in the range of 6%-15%. There was significant mean decrease in GTV of 4.63 cc (p=0.000). There was a significant decrease in CTV on repeat CT done after 36 Gy by 23.31 cc (p=0.000) and in PTV by 23.31 cc (p=0.000). There was a statistically significant increase in CTV D98, CTV D95, CTV D50 and CTV D2 in repeat planning CT done after 36 Gy. There was no significant alteration in OARs doses. Conclusion: Despite tumour regression and increased target coverage in locally advanced carcinoma cervix after a delivery of 36 Gy there was no sparing of OARs. Primary advantage of adaptive RT seems to be in greater target coverage with non-significant normal tissue sparing.

scholarly journals Saturated water conductivity estimation based on X-ray CT images – evaluation of the impact of thresholding errors

2019 ◽  
Vol 33 (1) ◽  
pp. 49-60 ◽  
Author(s):  
Bartłomiej Gackiewicz ◽  
Krzysztof Lamorski ◽  
Cezary Sławiński
Keyword(s):  
Ct Images ◽  
Water Conductivity ◽  
X Ray ◽  
Saturated Water ◽  
The Impact

scholarly journals Reconstruction and Analysis of Tight Sandstone Digital Rock Combined with X-Ray CT Scanning and Multiple-Point Geostatistics Algorithm

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Yun Lei
Keyword(s):  
Pore Space ◽  
Full Range ◽  
Three Dimensional ◽  
Ct Scanning ◽  
Multiple Point ◽  
Tight Sandstone ◽  
Sandstone Sample ◽  
X Ray ◽  
Digital Rock ◽  
Experimental Values

Unconventional rocks such as tight sandstone and shale usually develop multiscale complex pore structures, with dimensions ranging from nanometers to millimeters, and the full range can be difficult to characterize for natural samples. In this paper, we developed a new hybrid digital rock construction approach to mimic the pore space of tight sandstone by combining X-ray CT scanning and multiple-point geostatistics algorithm (MPGA). First, a three-dimensional macropore digital rock describing the macroscopic pore structure of tight sandstone was constructed by micro-CT scanning. Then, high-resolution scanning electron microscopy (SEM) was performed on the tight sandstone sample, and the three-dimensional micropore digital rock was reconstructed by MPGA. Finally, the macropore digital rock and the micropore digital rock were superimposed into the full-pore digital rock. In addition, the nuclear magnetic resonance (NMR) response of digital rocks is simulated using a random walk method, and seepage simulation was performed by the lattice Boltzmann method (LBM). The results show that the full-pore digital rock has the same anisotropy and good connectivity as the actual rock. The porosity, NMR response, and permeability are in good agreement with the experimental values.

scholarly journals Using X-Ray CT Scanning to Study the Failure Mechanism of Concrete under Static and Dynamic Loadings

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Guangyu Lei ◽  
Jichang Han ◽  
Faning Dang
Keyword(s):  
Computed Tomography ◽  
Failure Mechanism ◽  
Static Load ◽  
Ct Scanning ◽  
Ct Images ◽  
X Ray ◽  
Dynamic Loadings ◽  
Ultimate Failure ◽  
X Ray Computed ◽  
Straight Lines

X-ray images can be used to nondestructively monitor the initiation, extension, and combination of cracks in concrete. In this study, real-time X-ray computed tomography (CT) scanning of concrete specimens under static and dynamic loadings was done. The CT images showed the growth, propagation, and penetration of the cracks and showed the ultimate failure of the concrete samples. Analysis of the CT images and CT numbers showed that the failure followed the structure’s areas of weakness under the static load, but for dynamic loading, the cracks formed very rapidly along straight lines through the aggregate.

CNN-based Prediction of COVID-19 using Chest CT Images

2021 ◽  
pp. 2250039
Author(s):  
Tanvi Arora
Keyword(s):  
Ct Scan ◽  
Good Accuracy ◽  
Ct Images ◽  
Chest Ct ◽  
X Ray ◽  
Infected People ◽  
The World ◽  
Severity Of The Disease ◽  
Application Programs ◽  
Chest Ct Scan

The coronavirus disease (COVID-19) pandemic that is caused by the SARS-CoV2 has spread all over the world. It is an infectious disease that can spread from person to person. The severity of the disease can be categorized into five categories namely asymptomatic, mild, moderate, severe, and critical. From the reported cases thus, it has been seen that 80% of the cases that test positive with COVID-19 infection have less than moderate complications, whereas 20% of the positive cases develop severe and critical complications. The virus infects the lungs of an individual, therefore, it has been observed that the X-ray and computed tomography (CT) scan images of the infected people can be used by the machine learning-based application programs to predict the presence of the infection. Therefore, in the proposed work, a Convolutional Neural Network model based upon the DenseNet architecture is being used to predict the presence of COVID-19 infection using the CT scan images of the chest. The proposed work has been carried out using the dataset of the CT images from the COVID CT Dataset. It has 349 images marked as COVID-19 positive and 397 images have been marked as COVID-19 negative. The proposed system can categorize the test set images with an accuracy of 91.4%. The proposed method is capable of detecting the presence of COVID-19 infection with good accuracy using the chest CT scan images of the humans.

Permeability Upscaling for Carbonates From the Pore Scale by Use of Multiscale X-Ray-CT Images

2013 ◽  
Vol 16 (04) ◽  
pp. 353-368 ◽  
Author(s):  
A.. Dehghan Khalili ◽  
J.-Y.. -Y. Arns ◽  
F.. Hussain ◽  
Y.. Cinar ◽  
W.V.. V. Pinczewski ◽  
...  
Keyword(s):  
High Resolution ◽  
Error Bounds ◽  
Pore Space ◽  
Ct Images ◽  
Field Of View ◽  
Fine Scale ◽  
Pore Scale ◽  
Low Resolution ◽  
Coarse Scale ◽  
X Ray

Summary High-resolution X-ray-computed-tomography (CT) images are increasingly used to numerically derive petrophysical properties of interest at the pore scale—in particular, effective permeability. Current micro-X-ray-CT facilities typically offer a resolution of a few microns per voxel, resulting in a field of view of approximately 5 mm3 for a 2,0482 charge-coupled device. At this scale, the resolution is normally sufficient to resolve pore-space connectivity and calculate transport properties directly. For samples exhibiting heterogeneity above the field of view of such a single high-resolution tomogram with resolved pore space, a second low-resolution tomogram can provide a larger-scale porosity map. This low-resolution X-ray-CT image provides the correlation structure of porosity at an intermediate scale, for which high-resolution permeability calculations can be carried out, forming the basis for upscaling methods dealing with correlated heterogeneity. In this study, we characterize spatial heterogeneity by use of overlapping registered X-ray-CT images derived at different resolutions spanning orders of magnitude in length scales. A 38-mm-diameter carbonate core is studied in detail and imaged at low resolution—and at high resolution by taking four 5-mm-diameter subsets, one of which is imaged by use of full-length helical scanning. Fine-scale permeability transforms are derived by use of direct porosity/permeability relationships, random sampling of the porosity/permeability scatter plot as a function of porosity, and structural correlations combined with stochastic simulation. A range of these methods is applied at the coarse scale. We compare various upscaling methods, including renormalization theory, with direct solutions by use of a Laplace solver and report error bounds. Finally, we compare with experimental measurements of permeability at both the small-plug and the full-plug scale. We find that both numerically and experimentally for the carbonate sample considered, which displays nonconnecting vugs and intrafossil pores, permeability increases with scale. Although numerical and experimental results agree at the larger scale, the digital core-analysis results underestimate experimentally measured permeability at the smaller scale. Upscaling techniques that use basic averaging techniques fail to provide truthful vertical permeability at the fine scale because of large permeability contrasts. At this scale, the most accurate upscaling technique uses Darcy's law. At the coarse scale, an accurate permeability estimate with error bounds is feasible if spatial correlations are considered. All upscaling techniques work satisfactorily at this scale. A key part of the study is the establishment of porosity transforms between high-resolution and low-resolution images to arrive at a calibrated porosity map to constrain permeability estimates for the whole core.

scholarly journals A new CT scan methodology to characterize a small aggregation gravel clast contained in a soft sediment matrix

2017 ◽  
Vol 5 (1) ◽  
pp. 199-209 ◽  
Author(s):  
Laurent Fouinat ◽  
Pierre Sabatier ◽  
Jérôme Poulenard ◽  
Jean-Louis Reyss ◽  
Xavier Montet ◽  
...  
Keyword(s):  
Ct Scan ◽  
Ct Scanning ◽  
High Elevation ◽  
X Ray ◽  
The Past ◽  
Erosion Processes ◽  
X Ray Computed ◽  
The Alps ◽  
Non Destructive ◽  
Small Aggregation

Abstract. Over the past decades, X-ray computed tomography (CT) has been increasingly applied in the geosciences community. CT scanning is a rapid, non-destructive method allowing the assessment of relative density of clasts in natural archives samples. This study focuses on the use of this method to explore instantaneous deposits as major contributors to sedimentation of high-elevation lakes in the Alps, such as the Lake Lauvitel system (western French Alps). This lake is located within a very steep valley prone to episodic flooding and features gullies ending in the lake. This variety of erosion processes leads to deposition of sedimentary layers with distinct clastic properties. We identified 18 turbidites and 15 layers of poorly sorted fine sediment associated with the presence of gravels since AD 1880. These deposits are respectively interpreted as being induced by flood and wet avalanche. This constitutes a valuable record from a region where few historical records exist. This CT scan approach is suitable for instantaneous deposit identification to reconstruct past evolution and may be applicable to a wider variety of sedimentary archives alongside existing approaches.

scholarly journals The impact of tumour regression in locally advanced carcinoma cervix during external beam radiotherapy and the need for adaptive planning

2016 ◽  
Author(s):  
Amit Kumar Choudhary
Keyword(s):  
Ct Scan ◽  
Locally Advanced ◽  
Target Volume ◽  
Ct Images ◽  
Tumour Regression ◽  
Target Coverage ◽  
Carcinoma Cervix ◽  
Advanced Carcinoma ◽  
The Impact ◽  
Planning Ct

Aim: To study the impact of tumour regression occurring during IMRT for locally advanced Carcinoma cervix and study dose distribution to target volume and OARs and hence the need for any replanning. Methods and Materials: 40 patients undergoing IM-IGRT and weekly chemotherapy were included in the study. After 36Gy, a second planning CT-scan was done and target volume and OARs were recontoured. First plan (non-adaptive) was compared with second plan (adaptive plan) to evaluate whether it would still offer sufficient target coverage to the CTV and spare the OARs after having delivered 36Gy. Finally new plan was created based on CT-images to investigate whether creating a new treatment plan would optimize target coverage and critical organ sparing. To measure the response of the primary tumour and pathologic nodes to EBRT, the differences in the volumes of the primary GTV and nodal GTV between the pretreatment and intratreatment CT images was calculated. Second intratreatment IMRT plans was generated, using the delineations of the intratreatment CT images. The first IMRT plan (based on the first CT-scan or non adaptive plan) was compared with second IMRT plan (based on the second CT-scan or adaptive plan). Results: 35% patients had regression in GTV in the range of 4.1% to 5%, 20% in the range of 1.1%-2%, 15% in the range of 2.1%-3% and 20% in the range of 6%-15%. There was significant mean decrease in GTV of 4.63cc (p=0.000). There was a significant decrease in CTV on repeat CT done after 36Gy by 23.31cc (p=0.000) and in PTV by 23.31cc (p=0.000). There was a statistically significant increase in CTV D98, CTV D95, CTV D50 and CTV D2 in repeat planning CT done after 36Gy. There was no significant alteration in OARs doses. Conclusion: Despite tumour regression and increased target coverage in locally advanced carcinoma cervix after a delivery of 36Gy there was no sparing of OARs. Primary advantage of adaptive RT seems to be in greater target coverage with non-significant normal tissue sparing.

scholarly journals Morphological Functions with Parallel Sets for the Pore Space of X-ray CT Images of Soil Columns

2014 ◽  
Vol 173 (3) ◽  
pp. 995-1009 ◽  
Author(s):  
F. San José Martínez ◽  
F. J. Muñoz Ortega ◽  
F. J. Caniego Monreal ◽  
F. Peregrina
Keyword(s):  
Pore Space ◽  
Ct Images ◽  
Soil Columns ◽  
X Ray

scholarly journals Prognostic impact of posttransplant FDG PET/CT scan in multiple myeloma

2021 ◽  
Vol 5 (13) ◽  
pp. 2753-2759
Author(s):  
Marcella Kaddoura ◽  
David Dingli ◽  
Francis K. Buadi ◽  
Martha Q. Lacy ◽  
Morie A. Gertz ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Ct Scan ◽  
Prognostic Significance ◽  
Ct Scanning ◽  
Prognostic Impact ◽  
Cell Transplant ◽  
Entire Cohort ◽  
Pet Ct ◽  
The Impact ◽  
Pet Ct Scan

Abstract Multiple myeloma (MM) is a heterogeneous disease that may be evaluated by a broad array of imaging and laboratory techniques to measure disease activity and predict prognosis. Fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) scanning has been shown to be predictive of patient outcomes throughout the disease course. We sought to corroborate these findings by examining the prognostic impact of PET/CT scanning in the posttransplant setting. We retrospectively analyzed PET/CT scans in 229 MM patients receiving an autologous stem cell transplant (ASCT) near day 100, and correlated these findings with time to progression(TTP) and overall survival (OS) to assess the impact of day 100 PET/CT scan findings as an independent prognostic factor. The median OS for the entire cohort was 61.5 months (95% confidence interval [CI], 49-75) and the median TTP was 18.5 months (95% CI, 15.4-21.8). Among patients with abnormal day 100 PET findings (PET+), median TTP was 12.4 months vs 24 months among those with normal PET findings (PET−) (P < .0001). The median OS in the PET+ group was 46 months compared with 99 months in the PET− group (P < .0001). We conclude that an abnormal PET/CT scan near day 100 post-ASCT is predictive of shorter TTP and OS, with prognostic significance retained after adjusting for disease response and other prognostic variables in MM.

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