Spatial Distribution of Dialysate in Patients and its Implications to Intradialysate Diffusion

2002 ◽  
Vol 22 (6) ◽  
pp. 698-704 ◽  
Author(s):  
Brian A. Hills ◽  
Seamus Birch ◽  
John R. Burke ◽  
Anthony C. LaMont
Keyword(s):  
Spatial Distribution ◽  
Peritoneal Dialysis ◽  
Spatial Information ◽  
Three Dimensional ◽  
Bulk Diffusion ◽  
Ct Scanning ◽  
Effective Area ◽  
Pelvic Cavity ◽  
Ct Scanner ◽  
Computed Tomographic

Objective To visualize and quantify the spatial distribution of dialysate in patients on continuous ambulatory peritoneal dialysis (CAPD) and, hence, estimate diffusion times for fluid “pockets” wherever intradialysate concentration gradients may not be dissipated by convective currents. Design Contrast medium was added to the dialysate of three supine CAPD patients before an exchange prior to computed tomographic (CT) scanning. Spatial information in the CT scanner was then downloaded to other computers and processed to produce impressive three-dimensional models of dialysate distribution using “wire frame technology.” Results Models differed between patients but all demonstrated pooling of dialysate in the paracolic gutters, subphrenic space, and, especially, in the pelvic cavity. Some pockets of fluid were almost isolated. Quantitatively, the models can account for over 80% of the volume of the exchange (2.5 L), displaying an effective area of contact of 913 – 1450 cm2 between parietal peritoneum and dialysate. This amounts to only 11% – 21% of the anatomic area, again emphasizing the uneven distribution of dialysate. Ignoring very thin (< 0.1 mm) films of dialysate, the bulk (80%) had mean thicknesses ranging from 1.6 to 1.9 cm. Transcendental equations for bulk diffusion were then applied to these findings to determine a theoretical time for urea of about 2 – 3 hours to half-saturation, or 5 – 7 hours to 80% saturation, in the absence of convective currents. Conclusions The distribution of dialysate within the peritoneal cavity is very uneven, resulting in long diffusion times in fluid pockets wherever convective currents may be minimal. Hence, intradialysate diffusion should not be ignored when modeling peritoneal dialysis.

scholarly journals Vehicle Spatial Distribution and 3D Trajectory Extraction Algorithm in a Cross-Camera Traffic Scene

Sensors ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 6517
Author(s):  
Xinyao Tang ◽  
Huansheng Song ◽  
Wei Wang ◽  
Yanni Yang
Keyword(s):  
Spatial Distribution ◽  
Spatial Information ◽  
Three Dimensional ◽  
Physical Space ◽  
Extraction Methods ◽  
Geometric Constraints ◽  
Panoramic Image ◽  
Trajectory Data ◽  
Comparison Algorithms ◽  
Bounding Boxes

The three-dimensional trajectory data of vehicles have important practical meaning for traffic behavior analysis. To solve the problems of narrow visual angle in single-camera scenes and lack of continuous trajectories in 3D space by current cross-camera trajectory extraction methods, we propose an algorithm of vehicle spatial distribution and 3D trajectory extraction in this paper. First, a panoramic image of a road with spatial information is generated based on camera calibration, which is used to convert cross-camera perspectives into 3D physical space. Then, we choose YOLOv4 to obtain 2D bounding boxes of vehicles in cross-camera scenes. Based on the above information, 3D bounding boxes around vehicles are built with geometric constraints which are used to obtain projection centroids of vehicles. Finally, by calculating the spatial distribution of projection centroids in the panoramic image, 3D trajectories of vehicles are extracted. The experimental results indicate that our algorithm can effectively complete vehicle spatial distribution and 3D trajectory extraction in various traffic scenes, which outperforms other comparison algorithms.

scholarly journals Simulation of the Effect of Coal Microstructures on the Macroscopic Mechanical Behavior

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Yu Fu ◽  
Zhongliang Feng
Keyword(s):  
Spatial Distribution ◽  
Three Dimensional ◽  
Ct Scanning ◽  
Confining Pressure ◽  
Mineral Matter ◽  
Equivalent Diameter ◽  
Box Dimension ◽  
Distribution Characteristics ◽  
Two Phase ◽  
Mineral Structure

This paper investigates the influence of mineral structure on macromechanical behavior of coal under different loading conditions using X-ray CT scanning experimental and numerical methods. The three-dimensional (3D) reconstruction of coal was conducted to assess the spatial distribution characteristics of the mineral structure by AVIZO software. Based on fractal box dimension (BCD) and equivalent diameter, the mineral structures were quantitatively characterized. The 3D finite element models with three distribution characteristics of minerals were built, and the model was considered as a random heterogeneous two-phase material composed of coal matrix and mineral matter. The results show that the frequency of mineral structures decreases with the increase of equivalent diameter in the coal sample. The BCD of the original mineral structure in coal is greater than 2, but the BCD of each part of the minerals divided based on the screening principle is less than 2. Under uniaxial conditions, the elastic modulus, peak strength, and residual strength of coal are monotonically increasing with the size of the mineral structure. The larger the mineral structure size and the more complex the distribution are, the greater the area of stress concentration and the more uniformity the distribution will be. The failure (plasticity) first occurred at the interface between the matrix and the mineral, and the failure zone is significantly different due to the influence of different mineral structures. Under confining pressure, the presence of mineral structure decreases the brittleness of coal, and the variation of brittleness is related to the size and spatial distribution of mineral structures. The fitting relationship between confining pressure and brittleness index is linear, and the correlation coefficient exceeds 0.95.

StyroStone: A protocol for scanning and extracting three-dimensional meshes of stone artefacts using Micro-CT scanners v1

2021 ◽  
Author(s):  
Dominik Göldner ◽  
Fotios Alexandros Karakostis ◽  
Armando Falcucci
Keyword(s):  
Three Dimensional ◽  
Computation Time ◽  
Ct Scanning ◽  
3D Models ◽  
Stone Tools ◽  
Surface Model ◽  
Micro Ct ◽  
Ct Scanner ◽  
Micro Computed Tomography ◽  
Ct Scanners

This protocol presents the first detailed step-by-step pipeline for the 3D scanning and post processing of large batches of lithic artefacts using a micro-computed tomography (micro-CT) scanner (i.e., a Phoenix v-tome-x S model by General Electronics MCC, Boston MA) and an Artec Space Spider scanner (Artec Inc., Luxembourg). This protocol was used to scan and analyze ca. 700 lithic artefacts from the Protoaurignacian layers at Fumane Cave in north-eastern Italy (Falcucci et al., in preparation). For this study several costly scanners and proprietary software packages were employed. Although it is not easy to find a low-budget alternative for the scanners, it is possible to use free and open-source software programs, such as 3D-Slicer (https://www.slicer.org/) or MorphoDig (https://morphomuseum.com/morphodig), to process CT data as well as MeshLab (Cignoni et al. 2008) to interact with the 3D models in general. However, if alternative software is used, the steps and their order described in this protocol might diverge significantly. A cost-effective alternative to create 3D models is digital photogrammetry using commercial cameras and freely available software like Meshroom (https://alicevision.org). Although photogrammetry is an affordable technique to create accurate 3D models of objects, this method might not be useful when scanning large batches of artefacts, as it will require a lot of computation time and processing capacity. Likewise, it could be difficult to generate accurate 3D models of very small and/or detailed tool shapes using 3D surface scanners because stone tools are often much smaller than the recommended minimum field of view. Similarly, the resolution of conventional medical CT scanners might not be sufficient to capture minor details of stone tools, such as the outline or dorsal scars. Thus, high-resolution micro-CT technology is the only reliable way to accurately capture the overall morphology of small stone tools. This protocol aims at providing the first detailed procedure dedicated to the scanning of small lithic implements for further three-dimensional analysis. Note that some of the steps must be repeated at different working stages throughout this protocol. In cases where a task must be done in the exact same way as described in a previous step, a reference to that step is provided. When slight changes were made, the step was modified and reported entirely. This protocol contains a few red and green colours (e.g., arrows or within-program colours) which might be perceived differently by people with dyschromatopsia. However, the display of these colours has been kept to a minimum. We recommend the reader to go over the entire protocol carefully, even if only some specific parts are required. A few points are in fact interdependent, and some of them must be applied simultaneously. Content: Part 1 – Styrofoam preparation Part 2 – Micro-CT scanning Part 3 – 3D model extraction of CT scanned stone artifacts using Avizo Part 4 – Cropping extracted surface model to separate Face A and B in Artec Studio Part 5 – Cropping Face A to separate the lines in Artec Studio Part 6 – Cropping each stone artefact from the lines in Artec Studio Part 7 – Virtually control measurements in MeshLab Part 8 – Artec scanning of larger artifacts Part 9 – Export meshes as non-binary ply models for successive analysis in geomorph Three-dimensional example (in ply format) of the effectivity of the StyroStone Protocol: You can download an example of one Styrofoam line in 3D obtained using our protocol to appreciate the result that can be achieved. We have selected a line where objects are characterized by different metric and morphological attributes. Notice the retouching well visible in the last five smaller artifacts (counting from the left when artifact are oriented with the dorsal face in front of the observer and the butt down), as well as the platforms and bulbs of all artifacts. For more information and examples, feel free to contact us!

scholarly journals Assessment of Common Scab-Inducing Pathogen Effects on Potato Underground Organs Via Computed Tomography Scanning

2008 ◽  
Vol 98 (10) ◽  
pp. 1118-1125 ◽  
Author(s):  
L. Han ◽  
P. Dutilleul ◽  
S. O. Prasher ◽  
C. Beaulieu ◽  
D. L. Smith
Keyword(s):  
Computed Tomography ◽  
Common Scab ◽  
Surrounding Medium ◽  
Three Dimensional ◽  
Structural Complexity ◽  
Ct Scanning ◽  
Root Systems ◽  
Bacterial Disease ◽  
Ct Scanner ◽  
Computed Tomography Scanning

Common scab caused by Streptomyces scabies is a major bacterial disease of potato (Solanum tuberosum). Its best known symptom is superficial lesions on the surface of progeny potato tubers, observed at harvesting. In this study, effects of S. scabies on space occupancy by underground organs and on structural complexity of root systems are investigated during growth via computed tomography (CT) scanning. Two groups of potato plants were grown in a greenhouse in middle-sized plastic pots. Using a high-resolution X-ray CT scanner formerly used for medical applications, their underground organs and surrounding medium (sieved and autoclaved homogeneous sand) were submitted to CT scanning 4, 6, and 8 weeks after planting. For one group, sand was inoculated with the common scab-inducing pathogen (S. scabies EF-35) at potting. Space occupancy by underground organs was estimated via curve fitting applied to histograms of CT scan data, while three-dimensional skeletal images were used for fractal analysis. Root systems of diseased plants were found to be less complex than those of healthy plants 4 weeks after planting, and the relative growth rates derived from space occupancy measures were of different sign between the two groups from week 4 to week 8.

Management of Fractures of the Thoracolumbar and Lumbar Spine

Neurosurgery ◽  
1981 ◽  
Vol 8 (5) ◽  
pp. 555-561 ◽  
Author(s):  
Quentin J. Durward ◽  
Joseph F. Schweigel ◽  
Philip Harrison
Keyword(s):  
Lumbar Spine ◽  
Neurological Deficit ◽  
Spinal Injury ◽  
Ct Scanning ◽  
Fracture Dislocation ◽  
Poor Correlation ◽  
Ct Scanner ◽  
Injury Site ◽  
Computed Tomographic ◽  
Bone Fragments

Abstract Eleven cases of fracture or fracture/dislocation of the thoracolumbar or lumbar spine were studied to determine the effectiveness of three methods of management of the injuries. Ten of the patients had a neurological deficit as well as a spinal injury. All cases were studied by computed tomographic (CT) scanning of the injury site before and after treatment. CT scanning was found to be superior to linear tomography in determining the degree of canal compromise by bone at the injury site. Eight patients underwent operation, with the aims of achieving spinal stability in unstable injuries and of decompressing neural structures. These 8 patients had received Harrington distraction instrumentation (HDI) as an initial procedure. In those patients with fracture/dislocations from flexion-rotation injuries and canal compromise resulting from bony malalignment, reduction of the fracture/dislocation by HDI resulted in stabilization of the spine and increase of the open canal area at the injury site. However, in those patients with canal compromise resulting from bursting fractures with retropulsed bone fragments, HDI did not reduce the bone fragments. Removal of the anterior vertebral body and the bone fragments. however, did result in significant improvement of the canal dimensions. A poor correlation was found between the degree of canal compromise as measured by the CT scanner and the resulting neurological deficit. Reasons for this are presented. Six of the 10 neurologically compromised patients, including 2 patients with stable bursting injuries and retropulsed bone fragments treated conservatively, had improved one grade on Frankel's classification by 3 months after injury. The rate and degree of recovery were not related to the degree of canal decompression achieved at operation.

Micron-scale phenotyping quantification and three-dimensional microstructure reconstruction of vascular bundles within maize stalks based on micro-CT scanning

2017 ◽  
Vol 44 (1) ◽  
pp. 10 ◽  
Author(s):  
Jianjun Du ◽  
Ying Zhang ◽  
Xinyu Guo ◽  
Liming Ma ◽  
Meng Shao ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Spatial Configuration ◽  
Three Dimensional ◽  
Ct Scanning ◽  
Phenotypic Traits ◽  
Vascular Bundles ◽  
Micro Computed Tomography ◽  
Cross Sectional ◽  
Imaging Device ◽  
Maize Stalks

Vascular bundles within maize (Zea mays L.) stalks play a key role in the mechanical support of plant architecture as well as in water and nutrient transportation. Convenient and accurate phenotyping of vascular bundles may help phenotypic identification of germplasm resources for breeding. Based on practical sample preparation procedures for maize stalks, we acquired serials of cross-sectional images using a micro-computed tomography (CT) imaging device. An image processing pipeline dedicated to the phenotyping of vascular bundles was also developed to automatically segment and validate vascular bundles from the cross-sectional images of maize stalks, from which phenotypic traits of vascular bundles, i.e. number, area, and spatial distribution, were calculated. More profound quantification of spatial distribution was given as area ratio of vascular bundles, which described the distribution of vascular bundles associated with the centroid of maize stalks. In addition, three-dimensional visualisation was performed to reveal the spatial configuration and distribution of vascular bundles. The proposed method significantly improves computation accuracy for the phenotypic traits of vascular bundles compared with previous methods, and is expected to be useful for illustrating relationships between phenotypic traits of vascular bundles and their function.

Use of Three-dimensional Printing in the Development of Optimal Cardiac CT Scanning Protocols

2020 ◽  
Vol 16 (8) ◽  
pp. 967-977
Author(s):  
Zhonghua Sun
Keyword(s):  
Cardiovascular Disease ◽  
Cardiac Computed Tomography ◽  
Three Dimensional ◽  
Ct Scanning ◽  
Aortic Diseases ◽  
Clinical Value ◽  
Three Dimensional Printing ◽  
Doctor Patient Communication ◽  
Medical Education And Training ◽  
3D Printed

Three-dimensional (3D) printing is increasingly used in medical applications with most of the studies focusing on its applications in medical education and training, pre-surgical planning and simulation, and doctor-patient communication. An emerging area of utilising 3D printed models lies in the development of cardiac computed tomography (CT) protocols for visualisation and detection of cardiovascular disease. Specifically, 3D printed heart and cardiovascular models have shown potential value in the evaluation of coronary plaques and coronary stents, aortic diseases and detection of pulmonary embolism. This review article provides an overview of the clinical value of 3D printed models in these areas with regard to the development of optimal CT scanning protocols for both diagnostic evaluation of cardiovascular disease and reduction of radiation dose. The expected outcomes are to encourage further research towards this direction.

scholarly journals A Microcomputed Tomographic Evaluation of Root Canal Morphology of Maxillary Second Premolars in a Pakistani Cohort

2021 ◽  
Vol 11 (11) ◽  
pp. 5086
Author(s):  
Mazen F. Alkahtany ◽  
Saqib Ali ◽  
Abdul Khabeer ◽  
Shafqat A. Shah ◽  
Khalid H. Almadi ◽  
...  
Keyword(s):  
Root Canal ◽  
Three Dimensional ◽  
Ct Scanning ◽  
Micro Ct ◽  
Single Root ◽  
Root Canal Morphology ◽  
Spss Software ◽  
Variable Morphology ◽  
Canal Morphology

This study aimed to investigate variations in the root canal morphology of maxillary second premolar (MSP) teeth using microcomputed tomography (micro-CT). Sixty (N = 60) human extracted MSPs were collected and prepared for micro-CT scanning. The duration for scanning a single sample ranged between 30 and 40 min and a three-dimensional (3-D) image was obtained for all the MSPs. The images were evaluated by a single observer who recorded the canal morphology type, number of roots, canal orifices, apical foramina(s), apical delta(s), and accessory canals. The root canal configuration was categorized in agreement with Vertucci’s classification, and any configuration not in agreement with Vertucci’s classification was reported as an “additional canal configuration”. Descriptive statistics (such as mean percentages) were calculated using SPSS software. The most common types agreeing with Vertucci’s classification (in order of highest to lowest incidence) were types I, III, V, VII, II, and VI. The teeth also exhibited four additional configurations that were different from Vertucci’s classification: types 2-3, 1-2-3, 2-1-2-1, and 1-2-1-3. A single root was found in 96.7% and the majority of the samples demonstrated two canals (73.3%). Further, 80% of the teeth showed one canal orifice. The number of apical foramina’s in the teeth was variable, with 56.7% having solitary apical foramen. The accessory canal was found in 33.3%, and apical delta was found in only 20% of the samples. Variable morphology of the MSPs was detected in our study. The canal configuration most prevalent was type 1; however, the results also revealed some additional canal types.

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