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Sample records for project bhp reconstructed

  1. Hanford Environmental Dose Reconstruction Project

    International Nuclear Information System (INIS)

    Cannon, S.D.; Finch, S.M.

    1992-10-01

    The objective of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate the radiation doses that individuals and populations could have received from nuclear operations at Hanford since 1944. The independent Technical Steering Panel (TSP) provides technical direction. The project is divided into the following technical tasks. These tasks correspond to the path radionuclides followed from release to impact on humans (dose estimates):Source Terms, Environmental Transport, Environmental Monitoring Data, Demography, Food Consumption, and Agriculture, and Environmental Pathways and Dose Estimates

  2. Hanford Environmental Dose Reconstruction Project

    International Nuclear Information System (INIS)

    Finch, S.M.; McMakin, A.H.

    1991-04-01

    The objective of the Hanford Environmental Dose Reconstruction Project is to estimate the radiation doses that populations could have received from nuclear operations at Hanford since 1944. The project is being managed and conducted by the Pacific Northwest Laboratory (PNL) under the direction of an independent Technical Steering Panel (TSP). The project is divided into the following technical tasks. These tasks correspond to the path radionuclides followed, from released to impact on humans (dose estimates): source terms; environmental transport; environmental monitoring data; demographics, agriculture, food habits; and, environmental pathways and dose estimates

  3. Hanford Environmental Dose Reconstruction Project

    International Nuclear Information System (INIS)

    Finch, S.M.; McMakin, A.H.

    1992-06-01

    The objective of the Hanford Environmental Dose Reconstruction Project is to estimate the radiation doses that individuals and populations could have received from nuclear operations at Hanford since 1944. The project is being managed and conducted by the Battelle Pacific Northwest Laboratories under contract with the Centers for Disease Control. The independent Technical Steering Panel (TSP) provides technical direction. The project is divided into the following technical tasks. These tasks correspond to the path radionuclides followed, from release to impact on humans (dose estimates): source terms; environmental transport; environmental monitoring data; demography, food consumption, and agriculture; environmental pathways and dose estimates

  4. Hanford Environmental Dose Reconstruction Project

    International Nuclear Information System (INIS)

    McMakin, A.H.; Cannon, S.D.; Finch, S.M.

    1992-07-01

    The objective of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate the radiation doses that individuals and populations could have received from nuclear operations at Hanford since 1944. The TSP consists of experts in environmental pathways, epidemiology, surface-water transport, ground-water transport, statistics, demography, agriculture, meteorology, nuclear engineering, radiation dosimetry, and cultural anthropology. Included are appointed technical members representing the states of Oregon, Washington, and Idaho, a representative of Native American tribes, and an individual representing the public. The project is divided into the following technical tasks. These tasks correspond to the path radionuclides followed from release to impact on humans (dose estimates): Source terms, environmental transport, environmental monitoring data, demography, food consumption, and agriculture, and environmental pathways and dose estimates. Progress is discussed

  5. An iterative reconstruction from truncated projection data

    International Nuclear Information System (INIS)

    Anon.

    1985-01-01

    Various methods have been proposed for tomographic reconstruction from truncated projection data. In this paper, a reconstructive method is discussed which consists of iterations of filtered back-projection, reprojection and some nonlinear processings. First, the method is so constructed that it converges to a fixed point. Then, to examine its effectiveness, comparisons are made by computer experiments with two existing reconstructive methods for truncated projection data, that is, the method of extrapolation based on the smooth assumption followed by filtered back-projection, and modified additive ART

  6. Clinical application of domestica manufactured BHP6601 SPECT

    International Nuclear Information System (INIS)

    Zhang Shuwen; Tian Jiahe; Liu Zilai; He Yijie; Shao Mingzhe; Zhang Jinming

    2005-01-01

    Clinical imaging of 150 patients with varying demand is carried out with BHP6601 SPECT manufactured locally, and the results are compared with that obtained by an E. CAM system manufactured by Siemens. The results show that BHP6601 had an acceptable and stable performance from a technical point of view. It offers a sufficient ability for organ imaging of clinical requirement. (authors)

  7. Hanford Environmental Dose Reconstruction Project monthly report

    International Nuclear Information System (INIS)

    Finch, S.M.

    1991-10-01

    The objective of the Hanford Environmental Dose Reconstruction Project is to estimate the radiation doeses that individuals and populations could have received from nuclear operations at Hanford since 1944. The project is divided into the following technical tasks. These tasks correspond to the path radionuclides followed, from release to impact on humans (dose estimates): Source terms; environmental transport; environmental monitoring data; demographics, agriculture, food habits; environmental pathways and dose estimates

  8. Hanford environmental dose reconstruction project - an overview

    International Nuclear Information System (INIS)

    Shipler, D.B.; Napier, B.A.; Farris, W.T.

    1996-01-01

    The Hanford Environmental Dose Reconstruction Project was initiated because of public interest in the historical releases of radioactive materials from the Hanford Site, located in southcentral Washington State. By 1986, over 38,000 pages of environmental monitoring documentation from the early years of Hanford operations had been released. Special committees reviewing the documents recommended initiation of the Hanford Environmental Dose Reconstruction Project, which began in October 1987, and is conducted by Battelle, Pacific Northwest Laboratories. The technical approach taken was to reconstruct releases of radioactive materials based on facility operating information; develop and/or adapt transport, pathway, and dose models and computer codes; reconstruct environmental, meterological, and hydrological monitoring information; reconstruct demographic, agricultural, and lifestyle characteristics; apply statistical methods to all forms of uncertainty in the information, parameters, and models; and perform scientific investigation that were technically defensible. The geographic area for the study includes ∼2 x 10 5 km 2 (75,000 mi 2 ) in eastern Washington, western Idaho, and northeastern Oregon (essentially the Mid-columbia Basin of the Pacific Northwest). Three exposure pathways were considered: the atmosphere, the Columbia River, and ground water

  9. Hanford Environmental Dose Reconstruction Project monthly report

    International Nuclear Information System (INIS)

    Finch, S.M.

    1990-12-01

    The objective of the Hanford Environmental Dose Reconstruction Project is to estimate the radiation doses that populations could have been have received from nuclear operations at Hanford since 1944. The project is being managed and conducted by the Pacific Northwest Laboratory (PNL) under the direction of an independent Technical Steering Panel (TSP). The project is divided into the following technical tasks. These tasks correspond to the path radionuclides followed, from release to impact on humans (dose estimates): source terms; environmental transport; environmental monitoring data; demographics, agriculture, food habits; and environmental pathways and dose estimates. 3 figs., 3 tabs

  10. The Hanford Environmental Dose Reconstruction Project: Overview

    International Nuclear Information System (INIS)

    Haerer, H.A.; Freshley, M.D.; Gilbert, R.O.; Morgan, L.G.; Napier, B.A.; Rhoads, R.E.; Woodruff, R.K.

    1990-01-01

    In 1988, researchers began a multiyear effort to estimate radiation doses that people could have received since 1944 at the U.S. Department of Energy's Hanford Site. The study was prompted by increasing concern about potential health effects to the public from more than 40 yr of nuclear activities. We will provide an overview of the Hanford Environmental Dose Reconstruction Project and its technical approach. The work has required development of new methods and tools for dealing with unique technical and communication challenges. Scientists are using a probabilistic, rather than the more typical deterministic, approach to generate dose distributions rather than single-point estimates. Uncertainties in input parameters are reflected in dose results. Sensitivity analyses are used to optimize project resources and define the project's scope. An independent technical steering panel directs and approves the work in a public forum. Dose estimates are based on review and analysis of historical data related to operations, effluents, and monitoring; determination of important radionuclides; and reconstruction of source terms, environmental conditions that affected transport, concentrations in environmental media, and human elements, such as population distribution, agricultural practices, food consumption patterns, and lifestyles. A companion paper in this volume, The Hanford Environmental Dose Reconstruction Project: Technical Approach, describes the computational framework for the work

  11. Hanford Environmental Dose Reconstruction Project monthly report

    International Nuclear Information System (INIS)

    McMakin, A.H., Cannon, S.D.; Finch, S.M.

    1992-09-01

    The objective of the Hanford Environmental Dose Reconstruction MDR) Project is to estimate the radiation doses that individuals and populations could have received from nuclear operations at Hanford since 1944. The TSP consists of experts in envirorunental pathways. epidemiology, surface-water transport, ground-water transport, statistics, demography, agriculture, meteorology, nuclear engineering. radiation dosimetry. and cultural anthropology. Included are appointed members representing the states of Oregon, Washington, and Idaho, a representative of Native American tribes, and an individual representing the public. The project is divided into the following technical tasks. These tasks correspond to the path radionuclides followed from release to impact on humans (dose estimates): Source Terms; Environmental Transport; Environmental Monitoring Data Demography, Food Consumption, and Agriculture; and Environmental Pathways and Dose Estimates

  12. Saving turtles: Talisman, Elf and BHP make room for reptiles

    Energy Technology Data Exchange (ETDEWEB)

    Lorenz, A.

    1999-05-03

    Cooperation between Australia`s BHP Petroleum, Canada`s Talisman Energy and France`s El Aquitaine to help the Trinidadian government and conservation groups to save the nesting grounds of the Carribean sea turtle is described. The nesting ground is located near one of the projects the three companies are working on. The giant turtle, also called the leatherback, can weigh as much as a tonne and have a 2.4 metre flipper span, have their nesting places on Trinidad`s northeastern shore. The three companies are working in 36 metres of water opposite two of the turtles` last nesting places. Had the companies proceeded as planned, the project could have destroyed their nesting place. Instead, the companies put up $90,000 for a three-month research project to monitor the movement of the turtles with satellite telemetry. In order to assess the turtles` hearing, tiny wires were inserted in the the turtles` brain to measure brain wave patterns - a method similar to that used on human neo-natals. When it was discovered that the turtles did not adapt well to captivity, they were fitted with earphones and transmitter during 10-minute period when they were in the quiescent state of egg-laying. The companies proceeded with a seismic program that used cables on the sea floor. Rather than use a large and noisy survey vessel to lay long streamers on a wide area, they laid shorter strips on a grid with smaller, quieter boats. That was sufficient for the turtles to continue normal activity as females arrived on the beach in the usual numbers to nest and to lay eggs. The documentation provided to the Trinidadian government was well received and plans are afoot to use it as a benchmark in assessing future exploratory applications within Trinidadian jurisdiction.

  13. NASA Human Research Program Behavioral Health and Performance Element (BHP)

    Science.gov (United States)

    Whitmire, Sandra; Faulk, Jeremy; Leveton, Lauren

    2010-01-01

    The goal of NASA BHP is to identify, characterize, and prevent or reduce behavioral health and performance risks associated with space travel, exploration, and return to terrestrial life. The NASA Behavioral Health and Performance Operations Group (BHP Ops) supports astronauts and their families before, during, and after a long-duration mission (LDM) on the ISS. BHP Ops provides ISS crews with services such as preflight training (e.g., psychological factors of LDM, psychological support, cross-cultural); preflight, in-flight, and postflight support services, including counseling for astronauts and their families; and psychological support such as regular care packages and a voice-over IP phone system between crew members and their families to facilitate real-time one-on-one communication.

  14. Behavioral Health and Performance (BHP) Work-Rest Cycles

    Science.gov (United States)

    Leveton, Lauren B.; Whitmire, Alexandra

    2011-01-01

    BHP Program Element Goal: Identify, characterize, and prevent or reduce behavioral health and performance risks associated with space travel, exploration and return to terrestrial life. BHP Requirements: a) Characterize and assess risks (e.g., likelihood and consequences). b) Develop tools and technologies to prevent, monitor, and treat adverse outcomes. c) Inform standards. d) Develop technologies to: 1) reduce risks and human systems resource requirements (e.g., crew time, mass, volume, power) and 2) ensure effective human-system integration across exploration mission.

  15. Projection computation based on pixel in simultaneous algebraic reconstruction technique

    International Nuclear Information System (INIS)

    Wang Xu; Chen Zhiqiang; Xiong Hua; Zhang Li

    2005-01-01

    SART is an important arithmetic of image reconstruction, in which the projection computation takes over half of the reconstruction time. An efficient way to compute projection coefficient matrix together with memory optimization is presented in this paper. Different from normal method, projection lines are located based on every pixel, and the following projection coefficient computation can make use of the results. Correlation of projection lines and pixels can be used to optimize the computation. (authors)

  16. From EDI to Internet Commerce: The BHP Steel Experience.

    Science.gov (United States)

    Chan, Caroline; Swatman, Paula M. C.

    2000-01-01

    Discusses the issue of business-to-business electronic commerce implementation and the factors affecting it. Discusses electronic data interchange technology, describes the results of a case study of BHP Steel (Australia), and considers paradigm shifts in implementation issues related to electronic commerce that occur over time. (Author/LRW)

  17. The generalized back projection theorem for cone beam reconstruction

    International Nuclear Information System (INIS)

    Peyrin, F.C.

    1985-01-01

    The use of cone beam scanners raises the problem of three dimensional reconstruction from divergent projections. After a survey on bidimensional analytical reconstruction methods we examine their application to the 3D problem. Finally, it is shown that the back projection theorem can be generalized to cone beam projections. This allows to state a new inversion formula suitable for both the 4 π parallel and divergent geometries. It leads to the generalization of the ''rho-filtered back projection'' algorithm which is outlined

  18. Research on reconstruction of steel tube section from few projections

    International Nuclear Information System (INIS)

    Peng Shuaijun; Wu Haifeng; Wang Kai

    2007-01-01

    Most parameters of steel tube can be acquired from CT image of the section so as to evaluate its quality. But large numbers of projections are needed in order to reconstruct the section image, so the collection and calculation of the projections consume lots of time. In order to solve the problem, reconstruction algorithms of steel tube from few projections are researched and the results are validated with simulation data in the paper. Three iterative algorithms, ART, MAP and OSEM, are attempted to reconstruct the section of steel tube by using the simulation model. Considering the prior information distributing of steel tube, we improve the algorithms and get better reconstruction images. The results of simulation experiment indicate that ART, MAP and OSEM can reconstruct accurate section images of steel tube from less than 20 projections and approximate images from 10 projections. (authors)

  19. Coordinate reconstruction using box reconstruction and projection of X-ray photo

    International Nuclear Information System (INIS)

    Achmad Suntoro

    2011-01-01

    Some mathematical formula have been derived for a process of reconstruction to define the coordinate of any point relative to a pre set coordinate system. The process of reconstruction uses a reconstruction box in which each edge's length of the box is known, each top-bottom face and left-right face of the box having a cross marker, and the top face and the right face of the box as plane projections by X-ray source in perspective projection -system. Using the data of the two X-ray projection images, any point inside the reconstruction box, as long as its projection is recorded in the two photos, will be determined its coordinate relative to the midpoint of the reconstruction box as the central point coordinates. (author)

  20. Generalized Filtered Back-Projection for Digital Breast Tomosynthesis Reconstruction

    NARCIS (Netherlands)

    Erhard, K.; Grass, M.; Hitziger, S.; Iske, A.; Nielsen, T.

    2012-01-01

    Filtered back-projection (FBP) has been commonly used as an efficient and robust reconstruction technique in tomographic X-ray imagingduring the last decades. For limited angle tomography acquisitions such as digital breast tomosynthesis, however, standard FBP reconstruction algorithms provide poor

  1. Incomplete projection reconstruction of computed tomography based on the modified discrete algebraic reconstruction technique

    Science.gov (United States)

    Yang, Fuqiang; Zhang, Dinghua; Huang, Kuidong; Gao, Zongzhao; Yang, YaFei

    2018-02-01

    Based on the discrete algebraic reconstruction technique (DART), this study aims to address and test a new improved algorithm applied to incomplete projection data to generate a high quality reconstruction image by reducing the artifacts and noise in computed tomography. For the incomplete projections, an augmented Lagrangian based on compressed sensing is first used in the initial reconstruction for segmentation of the DART to get higher contrast graphics for boundary and non-boundary pixels. Then, the block matching 3D filtering operator was used to suppress the noise and to improve the gray distribution of the reconstructed image. Finally, simulation studies on the polychromatic spectrum were performed to test the performance of the new algorithm. Study results show a significant improvement in the signal-to-noise ratios (SNRs) and average gradients (AGs) of the images reconstructed from incomplete data. The SNRs and AGs of the new images reconstructed by DART-ALBM were on average 30%-40% and 10% higher than the images reconstructed by DART algorithms. Since the improved DART-ALBM algorithm has a better robustness to limited-view reconstruction, which not only makes the edge of the image clear but also makes the gray distribution of non-boundary pixels better, it has the potential to improve image quality from incomplete projections or sparse projections.

  2. Kuwaiti reconstruction project unprecedented in size, complexity

    Energy Technology Data Exchange (ETDEWEB)

    Tippee, B.

    1993-03-15

    There had been no challenge like it: a desert emirate ablaze; its main city sacked; the economically crucial oil industry devastated; countryside shrouded in smoke from oil well fires and littered with unexploded ordnance, disabled military equipment, and unignited crude oil. Like the well-documented effort that brought 749 burning wells under control in less than 7 months, Kuwaiti reconstruction had no precedent. Unlike the firefight, reconstruction is no-where complete. It nevertheless has placed two of three refineries back on stream, restored oil production to preinvasion levels, and repaired or rebuilt 17 of 26 oil field gathering stations. Most of the progress has come since the last well fire went out on Nov. 6, 1991. Expatriates in Kuwait since the days of Al-Awda- the return,' in Arabic- attribute much of the rapid progress under Al-Tameer- the reconstruction'- to decisions and preparations made while the well fires still raged. The article describes the planning for Al-Awda, reentering the country, drilling plans, facilities reconstruction, and special problems.

  3. CLINICAL-PHARMACOLOGICAL VALUE OF TREATMENT EFFICIENCY OF BHP-PATIENTS BY ANTITHROMBOTIC THERAPY

    Directory of Open Access Journals (Sweden)

    A.A. Svistunov

    2007-09-01

    Full Text Available Patients with BHP need in pharmacological treatment of thrombosis the most often in the first 3 cases because has dysfunctions of platelets and coagulation. According to results of analysis of efficiency antithrombotic therapy in BHP-patients confirmed clinical and biochemical influence antithrombotic therapy by Ticlid 250 mg twice on the day in comparison with Aspirin 100 mg and Dipiridomol 25 mg on the basic therapy of the BHP by Permixon 160 mg. The received results have had statistically meant differences. Manifestation of BHP and value QOL and others urodynamic complications most often appear on the basic specific monotherapy of BHP and lost after antithrombotic therapy for 1-3 months. The important complications of antithrombotic therapy of BHP-patients did not observe.

  4. Comparison of power spectra for tomosynthesis projections and reconstructed images

    International Nuclear Information System (INIS)

    Engstrom, Emma; Reiser, Ingrid; Nishikawa, Robert

    2009-01-01

    Burgess et al. [Med. Phys. 28, 419-437 (2001)] showed that the power spectrum of mammographic breast background follows a power law and that lesion detectability is affected by the power-law exponent β which measures the amount of structure in the background. Following the study of Burgess et al., the authors measured and compared the power-law exponent of mammographic backgrounds in tomosynthesis projections and reconstructed slices to investigate the effect of tomosynthesis imaging on background structure. Our data set consisted of 55 patient cases. For each case, regions of interest (ROIs) were extracted from both projection images and reconstructed slices. The periodogram of each ROI was computed by taking the squared modulus of the Fourier transform of the ROI. The power-law exponent was determined for each periodogram and averaged across all ROIs extracted from all projections or reconstructed slices for each patient data set. For the projections, the mean β averaged across the 55 cases was 3.06 (standard deviation of 0.21), while it was 2.87 (0.24) for the corresponding reconstructions. The difference in β for a given patient between the projection ROIs and the reconstructed ROIs averaged across the 55 cases was 0.194, which was statistically significant (p<0.001). The 95% CI for the difference between the mean value of β for the projections and reconstructions was [0.170, 0.218]. The results are consistent with the observation that the amount of breast structure in the tomosynthesis slice is reduced compared to projection mammography and that this may lead to improved lesion detectability.

  5. Business Process Redesign Using EDI: the BHP steel experience

    Directory of Open Access Journals (Sweden)

    Paula Swatman

    1994-05-01

    Full Text Available EDI should not be seen as a competitive weapon - it does not offer a sustainable competitive advantage to its users as did the earlier inter-organisational systems (such as the various airline reservation systems. Instead EDI provides a standardised infrastructure upon which an adopting organisation can reengineer its business processes and thus confers a long-term, strategic and comparative advantage upon such an adopter. The potential for sustained competitive advantage to be derived from EDI arises from its integration with the organisational structure of its implementor, depending upon the implementing organisation's ability to redesign its business processes appropriately. This paper examines the case of (arguably the most sophisticated EDI-using company in Australia, BHP Steel, demonstrating the advantages obtainable by an organisation using EDI as a foundation for its reengineered organisational structure and business processes and concludes that: • there are real benefits to be obtained from an inter organisational electronic trading strategy founded on EDI as the enabling mechanism - benefits which are considerably more extensive than EDI's comparatively simple technical nature would appear to offer; • organisational gateways utilising an Application Generic approach to system integration and isolating the communications issue by insisting on the use of international data communications standards do offer a realistic and successful solution to the problem of internal and external trade for large and sophisticated organisations; • the majority of these achievements would have been either unlikely or totally impossible without BHP Steel's commitment to organisation-wide Business Process Redesign.

  6. Image reconstruction technique using projection data from neutron tomography system

    Directory of Open Access Journals (Sweden)

    Waleed Abd el Bar

    2015-12-01

    Full Text Available Neutron tomography is a very powerful technique for nondestructive evaluation of heavy industrial components as well as for soft hydrogenous materials enclosed in heavy metals which are usually difficult to image using X-rays. Due to the properties of the image acquisition system, the projection images are distorted by several artifacts, and these reduce the quality of the reconstruction. In order to eliminate these harmful effects the projection images should be corrected before reconstruction. This paper gives a description of a filter back projection (FBP technique, which is used for reconstruction of projected data obtained from transmission measurements by neutron tomography system We demonstrated the use of spatial Discrete Fourier Transform (DFT and the 2D Inverse DFT in the formulation of the method, and outlined the theory of reconstruction of a 2D neutron image from a sequence of 1D projections taken at different angles between 0 and π in MATLAB environment. Projections are generated by applying the Radon transform to the original image at different angles.

  7. Parametric image reconstruction using spectral analysis of PET projection data

    International Nuclear Information System (INIS)

    Meikle, Steven R.; Matthews, Julian C.; Cunningham, Vincent J.; Bailey, Dale L.; Livieratos, Lefteris; Jones, Terry; Price, Pat

    1998-01-01

    Spectral analysis is a general modelling approach that enables calculation of parametric images from reconstructed tracer kinetic data independent of an assumed compartmental structure. We investigated the validity of applying spectral analysis directly to projection data motivated by the advantages that: (i) the number of reconstructions is reduced by an order of magnitude and (ii) iterative reconstruction becomes practical which may improve signal-to-noise ratio (SNR). A dynamic software phantom with typical 2-[ 11 C]thymidine kinetics was used to compare projection-based and image-based methods and to assess bias-variance trade-offs using iterative expectation maximization (EM) reconstruction. We found that the two approaches are not exactly equivalent due to properties of the non-negative least-squares algorithm. However, the differences are small ( 1 and, to a lesser extent, VD). The optimal number of EM iterations was 15-30 with up to a two-fold improvement in SNR over filtered back projection. We conclude that projection-based spectral analysis with EM reconstruction yields accurate parametric images with high SNR and has potential application to a wide range of positron emission tomography ligands. (author)

  8. Reconstruction for limited-projection fluorescence molecular tomography based on projected restarted conjugate gradient normal residual.

    Science.gov (United States)

    Cao, Xu; Zhang, Bin; Liu, Fei; Wang, Xin; Bai, Jing

    2011-12-01

    Limited-projection fluorescence molecular tomography (FMT) can greatly reduce the acquisition time, which is suitable for resolving fast biology processes in vivo but suffers from severe ill-posedness because of the reconstruction using only limited projections. To overcome the severe ill-posedness, we report a reconstruction method based on the projected restarted conjugate gradient normal residual. The reconstruction results of two phantom experiments demonstrate that the proposed method is feasible for limited-projection FMT. © 2011 Optical Society of America

  9. Reconstruction of CT images by the Bayes- back projection method

    CERN Document Server

    Haruyama, M; Takase, M; Tobita, H

    2002-01-01

    In the course of research on quantitative assay of non-destructive measurement of radioactive waste, the have developed a unique program based on the Bayesian theory for reconstruction of transmission computed tomography (TCT) image. The reconstruction of cross-section images in the CT technology usually employs the Filtered Back Projection method. The new imaging reconstruction program reported here is based on the Bayesian Back Projection method, and it has a function of iterative improvement images by every step of measurement. Namely, this method has the capability of prompt display of a cross-section image corresponding to each angled projection data from every measurement. Hence, it is possible to observe an improved cross-section view by reflecting each projection data in almost real time. From the basic theory of Baysian Back Projection method, it can be not only applied to CT types of 1st, 2nd, and 3rd generation. This reported deals with a reconstruction program of cross-section images in the CT of ...

  10. Developing milk industry estimates for dose reconstruction projects

    International Nuclear Information System (INIS)

    Beck, D.M.; Darwin, R.F.

    1991-01-01

    One of the most important contributors to radiation doses from hanford during the 1944-1947 period was radioactive iodine. Consumption of milk from cows that ate vegetation contaminated with iodine is likely the dominant pathway of human exposure. To estimate the doses people could have received from this pathway, it is necessary to reconstruct the amount of milk consumed by people living near Hanford, the source of the milk, and the type of feed that the milk cows ate. This task is challenging because the dairy industry has undergone radical changes since the end of World War 2, and records that document the impact of these changes on the study area are scarce. Similar problems are faced by researchers on most dose reconstruction efforts. The purpose of this work is to document and evaluate the methods used on the Hanford Environmental Dose Reconstruction (HEDR) Project to reconstruct the milk industry and to present preliminary results

  11. Overview of the Hanford Environmental Dose Reconstruction Project

    International Nuclear Information System (INIS)

    Shipler, D.B.; Napier, B.A.; Ikenberry, T.A.

    1992-04-01

    The objective of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate the radiation doses that specific and representative individuals and populations may have received as a result of releases of radioactive materials from historical operations at the Hanford Site. These dose estimates would account for the uncertainties of information regarding facilities operations, environmental monitoring, demography, food consumption and lifestyles, and the variability of natural phenomena. Other objectives of the HEDR Project include: supporting the Hanford Thyroid Disease Study (HTDS), declassifying Hanford-generated information and making it available to the public, performing high-quality, credible science, and conducting the project in an open, public forum. The project is briefly described

  12. Hanford Environmental Dose Reconstruction Project monthly report, August 1992

    International Nuclear Information System (INIS)

    McMakin, A.H.; Cannon, S.D.; Finch, S.M.

    1992-01-01

    The objective of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate the radiation doses that individuals and populations could have received from nuclear operations at Hanford since 1944. The project is divided into the following technical tasks. These tasks correspond to the path radionuclides followed from release to impact on humans (dose estimates): source terms; environmental transport; environmental monitoring data; demography; food consumption; and agriculture; and environmental pathway and dose estimates

  13. Project RAMA: Reconstructing Asteroids Into Mechanical Automata

    Science.gov (United States)

    Dunn, Jason; Fagin, Max; Snyder, Michael; Joyce, Eric

    2017-01-01

    Many interesting ideas have been conceived for building space-based infrastructure in cislunar space. From O'Neill's space colonies, to solar power satellite farms, and even prospecting retrieved near earth asteroids. In all the scenarios, one thing remained fixed - the need for space resources at the outpost. To satisfy this need, O'Neill suggested an electromagnetic railgun to deliver resources from the lunar surface, while NASA's Asteroid Redirect Mission called for a solar electric tug to deliver asteroid materials from interplanetary space. At Made In Space, we propose an entirely new concept. One which is scalable, cost effective, and ensures that the abundant material wealth of the inner solar system becomes readily available to humankind in a nearly automated fashion. We propose the RAMA architecture, which turns asteroids into self-contained spacecraft capable of moving themselves back to cislunar space. The RAMA architecture is just as capable of transporting conventional-sized asteroids on the 10-meter length scale as transporting asteroids 100 meters or larger, making it the most versatile asteroid retrieval architecture in terms of retrieved-mass capability. This report describes the results of the Phase I study funded by the NASA NIAC program for Made In Space to establish the concept feasibility of using space manufacturing to convert asteroids into autonomous, mechanical spacecraft. Project RAMA, Reconstituting Asteroids into Mechanical Automata, is designed to leverage the future advances of additive manufacturing (AM), in-situ resource utilization (ISRU) and in-situ manufacturing (ISM) to realize enormous efficiencies in repeated asteroid redirect missions. A team of engineers at Made In Space performed the study work with consultation from the asteroid mining industry, academia, and NASA. Previous studies for asteroid retrieval have been constrained to studying only asteroids that are both large enough to be discovered, and small enough to be

  14. Communication tools for the Hanford Environmental Dose Reconstruction Project

    International Nuclear Information System (INIS)

    Blazek, Mary Lou; Power, Max S.

    1992-01-01

    From 1944 to 1989, the U.S. Department of Energy produced plutonium at the Hanford Site in southeast Washington State. In the early days of operation, large amounts of radioactive materials were released to the environment. Documents about the releases were made public in 1986. The Hanford Environmental Dose Reconstruction Project began in 1987. The Project will determine how much radioactive material was released, how that material may have exposed people, and what radiation doses people may have received. The Project will be complete in 1995. The federal government pays for the work. The scientific work on the study is done by Battelle's Pacific Northwest Laboratory. Public credibility and valid science are equally important to those directing the dose reconstruction work. A number of tools are used to inform the public and encourage public participation. These tools are examined in this paper. (author)

  15. Regional absolute conductivity reconstruction using projected current density in MREIT

    International Nuclear Information System (INIS)

    Sajib, Saurav Z K; Kim, Hyung Joong; Woo, Eung Je; Kwon, Oh In

    2012-01-01

    Magnetic resonance electrical impedance tomography (MREIT) is a non-invasive technique for imaging the internal conductivity distribution in tissue within an MRI scanner, utilizing the magnetic flux density, which is introduced when a current is injected into the tissue from external electrodes. This magnetic flux alters the MRI signal, so that appropriate reconstruction can provide a map of the additional z-component of the magnetic field (B z ) as well as the internal current density distribution that created it. To extract the internal electrical properties of the subject, including the conductivity and/or the current density distribution, MREIT techniques use the relationship between the external injection current and the z-component of the magnetic flux density B = (B x , B y , B z ). The tissue studied typically contains defective regions, regions with a low MRI signal and/or low MRI signal-to-noise-ratio, due to the low density of nuclear magnetic resonance spins, short T 2 or T* 2 relaxation times, as well as regions with very low electrical conductivity, through which very little current traverses. These defective regions provide noisy B z data, which can severely degrade the overall reconstructed conductivity distribution. Injecting two independent currents through surface electrodes, this paper proposes a new direct method to reconstruct a regional absolute isotropic conductivity distribution in a region of interest (ROI) while avoiding the defective regions. First, the proposed method reconstructs the contrast of conductivity using the transversal J-substitution algorithm, which blocks the propagation of severe accumulated noise from the defective region to the ROI. Second, the proposed method reconstructs the regional projected current density using the relationships between the internal current density, which stems from a current injection on the surface, and the measured B z data. Combining the contrast conductivity distribution in the entire imaging

  16. Preconditioned alternating projection algorithms for maximum a posteriori ECT reconstruction

    International Nuclear Information System (INIS)

    Krol, Andrzej; Li, Si; Shen, Lixin; Xu, Yuesheng

    2012-01-01

    We propose a preconditioned alternating projection algorithm (PAPA) for solving the maximum a posteriori (MAP) emission computed tomography (ECT) reconstruction problem. Specifically, we formulate the reconstruction problem as a constrained convex optimization problem with the total variation (TV) regularization. We then characterize the solution of the constrained convex optimization problem and show that it satisfies a system of fixed-point equations defined in terms of two proximity operators raised from the convex functions that define the TV-norm and the constraint involved in the problem. The characterization (of the solution) via the proximity operators that define two projection operators naturally leads to an alternating projection algorithm for finding the solution. For efficient numerical computation, we introduce to the alternating projection algorithm a preconditioning matrix (the EM-preconditioner) for the dense system matrix involved in the optimization problem. We prove theoretically convergence of the PAPA. In numerical experiments, performance of our algorithms, with an appropriately selected preconditioning matrix, is compared with performance of the conventional MAP expectation-maximization (MAP-EM) algorithm with TV regularizer (EM-TV) and that of the recently developed nested EM-TV algorithm for ECT reconstruction. Based on the numerical experiments performed in this work, we observe that the alternating projection algorithm with the EM-preconditioner outperforms significantly the EM-TV in all aspects including the convergence speed, the noise in the reconstructed images and the image quality. It also outperforms the nested EM-TV in the convergence speed while providing comparable image quality. (paper)

  17. The NIOSH Radiation Dose Reconstruction Project: managing technical challenges.

    Science.gov (United States)

    Moeller, Matthew P; Townsend, Ronald D; Dooley, David A

    2008-07-01

    Approximately two years after promulgation of the Energy Employees Occupational Illness Compensation Program Act, the National Institute for Occupational Safety and Health Office of Compensation and Analysis Support selected a contractor team to perform many aspects of the radiation dose reconstruction process. The project scope and schedule necessitated the development of an organization involving a comparatively large number of health physicists. From the initial stages, there were many technical and managerial challenges that required continuous planning, integration, and conflict resolution. This paper identifies those challenges and describes the resolutions and lessons learned. These insights are hopefully useful to managers of similar scientific projects, especially those requiring significant data, technical methods, and calculations. The most complex challenge has been to complete defensible, individualized dose reconstructions that support timely compensation decisions at an acceptable production level. Adherence to applying claimant-favorable and transparent science consistent with the requirements of the Act has been the key to establishing credibility, which is essential to this large and complex project involving tens of thousands of individual stakeholders. The initial challenges included garnering sufficient and capable scientific staff, developing an effective infrastructure, establishing necessary methods and procedures, and integrating activities to ensure consistent, quality products. The continuing challenges include maintaining the project focus on recommending a compensation determination (rather than generating an accurate dose reconstruction), managing the associated very large data and information management challenges, and ensuring quality control and assurance in the presence of an evolving infrastructure. The lessons learned concern project credibility, claimant favorability, project priorities, quality and consistency, and critical

  18. Image reconstruction from multiple fan-beam projections

    International Nuclear Information System (INIS)

    Jelinek, J.; Overton, T.R.

    1984-01-01

    Special-purpose third-generation fan-beam CT systems can be greatly simplified by limiting the number of detectors, but this requires a different mode of data collection to provide a set of projections appropriate to the required spatial resolution in the reconstructed image. Repeated rotation of the source-detector fan, combined with shift of the detector array and perhaps offset of the source with respect to the fan's axis after each 360 0 rotation(cycle), provides a fairly general pattern of projection space filling. The authors' investigated the problem of optimal data-collection geometry for a multiple-rotation fan-beam scanner and of corresponding reconstruction algorithm

  19. Questions of uniqueness and resolution in reconstruction from projections

    CERN Document Server

    Katz, Myron Bernard

    1978-01-01

    Reconstruction from projections has revolutionized radiology and as now become one of the most important tools of medical diagnosi- he E. M. I. Scanner is one example. In this text, some fundamental heoretical and practical questions are resolved. Despite recent research activity in the area, the crucial subject ·f the uniqueness of the reconstruction and the effect of noise in the ata posed some unsettled fundamental questions. In particular, Kennan mith proved that if we describe an object by a C~ function, i. e. , nfinitely differentiable with compact support, then there are other bjects with the same shape, i. e. , support, which can differ almost rhitrarily and still have the same projections in finitely many direc­ ions. On the other hand, he proved that objects in finite dimensional unction spaces are uniquely determined by a single projection for almost 11 angles, i. e. , except on a set of measure zero. Along these lines, erman and Rowland in [41) showed that reconstructions obtained from he common...

  20. Decision management for the Hanford Environmental Dose Reconstruction Project

    Energy Technology Data Exchange (ETDEWEB)

    Roberds, W.J.; Haerer, H.A. [Golder Associates, Inc., Redmond, WA (United States); Winterfeldt, D.V. [Decision Insights, Laguna Beach, CA (United States)

    1992-04-01

    The Hanford Environmental Dose Reconstruction (HEDR) Project is in the process of developing estimates for the radiation doses that individuals and population groups may have received as a result of past activities at the Hanford Reservation in Eastern Washington. A formal decision-aiding methodology has been developed to assist the HEDR Project in making significant and defensible decisions regarding how this study will be conducted. These decisions relate primarily to policy (e.g., the appropriate level of public participation in the study) and specific technical aspects (e.g., the appropriate domain and depth of the study), and may have significant consequences with respect to technical results, costs, and public acceptability.

  1. Decision management for the Hanford Environmental Dose Reconstruction Project

    International Nuclear Information System (INIS)

    Roberds, W.J.; Haerer, H.A.; Winterfeldt, D.V.

    1992-04-01

    The Hanford Environmental Dose Reconstruction (HEDR) Project is in the process of developing estimates for the radiation doses that individuals and population groups may have received as a result of past activities at the Hanford Reservation in Eastern Washington. A formal decision-aiding methodology has been developed to assist the HEDR Project in making significant and defensible decisions regarding how this study will be conducted. These decisions relate primarily to policy (e.g., the appropriate level of public participation in the study) and specific technical aspects (e.g., the appropriate domain and depth of the study), and may have significant consequences with respect to technical results, costs, and public acceptability

  2. In vitro and in vivo hepatoprotective effect of ganodermanontriol against t-BHP-induced oxidative stress

    DEFF Research Database (Denmark)

    Ha, Do Thi; Oh, Joonseok; Khoi, Nguyen Minh

    2013-01-01

    the evaluation of hepatoprotective activity of ganodermanontriol, a sterol isolated from Ganoderma lucidum, and the investigation of its mechanism of action in Hepa1c1c7 and murine liver cells upon tert-butyl hydroperoxide (t-BHP)-induced inflammation. t-BHP was utilized to stimulate an anti...... were monitored to assess whether GDT protected the cells from the t-BHP-mediated oxidative stimuli. RESULTS: GDT induced HO-1 expression via the activation of Nrf-2 nuclear translocation and the subsequent transcription of the HO-1 gene in vitro and in vivo, which seemed to be regulated...... the ethnopharmacological application of Ganoderma lucidum as a treatment for hepatic disorders. GDT induced in vitro and in vivo anti-inflammatory activity in t-BHP-damaged hepatic cells through the expression of HO-1, and in which PI3K/Akt and p38 kinases are involved. Our study motivates further research...

  3. Work plan for the Hanford Environmental Dose Reconstruction Project

    Energy Technology Data Exchange (ETDEWEB)

    1989-12-01

    The primary objective of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate the radiation doses that populations could have received from nuclear operations at the Hanford Site since 1944, with descriptions of uncertainties inherent in such estimates. The secondary objective is to make project records--information that HEDR staff members used to estimate radiation doses--available to the public. Preliminary dose estimates for a limited geographic area and time period, certain radionuclides, and certain populations are planned to be available in 1990; complete results are planned to be reported in 1993. Project reports and references used in the reports are available to the public in the DOE Public Reading Room in Richland, Washington. Project progress is documented in monthly reports, which are also available to the public in the DOE Public Reading Room.

  4. Hanford Environmental Dose Reconstruction Project independent direction and oversight

    International Nuclear Information System (INIS)

    Blazek, M.L.; Power, M.

    1991-01-01

    Hanford was selected in 1942 as one of the sites for the Manhattan Project. It produced plutonium for one of the world's first nuclear weapons. The US Department of Energy (DOE) and its predecessors continued to make plutonium for nuclear weapons at Hanford for more than four decades. In the early days of Hanford operations, radioactive materials routinely were released to the environment by many processes. The DOE disclosed documents about these releases in 1986. In 1987, Washington, Oregon, and regional Indian tribes gathered an independent panel of experts. This group recommended dose reconstruction and health effects feasibility studies. Later that year, DOE hired Battelle Pacific Northwest Laboratory (PNL) to reconstruct potential public radiation doses from Hanford's past releases of radioactive material. The DOE agreed with the states and tribes that project direction would come from an independent technical steering panel (TSP). This approach was critical to gain public credibility for the project and the science. The TSP directs the project and makes policy. That is now clear - but, it was hard-earned. Conducting science in an open public process is new, challenging, and clearly worthwhile. The panel's product is good science that is believed and accepted by the public - our client

  5. Phase 1 of the Hanford Environmental Dose Reconstruction Project

    International Nuclear Information System (INIS)

    1991-08-01

    The work described in this report was prompted by the public's concern about potential effect from the radioactive materials released from the Hanford Site. The Hanford Environmental Dose Reconstruction (HEDR) Project was established to estimate radiation dose the public might have received from the Hanford Site since 1944, when facilities began operating. Phase 1 of the HEDR Project is a ''pilot'' or ''demonstration'' phase. The objectives of this initial phase were to determine whether enough historical information could be found or reconstructed to be used for dose estimation and develop and test conceptual and computational models for calculating credible dose estimates. Preliminary estimates of radiation doses were produced in Phase 1 because they are needed to achieve these objectives. The reader is cautioned that the dose estimates provided in this and other Phase 1 HEDR reports are preliminary. As the HEDR Project continues, the dose estimates will change for at least three reasons: more complete input information for models will be developed; the models themselves will be refined; and the size and shape of the geographic study area will change. This is one of three draft reports that summarize the first phase of the four-phased HEDR Project. This, the Summary Report, is directed to readers who want a general understanding of the Phase 1 work and preliminary dose estimates. The two other reports -- the Air Pathway Report and the Columbia River Pathway Report -- are for readers who understand the radiation dose assessment process and want to see more technical detail. Detailed descriptions of the dose reconstruction process are available in more than 20 supporting reports listed in Appendix A. 32 refs., 46 figs

  6. Forensic facial reconstruction: Nasal projection in Brazilian adults.

    Science.gov (United States)

    Tedeschi-Oliveira, Silvia Virginia; Beaini, Thiago Leite; Melani, Rodolfo Francisco Haltenhoff

    2016-09-01

    The nose has a marked cognitive influence on facial image; however, it loses its shape during cadaveric decomposition. The known methods of estimating nasal projection using Facial Reconstruction are lacking in practicality and reproducibility. We attempted to relate the points Rhinion, Pronasale and Prosthion by studying the angle formed by straight lines that connect them. Two examiners measured this angle with the help of analysis and image-processing software, Image J, directly from cephalometric radiographs. The sample consisted of 300 males, aged between 24 and 77 years, and 300 females, aged 24 to 69 years. The proposed angle ranged from 80° to 100° in both sexes and all ages. It was considered possible to use a 90° angle from projections of the Rhinion and Prosthion points in order to determine the Pronasale position, as well as to estimate the nasal projection of Brazilian adults. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  7. Oak Ridge Dose Reconstruction Project Summary Report; Reports of the Oak Ridge Dose Reconstruction, Vol. 7

    Energy Technology Data Exchange (ETDEWEB)

    Thomas E. Widner; et. al.

    1999-07-01

    In the early 1990s, concern about the Oak Ridge Reservation's past releases of contaminants to the environment prompted Tennessee's public health officials to pursue an in-depth study of potential off-site health effects at Oak Ridge. This study, the Oak Ridge dose reconstruction, was supported by an agreement between the U.S. Department of Energy (DOE) and the State of Tennessee, and was overseen by a 12-member panel of individuals appointed by Tennessee's Commissioner of Health. The panel requested that the principal investigator for the project prepare the following report, ''Oak Ridge Dose Reconstruction Project Summary Report,'' to serve the following purposes: (1) summarize in a single, less technical report, the methods and results of the various investigations that comprised the Phase II of the dose reconstruction; (2) describe the systematic searching of classified and unclassified historical records that was a vital component of the project; and (3) summarize the less detailed, screening-level assessments that were performed to evaluate the potential health significance of a number of materials, such a uranium, whose priority did not require a complete dose reconstruction effort. This report describes each major step of the dose reconstruction study: (1) the review of thousands of historical records to obtain information relating to past operations at each facility; (2) estimation of the quantity and timing of releases of radioiodines from X-10, of mercury from Y-12, of PCB's from all facilities, and of cesium-137 and other radionuclides from White Oak Creek; (3) evaluation of the routes taken by these contaminants through the environment to nearby populations; and (4) estimation of doses and health risks to exposed groups. Calculations found the highest excess cancer risks for a female born in 1952 who drank goat milk; the highest non-cancer health risk was for children in a farm family exposed to PCBs in and near

  8. Oak Ridge Dose Reconstruction Project Summary Report; Reports of the Oak Ridge Dose Reconstruction, Vol. 7

    International Nuclear Information System (INIS)

    Widner, Thomas E.; email = twidner@jajoneses.com

    1999-01-01

    In the early 1990s, concern about the Oak Ridge Reservation's past releases of contaminants to the environment prompted Tennessee's public health officials to pursue an in-depth study of potential off-site health effects at Oak Ridge. This study, the Oak Ridge dose reconstruction, was supported by an agreement between the U.S. Department of Energy (DOE) and the State of Tennessee, and was overseen by a 12-member panel of individuals appointed by Tennessee's Commissioner of Health. The panel requested that the principal investigator for the project prepare the following report, ''Oak Ridge Dose Reconstruction Project Summary Report,'' to serve the following purposes: (1) summarize in a single, less technical report, the methods and results of the various investigations that comprised the Phase II of the dose reconstruction; (2) describe the systematic searching of classified and unclassified historical records that was a vital component of the project; and (3) summarize the less detailed, screening-level assessments that were performed to evaluate the potential health significance of a number of materials, such a uranium, whose priority did not require a complete dose reconstruction effort. This report describes each major step of the dose reconstruction study: (1) the review of thousands of historical records to obtain information relating to past operations at each facility; (2) estimation of the quantity and timing of releases of radioiodines from X-10, of mercury from Y-12, of PCB's from all facilities, and of cesium-137 and other radionuclides from White Oak Creek; (3) evaluation of the routes taken by these contaminants through the environment to nearby populations; and (4) estimation of doses and health risks to exposed groups. Calculations found the highest excess cancer risks for a female born in 1952 who drank goat milk; the highest non-cancer health risk was for children in a farm family exposed to PCBs in and near East Fork Poplar Creek. More detailed

  9. Behavioral Health and Performance at NASA JSC: Recent Successes and Future Plan for BHP Research and Operations

    Science.gov (United States)

    Leveton, L. B.; VanderArk, S. T.

    2014-01-01

    The Behavioral Health and Performance discipline at NASA Johnson Space Center is organized into two distinct Divisions (Biomedical Research and Environmental Science Division and Space and Clinical Operations Division) but is integrated and interrelated in its day-to-day work. Ongoing operations supporting NASA's spaceflight goals benefit from the research portfolios that address risks to mission success. Similarly, these research portfolios are informed by operations to ensure investigations stay relevant given the dynamic environment of spaceflight. There are many success stories that can be presented where initial work begun as a BHP Research project, and funded through the Human Research Program, was fully implemented in operations or addressed an operational need. Examples include improving effectiveness of the debriefings used within Mission Control by the Mission Operations Directorate and countermeasures for fatigue management. There is also ongoing collaboration with research and operations for developing selection methods for future generation astronauts, and to enhance and inform the current family support function. The objective of this panel is to provide examples of recent success stories, describe areas where close collaboration is benefitting ongoing research and operations, and summarize how this will come together as NASA plans for the one year ISS mission - a unique opportunity for both BHP operations and research to learn more about preparing and supporting crewmembers for extended missions in space. The proposed panel will be comprised of six presentations, each describing a unique aspect of research or operations and the benefits to current and future spaceflight.

  10. Integration of models for the Hanford Environmental Dose Reconstruction Project

    International Nuclear Information System (INIS)

    Napier, B.A.

    1991-01-01

    The objective of the Hanford Environmental Dose Reconstruction Project is to estimate the radiation dose that individuals could have received as a result of emissions from nuclear operations at Hanford since 1944. The objective of phase 1 of the project was to demonstrate through calculations that adequate models and support data exist or could be developed to allow realistic estimations of doses to individuals from releases of radionuclides to the environment that occurred as long as 45 years ago. Much of the data used in phase 1 was preliminary; therefore, the doses calculated must be considered preliminary approximations. This paper describes the integration of various models that was implemented for initial computer calculations. Models were required for estimating the quantity of radioactive material released, for evaluating its transport through the environment, for estimating human exposure, and for evaluating resultant doses

  11. Studies on various properties of pure and Li-doped Barium Hydrogen Phosphate (BHP) single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Nallamuthu, D. [Department of Physics, Aditanar College of Arts and Science, Tiruchendur 628216, Tamil Nadu (India); Selvarajan, P., E-mail: pselvarajanphy@yahoo.co.i [Department of Physics, Aditanar College of Arts and Science, Tiruchendur 628216, Tamil Nadu (India); Freeda, T.H. [Physics Research Centre, S.T. Hindu College, Nagercoil 629002 (India)

    2010-12-15

    Single crystals of pure and Li-doped barium hydrogen phosphate (BHP) were grown by solution method with gel technique. Various properties of the harvested crystals were studied by carrying out single crystal and powder XRD, FTIR, TG/DTA, microhardness and dielectric studies. Atomic absorption study was carried out for Li-doped BHP crystal to check the presence of Li dopants. Unit cell dimensions and diffracting planes of the grown crystals have been identified from XRD studies. Functional groups of the title compounds have been identified from FTIR studies. Density of the grown crystals was calculated using the XRD data. Thermal stability of the samples was checked by TG/DTA studies. Mechanical and dielectric characterizations of the harvested pure and Li-doped BHP crystals reveal the mechanical strength and ferroelectric transition. The observed results are reported and discussed.

  12. FY 1991 project plan for the Hanford Environmental Dose Reconstruction Project, Phase 2

    International Nuclear Information System (INIS)

    1991-02-01

    Phase 1 of the Hanford Environmental Dose Reconstruction Project was designed to develop and demonstrate a method for estimating radiation doses people may have received from Hanford Site operations since 1944. The method researchers developed relied on a variety of measured and reconstructed data as input to a modular computer model that generates dose estimates and their uncertainties. As part of Phase 1, researchers used the reconstructed data and computer model to calculate preliminary dose estimates for populations in a limited geographical area and time period. Phase 2, now under way, is designed to evaluate the Phase 1 data and model and improve them to calculate more accurate and precise dose estimates. Phase 2 will also be used to obtain preliminary estimates of two categories of doses: for Native American tribes and for individuals included in the pilot phase of the Hanford Thyroid Disease Study (HTDS). TSP Directive 90-1 required HEDR staff to develop Phase 2 task plans for TSP approval. Draft task plans for Phase 2 were submitted to the TSP at the October 11--12, 1990 public meeting, and, after discussions of each activity and associated budget needs, the TSP directed HEDR staff to proceed with a slate of specific project activities for FY 1991 of Phase 2. This project plan contains detailed information about those activities. Phase 2 is expected to last 15--18 months. In mid-FY 1991, project activities and budget will be reevaluated to determine whether technical needs or priorities have changed. Separate from, but related to, this project plan, will be an integrated plan for the remainder of the project. HEDR staff will work with the TSP to map out a strategy that clearly describes ''end products'' for the project and the work necessary to complete them. This level of planning will provide a framework within which project decisions in Phases 2, 3, and 4 can be made

  13. Qualitative and quantitative analysis of reconstructed images using projections with noises

    International Nuclear Information System (INIS)

    Lopes, R.T.; Assis, J.T. de

    1988-01-01

    The reconstruction of a two-dimencional image from one-dimensional projections in an analytic algorithm ''convolution method'' is simulated on a microcomputer. In this work it was analysed the effects caused in the reconstructed image in function of the number of projections and noise level added to the projection data. Qualitative and quantitative (distortion and image noise) comparison were done with the original image and the reconstructed images. (author) [pt

  14. A Novel Nipple Reconstruction Technique for Maintaining Nipple Projection: The Boomerang Flap.

    Science.gov (United States)

    Kim, Young-Eun; Hong, Ki Yong; Minn, Kyung Won; Jin, Ung Sik

    2016-09-01

    Nipple-areolar complex (NAC) reconstruction is the final step in the long journey of breast reconstruction for mastectomy patients. Successful NAC reconstruction depends on the use of appropriate surgical techniques that are simple and reliable. To date, numerous techniques have been used for nipple reconstruction, including contralateral nipple sharing and various local flaps. Recently, it has been common to utilize local flaps. However, the most common nipple reconstruction problem encountered with local flaps is the loss of nipple projection; there can be approximately 50% projection loss in reconstructed nipples over long-term follow-up. Several factors might contribute to nipple projection loss, and we tried to overcome these factors by performing nipple reconstructions using a boomerang flap technique, which is a modified C-V flap that utilizes the previous mastectomy scar to maintain long-term nipple projection.

  15. A Novel Nipple Reconstruction Technique for Maintaining Nipple Projection: The Boomerang Flap

    Directory of Open Access Journals (Sweden)

    Young-Eun Kim

    2016-09-01

    Full Text Available Nipple-areolar complex (NAC reconstruction is the final step in the long journey of breast reconstruction for mastectomy patients. Successful NAC reconstruction depends on the use of appropriate surgical techniques that are simple and reliable. To date, numerous techniques have been used for nipple reconstruction, including contralateral nipple sharing and various local flaps. Recently, it has been common to utilize local flaps. However, the most common nipple reconstruction problem encountered with local flaps is the loss of nipple projection; there can be approximately 50% projection loss in reconstructed nipples over long-term follow-up. Several factors might contribute to nipple projection loss, and we tried to overcome these factors by performing nipple reconstructions using a boomerang flap technique, which is a modified C–V flap that utilizes the previous mastectomy scar to maintain long-term nipple projection.

  16. The Hanford Environmental Dose Reconstruction (HEDR) Project: Technical approach

    International Nuclear Information System (INIS)

    Napier, B.A.; Freshley, M.D.; Gilbert, R.O.; Haerer, H.A.; Morgan, L.G.; Rhoads, R.E.; Woodruff, R.K.

    1990-01-01

    Historical measurements and current assessment techniques are being combined to estimate potential radiation doses to people from radioactive releases to the air, the Columbia River, soils, and ground water at the Hanford Site since 1944. Environmental contamination from these releases has been monitored, at varying levels of detail, for 45 yr. Phase I of the Hanford Environmental Reconstruction Project will estimate the magnitude of potential doses, their areal extends, and their associated uncertainties. The Phase I study area comprises 10 counties in eastern Washington and northern Oregon, within a 100-mi radius of the site, including a stretch of the Columbia River that was most significantly affected. These counties contain a range of projected and measured contaminant levels, environmental exposure pathways, and population groups. Phase I dose estimates are being developed for the periods 1944 through 1947 for air pathways and 1964 through 1966 for river pathways. Important radionuclide/pathway combinations include fission products, such as 131 I, in milk for early atmospheric releases and activation products, such as 32 P and 65 Zn, in fish for releases to the river. Potential doses range over several orders of magnitude within the study area. We will expand the time periods and study are in three successive phases, as warranted by results of Phase I

  17. A comparative study between matched and mis-matched projection/back projection pairs used with ASIRT reconstruction method

    International Nuclear Information System (INIS)

    Guedouar, R.; Zarrad, B.

    2010-01-01

    For algebraic reconstruction techniques both forward and back projection operators are needed. The ability to perform accurate reconstruction relies fundamentally on the forward projection and back projection methods which are usually, the transpose of each other. Even though the mis-matched pairs may introduce additional errors during the iterative process, the usefulness of mis-matched projector/back projector pairs has been proved in image reconstruction. This work investigates the performance of matched and mis-matched reconstruction pairs using popular forward projectors and their transposes when used in reconstruction tasks with additive simultaneous iterative reconstruction techniques (ASIRT) in a parallel beam approach. Simulated noiseless phantoms are used to compare the performance of the investigated pairs in terms of the root mean squared errors (RMSE) which are calculated between reconstructed slices and the reference in different regions. Results show that mis-matched projection/back projection pairs can promise more accuracy of reconstructed images than matched ones. The forward projection operator performance seems independent of the choice of the back projection operator and vice versa.

  18. A comparative study between matched and mis-matched projection/back projection pairs used with ASIRT reconstruction method

    Energy Technology Data Exchange (ETDEWEB)

    Guedouar, R., E-mail: raja_guedouar@yahoo.f [Higher School of Health Sciences and Techniques of Monastir, Av. Avicenne, 5060 Monastir, B.P. 128 (Tunisia); Zarrad, B., E-mail: boubakerzarrad@yahoo.f [Higher School of Health Sciences and Techniques of Monastir, Av. Avicenne, 5060 Monastir, B.P. 128 (Tunisia)

    2010-07-21

    For algebraic reconstruction techniques both forward and back projection operators are needed. The ability to perform accurate reconstruction relies fundamentally on the forward projection and back projection methods which are usually, the transpose of each other. Even though the mis-matched pairs may introduce additional errors during the iterative process, the usefulness of mis-matched projector/back projector pairs has been proved in image reconstruction. This work investigates the performance of matched and mis-matched reconstruction pairs using popular forward projectors and their transposes when used in reconstruction tasks with additive simultaneous iterative reconstruction techniques (ASIRT) in a parallel beam approach. Simulated noiseless phantoms are used to compare the performance of the investigated pairs in terms of the root mean squared errors (RMSE) which are calculated between reconstructed slices and the reference in different regions. Results show that mis-matched projection/back projection pairs can promise more accuracy of reconstructed images than matched ones. The forward projection operator performance seems independent of the choice of the back projection operator and vice versa.

  19. Clotrimazole enhances lysis of human erythrocytes induced by t-BHP.

    Science.gov (United States)

    Lisovskaya, Irene L; Shcherbachenko, Irina M; Volkova, Rimma I; Ataullakhanov, Fazoil I

    2009-08-14

    Clotrimazole (CLT) is an antifungal and antimalarial agent also effective as a Gardos channel inhibitor. In addition, CLT possesses antitumor properties. Recent data provide evidence that CLT forms a complex with heme (hemin), which produces a more potent lytic effect than heme alone. This study addressed the effect of CLT on the lysis of normal human erythrocytes induced by tert-butyl hydroperoxide (t-BHP). For the first time, it was shown that 10 microM CLT significantly enhanced the lytic effect of t-BHP on erythrocytes in both Ca(2+)-containing and Ca(2+)-free media, suggesting that the effect is not related to Gardos channels. CLT did not affect the rate of free radical generation, the kinetics of GSH degradation, methemoglobin formation and TBARS generation; therefore, we concluded that CLT does not cause additional oxidative damage to erythrocytes treated with t-BHP. It is tempted to speculate that CLT enhances t-BHP-induced changes in erythrocyte volume and lysis largely by forming a complex with hemin released during hemoglobin oxidation in erythrocytes: the CLT-hemin complex destabilizes the cell membrane more potently than hemin alone. If so, the effect of CLT on cell membrane damage during free-radical oxidation may be used to increase the efficacy of antitumor therapy.

  20. The reconstruction of HT-7 superconducting tokamak and the present status of HT-7U project

    International Nuclear Information System (INIS)

    Weng, P.D.

    2000-01-01

    The first Chinese superconducting tokamak HT-7 was reconstructed from T-7. The main purposes of reconstruction are to improve the accessibility of the device and to provide a possibility of long pulse operation with high performance. The reconstruction has been done successfully. The HT-7U project has been approved and funded as a National Project, the engineering design and R and D are on the way. (author)

  1. A reconstruction algorithm for coherent scatter computed tomography based on filtered back-projection

    International Nuclear Information System (INIS)

    Stevendaal, U. van; Schlomka, J.-P.; Harding, A.; Grass, M.

    2003-01-01

    Coherent scatter computed tomography (CSCT) is a reconstructive x-ray imaging technique that yields the spatially resolved coherent-scatter form factor of the investigated object. Reconstruction from coherently scattered x-rays is commonly done using algebraic reconstruction techniques (ART). In this paper, we propose an alternative approach based on filtered back-projection. For the first time, a three-dimensional (3D) filtered back-projection technique using curved 3D back-projection lines is applied to two-dimensional coherent scatter projection data. The proposed algorithm is tested with simulated projection data as well as with projection data acquired with a demonstrator setup similar to a multi-line CT scanner geometry. While yielding comparable image quality as ART reconstruction, the modified 3D filtered back-projection algorithm is about two orders of magnitude faster. In contrast to iterative reconstruction schemes, it has the advantage that subfield-of-view reconstruction becomes feasible. This allows a selective reconstruction of the coherent-scatter form factor for a region of interest. The proposed modified 3D filtered back-projection algorithm is a powerful reconstruction technique to be implemented in a CSCT scanning system. This method gives coherent scatter CT the potential of becoming a competitive modality for medical imaging or nondestructive testing

  2. Computed Tomography Image Quality Evaluation of a New Iterative Reconstruction Algorithm in the Abdomen (Adaptive Statistical Iterative Reconstruction-V) a Comparison With Model-Based Iterative Reconstruction, Adaptive Statistical Iterative Reconstruction, and Filtered Back Projection Reconstructions.

    Science.gov (United States)

    Goodenberger, Martin H; Wagner-Bartak, Nicolaus A; Gupta, Shiva; Liu, Xinming; Yap, Ramon Q; Sun, Jia; Tamm, Eric P; Jensen, Corey T

    The purpose of this study was to compare abdominopelvic computed tomography images reconstructed with adaptive statistical iterative reconstruction-V (ASIR-V) with model-based iterative reconstruction (Veo 3.0), ASIR, and filtered back projection (FBP). Abdominopelvic computed tomography scans for 36 patients (26 males and 10 females) were reconstructed using FBP, ASIR (80%), Veo 3.0, and ASIR-V (30%, 60%, 90%). Mean ± SD patient age was 32 ± 10 years with mean ± SD body mass index of 26.9 ± 4.4 kg/m. Images were reviewed by 2 independent readers in a blinded, randomized fashion. Hounsfield unit, noise, and contrast-to-noise ratio (CNR) values were calculated for each reconstruction algorithm for further comparison. Phantom evaluation of low-contrast detectability (LCD) and high-contrast resolution was performed. Adaptive statistical iterative reconstruction-V 30%, ASIR-V 60%, and ASIR 80% were generally superior qualitatively compared with ASIR-V 90%, Veo 3.0, and FBP (P ASIR-V 60% with respective CNR values of 5.54 ± 2.39, 8.78 ± 3.15, and 3.49 ± 1.77 (P ASIR 80% had the best and worst spatial resolution, respectively. Adaptive statistical iterative reconstruction-V 30% and ASIR-V 60% provided the best combination of qualitative and quantitative performance. Adaptive statistical iterative reconstruction 80% was equivalent qualitatively, but demonstrated inferior spatial resolution and LCD.

  3. Neural network algorithm for image reconstruction using the grid friendly projections

    International Nuclear Information System (INIS)

    Cierniak, R.

    2011-01-01

    Full text: The presented paper describes a development of original approach to the reconstruction problem using a recurrent neural network. Particularly, the 'grid-friendly' angles of performed projections are selected according to the discrete Radon transform (DRT) concept to decrease the number of projections required. The methodology of our approach is consistent with analytical reconstruction algorithms. Reconstruction problem is reformulated in our approach to optimization problem. This problem is solved in present concept using method based on the maximum likelihood methodology. The reconstruction algorithm proposed in this work is consequently adapted for more practical discrete fan beam projections. Computer simulation results show that the neural network reconstruction algorithm designed to work in this way improves obtained results and outperforms conventional methods in reconstructed image quality. (author)

  4. On proton CT reconstruction using MVCT-converted virtual proton projections

    Energy Technology Data Exchange (ETDEWEB)

    Wang Dongxu; Mackie, T. Rockwell; Tome, Wolfgang A. [Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53705 and Department of Radiation Oncology, University of Iowa Hospitals and Clinics, Iowa City, Iowa 52242 (United States); Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53705 and Morgridge Institute of Research, University of Wisconsin, Madison, Wisconsin 53715 (United States); Department of Medical Physics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53705 and Oncophysics Institute, Albert Einstein College of Medicine, Yeshiva University, Bronx, New York 10461 (United States)

    2012-06-15

    Purpose: To describe a novel methodology of converting megavoltage x-ray projections into virtual proton projections that are otherwise missing due to the proton range limit. These converted virtual proton projections can be used in the reconstruction of proton computed tomography (pCT). Methods: Relations exist between proton projections and multispectral megavoltage x-ray projections for human tissue. Based on these relations, these tissues can be categorized into: (a) adipose tissue; (b) nonadipose soft tissues; and (c) bone. These three tissue categories can be visibly identified on a regular megavoltage x-ray computed tomography (MVCT) image. With an MVCT image and its projection data available, the x-ray projections through heterogeneous anatomy can be converted to the corresponding proton projections using predetermined calibration curves for individual materials, aided by a coarse segmentation on the x-ray CT image. To show the feasibility of this approach, mathematical simulations were carried out. The converted proton projections, plotted on a proton sinogram, were compared to the simulated ground truth. Proton stopping power images were reconstructed using either the virtual proton projections only or a blend of physically available proton projections and virtual proton projections that make up for those missing due to the range limit. These images were compared to a reference image reconstructed from theoretically calculated proton projections. Results: The converted virtual projections had an uncertainty of {+-}0.8% compared to the calculated ground truth. Proton stopping power images reconstructed using a blend of converted virtual projections (48%) and physically available projections (52%) had an uncertainty of {+-}0.86% compared with that reconstructed from theoretically calculated projections. Reconstruction solely from converted virtual proton projections had an uncertainty of {+-}1.1% compared with that reconstructed from theoretical projections

  5. On proton CT reconstruction using MVCT-converted virtual proton projections

    International Nuclear Information System (INIS)

    Wang Dongxu; Mackie, T. Rockwell; Tomé, Wolfgang A.

    2012-01-01

    Purpose: To describe a novel methodology of converting megavoltage x-ray projections into virtual proton projections that are otherwise missing due to the proton range limit. These converted virtual proton projections can be used in the reconstruction of proton computed tomography (pCT). Methods: Relations exist between proton projections and multispectral megavoltage x-ray projections for human tissue. Based on these relations, these tissues can be categorized into: (a) adipose tissue; (b) nonadipose soft tissues; and (c) bone. These three tissue categories can be visibly identified on a regular megavoltage x-ray computed tomography (MVCT) image. With an MVCT image and its projection data available, the x-ray projections through heterogeneous anatomy can be converted to the corresponding proton projections using predetermined calibration curves for individual materials, aided by a coarse segmentation on the x-ray CT image. To show the feasibility of this approach, mathematical simulations were carried out. The converted proton projections, plotted on a proton sinogram, were compared to the simulated ground truth. Proton stopping power images were reconstructed using either the virtual proton projections only or a blend of physically available proton projections and virtual proton projections that make up for those missing due to the range limit. These images were compared to a reference image reconstructed from theoretically calculated proton projections. Results: The converted virtual projections had an uncertainty of ±0.8% compared to the calculated ground truth. Proton stopping power images reconstructed using a blend of converted virtual projections (48%) and physically available projections (52%) had an uncertainty of ±0.86% compared with that reconstructed from theoretically calculated projections. Reconstruction solely from converted virtual proton projections had an uncertainty of ±1.1% compared with that reconstructed from theoretical projections. If

  6. Analogs and the BHP Risk Reduction Strategy for Future Spaceflight Missions

    Science.gov (United States)

    Whitmire, Sandra; Leveton, Lauren

    2011-01-01

    In preparation for future exploration missions to distant destinations (e.g., Moon, Near Earth Objects (NEO), and Mars), the NASA Human Research Program s (HRP) Behavioral Health and Performance Element (BHP) conducts and supports research to address four human health risks: Risk of Behavioral Conditions; Risk of Psychiatric Conditions; Risk of Performance Decrements Due to Inadequate Cooperation, Coordination, Communication, and Psychosocial Adaptation within a Team; and Risk of Performance Errors due to Sleep Loss, Fatigue, Circadian Desynchronization, and Work Overload (HRP Science Management Plan, 2008). BHP Research, in collaboration with internal and external research investigators, as well as subject matter experts within NASA operations including flight surgeons, astronauts, and mission planners and others within the Mission Operations Directorate (MOD), identifies knowledge and technology gaps within each Risk. BHP Research subsequently manages and conducts research tasks to address and close the gaps, either through risk assessment and quantification, or the development of countermeasures and monitoring technologies. The resulting deliverables, in many instances, also support current Medical Operations and/or Mission Operations for the International Space Station (ISS).

  7. Angular integration and inter-projection correlation effects in CT reconstruction

    International Nuclear Information System (INIS)

    Crawford, C.R.; Pele, N.J.

    1987-01-01

    CT reconstruction algorithms require snap-shot projections of an object. In order to minimize scan times, CT scanners rotate continuously which, in turn, prevents the acquisition of snap-shot projections. Acquired projections are integrals over angular position and may be correlated inter-projection. This paper shows that angular integration and inter-projection correlation introduce a radially dependent degradation of the spatial resolution and cause the image noise to vary non-linearly with radial position

  8. Iterative reconstruction with attenuation compensation from cone-beam projections acquired via nonplanar orbits

    International Nuclear Information System (INIS)

    Zeng, G.L.; Weng, Y.; Gullberg, G.T.

    1997-01-01

    Single photon emission computed tomography (SPECT) imaging with cone-beam collimators provides improved sensitivity and spatial resolution for imaging small objects with large field-of-view detectors. It is known that Tuy's cone-beam data sufficiency condition must be met to obtain artifact-free reconstructions. Even though Tuy's condition was derived for an attenuation-free situation, the authors hypothesize that an artifact-free reconstruction can be obtained even if the cone-beam data are attenuated, provided the imaging orbit satisfies Tuy's condition and the exact attenuation map is known. In the authors' studies, emission data are acquired using nonplanar circle-and-line orbits to acquire cone-beam data for tomographic reconstructions. An extended iterative ML-EM (maximum likelihood-expectation maximization) reconstruction algorithm is derived and used to reconstruct projection data with either a pre-acquired or assumed attenuation map. Quantitative accuracy of the attenuation corrected emission reconstruction is significantly improved

  9. Intensity-based bayesian framework for image reconstruction from sparse projection data

    International Nuclear Information System (INIS)

    Rashed, E.A.; Kudo, Hiroyuki

    2009-01-01

    This paper presents a Bayesian framework for iterative image reconstruction from projection data measured over a limited number of views. The classical Nyquist sampling rule yields the minimum number of projection views required for accurate reconstruction. However, challenges exist in many medical and industrial imaging applications in which the projection data is undersampled. Classical analytical reconstruction methods such as filtered backprojection (FBP) are not a good choice for use in such cases because the data undersampling in the angular range introduces aliasing and streak artifacts that degrade lesion detectability. In this paper, we propose a Bayesian framework for maximum likelihood-expectation maximization (ML-EM)-based iterative reconstruction methods that incorporates a priori knowledge obtained from expected intensity information. The proposed framework is based on the fact that, in tomographic imaging, it is often possible to expect a set of intensity values of the reconstructed object with relatively high accuracy. The image reconstruction cost function is modified to include the l 1 norm distance to the a priori known information. The proposed method has the potential to regularize the solution to reduce artifacts without missing lesions that cannot be expected from the a priori information. Numerical studies showed a significant improvement in image quality and lesion detectability under the condition of highly undersampled projection data. (author)

  10. Comparison of tomography reconstruction by maximum entropy and filtered retro projection

    International Nuclear Information System (INIS)

    Abdala, F.J.P.; Simpson, D.M.; Roberty, N.C.

    1992-01-01

    The tomographic reconstruction with few projections is studied, comparing the maximum entropy method with filtered retro projection. Simulations with and without the presence of noise and also with the presence of an object of high density inside of the skull are showed. (C.G.C.)

  11. SYRMEP Tomo Project: a graphical user interface for customizing CT reconstruction workflows.

    Science.gov (United States)

    Brun, Francesco; Massimi, Lorenzo; Fratini, Michela; Dreossi, Diego; Billé, Fulvio; Accardo, Agostino; Pugliese, Roberto; Cedola, Alessia

    2017-01-01

    When considering the acquisition of experimental synchrotron radiation (SR) X-ray CT data, the reconstruction workflow cannot be limited to the essential computational steps of flat fielding and filtered back projection (FBP). More refined image processing is often required, usually to compensate artifacts and enhance the quality of the reconstructed images. In principle, it would be desirable to optimize the reconstruction workflow at the facility during the experiment (beamtime). However, several practical factors affect the image reconstruction part of the experiment and users are likely to conclude the beamtime with sub-optimal reconstructed images. Through an example of application, this article presents SYRMEP Tomo Project (STP), an open-source software tool conceived to let users design custom CT reconstruction workflows. STP has been designed for post-beamtime (off-line use) and for a new reconstruction of past archived data at user's home institution where simple computing resources are available. Releases of the software can be downloaded at the Elettra Scientific Computing group GitHub repository https://github.com/ElettraSciComp/STP-Gui.

  12. Hepatoprotective Effect of Terminalia chebula against t-BHP-Induced Acute Liver Injury in C57/BL6 Mice

    Directory of Open Access Journals (Sweden)

    Min-Kyung Choi

    2015-01-01

    Full Text Available We aimed to identify the hepatoprotective effects of Terminalia chebula water extract (TCW and its corresponding pharmacological actions using C57/BL6 mice model of tert-butylhydroperoxide-(t-BHP- induced acute liver injury. Mice were orally administered with TCW (0, 50, 100, or 200 mg/kg or gallic acid (100 mg/kg for 5 days before t-BHP (2.5 mM/kg injection. Liver enzymes, histopathology, oxidative stress parameters, antioxidant components, and inflammatory cytokines were examined 18 h after t-BHP injection. t-BHP injection caused dramatic elevation of serum AST, ALT, and LDH level, while TCW pretreatment notably attenuated these elevations. Inflammatory cytokines including TNF-α, IL-1β, and IL-6 were notably increased in hepatic tissues, and then these were efficiently attenuated by TCW pretreatment. t-BHP injection notably increased malondialdehyde, total reactive oxygen species, and nitric oxide in the liver tissue, while it markedly dropped the antioxidant activities including total antioxidant capacity, total glutathione contents, glutathione peroxidase, superoxide dismutase, and catalase. TCW pretreatment remarkably ameliorated these alterations, and these effects were relevant to gene expressions. Histopathological examinations supported the above findings. Collectively, these findings well prove that TCW beneficially prevents acute and severe liver injury and clarify its corresponding mechanisms involved in the inhibition of oxidative stress and inflammatory cytokines.

  13. PR-CALC: A Program for the Reconstruction of NMR Spectra from Projections

    International Nuclear Information System (INIS)

    Coggins, Brian E.; Zhou Pei

    2006-01-01

    Projection-reconstruction NMR (PR-NMR) has attracted growing attention as a method for collecting multidimensional NMR data rapidly. The PR-NMR procedure involves measuring lower-dimensional projections of a higher-dimensional spectrum, which are then used for the mathematical reconstruction of the full spectrum. We describe here the program PR-CALC, for the reconstruction of NMR spectra from projection data. This program implements a number of reconstruction algorithms, highly optimized to achieve maximal performance, and manages the reconstruction process automatically, producing either full spectra or subsets, such as regions or slices, as requested. The ability to obtain subsets allows large spectra to be analyzed by reconstructing and examining only those subsets containing peaks, offering considerable savings in processing time and storage space. PR-CALC is straightforward to use, and integrates directly into the conventional pipeline for data processing and analysis. It was written in standard C+ + and should run on any platform. The organization is flexible, and permits easy extension of capabilities, as well as reuse in new software. PR-CALC should facilitate the widespread utilization of PR-NMR in biomedical research

  14. Comparison of maximum intensity projection and digitally reconstructed radiographic projection for carotid artery stenosis measurement

    International Nuclear Information System (INIS)

    Hyde, Derek E.; Habets, Damiaan F.; Fox, Allan J.; Gulka, Irene; Kalapos, Paul; Lee, Don H.; Pelz, David M.; Holdsworth, David W.

    2007-01-01

    Digital subtraction angiography is being supplanted by three-dimensional imaging techniques in many clinical applications, leading to extensive use of maximum intensity projection (MIP) images to depict volumetric vascular data. The MIP algorithm produces intensity profiles that are different than conventional angiograms, and can also increase the vessel-to-tissue contrast-to-noise ratio. We evaluated the effect of the MIP algorithm in a clinical application where quantitative vessel measurement is important: internal carotid artery stenosis grading. Three-dimensional computed rotational angiography (CRA) was performed on 26 consecutive symptomatic patients to verify an internal carotid artery stenosis originally found using duplex ultrasound. These volumes of data were visualized using two different postprocessing projection techniques: MIP and digitally reconstructed radiographic (DRR) projection. A DRR is a radiographic image simulating a conventional digitally subtracted angiogram, but it is derived computationally from the same CRA dataset as the MIP. By visualizing a single volume with two different projection techniques, the postprocessing effect of the MIP algorithm is isolated. Vessel measurements were made, according to the NASCET guidelines, and percentage stenosis grades were calculated. The paired t-test was used to determine if the measurement difference between the two techniques was statistically significant. The CRA technique provided an isotropic voxel spacing of 0.38 mm. The MIPs and DRRs had a mean signal-difference-to-noise-ratio of 30:1 and 26:1, respectively. Vessel measurements from MIPs were, on average, 0.17 mm larger than those from DRRs (P<0.0001). The NASCET-type stenosis grades tended to be underestimated on average by 2.4% with the MIP algorithm, although this was not statistically significant (P=0.09). The mean interobserver variability (standard deviation) of both the MIP and DRR images was 0.35 mm. It was concluded that the MIP

  15. Reconstruction of a cone-beam CT image via forward iterative projection matching

    International Nuclear Information System (INIS)

    Brock, R. Scott; Docef, Alen; Murphy, Martin J.

    2010-01-01

    Purpose: To demonstrate the feasibility of reconstructing a cone-beam CT (CBCT) image by deformably altering a prior fan-beam CT (FBCT) image such that it matches the anatomy portrayed in the CBCT projection data set. Methods: A prior FBCT image of the patient is assumed to be available as a source image. A CBCT projection data set is obtained and used as a target image set. A parametrized deformation model is applied to the source FBCT image, digitally reconstructed radiographs (DRRs) that emulate the CBCT projection image geometry are calculated and compared to the target CBCT projection data, and the deformation model parameters are adjusted iteratively until the DRRs optimally match the CBCT projection data set. The resulting deformed FBCT image is hypothesized to be an accurate representation of the patient's anatomy imaged by the CBCT system. The process is demonstrated via numerical simulation. A known deformation is applied to a prior FBCT image and used to create a synthetic set of CBCT target projections. The iterative projection matching process is then applied to reconstruct the deformation represented in the synthetic target projections; the reconstructed deformation is then compared to the known deformation. The sensitivity of the process to the number of projections and the DRR/CBCT projection mismatch is explored by systematically adding noise to and perturbing the contrast of the target projections relative to the iterated source DRRs and by reducing the number of projections. Results: When there is no noise or contrast mismatch in the CBCT projection images, a set of 64 projections allows the known deformed CT image to be reconstructed to within a nRMS error of 1% and the known deformation to within a nRMS error of 7%. A CT image nRMS error of less than 4% is maintained at noise levels up to 3% of the mean projection intensity, at which the deformation error is 13%. At 1% noise level, the number of projections can be reduced to 8 while maintaining

  16. Feasibility study of Pridneprovskaya Thermal Power Plant reconstruction project

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-03-01

    With objectives of saving energy and reducing greenhouse gas emission at the Pridneprovskaya power plant in Ukraine, a scrap and build project has been discussed. This project will abolish the unit No.12 among the eight units in the existing coal burning power generation facilities, and install a natural gas burning combined cycle plant comprising of three units each with an output of 100 MW. The new plant facilities will consist of gas turbines, steam turbines, HRSG and auxiliary devices, and an air-cooled synchronous power generator with a capacity of 119 MVA. Use of natural gas as fuel reduces generation of soot, sulfur oxides, nitrogen oxides, and CO. In addition, the hot effluent and waste liquor effluent will decrease from those at the present plant. The required fund will be 30,107 million yen. The energy saving effect of this project is reduction of about 7.5 million tons of crude oil equivalent as a total in 40 years. The greenhouse effect gas will decrease by about 39 million tons as a total in 40 years. The profitability estimation calls for the number of investment recovery year of 16 years, and internal profit rate of 7.32%, wherein the implementation of the project cannot be expected as a project to be carried out by private funds. (NEDO)

  17. Quasi Gradient Projection Algorithm for Sparse Reconstruction in Compressed Sensing

    Directory of Open Access Journals (Sweden)

    Xin Meng

    2014-02-01

    Full Text Available Compressed sensing is a novel signal sampling theory under the condition that the signal is sparse or compressible. The existing recovery algorithms based on the gradient projection can either need prior knowledge or recovery the signal poorly. In this paper, a new algorithm based on gradient projection is proposed, which is referred as Quasi Gradient Projection. The algorithm presented quasi gradient direction and two step sizes schemes along this direction. The algorithm doesn’t need any prior knowledge of the original signal. Simulation results demonstrate that the presented algorithm cans recovery the signal more correctly than GPSR which also don’t need prior knowledge. Meanwhile, the algorithm has a lower computation complexity.

  18. Optimized image acquisition for breast tomosynthesis in projection and reconstruction space

    International Nuclear Information System (INIS)

    Chawla, Amarpreet S.; Lo, Joseph Y.; Baker, Jay A.; Samei, Ehsan

    2009-01-01

    Breast tomosynthesis has been an exciting new development in the field of breast imaging. While the diagnostic improvement via tomosynthesis is notable, the full potential of tomosynthesis has not yet been realized. This may be attributed to the dependency of the diagnostic quality of tomosynthesis on multiple variables, each of which needs to be optimized. Those include dose, number of angular projections, and the total angular span of those projections. In this study, the authors investigated the effects of these acquisition parameters on the overall diagnostic image quality of breast tomosynthesis in both the projection and reconstruction space. Five mastectomy specimens were imaged using a prototype tomosynthesis system. 25 angular projections of each specimen were acquired at 6.2 times typical single-view clinical dose level. Images at lower dose levels were then simulated using a noise modification routine. Each projection image was supplemented with 84 simulated 3 mm 3D lesions embedded at the center of 84 nonoverlapping ROIs. The projection images were then reconstructed using a filtered backprojection algorithm at different combinations of acquisition parameters to investigate which of the many possible combinations maximizes the performance. Performance was evaluated in terms of a Laguerre-Gauss channelized Hotelling observer model-based measure of lesion detectability. The analysis was also performed without reconstruction by combining the model results from projection images using Bayesian decision fusion algorithm. The effect of acquisition parameters on projection images and reconstructed slices were then compared to derive an optimization rule for tomosynthesis. The results indicated that projection images yield comparable but higher performance than reconstructed images. Both modes, however, offered similar trends: Performance improved with an increase in the total acquisition dose level and the angular span. Using a constant dose level and angular

  19. Influence of sampling interval and number of projections on the quality of SR-XFMT reconstruction

    International Nuclear Information System (INIS)

    Deng Biao; Yu Xiaohan; Xu Hongjie

    2007-01-01

    Synchrotron Radiation based X-ray Fluorescent Microtomography (SR-XFMT) is a nondestructive technique for detecting elemental composition and distribution inside a specimen with high spatial resolution and sensitivity. In this paper, computer simulation of SR-XFMT experiment is performed. The influence of the sampling interval and the number of projections on the quality of SR-XFMT image reconstruction is analyzed. It is found that the sampling interval has greater effect on the quality of reconstruction than the number of projections. (authors)

  20. The Acquarossa Memory Project : Reconstructing an Etruscan Town

    NARCIS (Netherlands)

    Lulof, P.S.; Sepers, M.H.

    2017-01-01

    Digital techniques and cultural heritage connect, in an innovative way, new and old within the Humanities. In this new project, an Etruscan townscape will be recreated; modelled results created by the 4D Research Lab will be integrated in an Archaeological Park and Museum in such a way that

  1. THE PROJECT MANAGEMENT OF INDUSTRIAL BUILDINGS REENGINEERING (RECONSTRUCTION AND COMPLETION

    Directory of Open Access Journals (Sweden)

    K. Kolesnikova

    2017-06-01

    Full Text Available Creative element fate of any activity may not fall to zero because of the turbulent environment in which these activities are carried out, always prevents this. Environment that makes each building unique, that is, provides the main basis of the project. When we are talking about complex construction, the share of the creative component becomes very significant. First and foremost, this is explained by the duration of the construction work, during which time to happen risk events. The article analyses the processes of construction from the point of view of their conformity to the concept of project activities. It is shown that with increasing degree of difficulty of construction or time of the last share of creative activities in the overall project grows. In recent times more and more widespread work on re-engineering complex systems, for example, building constructions. This means repair of the building, but not a simple repair with restoration of the original, incorporated in the design of building elements and their interfaces, and partial or full replacement of items that fail or are outdated, new ones require first, a new design of their structures and production technologies, as well as the design of the accessories for the installation and technology is reshaping the object. Combining the two above-mentioned factors of growth of the share of creative activities during the project management of the re-engineering of building structures: complexity and construction time, received a cognitive model of such growth. Introduced the concept of "reengineering in construction" as a combination of the processes of adjustment and worn or completion of unfinished buildings. It is proved that any re-engineering in construction is the project activities. Provisions are tested in a real reengineering of industrial buildings with a positive technical and economic effect.

  2. THE PROJECT MANAGEMENT OF INDUSTRIAL BUILDINGS REENGINEERING (RECONSTRUCTION AND COMPLETION

    Directory of Open Access Journals (Sweden)

    Katerina Kolesikova

    2017-05-01

    Full Text Available Creative element fate of any activity may not fall to zero because of the turbulent environment in which these activities are carried out, always prevents this. Environment that makes each building unique, that is, provides the main basis of the project. When we are talking about complex construction, the share of the creative component becomes very significant. First and foremost, this is explained by the duration of the construction work, during which time to happen risk events. The article analyses the processes of construction from the point of view of their conformity to the concept of project activities. It is shown that with increasing degree of difficulty of construction or time of the last share of creative activities in the overall project grows. In recent times more and more widespread work on re-engineering complex systems, for example, building constructions. This means repair of the building, but not a simple repair with restoration of the original, incorporated in the design of building elements and their interfaces, and partial or full replacement of items that fail or are outdated, new ones require first, a new design of their structures and production technologies, as well as the design of the accessories for the installation and technology is reshaping the object. Combining the two above-mentioned factors of growth of the share of creative activities during the project management of the re-engineering of building structures: complexity and construction time, received a cognitive model of such growth. Introduced the concept of "reengineering in construction" as a combination of the processes of adjustment and worn or completion of unfinished buildings. It is proved that any re-engineering in construction is the project activities. Provisions are tested in a real reengineering of industrial buildings with a positive technical and economic effect.

  3. 3D reconstruction of laser projective point with projection invariant generated from five points on 2D target.

    Science.gov (United States)

    Xu, Guan; Yuan, Jing; Li, Xiaotao; Su, Jian

    2017-08-01

    Vision measurement on the basis of structured light plays a significant role in the optical inspection research. The 2D target fixed with a line laser projector is designed to realize the transformations among the world coordinate system, the camera coordinate system and the image coordinate system. The laser projective point and five non-collinear points that are randomly selected from the target are adopted to construct a projection invariant. The closed form solutions of the 3D laser points are solved by the homogeneous linear equations generated from the projection invariants. The optimization function is created by the parameterized re-projection errors of the laser points and the target points in the image coordinate system. Furthermore, the nonlinear optimization solutions of the world coordinates of the projection points, the camera parameters and the lens distortion coefficients are contributed by minimizing the optimization function. The accuracy of the 3D reconstruction is evaluated by comparing the displacements of the reconstructed laser points with the actual displacements. The effects of the image quantity, the lens distortion and the noises are investigated in the experiments, which demonstrate that the reconstruction approach is effective to contribute the accurate test in the measurement system.

  4. Hanford Environmental Dose Reconstruction Project, Quarterly report, September--November 1993

    International Nuclear Information System (INIS)

    Cannon, S.D.; Finch, S.M.

    1993-01-01

    The objective of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate the radiation doses that individuals and populations could have received from nuclear operations at Hanford since 1944. The project is divided into the following technical tasks. These tasks correspond to the path radionuclides followed from release to impact on humans (dose estimates); Source Terms, Environmental Transport, Environmental Monitoring Data, Demography, Food Consumption, and Agriculture, and Environmental Pathways and Dose Estimates

  5. Radionuclide releases to the atmosphere from Hanford Operations, 1944--1972. Hanford Environmental Dose Reconstruction Project

    Energy Technology Data Exchange (ETDEWEB)

    Heeb, C.M.

    1994-05-01

    The purpose of the Hanford Environmental Dose Reconstruction Project is to estimate the radiation dose that individuals could have received as a result of radionuclide emissions since 1944 from the Hanford Site. The first step in determining dose is to estimate the amount and timing of radionuclide releases to air and water. This report provides the air release information.

  6. A Prospective Analysis of Dynamic Loss of Breast Projection in Tissue Expander-Implant Reconstruction

    Directory of Open Access Journals (Sweden)

    Lauren M Mioton

    2015-05-01

    Full Text Available BackgroundBreast projection is a critical element of breast reconstruction aesthetics, but little has been published regarding breast projection as the firm expander is changed to a softer implant. Quantitative data representing this loss in projection may enhance patient education and improve our management of patient expectations.MethodsFemale patients who were undergoing immediate tissue-expander breast reconstruction with the senior author were enrolled in this prospective study. Three-dimensional camera software was used for all patient photographs and data analysis. Projection was calculated as the distance between the chest wall and the point of maximal projection of the breast form. Values were calculated for final tissue expander expansion and at varying intervals 3, 6, and 12 months after implant placement.ResultsFourteen breasts from 12 patients were included in the final analysis. Twelve of the 14 breasts had a loss of projection at three months following the implant placement or beyond. The percentage of projection lost in these 12 breasts ranged from 6.30% to 43.4%, with an average loss of projection of 21.05%.ConclusionsThis study is the first prospective quantitative analysis of temporal changes in breast projection after expander-implant reconstruction. By prospectively capturing projection data with three-dimensional photographic software, we reveal a loss of projection in this population by three months post-implant exchange. These findings will not only aid in managing patient expectations, but our methodology provides a foundation for future objective studies of the breast form.

  7. External force back-projective composition and globally deformable optimization for 3-D coronary artery reconstruction

    International Nuclear Information System (INIS)

    Yang, Jian; Cong, Weijian; Fan, Jingfan; Liu, Yue; Wang, Yongtian; Chen, Yang

    2014-01-01

    The clinical value of the 3D reconstruction of a coronary artery is important for the diagnosis and intervention of cardiovascular diseases. This work proposes a method based on a deformable model for reconstructing coronary arteries from two monoplane angiographic images acquired from different angles. First, an external force back-projective composition model is developed to determine the external force, for which the force distributions in different views are back-projected to the 3D space and composited in the same coordinate system based on the perspective projection principle of x-ray imaging. The elasticity and bending forces are composited as an internal force to maintain the smoothness of the deformable curve. Second, the deformable curve evolves rapidly toward the true vascular centerlines in 3D space and angiographic images under the combination of internal and external forces. Third, densely matched correspondence among vessel centerlines is constructed using a curve alignment method. The bundle adjustment method is then utilized for the global optimization of the projection parameters and the 3D structures. The proposed method is validated on phantom data and routine angiographic images with consideration for space and re-projection image errors. Experimental results demonstrate the effectiveness and robustness of the proposed method for the reconstruction of coronary arteries from two monoplane angiographic images. The proposed method can achieve a mean space error of 0.564 mm and a mean re-projection error of 0.349 mm. (paper)

  8. Reconstruction of tomographic image from x-ray projections of a few views

    International Nuclear Information System (INIS)

    Kobayashi, Fujio; Yamaguchi, Shoichiro

    1982-01-01

    Computer tomographs have progressed rapidly, and in the latest high performance types, the photographing time has been shortened to less than 5 sec, but the clear images of hearts have not yet been obtained. The X-ray tomographs used so far irradiate X-ray from many directions and measure the projected data, but by limiting projection direction to a small number, it was planned to shorter the X-ray photographing time and to reduce X-ray exposure as the objective of this study. In this paper, a method is proposed, by which tomographic images are reconstructed from projected data in a small number of direction by generalized inverse matrix penalty method. This method is the calculation method newly devised by the authors for this purpose. It is a kind of the nonlinear planning method added with the restrictive condition using a generalized inverse matrix, and it is characterized by the simple calculation procedure and rapid convergence. Moreover, the effect on reconstructed images when errors are included in projected data was examined. Also, the simple computer simulation to reconstruct tomographic images using the projected data in four directions was performed, and the usefulness of this method was confirmed. It contributes to the development of superhigh speed tomographs in future. (Kako, I.)

  9. n-BA/KOH/t-BHP behaviour in the natural rubber latex vulcanization by gamma rays

    International Nuclear Information System (INIS)

    Souza, A. de.

    1994-01-01

    Natural rubber latex was vulcanized in the absence and in the presence of sensitizer (S), with gamma ray from 60 Co source, panoramic type, at the dose rate range of 1,20-1,33 kGy/h. The components of used S were n-butyl acrylate (n-BA), the KOH as stabilizer and t-butyl hydroperoxide (t-BHP) as co-S. The purpose of this work was to study the efficiency and the behaviour of each component of S in the irradiated latex crosslinking by tensile strength (T b ), volume fraction and permanent set. In the absence of S occur straight crosslinking between macromolecular adjacent radicals. IN the presence of S, the n-BA participates in the crosslinking through acrylic bridges between macromolecules. (author)

  10. A jewel in the desert: BHP Billiton's San Juan underground mine

    Energy Technology Data Exchange (ETDEWEB)

    Buchsbaum, L.

    2007-12-15

    The Navajo Nation is America's largest native American tribe by population and acreage, and is blessed with large tracks of good coal deposits. BHP Billiton's New Mexico Coal Co. is the largest in the Navajo regeneration area. The holdings comprise the San Juan underground mine, the La Plata surface mine, now in reclamation, and the expanding Navajo surface mine. The article recounts the recent history of the mines. It stresses the emphasis on sensitivity to and helping to sustain tribal culture, and also on safety. San Juan's longwall system is unique to the nation. It started up as an automated system from the outset. Problems caused by hydrogen sulfide are being tackled. San Juan has a bleederless ventilation system to minimise the risk of spontaneous combustion of methane and the atmospheric conditions in the mine are heavily monitored, especially within the gob areas. 3 photos.

  11. FY 1992 revised task plans for the Hanford Environmental Dose Reconstruction Project

    International Nuclear Information System (INIS)

    Shipler, D.B.

    1992-04-01

    The purpose of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate radiation doses from Hanford Site operations since 1944 to populations and individuals. The primary objectives of work to be performed in FY 1992 is to determine the appropriate scope (space, time, and radionuclides, pathways and individuals/population groups) and accuracy (level of uncertainty in dose estimates) for the project. Another objective is to use a refined computer model to estimate Native American tribal doses and individual doses for the Hanford Thyroid Disease Study (HTDS). Project scope and accuracy requirements defined in FY 1992 can translated into model and data requirements that must be satisfied during FY 1993

  12. Surgical outcomes and nipple projection using the modified skate flap for nipple-areolar reconstruction in a series of 422 implant reconstructions.

    Science.gov (United States)

    Zhong, Toni; Antony, Anu; Cordeiro, Peter

    2009-05-01

    Numerous techniques have been used in an attempt to achieve long-term nipple projection following nipple-areolar reconstruction (NAR). A common setback, however, is the diminution of projection over time; this phenomenon is particularly evident following implant based breast reconstruction. The purpose of this report was thus to evaluate surgical outcomes and long-term nipple projection with the use of "modified skate flap" technique in exclusively implant based postmastectomy reconstructions. A retrospective review was performed for the period between 1993 and 2007. All consecutive patients with 2-staged tissue expander/implant reconstructions followed by NAR using the modified skate flap technique performed by the senior author (P.C.) were identified in a prospectively maintained breast reconstruction database. Only patients with a minimum of 1-year follow-up were included in the study. Patients with a history of irradiation to the breast were excluded from nipple projection assessment. Clinical outcome measurements included long-term nipple projection as well as incidence of complications from the NAR procedure using the modified skate flap technique. Over the 15-year study period, 475 patients underwent 2-staged tissue expander/implant reconstruction followed by NAR using the modified skate flap technique. Of these, there was a total of 292 patients with the minimum requirement of 1-year follow-up post NAR (61% follow-up rate). The total number of reconstructed nipple areolar complexes evaluated in this series was 422 (130 bilateral and 162 unilateral NAR). Forty patients (28 unilateral and 12 bilateral NAR) who received radiation to their breasts were excluded from nipple projection assessment. At a median follow-up of 44 months (range: 12-84 months), mean nipple projection was 2.5 mm (range: 1-4 mm). Minor complications occurred in 7.2% of the patients (n = 292). Skin graft donor site dehiscence was the most common complication (3.1%) followed by partial skin

  13. Quantitative analysis of emphysema and airway measurements according to iterative reconstruction algorithms: comparison of filtered back projection, adaptive statistical iterative reconstruction and model-based iterative reconstruction

    International Nuclear Information System (INIS)

    Choo, Ji Yung; Goo, Jin Mo; Park, Chang Min; Park, Sang Joon; Lee, Chang Hyun; Shim, Mi-Suk

    2014-01-01

    To evaluate filtered back projection (FBP) and two iterative reconstruction (IR) algorithms and their effects on the quantitative analysis of lung parenchyma and airway measurements on computed tomography (CT) images. Low-dose chest CT obtained in 281 adult patients were reconstructed using three algorithms: FBP, adaptive statistical IR (ASIR) and model-based IR (MBIR). Measurements of each dataset were compared: total lung volume, emphysema index (EI), airway measurements of the lumen and wall area as well as average wall thickness. Accuracy of airway measurements of each algorithm was also evaluated using an airway phantom. EI using a threshold of -950 HU was significantly different among the three algorithms in decreasing order of FBP (2.30 %), ASIR (1.49 %) and MBIR (1.20 %) (P < 0.01). Wall thickness was also significantly different among the three algorithms with FBP (2.09 mm) demonstrating thicker walls than ASIR (2.00 mm) and MBIR (1.88 mm) (P < 0.01). Airway phantom analysis revealed that MBIR showed the most accurate value for airway measurements. The three algorithms presented different EIs and wall thicknesses, decreasing in the order of FBP, ASIR and MBIR. Thus, care should be taken in selecting the appropriate IR algorithm on quantitative analysis of the lung. (orig.)

  14. Quantitative analysis of emphysema and airway measurements according to iterative reconstruction algorithms: comparison of filtered back projection, adaptive statistical iterative reconstruction and model-based iterative reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Choo, Ji Yung [Seoul National University Medical Research Center, Department of Radiology, Seoul National University College of Medicine, and Institute of Radiation Medicine, Seoul (Korea, Republic of); Korea University Ansan Hospital, Ansan-si, Department of Radiology, Gyeonggi-do (Korea, Republic of); Goo, Jin Mo; Park, Chang Min; Park, Sang Joon [Seoul National University Medical Research Center, Department of Radiology, Seoul National University College of Medicine, and Institute of Radiation Medicine, Seoul (Korea, Republic of); Seoul National University, Cancer Research Institute, Seoul (Korea, Republic of); Lee, Chang Hyun; Shim, Mi-Suk [Seoul National University Medical Research Center, Department of Radiology, Seoul National University College of Medicine, and Institute of Radiation Medicine, Seoul (Korea, Republic of)

    2014-04-15

    To evaluate filtered back projection (FBP) and two iterative reconstruction (IR) algorithms and their effects on the quantitative analysis of lung parenchyma and airway measurements on computed tomography (CT) images. Low-dose chest CT obtained in 281 adult patients were reconstructed using three algorithms: FBP, adaptive statistical IR (ASIR) and model-based IR (MBIR). Measurements of each dataset were compared: total lung volume, emphysema index (EI), airway measurements of the lumen and wall area as well as average wall thickness. Accuracy of airway measurements of each algorithm was also evaluated using an airway phantom. EI using a threshold of -950 HU was significantly different among the three algorithms in decreasing order of FBP (2.30 %), ASIR (1.49 %) and MBIR (1.20 %) (P < 0.01). Wall thickness was also significantly different among the three algorithms with FBP (2.09 mm) demonstrating thicker walls than ASIR (2.00 mm) and MBIR (1.88 mm) (P < 0.01). Airway phantom analysis revealed that MBIR showed the most accurate value for airway measurements. The three algorithms presented different EIs and wall thicknesses, decreasing in the order of FBP, ASIR and MBIR. Thus, care should be taken in selecting the appropriate IR algorithm on quantitative analysis of the lung. (orig.)

  15. Exact Reconstruction From Uniformly Attenuated Helical Cone-Beam Projections in SPECT

    International Nuclear Information System (INIS)

    Gullberg, Grant T.; Huang, Qiu; You, Jiangsheng; Zeng, Gengsheng L.

    2008-01-01

    In recent years the development of cone-beam reconstruction algorithms has been an active research area in x-ray computed tomography (CT), and significant progress has been made in the advancement of algorithms. Theoretically exact and computationally efficient analytical algorithms can be found in the literature. However, in single photon emission computed tomography (SPECT), published cone-beam reconstruction algorithms are either approximate or involve iterative methods. The SPECT reconstruction problem is more complicated due to degradations in the imaging detection process, one of which is the effect of attenuation of gamma ray photons. Attenuation should be compensated for to obtain quantitative results. In this paper, an analytical reconstruction algorithm for uniformly attenuated cone-beam projection data is presented for SPECT imaging. The algorithm adopts the DBH method, a procedure consisting of differentiation and backprojection followed by a finite inverse cosh-weighted Hilbert transform. The significance of the proposed approach is that a selected region of interest can be reconstructed even with a detector with a reduced field of view. The algorithm is designed for a general trajectory. However, to validate the algorithm, a numerical study was performed using a helical trajectory. The implementation is efficient and the simulation result is promising

  16. Zooming in on vibronic structure by lowest-value projection reconstructed 4D coherent spectroscopy

    Science.gov (United States)

    Harel, Elad

    2018-05-01

    A fundamental goal of chemical physics is an understanding of microscopic interactions in liquids at and away from equilibrium. In principle, this microscopic information is accessible by high-order and high-dimensionality nonlinear optical measurements. Unfortunately, the time required to execute such experiments increases exponentially with the dimensionality, while the signal decreases exponentially with the order of the nonlinearity. Recently, we demonstrated a non-uniform acquisition method based on radial sampling of the time-domain signal [W. O. Hutson et al., J. Phys. Chem. Lett. 9, 1034 (2018)]. The four-dimensional spectrum was then reconstructed by filtered back-projection using an inverse Radon transform. Here, we demonstrate an alternative reconstruction method based on the statistical analysis of different back-projected spectra which results in a dramatic increase in sensitivity and at least a 100-fold increase in dynamic range compared to conventional uniform sampling and Fourier reconstruction. These results demonstrate that alternative sampling and reconstruction methods enable applications of increasingly high-order and high-dimensionality methods toward deeper insights into the vibronic structure of liquids.

  17. Neural network CT image reconstruction method for small amount of projection data

    CERN Document Server

    Ma, X F; Takeda, T

    2000-01-01

    This paper presents a new method for two-dimensional image reconstruction by using a multi-layer neural network. Though a conventionally used object function of such a neural network is composed of a sum of squared errors of the output data, we define an object function composed of a sum of squared residuals of an integral equation. By employing an appropriate numerical line integral for this integral equation, we can construct a neural network which can be used for CT image reconstruction for cases with small amount of projection data. We applied this method to some model problems and obtained satisfactory results. This method is especially useful for analyses of laboratory experiments or field observations where only a small amount of projection data is available in comparison with the well-developed medical applications.

  18. Neural network CT image reconstruction method for small amount of projection data

    International Nuclear Information System (INIS)

    Ma, X.F.; Fukuhara, M.; Takeda, T.

    2000-01-01

    This paper presents a new method for two-dimensional image reconstruction by using a multi-layer neural network. Though a conventionally used object function of such a neural network is composed of a sum of squared errors of the output data, we define an object function composed of a sum of squared residuals of an integral equation. By employing an appropriate numerical line integral for this integral equation, we can construct a neural network which can be used for CT image reconstruction for cases with small amount of projection data. We applied this method to some model problems and obtained satisfactory results. This method is especially useful for analyses of laboratory experiments or field observations where only a small amount of projection data is available in comparison with the well-developed medical applications

  19. Projection matrix acquisition for cone-beam computed tomography iterative reconstruction

    Science.gov (United States)

    Yang, Fuqiang; Zhang, Dinghua; Huang, Kuidong; Shi, Wenlong; Zhang, Caixin; Gao, Zongzhao

    2017-02-01

    Projection matrix is an essential and time-consuming part in computed tomography (CT) iterative reconstruction. In this article a novel calculation algorithm of three-dimensional (3D) projection matrix is proposed to quickly acquire the matrix for cone-beam CT (CBCT). The CT data needed to be reconstructed is considered as consisting of the three orthogonal sets of equally spaced and parallel planes, rather than the individual voxels. After getting the intersections the rays with the surfaces of the voxels, the coordinate points and vertex is compared to obtain the index value that the ray traversed. Without considering ray-slope to voxel, it just need comparing the position of two points. Finally, the computer simulation is used to verify the effectiveness of the algorithm.

  20. Image reconstruction from projections and its application in emission computer tomography

    International Nuclear Information System (INIS)

    Kuba, Attila; Csernay, Laszlo

    1989-01-01

    Computer tomography is an imaging technique for producing cross sectional images by reconstruction from projections. Its two main branches are called transmission and emission computer tomography, TCT and ECT, resp. After an overview of the theory and practice of TCT and ECT, the first Hungarian ECT type MB 9300 SPECT consisting of a gamma camera and Ketronic Medax N computer is described, and its applications to radiological patient observations are discussed briefly. (R.P.) 28 refs.; 4 figs

  1. Reconstructing sea level from paleo and projected temperatures 200 to 2100 AD

    DEFF Research Database (Denmark)

    Grinsted, Aslak; Moore, John; Jevrejeva, Svetlana

    2010-01-01

    -proxy reconstructions assuming that the established relationship between temperature and sea level holds from 200 to 2100 ad. Over the last 2,000 years minimum sea level (-19 to -26 cm) occurred around 1730 ad, maximum sea level (12–21 cm) around 1150 AD. Sea level 2090–2099 is projected to be 0.9 to 1.3 m for the A1B...

  2. The CHT2 Project: Diachronic 3d Reconstruction of Historic Sites

    Science.gov (United States)

    Guidi, G.; Micoli, L.; Gonizzi Barsanti, S.; Malik, U.

    2017-08-01

    Digital modelling archaeological and architectural monuments in their current state and in their presumed past aspect has been recognized not only as a way for explaining to the public the genesis of a historical site, but also as an effective tool for research. The search for historical sources, their proper analysis and interdisciplinary relationship between technological disciplines and the humanities are fundamental for obtaining reliable hypothetical reconstructions. This paper presents an experimental activity defined by the project Cultural Heritage Through Time - CHT2 (http://cht2-project.eu), funded in the framework of the Joint Programming Initiative on Cultural Heritage (JPI-CH) of the European Commission. Its goal is to develop time-varying 3D products, from landscape to architectural scale, deals with the implementation of the methodology on one of the case studies: the late Roman circus of Milan, built in the era when the city was the capital of the Western Roman Empire (286-402 A.D). The work presented here covers one of the cases in which the physical evidences have now been almost entirely disappeared. The diachronic reconstruction is based on a proper mix of quantitative data originated by 3D surveys at present time, and historical sources like ancient maps, drawings, archaeological reports, archaeological restrictions decrees and old photographs. Such heterogeneous sources have been first georeferenced and then properly integrated according to the methodology defined in the framework of the CHT2 project, to hypothesize a reliable reconstruction of the area in different historical periods.

  3. An electron tomography algorithm for reconstructing 3D morphology using surface tangents of projected scattering interfaces

    Science.gov (United States)

    Petersen, T. C.; Ringer, S. P.

    2010-03-01

    Upon discerning the mere shape of an imaged object, as portrayed by projected perimeters, the full three-dimensional scattering density may not be of particular interest. In this situation considerable simplifications to the reconstruction problem are possible, allowing calculations based upon geometric principles. Here we describe and provide an algorithm which reconstructs the three-dimensional morphology of specimens from tilt series of images for application to electron tomography. Our algorithm uses a differential approach to infer the intersection of projected tangent lines with surfaces which define boundaries between regions of different scattering densities within and around the perimeters of specimens. Details of the algorithm implementation are given and explained using reconstruction calculations from simulations, which are built into the code. An experimental application of the algorithm to a nano-sized Aluminium tip is also presented to demonstrate practical analysis for a real specimen. Program summaryProgram title: STOMO version 1.0 Catalogue identifier: AEFS_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEFS_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 2988 No. of bytes in distributed program, including test data, etc.: 191 605 Distribution format: tar.gz Programming language: C/C++ Computer: PC Operating system: Windows XP RAM: Depends upon the size of experimental data as input, ranging from 200 Mb to 1.5 Gb Supplementary material: Sample output files, for the test run provided, are available. Classification: 7.4, 14 External routines: Dev-C++ ( http://www.bloodshed.net/devcpp.html) Nature of problem: Electron tomography of specimens for which conventional back projection may fail and/or data for which there is a limited angular

  4. Methods of X-ray CT image reconstruction from few projections

    International Nuclear Information System (INIS)

    Wang, H.

    2011-01-01

    To improve the safety (low dose) and the productivity (fast acquisition) of a X-ray CT system, we want to reconstruct a high quality image from a small number of projections. The classical reconstruction algorithms generally fail since the reconstruction procedure is unstable and suffers from artifacts. A new approach based on the recently developed 'Compressed Sensing' (CS) theory assumes that the unknown image is in some sense 'sparse' or 'compressible', and the reconstruction is formulated through a non linear optimization problem (TV/l1 minimization) by enhancing the sparsity. Using the pixel (or voxel in 3D) as basis, to apply the CS framework in CT one usually needs a 'sparsifying' transform, and combines it with the 'X-ray projector' which applies on the pixel image. In this thesis, we have adapted a 'CT-friendly' radial basis of Gaussian family called 'blob' to the CS-CT framework. The blob has better space-frequency localization properties than the pixel, and many operations, such as the X-ray transform, can be evaluated analytically and are highly parallelizable (on GPU platform). Compared to the classical Kaisser-Bessel blob, the new basis has a multi-scale structure: an image is the sum of dilated and translated radial Mexican hat functions. The typical medical objects are compressible under this basis, so the sparse representation system used in the ordinary CS algorithms is no more needed. 2D simulations show that the existing TV and l1 algorithms are more efficient and the reconstructions have better visual quality than the equivalent approach based on the pixel or wavelet basis. The new approach has also been validated on 2D experimental data, where we have observed that in general the number of projections can be reduced to about 50%, without compromising the image quality. (author) [fr

  5. Fast cross-projection algorithm for reconstruction of seeds in prostate brachytherapy

    International Nuclear Information System (INIS)

    Narayanan, Sreeram; Cho, Paul S.; Marks, Robert J. II

    2002-01-01

    A fast method of seed matching and reconstruction in prostrate brachytherapy is proposed. Previous approaches have required all seeds to be matched with all other seeds in other projections. The fast cross-projection algorithm for the reconstruction of seeds (Fast-CARS) allows for matching of a given seed with a subset of seeds in other projections. This subset lies in a proximal region centered about the projection of a line, connecting the seed to its source, onto other projection planes. The proposed technique permits a significant reduction in computational overhead, as measured by the required number of matching tests. The number of multiplications and additions is also vastly reduced at no trade-off in accuracy. Because of its speed, Fast-CARS can be used in applications requiring real-time performance such as intraoperative dosimetry of prostate brachytherapy. Furthermore, the proposed method makes practical the use of a larger number of views as opposed to previous techniques limited to a maximum use of three views

  6. Direct image reconstruction with limited angle projection data for computerized tomography

    International Nuclear Information System (INIS)

    Inouye, T.

    1980-01-01

    Discussions are made on the minimum angle range for projection data necessary to reconstruct the complete CT image. As is easily shown from the image reconstruction theorem, the lack of projection angle provides no data for the Fourier transformed function of the object on the corresponding angular directions, where the projections are missing. In a normal situation, the Fourier transformed function of an object image holds an analytic characteristic with respect to two-dimensional orthogonal parameters. This characteristic enables uniquely prolonging the function outside the obtained region employing a sort of analytic continuation with respect to both parameters. In the method reported here, an object pattern, which is confined within a finite range, is shifted to a specified region to have complete orthogonal function expansions without changing the projection angle directions. These orthogonal functions are analytically extended to the missing projection angle range and the whole function is determined. This method does not include any estimation process, whose effectiveness is often seriously jeopardized by the presence of a slight fluctuation component. Computer simulations were carried out to demonstrate the effectiveness of the method

  7. Exact fan-beam image reconstruction algorithm for truncated projection data acquired from an asymmetric half-size detector

    International Nuclear Information System (INIS)

    Leng Shuai; Zhuang Tingliang; Nett, Brian E; Chen Guanghong

    2005-01-01

    In this paper, we present a new algorithm designed for a specific data truncation problem in fan-beam CT. We consider a scanning configuration in which the fan-beam projection data are acquired from an asymmetrically positioned half-sized detector. Namely, the asymmetric detector only covers one half of the scanning field of view. Thus, the acquired fan-beam projection data are truncated at every view angle. If an explicit data rebinning process is not invoked, this data acquisition configuration will reek havoc on many known fan-beam image reconstruction schemes including the standard filtered backprojection (FBP) algorithm and the super-short-scan FBP reconstruction algorithms. However, we demonstrate that a recently developed fan-beam image reconstruction algorithm which reconstructs an image via filtering a backprojection image of differentiated projection data (FBPD) survives the above fan-beam data truncation problem. Namely, we may exactly reconstruct the whole image object using the truncated data acquired in a full scan mode (2π angular range). We may also exactly reconstruct a small region of interest (ROI) using the truncated projection data acquired in a short-scan mode (less than 2π angular range). The most important characteristic of the proposed reconstruction scheme is that an explicit data rebinning process is not introduced. Numerical simulations were conducted to validate the new reconstruction algorithm

  8. Simultaneous static and cine nonenhanced MR angiography using radial sampling and highly constrained back projection reconstruction.

    Science.gov (United States)

    Koktzoglou, Ioannis; Mistretta, Charles A; Giri, Shivraman; Dunkle, Eugene E; Amin, Parag; Edelman, Robert R

    2014-10-01

    To describe a pulse sequence for simultaneous static and cine nonenhanced magnetic resonance angiography (NEMRA) of the peripheral arteries. The peripheral arteries of 10 volunteers and 6 patients with peripheral arterial disease (PAD) were imaged with the proposed cine NEMRA sequence on a 1.5 Tesla (T) system. The impact of multi-shot imaging and highly constrained back projection (HYPR) reconstruction was examined. The propagation rate of signal along the length of the arterial tree in the cine nonenhanced MR angiograms was quantified. The cine NEMRA sequence simultaneously provided a static MR angiogram showing vascular anatomy as well as a cine display of arterial pulse wave propagation along the entire length of the peripheral arteries. Multi-shot cine NEMRA improved temporal resolution and reduced image artifacts. HYPR reconstruction improved image quality when temporal reconstruction footprints shorter than 100 ms were used (P cine NEMRA was slower in patients with PAD than in volunteers. Simultaneous static and cine NEMRA of the peripheral arteries is feasible. Multi-shot acquisition and HYPR reconstruction can be used to improve arterial conspicuity and temporal resolution. Copyright © 2013 Wiley Periodicals, Inc.

  9. Minimizing image noise in on-board CT reconstruction using both kilovoltage and megavoltage beam projections

    International Nuclear Information System (INIS)

    Zhang Junan; Yin Fangfang

    2007-01-01

    We studied a recently proposed aggregated CT reconstruction technique which combines the complementary advantages of kilovoltage (kV) and megavoltage (MV) x-ray imaging. Various phantoms were imaged to study the effects of beam orientations and geometry of the imaging object on image quality of reconstructed CT. It was shown that the quality of aggregated CT was correlated with both kV and MV beam orientations and the degree of this correlation depended upon the geometry of the imaging object. The results indicated that the optimal orientations were those when kV beams pass through the thinner portion and MV beams pass through the thicker portion of the imaging object. A special preprocessing procedure was also developed to perform contrast conversions between kV and MV information prior to image reconstruction. The performance of two reconstruction methods, one filtered backprojection method and one iterative method, were compared. The effects of projection number, beam truncation, and contrast conversion on the CT image quality were investigated

  10. Initial communication survey results for the Hanford Environmental Dose Reconstruction Project

    International Nuclear Information System (INIS)

    Beck, D.M.

    1991-03-01

    To support the public communication efforts of the Technical Steering Panel of the Hanford Environmental Dose Reconstruction (HEDR) Project, a public survey was conducted. The survey was intended to provide information about the public's knowledge and interest in the project and the best ways to communicate project results. Questions about the project were included as part of an omnibus survey conducted by Washington State University. The survey was conducted by phone to Washington State residents in the spring of 1990. This report gives the HEDR-related questions and summary data of responses. Questions associated with the HEDR Project were grouped into four categories: knowledge of the HEDR Project; interest in the project; preferred ways of receiving information about the project (including public information meetings, a newsletter mailed to homes, presentations to civic groups in the respondent's community, a computer bulletin board respondent could access with a modem, information displays at public buildings and shopping malls, and an information video sent to respondent); and level of concern over past exposure from Hanford operations. Questions abut whom state residents are most likely to trust about radiation issues were also part of the omnibus survey, and responses are included in this report

  11. Restoration of the analytically reconstructed OpenPET images by the method of convex projections

    Energy Technology Data Exchange (ETDEWEB)

    Tashima, Hideaki; Murayama, Hideo; Yamaya, Taiga [National Institute of Radiological Sciences, Chiba (Japan); Katsunuma, Takayuki; Suga, Mikio [Chiba Univ. (Japan). Graduate School of Engineering; Kinouchi, Shoko [National Institute of Radiological Sciences, Chiba (Japan); Chiba Univ. (Japan). Graduate School of Engineering; Obi, Takashi [Tokyo Institute of Technology (Japan). Interdisciplinary Graduate School of Science and Engineering; Kudo, Hiroyuki [Tsukuba Univ. (Japan). Graduate School of Systems and Information Engineering

    2011-07-01

    We have proposed the OpenPET geometry which has gaps between detector rings and physically opened field-of-view. The image reconstruction of the OpenPET is classified into an incomplete problem because it does not satisfy the Orlov's condition. Even so, the simulation and experimental studies have shown that applying iterative methods such as the maximum likelihood expectation maximization (ML-EM) algorithm successfully reconstruct images in the gap area. However, the imaging process of the iterative methods in the OpenPET imaging is not clear. Therefore, the aim of this study is to analytically analyze the OpenPET imaging and estimate implicit constraints involved in the iterative methods. To apply explicit constraints in the OpenPET imaging, we used the method of convex projections for restoration of the images reconstructed by the analytical way in which low-frequency components are lost. Numerical simulations showed that the similar restoration effects are involved both in the ML-EM and the method of convex projections. Therefore, the iterative methods have advantageous effect of restoring lost frequency components of the OpenPET imaging. (orig.)

  12. Analytical algorithm for the generation of polygonal projection data for tomographic reconstruction

    International Nuclear Information System (INIS)

    Davis, G.R.

    1996-01-01

    Tomographic reconstruction algorithms and filters can be tested using a mathematical phantom, that is, a computer program which takes numerical data as its input and outputs derived projection data. The input data is usually in the form of pixel ''densities'' over a regular grid, or position and dimensions of simple, geometrical objects. The former technique allows a greater variety of objects to be simulated, but is less suitable in the case when very small (relative to the ray-spacing) features are to be simulated. The second technique is normally used to simulate biological specimens, typically a human skull, modelled as a number of ellipses. This is not suitable for simulating non-biological specimens with features such as straight edges and fine cracks. We have therefore devised an algorithm for simulating objects described as a series of polygons. These polygons, or parts of them, may be smaller than the ray-spacing and there is no limit, except that imposed by computing resources, on the complexity, number or superposition of polygons. A simple test of such a phantom, reconstructed using the filtered back-projection method, revealed reconstruction artefacts not normally seen with ''biological'' phantoms. (orig.)

  13. Revisiting a Dramatic Triangle: The State, Villagers, and Social Activists in Chinese Rural Reconstruction Projects

    Directory of Open Access Journals (Sweden)

    Stig Thøgersen

    2009-01-01

    Full Text Available As part of the movement to “construct a new socialist countryside”, Chinese officials and social activists are experimenting with transforming rural social and economic relations. They often draw on discourses dating back to the Rural Reconstruction Movement of the 1920s and 1930s, which saw urban intellectuals making similar efforts to modernize the villages and their inhabitants. This paper analyses the different types of relationships between the state, social activists, and villagers in a number of rural reconstruction projects. The state is still the major player in this field, but traditional top-down procedures are often perceived to be unproductive when it comes to micro-level community building, so state actors are forced to find allies among village elites and social activists.

  14. Design and implementation of a safety health and environment management system in BHP Petroleum

    Energy Technology Data Exchange (ETDEWEB)

    Mattes, B.W.; Walters, C. [BHP Petroleum, Melbourne, VIC (Australia)

    1995-12-31

    The Australian/Asian operations group within BHP Petroleum (BHPP) is implementing and integrated management system with safety, occupational health and environmental elements as crucial components of all BHPP operations. Responsibility for the development, implementation and maintenance of the management system, and compliance with its provisions, rests with line management, a logical extension of the accountability and responsibility for safety, health and environment matters that rests with line managers within BHPP. Contractors are scrutinized to assess their safety, health and environmental performance and failure to meet minimal standards will result in their disqualification. The effectiveness of the BHPP Management System is yet to be fully determined, however, it will be measured against the performance of the company in the areas of zero lost time due to injuries, a drop in incidences requiring medical treatment or first aid, lower absenteeism and workers compensation bills, no oil spills, less car accidents, less back pain and RSI, better management of waste emissions to air, land and sea, and less equipment breakdowns. The trend in improved safety, health and environment performance are already apparent and auger well for the Company as it moves towards the new millennium. 7 figs., 2 photos., 4 refs.

  15. Comparison of adaptive statistical iterative and filtered back projection reconstruction techniques in brain CT

    International Nuclear Information System (INIS)

    Ren, Qingguo; Dewan, Sheilesh Kumar; Li, Ming; Li, Jianying; Mao, Dingbiao; Wang, Zhenglei; Hua, Yanqing

    2012-01-01

    Purpose: To compare image quality and visualization of normal structures and lesions in brain computed tomography (CT) with adaptive statistical iterative reconstruction (ASIR) and filtered back projection (FBP) reconstruction techniques in different X-ray tube current–time products. Materials and methods: In this IRB-approved prospective study, forty patients (nineteen men, twenty-one women; mean age 69.5 ± 11.2 years) received brain scan at different tube current–time products (300 and 200 mAs) in 64-section multi-detector CT (GE, Discovery CT750 HD). Images were reconstructed with FBP and four levels of ASIR-FBP blending. Two radiologists (please note that our hospital is renowned for its geriatric medicine department, and these two radiologists are more experienced in chronic cerebral vascular disease than in neoplastic disease, so this research did not contain cerebral tumors but as a discussion) assessed all the reconstructed images for visibility of normal structures, lesion conspicuity, image contrast and diagnostic confidence in a blinded and randomized manner. Volume CT dose index (CTDI vol ) and dose-length product (DLP) were recorded. All the data were analyzed by using SPSS 13.0 statistical analysis software. Results: There was no statistically significant difference between the image qualities at 200 mAs with 50% ASIR blending technique and 300 mAs with FBP technique (p > .05). While between the image qualities at 200 mAs with FBP and 300 mAs with FBP technique a statistically significant difference (p < .05) was found. Conclusion: ASIR provided same image quality and diagnostic ability in brain imaging with greater than 30% dose reduction compared with FBP reconstruction technique

  16. Comparison of adaptive statistical iterative and filtered back projection reconstruction techniques in brain CT

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Qingguo, E-mail: renqg83@163.com [Department of Radiology, Hua Dong Hospital of Fudan University, Shanghai 200040 (China); Dewan, Sheilesh Kumar, E-mail: sheilesh_d1@hotmail.com [Department of Geriatrics, Hua Dong Hospital of Fudan University, Shanghai 200040 (China); Li, Ming, E-mail: minli77@163.com [Department of Radiology, Hua Dong Hospital of Fudan University, Shanghai 200040 (China); Li, Jianying, E-mail: Jianying.Li@med.ge.com [CT Imaging Research Center, GE Healthcare China, Beijing (China); Mao, Dingbiao, E-mail: maodingbiao74@163.com [Department of Radiology, Hua Dong Hospital of Fudan University, Shanghai 200040 (China); Wang, Zhenglei, E-mail: Williswang_doc@yahoo.com.cn [Department of Radiology, Shanghai Electricity Hospital, Shanghai 200050 (China); Hua, Yanqing, E-mail: cjr.huayanqing@vip.163.com [Department of Radiology, Hua Dong Hospital of Fudan University, Shanghai 200040 (China)

    2012-10-15

    Purpose: To compare image quality and visualization of normal structures and lesions in brain computed tomography (CT) with adaptive statistical iterative reconstruction (ASIR) and filtered back projection (FBP) reconstruction techniques in different X-ray tube current–time products. Materials and methods: In this IRB-approved prospective study, forty patients (nineteen men, twenty-one women; mean age 69.5 ± 11.2 years) received brain scan at different tube current–time products (300 and 200 mAs) in 64-section multi-detector CT (GE, Discovery CT750 HD). Images were reconstructed with FBP and four levels of ASIR-FBP blending. Two radiologists (please note that our hospital is renowned for its geriatric medicine department, and these two radiologists are more experienced in chronic cerebral vascular disease than in neoplastic disease, so this research did not contain cerebral tumors but as a discussion) assessed all the reconstructed images for visibility of normal structures, lesion conspicuity, image contrast and diagnostic confidence in a blinded and randomized manner. Volume CT dose index (CTDI{sub vol}) and dose-length product (DLP) were recorded. All the data were analyzed by using SPSS 13.0 statistical analysis software. Results: There was no statistically significant difference between the image qualities at 200 mAs with 50% ASIR blending technique and 300 mAs with FBP technique (p > .05). While between the image qualities at 200 mAs with FBP and 300 mAs with FBP technique a statistically significant difference (p < .05) was found. Conclusion: ASIR provided same image quality and diagnostic ability in brain imaging with greater than 30% dose reduction compared with FBP reconstruction technique.

  17. An accelerated threshold-based back-projection algorithm for Compton camera image reconstruction

    International Nuclear Information System (INIS)

    Mundy, Daniel W.; Herman, Michael G.

    2011-01-01

    Purpose: Compton camera imaging (CCI) systems are currently under investigation for radiotherapy dose reconstruction and verification. The ability of such a system to provide real-time images during dose delivery will be limited by the computational speed of the image reconstruction algorithm. In this work, the authors present a fast and simple method by which to generate an initial back-projected image from acquired CCI data, suitable for use in a filtered back-projection algorithm or as a starting point for iterative reconstruction algorithms, and compare its performance to the current state of the art. Methods: Each detector event in a CCI system describes a conical surface that includes the true point of origin of the detected photon. Numerical image reconstruction algorithms require, as a first step, the back-projection of each of these conical surfaces into an image space. The algorithm presented here first generates a solution matrix for each slice of the image space by solving the intersection of the conical surface with the image plane. Each element of the solution matrix is proportional to the distance of the corresponding voxel from the true intersection curve. A threshold function was developed to extract those pixels sufficiently close to the true intersection to generate a binary intersection curve. This process is repeated for each image plane for each CCI detector event, resulting in a three-dimensional back-projection image. The performance of this algorithm was tested against a marching algorithm known for speed and accuracy. Results: The threshold-based algorithm was found to be approximately four times faster than the current state of the art with minimal deficit to image quality, arising from the fact that a generically applicable threshold function cannot provide perfect results in all situations. The algorithm fails to extract a complete intersection curve in image slices near the detector surface for detector event cones having axes nearly

  18. GPU-based fast cone beam CT reconstruction from undersampled and noisy projection data via total variation

    International Nuclear Information System (INIS)

    Jia Xun; Lou Yifei; Li Ruijiang; Song, William Y.; Jiang, Steve B.

    2010-01-01

    Purpose: Cone-beam CT (CBCT) plays an important role in image guided radiation therapy (IGRT). However, the large radiation dose from serial CBCT scans in most IGRT procedures raises a clinical concern, especially for pediatric patients who are essentially excluded from receiving IGRT for this reason. The goal of this work is to develop a fast GPU-based algorithm to reconstruct CBCT from undersampled and noisy projection data so as to lower the imaging dose. Methods: The CBCT is reconstructed by minimizing an energy functional consisting of a data fidelity term and a total variation regularization term. The authors developed a GPU-friendly version of the forward-backward splitting algorithm to solve this model. A multigrid technique is also employed. Results: It is found that 20-40 x-ray projections are sufficient to reconstruct images with satisfactory quality for IGRT. The reconstruction time ranges from 77 to 130 s on an NVIDIA Tesla C1060 (NVIDIA, Santa Clara, CA) GPU card, depending on the number of projections used, which is estimated about 100 times faster than similar iterative reconstruction approaches. Moreover, phantom studies indicate that the algorithm enables the CBCT to be reconstructed under a scanning protocol with as low as 0.1 mA s/projection. Comparing with currently widely used full-fan head and neck scanning protocol of ∼360 projections with 0.4 mA s/projection, it is estimated that an overall 36-72 times dose reduction has been achieved in our fast CBCT reconstruction algorithm. Conclusions: This work indicates that the developed GPU-based CBCT reconstruction algorithm is capable of lowering imaging dose considerably. The high computation efficiency in this algorithm makes the iterative CBCT reconstruction approach applicable in real clinical environments.

  19. GPU-based fast cone beam CT reconstruction from undersampled and noisy projection data via total variation.

    Science.gov (United States)

    Jia, Xun; Lou, Yifei; Li, Ruijiang; Song, William Y; Jiang, Steve B

    2010-04-01

    Cone-beam CT (CBCT) plays an important role in image guided radiation therapy (IGRT). However, the large radiation dose from serial CBCT scans in most IGRT procedures raises a clinical concern, especially for pediatric patients who are essentially excluded from receiving IGRT for this reason. The goal of this work is to develop a fast GPU-based algorithm to reconstruct CBCT from undersampled and noisy projection data so as to lower the imaging dose. The CBCT is reconstructed by minimizing an energy functional consisting of a data fidelity term and a total variation regularization term. The authors developed a GPU-friendly version of the forward-backward splitting algorithm to solve this model. A multigrid technique is also employed. It is found that 20-40 x-ray projections are sufficient to reconstruct images with satisfactory quality for IGRT. The reconstruction time ranges from 77 to 130 s on an NVIDIA Tesla C1060 (NVIDIA, Santa Clara, CA) GPU card, depending on the number of projections used, which is estimated about 100 times faster than similar iterative reconstruction approaches. Moreover, phantom studies indicate that the algorithm enables the CBCT to be reconstructed under a scanning protocol with as low as 0.1 mA s/projection. Comparing with currently widely used full-fan head and neck scanning protocol of approximately 360 projections with 0.4 mA s/projection, it is estimated that an overall 36-72 times dose reduction has been achieved in our fast CBCT reconstruction algorithm. This work indicates that the developed GPU-based CBCT reconstruction algorithm is capable of lowering imaging dose considerably. The high computation efficiency in this algorithm makes the iterative CBCT reconstruction approach applicable in real clinical environments.

  20. A work bibliography on native food consumption, demography and lifestyle. Hanford Environmental Dose Reconstruction Project

    Energy Technology Data Exchange (ETDEWEB)

    Murray, C.E.; Lee, W.J.

    1992-12-01

    The purpose of this report is to provide a bibliography for the Native American tribe participants in the Hanford Environmental Dose Reconstruction (HEDR) Project to use. The HEDR Project`s primary objective is to estimate the radiation dose that individuals could have received as a result of emissions since 1944 from the US Department of Energy`s Hanford Site near Richland, Washington. Eight Native American tribes are responsible for estimating daily and seasonal consumption of traditional foods, demography, and other lifestyle factors that could have affected the radiation dose received by tribal members. This report provides a bibliography of recorded accounts that tribal researchers may use to verify their estimates. The bibliographic citations include references to information on the specific tribes, Columbia River plateau ethnobotany, infant feeding practices and milk consumption, nutritional studies and radiation, tribal economic and demographic characteristics (1940--1970), research methods, primary sources from the National Archives, regional archives, libraries, and museums.

  1. Use of the geometric mean of opposing planar projections in pre-reconstruction restoration of SPECT images

    International Nuclear Information System (INIS)

    Boulfelfel, D.; Rangayyan, R.M.; Hahn, L.J.; Kloiber, R.

    1992-01-01

    This paper presents a restoration scheme for single photon emission computed tomography (SPECT) images that performs restoration before reconstruction (pre-reconstruction restoration) from planar (projection) images. In this scheme, the pixel-by-pixel geometric mean of each pair of opposing (conjugate) planar projections is computed prior to the reconstruction process. The averaging process is shown to help in making the degradation phenomenon less dependent on the distance of each point of the object from the camera. The restoration filters investigated are the Wiener and power spectrum equalization filters. (author)

  2. GPU acceleration of 3D forward and backward projection using separable footprints for X-ray CT image reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Meng; Fessler, Jeffrey A. [Michigan Univ., Ann Arbor, MI (United States). Dept. of Electrical Engineering and Computer Science

    2011-07-01

    Iterative 3D image reconstruction methods can improve image quality over conventional filtered back projection (FBP) in X-ray computed tomography. However, high computational costs deter the routine use of iterative reconstruction clinically. The separable footprint method for forward and back-projection simplifies the integrals over a detector cell in a way that is quite accurate and also has a relatively efficient CPU implementation. In this project, we implemented the separable footprints method for both forward and backward projection on a graphics processing unit (GPU) with NVDIA's parallel computing architecture (CUDA). This paper describes our GPU kernels for the separable footprint method and simulation results. (orig.)

  3. Columbia River pathway report: phase I of the Hanford Environmental Dose Reconstruction Project

    Energy Technology Data Exchange (ETDEWEB)

    1991-07-01

    This report summarizes the river-pathway portion of the first phase of the Hanford Environmental Dose Reconstruction (HEDR) Project. The HEDR Project is estimating radiation doses that could have been received by the public from the Department of Energy's Hanford Site, in southeastern Washington State. Phase 1 of the river-pathway dose reconstruction effort sought to determine whether dose estimates could be calculated for populations in the area from above the Hanford Site at Priest Rapids Dam to below the site at McNary Dam from January 1964 to December 1966. Of the potential sources of radionuclides from the river, fish consumption was the most important. Doses from drinking water were lower at Pasco than at Richland and lower at Kennewick than at Pasco. The median values of preliminary dose estimates calculated by HEDR are similar to independent, previously published estimates of average doses to Richland residents. Later phases of the HEDR Project will address dose estimates for periods other than 1964--1966 and for populations downstream of McNary Dam. 17 refs., 19 figs., 1 tab.

  4. Development of an image reconstruction algorithm for a few number of projection data

    International Nuclear Information System (INIS)

    Vieira, Wilson S.; Brandao, Luiz E.; Braz, Delson

    2007-01-01

    An image reconstruction algorithm was developed for specific cases of radiotracer applications in industry (rotating cylindrical mixers), involving a very few number of projection data. The algorithm was planned for imaging radioactive isotope distributions around the center of circular planes. The method consists of adapting the original expectation maximization algorithm (EM) to solve the ill-posed emission tomography inverse problem in order to reconstruct transversal 2D images of an object with only four projections. To achieve this aim, counts of photons emitted by selected radioactive sources in the plane, after they had been simulated using the commercial software MICROSHIELD 5.05, constitutes the projections and a computational code (SPECTEM) was developed to generate activity vectors or images related to those sources. SPECTEM is flexible to support simultaneous changes of the detectors's geometry, the medium under investigation and the properties of the gamma radiation. As a consequence of the code had been followed correctly the proposed method, good results were obtained and they encouraged us to continue the next step of the research: the validation of SPECTEM utilizing experimental data to check its real performance. We aim this code will improve considerably radiotracer methodology, making easier the diagnosis of fails in industrial processes. (author)

  5. Development of an image reconstruction algorithm for a few number of projection data

    Energy Technology Data Exchange (ETDEWEB)

    Vieira, Wilson S.; Brandao, Luiz E. [Instituto de Engenharia Nuclear (IEN-CNEN/RJ), Rio de Janeiro , RJ (Brazil)]. E-mails: wilson@ien.gov.br; brandao@ien.gov.br; Braz, Delson [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programa de Pos-graduacao de Engenharia (COPPE). Lab. de Instrumentacao Nuclear]. E-mail: delson@mailhost.lin.ufrj.br

    2007-07-01

    An image reconstruction algorithm was developed for specific cases of radiotracer applications in industry (rotating cylindrical mixers), involving a very few number of projection data. The algorithm was planned for imaging radioactive isotope distributions around the center of circular planes. The method consists of adapting the original expectation maximization algorithm (EM) to solve the ill-posed emission tomography inverse problem in order to reconstruct transversal 2D images of an object with only four projections. To achieve this aim, counts of photons emitted by selected radioactive sources in the plane, after they had been simulated using the commercial software MICROSHIELD 5.05, constitutes the projections and a computational code (SPECTEM) was developed to generate activity vectors or images related to those sources. SPECTEM is flexible to support simultaneous changes of the detectors's geometry, the medium under investigation and the properties of the gamma radiation. As a consequence of the code had been followed correctly the proposed method, good results were obtained and they encouraged us to continue the next step of the research: the validation of SPECTEM utilizing experimental data to check its real performance. We aim this code will improve considerably radiotracer methodology, making easier the diagnosis of fails in industrial processes. (author)

  6. The Avignon Bridge: a 3d Reconstruction Project Integrating Archaeological, Historical and Gemorphological Issues

    Science.gov (United States)

    Berthelot, M.; Nony, N.; Gugi, L.; Bishop, A.; De Luca, L.

    2015-02-01

    The history and identity of the Avignon's bridge is inseparable from that of the Rhône river. Therefore, in order to share the history and memory of the Rhône, it is essential to get to know this bridge and especially to identify and make visible the traces of its past, its construction, its interaction with the river dynamics, which greatly influenced his life. These are the objectives of the PAVAGE project that focuses on digitally surveying, modelling and re-visiting a heritage site of primary importance with the aim of virtually restoring the link between the two sides which, after the disappearance of the Roman bridge of Arles, constituted for a long time the only connection between Lyon or Vienna and the sea. Therefore, this project has an important geo-historical dimension for which geo-morphological and paleoenvironmental studies were implemented in connection with the latest digital simulation methods exploiting geographic information systems. By integrating knowledge and reflections of archaeologists, historians, geomorphologists, environmentalists, architects, engineers and computer scientists, the result of this project (which involved 5 laboratories during 4 years) is a 3D digital model covering an extension of 50 km2 achieved by integrating satellite imagery, UAV-based acquisitions, terrestrial laser scanning and photogrammetry, etc. Beyond the actions of scientific valorisation concerning the historical and geomorphological dimensions of the project, the results of this work of this interdisciplinary investigation and interpretation of this site are today integrated within a location-based augmented reality application allowing tourists to exploring the virtual reconstruction of the bridge and its environment through tablets inside the portion of territory covered by this project (between Avignon and Villeneuve-lez-Avignon). This paper presents the main aspects of the 3D virtual reconstruction approach.

  7. Sub-sequence Factorization-an Effective Approach for Projective Reconstruction under Occlusion

    Institute of Scientific and Technical Information of China (English)

    LU Le; HU Zhanyi

    2001-01-01

    Projective reconstruction is a key step for 3D metric reconstruction from a sequence of images captured by an uncalibrated camera. Due to its inherent robustness, the factorization method is widely used in literatures. However, the main shortcoming of the standard factorization method is that it requires the corresponding points to appear across ALL the images. When large changes of view angles occur in the image sequence, or the scene is easy to be self-occluded, nearly it will be very difficult to have some corresponding points visible across all the images. But it is much easier for only several images to have enough correspondences required by factorization method. These images are called as a subsequence in the whole image set. In this paper,a sub-sequence factorization method is proposed to cope with the problem. The basic principle of the sub-sequence factorization method is to divide a long image sequence into several short subsequences according to its spatial continuity, and the standard factorization method is employed for each subsequence.Then, a novel alignment process is invoked to transform different reconstructions under different subsequences into one reference coordinates system. It is more practical as it only demands that there are enough correspondences in each subsequence, not the whole sequence. The proposed sub-sequence factorization method preserves the robustness aspect embedded in the standard factorization method. The experiments on synthetic and real images validate our proposed new method.

  8. Block matching sparsity regularization-based image reconstruction for incomplete projection data in computed tomography

    Science.gov (United States)

    Cai, Ailong; Li, Lei; Zheng, Zhizhong; Zhang, Hanming; Wang, Linyuan; Hu, Guoen; Yan, Bin

    2018-02-01

    In medical imaging many conventional regularization methods, such as total variation or total generalized variation, impose strong prior assumptions which can only account for very limited classes of images. A more reasonable sparse representation frame for images is still badly needed. Visually understandable images contain meaningful patterns, and combinations or collections of these patterns can be utilized to form some sparse and redundant representations which promise to facilitate image reconstructions. In this work, we propose and study block matching sparsity regularization (BMSR) and devise an optimization program using BMSR for computed tomography (CT) image reconstruction for an incomplete projection set. The program is built as a constrained optimization, minimizing the L1-norm of the coefficients of the image in the transformed domain subject to data observation and positivity of the image itself. To solve the program efficiently, a practical method based on the proximal point algorithm is developed and analyzed. In order to accelerate the convergence rate, a practical strategy for tuning the BMSR parameter is proposed and applied. The experimental results for various settings, including real CT scanning, have verified the proposed reconstruction method showing promising capabilities over conventional regularization.

  9. Comparison of adaptive statistical iterative and filtered back projection reconstruction techniques in quantifying coronary calcium.

    Science.gov (United States)

    Takahashi, Masahiro; Kimura, Fumiko; Umezawa, Tatsuya; Watanabe, Yusuke; Ogawa, Harumi

    2016-01-01

    Adaptive statistical iterative reconstruction (ASIR) has been used to reduce radiation dose in cardiac computed tomography. However, change of image parameters by ASIR as compared to filtered back projection (FBP) may influence quantification of coronary calcium. To investigate the influence of ASIR on calcium quantification in comparison to FBP. In 352 patients, CT images were reconstructed using FBP alone, FBP combined with ASIR 30%, 50%, 70%, and ASIR 100% based on the same raw data. Image noise, plaque density, Agatston scores and calcium volumes were compared among the techniques. Image noise, Agatston score, and calcium volume decreased significantly with ASIR compared to FBP (each P ASIR reduced Agatston score by 10.5% to 31.0%. In calcified plaques both of patients and a phantom, ASIR decreased maximum CT values and calcified plaque size. In comparison to FBP, adaptive statistical iterative reconstruction (ASIR) may significantly decrease Agatston scores and calcium volumes. Copyright © 2016 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.

  10. A technique for on-board CT reconstruction using both kilovoltage and megavoltage beam projections for 3D treatment verification

    International Nuclear Information System (INIS)

    Yin Fangfang; Guan Huaiqun; Lu Wenkai

    2005-01-01

    The technologies with kilovoltage (kV) and megavoltage (MV) imaging in the treatment room are now available for image-guided radiation therapy to improve patient setup and target localization accuracy. However, development of strategies to efficiently and effectively implement these technologies for patient treatment remains challenging. This study proposed an aggregated technique for on-board CT reconstruction using combination of kV and MV beam projections to improve the data acquisition efficiency and image quality. These projections were acquired in the treatment room at the patient treatment position with a new kV imaging device installed on the accelerator gantry, orthogonal to the existing MV portal imaging device. The projection images for a head phantom and a contrast phantom were acquired using both the On-Board Imager TM kV imaging device and the MV portal imager mounted orthogonally on the gantry of a Varian Clinac TM 21EX linear accelerator. MV projections were converted into kV information prior to the aggregated CT reconstruction. The multilevel scheme algebraic-reconstruction technique was used to reconstruct CT images involving either full, truncated, or a combination of both full and truncated projections. An adaptive reconstruction method was also applied, based on the limited numbers of kV projections and truncated MV projections, to enhance the anatomical information around the treatment volume and to minimize the radiation dose. The effects of the total number of projections, the combination of kV and MV projections, and the beam truncation of MV projections on the details of reconstructed kV/MV CT images were also investigated

  11. Weighted regularized statistical shape space projection for breast 3D model reconstruction.

    Science.gov (United States)

    Ruiz, Guillermo; Ramon, Eduard; García, Jaime; Sukno, Federico M; Ballester, Miguel A González

    2018-05-02

    The use of 3D imaging has increased as a practical and useful tool for plastic and aesthetic surgery planning. Specifically, the possibility of representing the patient breast anatomy in a 3D shape and simulate aesthetic or plastic procedures is a great tool for communication between surgeon and patient during surgery planning. For the purpose of obtaining the specific 3D model of the breast of a patient, model-based reconstruction methods can be used. In particular, 3D morphable models (3DMM) are a robust and widely used method to perform 3D reconstruction. However, if additional prior information (i.e., known landmarks) is combined with the 3DMM statistical model, shape constraints can be imposed to improve the 3DMM fitting accuracy. In this paper, we present a framework to fit a 3DMM of the breast to two possible inputs: 2D photos and 3D point clouds (scans). Our method consists in a Weighted Regularized (WR) projection into the shape space. The contribution of each point in the 3DMM shape is weighted allowing to assign more relevance to those points that we want to impose as constraints. Our method is applied at multiple stages of the 3D reconstruction process. Firstly, it can be used to obtain a 3DMM initialization from a sparse set of 3D points. Additionally, we embed our method in the 3DMM fitting process in which more reliable or already known 3D points or regions of points, can be weighted in order to preserve their shape information. The proposed method has been tested in two different input settings: scans and 2D pictures assessing both reconstruction frameworks with very positive results. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. Summary of literature review of risk communication: Hanford Environmental Dose Reconstruction Project

    International Nuclear Information System (INIS)

    Byram, S.J.

    1991-05-01

    The Hanford Environmental Dose Reconstruction (HEDR) Project will estimate radiation exposures people may have received from radioactive materials released during past operations at the Department of Energy's Hanford Site near Richland, Washington. The project is being conducted by Pacific Northwest Laboratory (PNL) under the direction of an independent Technical Steering Panel (TSP). The Centers for Disease Control (CDC) will use HEDR dose estimates in studies to investigate a potential link between thyroid disease and historical Hanford emissions. The HEDR Project was initiated to address public concerns about the possible health impacts from past releases of radioactive materials from Hanford. The TSP recognized early in the project that special mechanisms would be required to communicate effectively to the many different concerned audiences. To identify and develop these mechanisms, the TSP issued Directive 89-7 to PNL in May 1989. The TSP directed PNL to examine methods to communicate the causes and effects of uncertainties in the dose estimates. A literature review was conducted as the first activity in response to the TSP's directive. This report presents the results of the literature review. The objective of the literature review was to identify ''key principles'' that could be applied to develop communications strategies for the project. 26 refs., 6 figs

  13. Integrated task plans for the Hanford Environmental Dose Reconstruction Project, June 1992 through May 1994

    International Nuclear Information System (INIS)

    Shipler, D.B.

    1993-09-01

    The purpose of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate radiation doses from Hanford Site operations since 1944 to representative individuals. The primary objective of work to be performed through May 1994 is to determine the project's appropriate scope: space, time, radionuclides, pathways and representative individuals; determine the project's appropriate level of accuracy/level of uncertainty in dose estimates; complete model and data development; and estimate doses for the Hanford Thyroid Disease Study and representative individuals. A major objective of the HEDR Project is to estimate doses to the thyroid of individuals who were exposed to iodine-131. A principal pathway for many of these individuals was milk from cows that ate vegetation contaminated by iodine-131 released into the air from Hanford facilities. The plan for June 1992 through May 1994 has been prepared based on activities and budgets approved by the Technical Steering Panel (TSP) at its meetings on January 7--9, 1993 and February 25--26, 1993. The activities can be divided into three broad categories: (1) computer code and data development activities, (2) calculation of doses, and (3) technical and communication support to the TSP and the TSP Native American Working Group (NAWG). The following activities will be conducted to accomplish project objectives through May 1994

  14. PROJECT OF THE TRANS-SIBERIAN RAILWAY RECONSTRUCTION AS AN OBJECT OF SOCIAL EFFICIENCY EVALUATION

    Directory of Open Access Journals (Sweden)

    Kibalov E. B.

    2015-06-01

    Full Text Available We consider the problem of social efficiency evaluation concerning the project of the Trans-Siberian Railway reconstruction. This project is to be realized in the situation of strategic (fundamental uncertainty. Existing tools are not sufficient for solving this problem (because of qualitatively different nature of the project as compared with those abroad, much higher degree of uncertainty, and the lack of estimates for a number of necessary norms. Our study aims at development of an approach that would be adequate to the problem under consideration. We developed a two-level model for investment decision-making for appraisal and selection of a variant of the large-scale project. The upper level of this model bases on the macroeconomic approach (with the use of a specialized version of the Inter-Sector Inter-Region Optimization Model; the lower level bases on the microeconomic approach. As opposed to the foreign practice, the efficiency evaluation and selection of a variant of the transport project is top-down. End-to-end taking uncertainty into account is implemented. A tool for this is the scenario approach on the upper level, and the fuzzy set theory at the lower one.

  15. FY 1991 Task plans for the Hanford Environmental Dose Reconstruction Project

    International Nuclear Information System (INIS)

    1991-04-01

    The purpose of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate radiation doses from Hanford Site operations since 1944 to populations and individuals. The objectives of work in Fiscal Year (FY) 1991 are to analyze data and models used in Phase 1 and restructure the models to increase accuracy and reduce uncertainty in dose estimation capability. Databases will be expanded and efforts will begin to determine the appropriate scope (space, time, radionuclides, pathways and individuals/population groups) and accuracy (level of uncertainty in dose estimates) for the project. Project scope and accuracy requirements, once defined, can be translated into additional model and data requirements later in the project. Task plans for FY 1991 have been prepared based on activities approved by the Technical Steering Panel (TSP) in October 1990 and mid-year revisions discussed at the TSP planning/budget workshop in February 1991. The activities can be divided into two broad categories: (1) model and data development and evaluation, (2) project, technical and communication support. 3 figs., 1 tab

  16. Image reconstruction for digital breast tomosynthesis (DBT) by using projection-angle-dependent filter functions

    Energy Technology Data Exchange (ETDEWEB)

    Park, Yeonok; Park, Chulkyu; Cho, Hyosung; Je, Uikyu; Hong, Daeki; Lee, Minsik; Cho, Heemoon; Choi, Sungil; Koo, Yangseo [Yonsei University, Wonju (Korea, Republic of)

    2014-09-15

    Digital breast tomosynthesis (DBT) is considered in clinics as a standard three-dimensional imaging modality, allowing the earlier detection of cancer. It typically acquires only 10-30 projections over a limited angle range of 15 - 60 .deg. with a stationary detector and typically uses a computationally-efficient filtered-backprojection (FBP) algorithm for image reconstruction. However, a common FBP algorithm yields poor image quality resulting from the loss of average image value and the presence of severe image artifacts due to the elimination of the dc component of the image by the ramp filter and to the incomplete data, respectively. As an alternative, iterative reconstruction methods are often used in DBT to overcome these difficulties, even though they are still computationally expensive. In this study, as a compromise, we considered a projection-angle dependent filtering method in which one-dimensional geometry-adapted filter kernels are computed with the aid of a conjugate-gradient method and are incorporated into the standard FBP framework. We implemented the proposed algorithm and performed systematic simulation works to investigate the imaging characteristics. Our results indicate that the proposed method is superior to a conventional FBP method for DBT imaging and has a comparable computational cost, while preserving good image homogeneity and edge sharpening with no serious image artifacts.

  17. Regional sea level projections with observed gauge, altimeter and reconstructed data along China coast

    Science.gov (United States)

    Du, L.; Shi, H.; Zhang, S.

    2017-12-01

    Acting as the typical shelf seas in northwest Pacific Ocean, regional sea level along China coasts exhibits complicated and multiscale spatial-temporal characteristics under circumstance of global change. In this paper, sea level variability is investigated with tide gauges records, satellite altimetry data, reconstructed sea surface height, and CMIP simulation fields. Sea level exhibits the interannual variability imposing on a remarkable sea level rising in the China seas and coastal region, although its seasonal signals are significant as the results of global ocean. Sea level exhibits faster rising rate during the satellite altimetry era, nearly twice to the rate during the last sixty years. AVISO data and reconstructed sea surface heights illustrate good correlation coefficient, more than 0.8. Interannual sea level variation is mainly modulated by the low-frequency variability of wind fields over northern Pacific Ocean by local and remote processes. Meanwhile sea level varies obviously by the transport fluctuation and bimodality path of Kuroshio. Its variability possibly linked to internal variability of the ocean-atmosphere system influenced by ENSO oscillation. China Sea level have been rising during the 20th century, and are projected to continue to rise during this century. Sea level can reach the highest extreme level in latter half of 21st century. Modeled sea level including regional sea level projection combined with the IPCC climate scenarios play a significant role on coastal storm surge evolution. The vulnerable regions along the ECS coast will suffer from the increasing storm damage with sea level variations.

  18. Draft Air Pathway Report: Phase 1 of the Hanford Environmental Dose Reconstruction Project

    Energy Technology Data Exchange (ETDEWEB)

    1990-07-20

    This report summarizes the air pathway portion of the first phase of the Hanford Environmental Dose Reconstruction (HEDR) Project, conducted by Battelle staff at the Pacific Northwest Laboratory under the direction of an independent Technical Steering Panel. The HEDR Project is estimating historical radiation doses that could have been received by populations near the Department of Energy's Hanford Site, in southeastern Washington State. Phase 1 of the air-pathway dose reconstruction sought to determine whether dose estimates could be calculated for populations in the 10 counties nearest the Hanford Site from atmospheric releases of iodine-131 from the site from 1944--1947. Phase 1 demonstrated the following: HEDR-calculated source-term estimates of iodine-131 releases to the atmosphere were within 20% of previously published estimates; calculated vegetation concentrations of iodine-131 agree well with previously published measurements; the highest of the Phase 1 preliminary dose estimates to the thyroid are consistent with independent, previously published estimates of doses to maximally exposed individuals; and relatively crude, previously published measurements of thyroid burdens for Hanford workers are in the range of average burdens that the HEDR model estimated for similar reference individuals'' for the period 1944--1947. 4 refs., 10 figs., 9 tabs.

  19. Coronary CT angiography: Comparison of a novel iterative reconstruction with filtered back projection for reconstruction of low-dose CT—Initial experience

    International Nuclear Information System (INIS)

    Takx, Richard A.P.; Schoepf, U. Joseph; Moscariello, Antonio; Das, Marco; Rowe, Garrett; Schoenberg, Stefan O.; Fink, Christian; Henzler, Thomas

    2013-01-01

    Objective: To prospectively compare subjective and objective image quality in 20% tube current coronary CT angiography (cCTA) datasets between an iterative reconstruction algorithm (SAFIRE) and traditional filtered back projection (FBP). Materials and methods: Twenty patients underwent a prospectively ECG-triggered dual-step cCTA protocol using 2nd generation dual-source CT (DSCT). CT raw data was reconstructed using standard FBP at full-dose (Group 1 a) and 80% tube current reduced low-dose (Group 1 b). The low-dose raw data was additionally reconstructed using iterative raw data reconstruction (Group 2 ). Attenuation and image noise were measured in three regions of interest and signal-to-noise-ratio (SNR) as well as contrast-to-noise-ratio (CNR) was calculated. Subjective diagnostic image quality was evaluated using a 4-point Likert scale. Results: Mean image noise of group 2 was lowered by 22% on average when compared to group 1 b (p 2 compared to group 1 b (p 2 (1.88 ± 0.63) was also rated significantly higher when compared to group 1 b (1.58 ± 0.63, p = 0.004). Conclusions: Image quality of 80% tube current reduced iteratively reconstructed cCTA raw data is significantly improved when compared to standard FBP and consequently may improve the diagnostic accuracy of cCTA

  20. Integrated Task Plans for the Hanford Environmental Dose Reconstruction Project, FY 1992 through May 1994

    International Nuclear Information System (INIS)

    Shipler, D.B.

    1992-09-01

    The purpose of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate radiation doses from Hanford Site operations since 1944 to populations and individuals. The primary objective of work to be performed through May 1994 is to (1) determine the project's appropriate scope (space, time, radionuclides, pathways and individuals/population groups), (2) determine the project's appropriate level of accuracy (level of uncertainty in dose estimates) for the project, (3) complete model and data development, and (4) estimate doses for the Hanford Thyroid Disease Study (HTDS), representative individuals, and special populations as described herein. The plan for FY 1992 through May 1994 has been prepared based on activities and budgets approved by the Technical Steering Panel (TSP) at its meetings on August 19--20, 1991, and April 23--25, 1992. The activities can be divided into four broad categories: (1) model and data evaluation activities, (2)additional dose estimates, (3) model and data development activities, and (4)technical and communication support

  1. [Reconstruction and measurement of a digital dental model using grating projection and reverse engineering].

    Science.gov (United States)

    Zhenzhen, Wang; Yi, Lu; Jun, Song; Jun, Chen; Qin, Zhou

    2015-02-01

    This work lays the foundation for establishing a digital model database with normal occlusion. A digital dental cast is acquired through grating projection, and model features are measured through reverse engineering. The grating projection system controlled by a computer was projected onto the surface of a normal dental model. Three-dimensional contour data were obtained through multi-angle shooting. A three-dimensional model was constructed, and the model features were analyzed by using reverse engineering. The digital model was compared with the plaster model to determine the accuracy of the measurement system. The structure of three-dimensional reconstruction model was clear. The digital models of two measurements exhibited no significant difference (P > 0.05). When digital and plaster models were measured, we found that the crown length and arch width were not statistically different (P > 0.05), whereas the difference between the crown width and arch length was statistically significant (P model by using the grating projection technique and reverse engineering can be used for dental model measurement in clinic al and scientific research and can provide a scientific method for establishing a digital model database with normal occlusion.

  2. Precise 3D track reconstruction algorithm for the ICARUS T600 liquid argon time projection chamber detector

    CERN Document Server

    Antonello, M

    2013-01-01

    Liquid Argon Time Projection Chamber (LAr TPC) detectors offer charged particle imaging capability with remarkable spatial resolution. Precise event reconstruction procedures are critical in order to fully exploit the potential of this technology. In this paper we present a new, general approach of three-dimensional reconstruction for the LAr TPC with a practical application to track reconstruction. The efficiency of the method is evaluated on a sample of simulated tracks. We present also the application of the method to the analysis of real data tracks collected during the ICARUS T600 detector operation with the CNGS neutrino beam.

  3. Precise 3D Track Reconstruction Algorithm for the ICARUS T600 Liquid Argon Time Projection Chamber Detector

    Directory of Open Access Journals (Sweden)

    M. Antonello

    2013-01-01

    Full Text Available Liquid Argon Time Projection Chamber (LAr TPC detectors offer charged particle imaging capability with remarkable spatial resolution. Precise event reconstruction procedures are critical in order to fully exploit the potential of this technology. In this paper we present a new, general approach to 3D reconstruction for the LAr TPC with a practical application to the track reconstruction. The efficiency of the method is evaluated on a sample of simulated tracks. We present also the application of the method to the analysis of stopping particle tracks collected during the ICARUS T600 detector operation with the CNGS neutrino beam.

  4. Comparison analysis between filtered back projection and algebraic reconstruction technique on microwave imaging

    Science.gov (United States)

    Ramadhan, Rifqi; Prabowo, Rian Gilang; Aprilliyani, Ria; Basari

    2018-02-01

    Victims of acute cancer and tumor are growing each year and cancer becomes one of the causes of human deaths in the world. Cancers or tumor tissue cells are cells that grow abnormally and turn to take over and damage the surrounding tissues. At the beginning, cancers or tumors do not have definite symptoms in its early stages, and can even attack the tissues inside of the body. This phenomena is not identifiable under visual human observation. Therefore, an early detection system which is cheap, quick, simple, and portable is essensially required to anticipate the further development of cancer or tumor. Among all of the modalities, microwave imaging is considered to be a cheaper, simple, and portable system method. There are at least two simple image reconstruction algorithms i.e. Filtered Back Projection (FBP) and Algebraic Reconstruction Technique (ART), which have been adopted in some common modalities. In this paper, both algorithms will be compared by reconstructing the image from an artificial tissue model (i.e. phantom), which has two different dielectric distributions. We addressed two performance comparisons, namely quantitative and qualitative analysis. Qualitative analysis includes the smoothness of the image and also the success in distinguishing dielectric differences by observing the image with human eyesight. In addition, quantitative analysis includes Histogram, Structural Similarity Index (SSIM), Mean Squared Error (MSE), and Peak Signal-to-Noise Ratio (PSNR) calculation were also performed. As a result, quantitative parameters of FBP might show better values than the ART. However, ART is likely more capable to distinguish two different dielectric value than FBP, due to higher contrast in ART and wide distribution grayscale level.

  5. FY 1993 task plans for the Hanford Environmental Dose Reconstruction Project

    International Nuclear Information System (INIS)

    Shipler, D.B.

    1991-10-01

    The purpose of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate radiation doses from Hanford Site operations since 1944 to individuals and populations. The primary objective of work to be performed in FY 1993 is to complete the source term estimates and dose estimates for key radionuclides for the air and river pathways. At the end of FY 1993, the capability will be in place to estimate doses for individuals in the extended (32-county) study area, 1944--1991. Native American research will continue to provide input for tribal dose estimates. In FY 1993, the Technical Steering Panel (TSP) will decide whether demographic and river pathways data collection should be extended beyond FY 1993 levels. The FY 1993 work scopes and milestones in this document are based on the work plan discussed at the TSP Budget/Fiscal Subcommittee meeting on August 19--20, 1991. Table 1 shows the FY 1993 milestones; Table 2 shows estimated costs. The subsequent work scope descriptions are based on the milestones. This document and the FY 1992 task plans will form the basis for a contract with Battelle and the Centers for Disease Control (CDC). The 2-year dose reconstruction contract is expected to begin in February 1992. This contract will replace the current arrangement, whereby the US Department of Energy directly funds the Pacific Northwest Laboratory to conduct dose reconstruction work. In late FY 1992, the FY 1993 task plans will be more fully developed with detailed technical approaches, data quality objectives, and budgeted labor hours. The task plans will be updated again in July 1993 to reflect any scope, milestone, or cost changes directed during the year by the TSP. 2 tabs

  6. Study of reconstruction methods for a time projection chamber with GEM gas amplification system

    Energy Technology Data Exchange (ETDEWEB)

    Diener, R.

    2006-12-15

    A new e{sup +}e{sup -} linear collider with an energy range up to 1TeV is planned in an international collaboration: the International Linear Collider (ILC). This collider will be able to do precision measurements of the Higgs particle and of physics beyond the Standard Model. In the Large Detector Concept (LDC) - which is one proposal for a detector at the ILC - a Time Projection Chamber (TPC) is foreseen as the main tracking device. To meet the requirements on the resolution and to be able to work in the environment at the ILC, the application of new gas amplification technologies in the TPC is necessary. One option is an amplification system based on Gas Electron Multipliers (GEMs). Due to the - in comparison with older technologies - small spatial width of the signals, this technology poses new requirements on the readout structures and the reconstruction methods. In this work, the performance and the systematics of different reconstruction methods have been studied, based on data measured with a TPC prototype in high magnetic fields of up to 4T and data from a Monte Carlo simulation. The latest results of the achievable point resolution are presented and their limitations have been investigated. (orig.)

  7. Study of reconstruction methods for a time projection chamber with GEM gas amplification system

    International Nuclear Information System (INIS)

    Diener, R.

    2006-12-01

    A new e + e - linear collider with an energy range up to 1TeV is planned in an international collaboration: the International Linear Collider (ILC). This collider will be able to do precision measurements of the Higgs particle and of physics beyond the Standard Model. In the Large Detector Concept (LDC) - which is one proposal for a detector at the ILC - a Time Projection Chamber (TPC) is foreseen as the main tracking device. To meet the requirements on the resolution and to be able to work in the environment at the ILC, the application of new gas amplification technologies in the TPC is necessary. One option is an amplification system based on Gas Electron Multipliers (GEMs). Due to the - in comparison with older technologies - small spatial width of the signals, this technology poses new requirements on the readout structures and the reconstruction methods. In this work, the performance and the systematics of different reconstruction methods have been studied, based on data measured with a TPC prototype in high magnetic fields of up to 4T and data from a Monte Carlo simulation. The latest results of the achievable point resolution are presented and their limitations have been investigated. (orig.)

  8. Imaging reconstruction based on improved wavelet denoising combined with parallel-beam filtered back-projection algorithm

    Science.gov (United States)

    Ren, Zhong; Liu, Guodong; Huang, Zhen

    2012-11-01

    The image reconstruction is a key step in medical imaging (MI) and its algorithm's performance determinates the quality and resolution of reconstructed image. Although some algorithms have been used, filter back-projection (FBP) algorithm is still the classical and commonly-used algorithm in clinical MI. In FBP algorithm, filtering of original projection data is a key step in order to overcome artifact of the reconstructed image. Since simple using of classical filters, such as Shepp-Logan (SL), Ram-Lak (RL) filter have some drawbacks and limitations in practice, especially for the projection data polluted by non-stationary random noises. So, an improved wavelet denoising combined with parallel-beam FBP algorithm is used to enhance the quality of reconstructed image in this paper. In the experiments, the reconstructed effects were compared between the improved wavelet denoising and others (directly FBP, mean filter combined FBP and median filter combined FBP method). To determine the optimum reconstruction effect, different algorithms, and different wavelet bases combined with three filters were respectively test. Experimental results show the reconstruction effect of improved FBP algorithm is better than that of others. Comparing the results of different algorithms based on two evaluation standards i.e. mean-square error (MSE), peak-to-peak signal-noise ratio (PSNR), it was found that the reconstructed effects of the improved FBP based on db2 and Hanning filter at decomposition scale 2 was best, its MSE value was less and the PSNR value was higher than others. Therefore, this improved FBP algorithm has potential value in the medical imaging.

  9. Atmospheric transport and dispersion modeling for the Hanford Environmental Dose Reconstruction Project

    International Nuclear Information System (INIS)

    Ramsdell, J.V.

    1991-07-01

    Radiation doses that may have resulted from operations at the Hanford Site are being estimated in the Hanford Environmental Dose Reconstruction (HEDR) Project. One of the project subtasks, atmospheric transport, is responsible for estimating the transport, diffusion and deposition of radionuclides released to the atmosphere. This report discusses modeling transport and diffusion in the atmospheric pathway. It is divided into three major sections. The first section of the report presents the atmospheric modeling approach selected following discussion with the Technical Steering Panel that directs the HEDR Project. In addition, the section discusses the selection of the MESOI/MESORAD suite of atmospheric dispersion models that form the basis for initial calculations and future model development. The second section of the report describes alternative modeling approaches that were considered. Emphasis is placed on the family of plume and puff models that are based on Gaussian solution to the diffusion equations. The final portion of the section describes the performance of various models. The third section of the report discusses factors that bear on the selection of an atmospheric transport modeling approach for HEDR. These factors, which include the physical setting of the Hanford Site and the available meteorological data, serve as constraints on model selection. Five appendices are included in the report. 39 refs., 4 figs., 2 tabs

  10. Accelerated perturbation-resilient block-iterative projection methods with application to image reconstruction.

    Science.gov (United States)

    Nikazad, T; Davidi, R; Herman, G T

    2012-03-01

    We study the convergence of a class of accelerated perturbation-resilient block-iterative projection methods for solving systems of linear equations. We prove convergence to a fixed point of an operator even in the presence of summable perturbations of the iterates, irrespective of the consistency of the linear system. For a consistent system, the limit point is a solution of the system. In the inconsistent case, the symmetric version of our method converges to a weighted least squares solution. Perturbation resilience is utilized to approximate the minimum of a convex functional subject to the equations. A main contribution, as compared to previously published approaches to achieving similar aims, is a more than an order of magnitude speed-up, as demonstrated by applying the methods to problems of image reconstruction from projections. In addition, the accelerated algorithms are illustrated to be better, in a strict sense provided by the method of statistical hypothesis testing, than their unaccelerated versions for the task of detecting small tumors in the brain from X-ray CT projection data.

  11. A preliminary examination of audience-related communications issues for the Hanford Environmental Dose Reconstruction Project

    Energy Technology Data Exchange (ETDEWEB)

    Holmes, C.W.

    1991-04-01

    The Hanford Environmental Dose Reconstruction (HEDR) Project will estimate radiation doses people may have received from exposure to radioactive materials released during past operations at the US Department of Energy's (DOE) Hanford Site near Richland, Washington. The HEDR Project was initiated in response to public concerns about possible health impacts from past releases of radioactive materials from Hanford. The TSP recognized early in the project that special mechanisms would be required to effectively communicate to the many different concerned audiences. Accordingly, the TSP directed PNL to examine methods for communicating causes and effects of uncertainties in the dose estimates. After considering the directive and discussing it with the Communications Subcommittee of the TSP, PNL undertook a broad investigation of communications methods to consider for inclusion in the TSP's current communications program. As part of this investigation, a literature review was conducted regarding risk communications. A key finding was that, in order to successfully communicate risk-related information, a thorough understanding of the knowledge level, concerns and information needs of the intended recipients (i.e., the audience) is necessary. Hence, a preliminary audience analysis was conducted as part of the present research. This report summarizes the results of this analysis. 1 ref., 9 tabs.

  12. Computational model design specification for Phase 1 of the Hanford Environmental Dose Reconstruction Project

    International Nuclear Information System (INIS)

    Napier, B.A.

    1991-07-01

    The objective of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate the radiation dose that individuals could have received as a result of emission from nuclear operations at Hanford since their inception in 1944. The purpose of this report is to outline the basic algorithm and necessary computer calculations to be used to calculate radiation doses specific and hypothetical individuals in the vicinity of Hanford. The system design requirements, those things that must be accomplished, are defined. The system design specifications, the techniques by which those requirements are met, are outlined. Included are the basic equations, logic diagrams, and preliminary definition of the nature of each input distribution. 4 refs., 10 figs., 9 tabs

  13. EFFECT OF DIGITAL FRINGE PROJECTION PARAMETERS ON 3D RECONSTRUCTION ACCURACY

    Directory of Open Access Journals (Sweden)

    A. Babaei

    2013-09-01

    This paper aims to evaluate different parameters which affect the accuracy of the final results. For this purpose, some test were designed and implemented. These tests assess the number of phase shifts, spatial frequency of the fringe pattern, light condition, noise level of images, and the color and material of target objects on the quality of resulted phase map. The evaluation results demonstrate that digital fringe projection method is capable of obtaining depth map of complicated object with high accuracy. The contrast test results showed that this method is able to work under different ambient light condition; although at places with high light condition will not work properly. The results of implementation on different objects with various materials, color and shapes demonstrate the high capability of this method of 3D reconstruction.

  14. Computational model design specification for Phase 1 of the Hanford Environmental Dose Reconstruction Project

    Energy Technology Data Exchange (ETDEWEB)

    Napier, B.A.

    1991-07-01

    The objective of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate the radiation dose that individuals could have received as a result of emission from nuclear operations at Hanford since their inception in 1944. The purpose of this report is to outline the basic algorithm and necessary computer calculations to be used to calculate radiation doses specific and hypothetical individuals in the vicinity of Hanford. The system design requirements, those things that must be accomplished, are defined. The system design specifications, the techniques by which those requirements are met, are outlined. Included are the basic equations, logic diagrams, and preliminary definition of the nature of each input distribution. 4 refs., 10 figs., 9 tabs.

  15. Dynamic SPECT reconstruction from few projections: a sparsity enforced matrix factorization approach

    Science.gov (United States)

    Ding, Qiaoqiao; Zan, Yunlong; Huang, Qiu; Zhang, Xiaoqun

    2015-02-01

    The reconstruction of dynamic images from few projection data is a challenging problem, especially when noise is present and when the dynamic images are vary fast. In this paper, we propose a variational model, sparsity enforced matrix factorization (SEMF), based on low rank matrix factorization of unknown images and enforced sparsity constraints for representing both coefficients and bases. The proposed model is solved via an alternating iterative scheme for which each subproblem is convex and involves the efficient alternating direction method of multipliers (ADMM). The convergence of the overall alternating scheme for the nonconvex problem relies upon the Kurdyka-Łojasiewicz property, recently studied by Attouch et al (2010 Math. Oper. Res. 35 438) and Attouch et al (2013 Math. Program. 137 91). Finally our proof-of-concept simulation on 2D dynamic images shows the advantage of the proposed method compared to conventional methods.

  16. FY 1992 task plans for the Hanford Environmental Dose Reconstruction Project

    International Nuclear Information System (INIS)

    1991-10-01

    Phase 1 of the HEDR Project was designed to develop and demonstrate a method for estimating radiation doses people may have received from Hanford Site operations since 1944. The method researchers developed relied on a variety of measured and reconstructed data as input to a modular computer model that generates dose estimates and their uncertainties. As part of Phase 1, researchers used the reconstructed data and computer model to calculate preliminary dose estimates for populations from limited radionuclides, in a limited geographical area and time period. Phase 1 ended in FY 1990. In February 1991, the TSP decided to shift the project planning approach away from phases--which were centered around completion of major portions of technical activities--to individual fiscal years (FYs), which span October of one year through September of the next. Therefore, activities that were previously designated to occur in phases are now designated in an integrated schedule to occur in one or more of the next fiscal years into FY 1995. Task plans are updated every 6 months. In FY 1992, scientists will continue to improve Phase 1 data and models to calculate more accurate and precise dose estimates. The plan for FY 1992 has been prepared based on activities and budgets approved by the Technical Steering Panel (TSP) at its meeting on August 19--20, 1991. The activities can be divided into four categories: (1) model and data evaluation activities, (2) additional dose estimates, (3) model and data development activities, and (4) technical and communication support. 3 figs., 2 tabs

  17. Breast EIT using a new projected image reconstruction method with multi-frequency measurements.

    Science.gov (United States)

    Lee, Eunjung; Ts, Munkh-Erdene; Seo, Jin Keun; Woo, Eung Je

    2012-05-01

    We propose a new method to produce admittivity images of the breast for the diagnosis of breast cancer using electrical impedance tomography(EIT). Considering the anatomical structure of the breast, we designed an electrode configuration where current-injection and voltage-sensing electrodes are separated in such a way that internal current pathways are approximately along the tangential direction of an array of voltage-sensing electrodes. Unlike conventional EIT imaging methods where the number of injected currents is maximized to increase the total amount of measured data, current is injected only twice between two pairs of current-injection electrodes attached along the circumferential side of the breast. For each current injection, the induced voltages are measured from the front surface of the breast using as many voltage-sensing electrodes as possible. Although this electrode configurational lows us to measure induced voltages only on the front surface of the breast,they are more sensitive to an anomaly inside the breast since such an injected current tends to produce a more uniform internal current density distribution. Furthermore, the sensitivity of a measured boundary voltage between two equipotential lines on the front surface of the breast is improved since those equipotential lines are perpendicular to the primary direction of internal current streamlines. One should note that this novel data collection method is different from those of other frontal plane techniques such as the x-ray projection and T-scan imaging methods because we do not get any data on the plane that is perpendicular to the current flow. To reconstruct admittivity images using two measured voltage data sets, a new projected image reconstruction algorithm is developed. Numerical simulations demonstrate the frequency-difference EIT imaging of the breast. The results show that the new method is promising to accurately detect and localize small anomalies inside the breast.

  18. Breast EIT using a new projected image reconstruction method with multi-frequency measurements

    International Nuclear Information System (INIS)

    Lee, Eunjung; Ts, Munkh-Erdene; Seo, Jin Keun; Woo, Eung Je

    2012-01-01

    We propose a new method to produce admittivity images of the breast for the diagnosis of breast cancer using electrical impedance tomography (EIT). Considering the anatomical structure of the breast, we designed an electrode configuration where current-injection and voltage-sensing electrodes are separated in such a way that internal current pathways are approximately along the tangential direction of an array of voltage-sensing electrodes. Unlike conventional EIT imaging methods where the number of injected currents is maximized to increase the total amount of measured data, current is injected only twice between two pairs of current-injection electrodes attached along the circumferential side of the breast. For each current injection, the induced voltages are measured from the front surface of the breast using as many voltage-sensing electrodes as possible. Although this electrode configuration allows us to measure induced voltages only on the front surface of the breast, they are more sensitive to an anomaly inside the breast since such an injected current tends to produce a more uniform internal current density distribution. Furthermore, the sensitivity of a measured boundary voltage between two equipotential lines on the front surface of the breast is improved since those equipotential lines are perpendicular to the primary direction of internal current streamlines. One should note that this novel data collection method is different from those of other frontal plane techniques such as the x-ray projection and T-scan imaging methods because we do not get any data on the plane that is perpendicular to the current flow. To reconstruct admittivity images using two measured voltage data sets, a new projected image reconstruction algorithm is developed. Numerical simulations demonstrate the frequency-difference EIT imaging of the breast. The results show that the new method is promising to accurately detect and localize small anomalies inside the breast. (paper)

  19. Reconstruction of computed tomographic image from a few x-ray projections by means of accelerative gradient method

    International Nuclear Information System (INIS)

    Kobayashi, Fujio; Yamaguchi, Shoichiro

    1982-01-01

    A method of the reconstruction of computed tomographic images was proposed to reduce the exposure dose to X-ray. The method is the small number of X-ray projection method by accelerative gradient method. The procedures of computation are described. The algorithm of these procedures is simple, the convergence of the computation is fast, and the required memory capacity is small. Numerical simulation was carried out to conform the validity of this method. A sample of simple shape was considered, projection data were given, and the images were reconstructed from 6 views. Good results were obtained, and the method is considered to be useful. (Kato, T.)

  20. Comparison of the image qualities of filtered back-projection, adaptive statistical iterative reconstruction, and model-based iterative reconstruction for CT venography at 80 kVp

    International Nuclear Information System (INIS)

    Kim, Jin Hyeok; Choo, Ki Seok; Moon, Tae Yong; Lee, Jun Woo; Jeon, Ung Bae; Kim, Tae Un; Hwang, Jae Yeon; Yun, Myeong-Ja; Jeong, Dong Wook; Lim, Soo Jin

    2016-01-01

    To evaluate the subjective and objective qualities of computed tomography (CT) venography images at 80 kVp using model-based iterative reconstruction (MBIR) and to compare these with those of filtered back projection (FBP) and adaptive statistical iterative reconstruction (ASIR) using the same CT data sets. Forty-four patients (mean age: 56.1 ± 18.1) who underwent 80 kVp CT venography (CTV) for the evaluation of deep vein thrombosis (DVT) during 4 months were enrolled in this retrospective study. The same raw data were reconstructed using FBP, ASIR, and MBIR. Objective and subjective image analysis were performed at the inferior vena cava (IVC), femoral vein, and popliteal vein. The mean CNR of MBIR was significantly greater than those of FBP and ASIR and images reconstructed using MBIR had significantly lower objective image noise (p <.001). Subjective image quality and confidence of detecting DVT by MBIR group were significantly greater than those of FBP and ASIR (p <.005), and MBIR had the lowest score for subjective image noise (p <.001). CTV at 80 kVp with MBIR was superior to FBP and ASIR regarding subjective and objective image qualities. (orig.)

  1. Fan-beam and cone-beam image reconstruction via filtering the backprojection image of differentiated projection data

    International Nuclear Information System (INIS)

    Zhuang Tingliang; Leng Shuai; Nett, Brian E; Chen Guanghong

    2004-01-01

    In this paper, a new image reconstruction scheme is presented based on Tuy's cone-beam inversion scheme and its fan-beam counterpart. It is demonstrated that Tuy's inversion scheme may be used to derive a new framework for fan-beam and cone-beam image reconstruction. In this new framework, images are reconstructed via filtering the backprojection image of differentiated projection data. The new framework is mathematically exact and is applicable to a general source trajectory provided the Tuy data sufficiency condition is satisfied. By choosing a piece-wise constant function for one of the components in the factorized weighting function, the filtering kernel is one dimensional, viz. the filtering process is along a straight line. Thus, the derived image reconstruction algorithm is mathematically exact and efficient. In the cone-beam case, the derived reconstruction algorithm is applicable to a large class of source trajectories where the pi-lines or the generalized pi-lines exist. In addition, the new reconstruction scheme survives the super-short scan mode in both the fan-beam and cone-beam cases provided the data are not transversely truncated. Numerical simulations were conducted to validate the new reconstruction scheme for the fan-beam case

  2. 3D virtual character reconstruction from projections: a NURBS-based approach

    Science.gov (United States)

    Triki, Olfa; Zaharia, Titus B.; Preteux, Francoise J.

    2004-05-01

    This work has been carried out within the framework of the industrial project, so-called TOON, supported by the French government. TOON aims at developing tools for automating the traditional 2D cartoon content production. This paper presents preliminary results of the TOON platform. The proposed methodology concerns the issues of 2D/3D reconstruction from a limited number of drawn projections, and 2D/3D manipulation/deformation/refinement of virtual characters. Specifically, we show that the NURBS-based modeling approach developed here offers a well-suited framework for generating deformable 3D virtual characters from incomplete 2D information. Furthermore, crucial functionalities such as animation and non-rigid deformation can be also efficiently handled and solved. Note that user interaction is enabled exclusively in 2D by achieving a multiview constraint specification method. This is fully consistent and compliant with the cartoon creator traditional practice and makes it possible to avoid the use of 3D modeling software packages which are generally complex to manipulate.

  3. Selection of dominant radionuclides for Phase 1 of the Hanford Environmental Dose Reconstruction Project

    Energy Technology Data Exchange (ETDEWEB)

    Napier, B.A.

    1991-07-01

    The objective of the Hanford Environmental Dose Reconstruction (HEDR) Project is to estimate the radiation dose that individuals could have received as a result of emissions from nuclear operations at Hanford since their inception in 1944. A vital step in the estimation of radiation doses is the determination of the source term,'' that is, the quantities of radionuclides that were released to the environment from the various Hanford operations. Hanford operations have at various times involved hundreds of different radionuclides, some in relatively large quantities. Those radionuclides present in the largest quantities, although significant from an operational handling point of view, may not necessarily have been those of greatest concern for offsite radiation dose. This report documents the selection of the dominant radionuclides (those that may have resulted in the largest portion of the received doses) in the source term for Phase 1 of the HEDR Project, that is, for atmospheric releases from 1944 through 1947 and for surface water releases from 1964 through 1966. 15 refs., 3 figs., 10 tabs.

  4. CT image reconstruction of steel pipe section from few projections using the method of rotating polar-coordinate

    International Nuclear Information System (INIS)

    Peng Shuaijun; Wu Zhifang

    2008-01-01

    Fast online inspection in steel pipe production is a big challenge. Radiographic CT imaging technology, a high performance non-destructive testing method, is quite appropriate for inspection and quality control of steel pipes. The method of rotating polar-coordinate is used to reconstruct the steel pipe section from few projections with the purpose of inspecting it online. It reduces the projection number needed and the data collection time, and accelerates the reconstruction algorithm and saves the inspection time evidently. The results of simulation experiment and actual experiment indicate that the image quality and reconstruction time of rotating polar-coordinate method meet the requirements of inspecting the steel tube section online basically. The study is of some theoretical significance and the method is expected to be widely used in practice. (authors)

  5. Applications of Siroquant in mineralogical analysis at BHP Billiton minerals technology

    International Nuclear Information System (INIS)

    Reynolds, J.; England, B.M.

    2002-01-01

    Full text: Newcastle Technology Centre is currently investigating ways of improving the accuracy and efficiency of quantitative mineralogical analysis of iron ores and environmental dusts using Siroquant. The only readily available technique for the quantification of iron oxide and gangue species in iron ores has been the time-consuming modal analysis (point counting) of specially prepared polished sections in reflected light using a petrological microscope. However there are uncertainties associated with bulk sampling and the true reprensensitivity of material mounted in these sections. In addition, the quality of the data depends largely on the training, skill and mineralogical experience of the operator as well as on the quality of the polished section. The data obtained from modal analysis is volumetric and must be converted to weight percent using calculations involving theoretical rather than actual densities. Previous X-ray powder diffraction (XRD) techniques using internal standards (such as corundum) have proved inaccurate and unreliable. To test the validity of using Siroquant to obtain quantitative mineralogical data for iron ores, a series of validation samples was made up to simulate a selection of BHP Billiton iron ores. The results show that reliable and reproducible data can be obtained for hematite/goethite ratios in a wide variety of ore types. However the technique was not without its problems and it was found that particle size, both actual and entered, had a significant effect on the results. It was also found that optimum particle size for samples containing such a wide range of absorption coefficients is smaller than that indicated by standard milling curves, but that longer milling times resulted in overgrinding and non-detection of softer species. Hence the quantification of minor species, especially kaolinite, still presents some problems and these will be investigated through the use of further validation samples. The quantitative

  6. Systematic Error in Lung Nodule Volumetry : Effect of Iterative Reconstruction Versus Filtered Back Projection at Different CT Parameters

    NARCIS (Netherlands)

    Willemink, Martin J.; Leiner, Tim; Budde, Ricardo P. J.; de Kort, Freek P. L.; Vliegenthart, Rozemarijn; van Ooijen, Peter M. A.; Oudkerk, Matthijs; de Jong, Pim A.

    2012-01-01

    OBJECTIVE. Iterative reconstruction potentially can reduce radiation dose compared with filtered back projection (FBP) for chest CT. This is especially important for repeated CT scanning, as is the case in patients with indeterminate lung nodules. It is currently unknown whether absolute nodule

  7. Reconstruction of brachytherapy seed positions and orientations from cone-beam CT x-ray projections via a novel iterative forward projection matching method.

    Science.gov (United States)

    Pokhrel, Damodar; Murphy, Martin J; Todor, Dorin A; Weiss, Elisabeth; Williamson, Jeffrey F

    2011-01-01

    To generalize and experimentally validate a novel algorithm for reconstructing the 3D pose (position and orientation) of implanted brachytherapy seeds from a set of a few measured 2D cone-beam CT (CBCT) x-ray projections. The iterative forward projection matching (IFPM) algorithm was generalized to reconstruct the 3D pose, as well as the centroid, of brachytherapy seeds from three to ten measured 2D projections. The gIFPM algorithm finds the set of seed poses that minimizes the sum-of-squared-difference of the pixel-by-pixel intensities between computed and measured autosegmented radiographic projections of the implant. Numerical simulations of clinically realistic brachytherapy seed configurations were performed to demonstrate the proof of principle. An in-house machined brachytherapy phantom, which supports precise specification of seed position and orientation at known values for simulated implant geometries, was used to experimentally validate this algorithm. The phantom was scanned on an ACUITY CBCT digital simulator over a full 660 sinogram projections. Three to ten x-ray images were selected from the full set of CBCT sinogram projections and postprocessed to create binary seed-only images. In the numerical simulations, seed reconstruction position and orientation errors were approximately 0.6 mm and 5 degrees, respectively. The physical phantom measurements demonstrated an absolute positional accuracy of (0.78 +/- 0.57) mm or less. The theta and phi angle errors were found to be (5.7 +/- 4.9) degrees and (6.0 +/- 4.1) degrees, respectively, or less when using three projections; with six projections, results were slightly better. The mean registration error was better than 1 mm/6 degrees compared to the measured seed projections. Each test trial converged in 10-20 iterations with computation time of 12-18 min/iteration on a 1 GHz processor. This work describes a novel, accurate, and completely automatic method for reconstructing seed orientations, as well as

  8. Reconstruction of brachytherapy seed positions and orientations from cone-beam CT x-ray projections via a novel iterative forward projection matching method

    Energy Technology Data Exchange (ETDEWEB)

    Pokhrel, Damodar; Murphy, Martin J.; Todor, Dorin A.; Weiss, Elisabeth; Williamson, Jeffrey F. [Department of Radiation Oncology, School of Medicine, Virginia Commonwealth University, Richmond, Virginia 23298 (United States)

    2011-01-15

    Purpose: To generalize and experimentally validate a novel algorithm for reconstructing the 3D pose (position and orientation) of implanted brachytherapy seeds from a set of a few measured 2D cone-beam CT (CBCT) x-ray projections. Methods: The iterative forward projection matching (IFPM) algorithm was generalized to reconstruct the 3D pose, as well as the centroid, of brachytherapy seeds from three to ten measured 2D projections. The gIFPM algorithm finds the set of seed poses that minimizes the sum-of-squared-difference of the pixel-by-pixel intensities between computed and measured autosegmented radiographic projections of the implant. Numerical simulations of clinically realistic brachytherapy seed configurations were performed to demonstrate the proof of principle. An in-house machined brachytherapy phantom, which supports precise specification of seed position and orientation at known values for simulated implant geometries, was used to experimentally validate this algorithm. The phantom was scanned on an ACUITY CBCT digital simulator over a full 660 sinogram projections. Three to ten x-ray images were selected from the full set of CBCT sinogram projections and postprocessed to create binary seed-only images. Results: In the numerical simulations, seed reconstruction position and orientation errors were approximately 0.6 mm and 5 deg., respectively. The physical phantom measurements demonstrated an absolute positional accuracy of (0.78{+-}0.57) mm or less. The {theta} and {phi} angle errors were found to be (5.7{+-}4.9) deg. and (6.0{+-}4.1) deg., respectively, or less when using three projections; with six projections, results were slightly better. The mean registration error was better than 1 mm/6 deg. compared to the measured seed projections. Each test trial converged in 10-20 iterations with computation time of 12-18 min/iteration on a 1 GHz processor. Conclusions: This work describes a novel, accurate, and completely automatic method for reconstructing

  9. Operational report, basics of the preliminary project for reconstruction of the RA reactor ventilation system

    International Nuclear Information System (INIS)

    Martinc, R.

    1982-01-01

    This report presents the summary of results needed for designing the reconstruction of the RA reactor ventilation system. The final complete report will published later, including results of possible additional analyses according to the needs of main detailed project. Due to the size of the facility the need of filters for particulates is expected in systems V-1 and V-2, as well as revision of the system V-4. Adsorption filters are not needed in case of operation under regular working conditions. It would be favorable, but not indispensable to construct an adsorption filter that could be used occasionally at the input of V-2 system under the upper water shielding. This filter would be switched on when dehermetization of the reactor is planned and increased radioactivity is indicated in the gas system or experimental space of the RA reactor as well as in case of fuel elements failure. The aim of applying filters is shortening the time these elements would spend in the hermetized reactor i.e. their fast removal from the reactor. It is indispensable to build-in 'emergency' highly efficient adsorption filters in the V-2 system which would be switched on in case of accidents that would cause fuel elements meltdown (with simultaneous accident dehermetization of the heavy water system) [sr

  10. Short-TE projection reconstruction MR microscopy in the evaluation of articular cartilage thickness

    International Nuclear Information System (INIS)

    Cova, M.; Pozzi-Mucelli, R.S.; Dalla-Palma, L.; Toffanin, R.; Szomolanyi, P.; Vittur, F.; Jellus, V.; Silvestri, F.

    2000-01-01

    The aim of this study was to assess the potential of projection-reconstruction (PR) MR microscopy in the accurate measurement of cartilage thickness. Short-TE PR microimages were acquired at 7.05 T on bone-cartilage cylindrical plugs excised from four regions of two disarticulated femoral heads (i. e. superior, inferior, posterior and anterior), using an NMR instrument equipped with a microimaging accessory. The PR microimages were then correlated with conventional spin-echo (SE) microimages and with histology. On PR microimages, acquired with an echo time of 3.2 ms, the cartilage signal was increased, allowing an accurate delineation of the cartilage from the tidemark/cortical bone region. As a consequence, by the PR method a more precise measurement of cartilage thickness compared with that performed by the conventional SE approach was feasible. An excellent correlation between PR microimages and histology was also obtained (r=0.90). By the proposed method it is possible to accurately determine the cartilage thickness better than with the conventional SE sequences. (orig.)

  11. Commercial milk distribution profiles and production locations. Hanford Environmental Dose Reconstruction Project

    Energy Technology Data Exchange (ETDEWEB)

    Deonigi, D.E.; Anderson, D.M.; Wilfert, G.L.

    1994-04-01

    The Hanford Environmental Dose Reconstruction (HEDR) Project was established to estimate radiation doses that people could have received from nuclear operations at the Hanford Site since 1944. For this period iodine-131 is the most important offsite contributor to radiation doses from Hanford operations. Consumption of milk from cows that ate vegetation contaminated by iodine-131 is the dominant radiation pathway for individuals who drank milk (Napier 1992). Information has been developed on commercial milk cow locations and commercial milk distribution during 1945 and 1951. The year 1945 was selected because during 1945 the largest amount of iodine-131 was released from Hanford facilities in a calendar year (Heeb 1993); therefore, 1945 was the year in which an individual was likely to have received the highest dose. The year 1951 was selected to provide data for comparing the changes that occurred in commercial milk flows (i.e., sources, processing locations, and market areas) between World War II and the post-war period. To estimate the doses people could have received from this milk flow, it is necessary to estimate the amount of milk people consumed, the source of the milk, the specific feeding regime used for milk cows, and the amount of iodine-131 contamination deposited on feed.

  12. Enhancing breast projection in autologous reconstruction using the St Andrew's coning technique and 3D volumetric analysis.

    Science.gov (United States)

    Chae, Michael P; Rozen, Warren Matthew; Patel, Nakul Gamanlal; Hunter-Smith, David J; Ramakrishnan, Venkat

    2017-12-01

    An increasing number of women undergo mastectomy for breast cancer and post-mastectomy autologous breast reconstruction has been shown to significantly improve the psychosexual wellbeing of the patients. A goal of treatment is to achieve symmetry and projection to match the native breast, and/or the contralateral breast in the case of a unilateral reconstruction. Autologous reconstruction, particularly with the deep inferior epigastric artery perforator (DIEP) flap, is particularly advantageous as it can be manipulated to mimic the shape and turgor of the native breast. However, very few techniques of shaping the breast conus when insetting the DIEP flap to enhance aesthetic outcome have been reported to date. With the aide of three-dimension (3D) photography and 3D-printed mirrored image of the contralateral breast as a guide intraoperatively, we describe our St Andrew's coning technique to create a personalized flap projection. We report a prospective case series of 3 delayed unilateral breast reconstructions where symmetrization procedure to the contralateral breast was not indicated. Using a commercial 3D scanner (VECTRA XR, Canfield Scientific), the breast region was imaged. The mirrored image was 3D-printed in-house using a desktop 3D printer. In all cases, projection of the breast mound was able to be safely achieved, with a demonstrated central volume (or 'cone') able to be highlighted on imaging and a 3D printed breast. A 3D print of the contralateral breast was able to be used intraoperatively to guide the operative approach. The St Andrew's coning technique is a useful aesthetic maneuver for achieving breast projection during DIEP flap breast reconstruction, with 3D imaging techniques able to assist in perioperative assessment of breast volume.

  13. Development of a Cummins ISL Natural Gas Engine at 1.4g/bhp-hr NOx + NMHC Using PLUS Technology: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Kamel, M. M.

    2005-07-01

    NREL subcontractor report describes Cummins Westport, Inc.'s development of an 8.9 L natural gas engine (320 hp, 1,000 ft-lb peak torque) with CARB emissions certification of 1.4 g/bhp-hr NOx + NMHC.

  14. Growth Period Effects on the Protective Properties of Aloe vera Against t-BHP-Induced Oxidative Stress in Chang Cells.

    Science.gov (United States)

    Hwang, Jin-Woo; Kim, Eun-Kyung; Kim, Yon-Suk; Lee, Jae Woong; Lee, Jeong-Jun; Pyo, Han-Jong; Moon, Sang-Ho; Jeon, Byong-Tae; Park, Pyo-Jam

    2015-12-28

    Aloe vera has been used in traditional medicine for the therapy of a variety of disorders, such as wounds and burns. However, few studies have examined the antioxidant capacities of A. vera plants during different growth periods. In order to investigate the effects of growth on antioxidant activity, A. vera was prepared from 2-, 4-, 6-, 8-, and 12-month-old aloe. The extracts from 6-month-old A. vera showed the highest contents of flavonoids (9.750 mg catechin equivalent/g extract) and polyphenols (23.375 mg gallic acid equivalent/g extract) and the highest ferric reducing antioxidant power (0.047 mM ferrous sulfate equivalent/mg extract). The extract from 6-month-old A. vera exhibited the highest free radical scavenging potential, and the lowest IC50 values were found for 2,2-diphenyl-1-picrylhydrazyl (0.26 mg/ml) and alkyl radicals (0.50 mg/ml). In addition, the extract from 6-month-old A. vera showed the greatest effects on cell viability in normal liver cells. Based on these findings, the extract from 6-month-old A. vera was examined further in order to determine its protective potential against tert-butyl hydroperoxide (t-BHP)-induced oxidative stress. The extract from 6-monthold A. vera at a concentration of 0.25 mg/ml showed the highest protective activity against t-BHP-induced reactive oxygen species production. These findings suggested that harvesting regimens were critical in the regulation of effects of the bioactive potential of A. vera on antioxidant activity.

  15. Analysis of Variance of the Effects of a Project’s Location on Key Issues and Challenges in Post-Disaster Reconstruction Projects

    Directory of Open Access Journals (Sweden)

    Dzulkarnaen Ismail

    2017-11-01

    Full Text Available After a disaster, the reconstruction phase is driven by immediate challenges. One of the main challenges in the post-disaster period is the way that reconstruction projects are implemented. Reconstruction cannot move forward until some complex issues are settled. The purposes of this research are to highlight the issues and challenges in post-disaster reconstruction (PDR projects and to determine the significant differences between the issues and challenges in different locations where PDR projects are carried out. The researchers collected data within international non-governmental organisations (INGOs on their experience of working with PDR projects. The findings of this research provide the foundation on which to build strategies for avoiding project failures; this may be useful for PDR project practitioners in the future.

  16. Image quality of ct angiography using model-based iterative reconstruction in infants with congenital heart disease: Comparison with filtered back projection and hybrid iterative reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Qianjun, E-mail: jiaqianjun@126.com [Southern Medical University, Guangzhou, Guangdong (China); Department of Radiology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong (China); Department of Catheterization Lab, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of South China Structural Heart Disease, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong (China); Zhuang, Jian, E-mail: zhuangjian5413@tom.com [Department of Cardiac Surgery, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of South China Structural Heart Disease, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong (China); Jiang, Jun, E-mail: 81711587@qq.com [Department of Radiology, Shenzhen Second People’s Hospital, Shenzhen, Guangdong (China); Li, Jiahua, E-mail: 970872804@qq.com [Department of Catheterization Lab, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of South China Structural Heart Disease, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong (China); Huang, Meiping, E-mail: huangmeiping_vip@163.com [Department of Catheterization Lab, Guangdong Cardiovascular Institute, Guangdong Provincial Key Laboratory of South China Structural Heart Disease, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong (China); Southern Medical University, Guangzhou, Guangdong (China); Liang, Changhong, E-mail: cjr.lchh@vip.163.com [Department of Radiology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, Guangdong (China); Southern Medical University, Guangzhou, Guangdong (China)

    2017-01-15

    Purpose: To compare the image quality, rate of coronary artery visualization and diagnostic accuracy of 256-slice multi-detector computed tomography angiography (CTA) with prospective electrocardiographic (ECG) triggering at a tube voltage of 80 kVp between 3 reconstruction algorithms (filtered back projection (FBP), hybrid iterative reconstruction (iDose{sup 4}) and iterative model reconstruction (IMR)) in infants with congenital heart disease (CHD). Methods: Fifty-one infants with CHD who underwent cardiac CTA in our institution between December 2014 and March 2015 were included. The effective radiation doses were calculated. Imaging data were reconstructed using the FBP, iDose{sup 4} and IMR algorithms. Parameters of objective image quality (noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR)); subjective image quality (overall image quality, image noise and margin sharpness); coronary artery visibility; and diagnostic accuracy for the three algorithms were measured and compared. Results: The mean effective radiation dose was 0.61 ± 0.32 mSv. Compared to FBP and iDose{sup 4}, IMR yielded significantly lower noise (P < 0.01), higher SNR and CNR values (P < 0.01), and a greater subjective image quality score (P < 0.01). The total number of coronary segments visualized was significantly higher for both iDose{sup 4} and IMR than for FBP (P = 0.002 and P = 0.025, respectively), but there was no significant difference in this parameter between iDose{sup 4} and IMR (P = 0.397). There was no significant difference in the diagnostic accuracy between the FBP, iDose{sup 4} and IMR algorithms (χ{sup 2} = 0.343, P = 0.842). Conclusions: For infants with CHD undergoing cardiac CTA, the IMR reconstruction algorithm provided significantly increased objective and subjective image quality compared with the FBP and iDose{sup 4} algorithms. However, IMR did not improve the diagnostic accuracy or coronary artery visualization compared with iDose{sup 4}.

  17. MO-FG-204-08: Optimization-Based Image Reconstruction From Unevenly Distributed Sparse Projection Views

    International Nuclear Information System (INIS)

    Xie, Huiqiao; Yang, Yi; Tang, Xiangyang; Niu, Tianye; Ren, Yi

    2015-01-01

    Purpose: Optimization-based reconstruction has been proposed and investigated for reconstructing CT images from sparse views, as such the radiation dose can be substantially reduced while maintaining acceptable image quality. The investigation has so far focused on reconstruction from evenly distributed sparse views. Recognizing the clinical situations wherein only unevenly sparse views are available, e.g., image guided radiation therapy, CT perfusion and multi-cycle cardiovascular imaging, we investigate the performance of optimization-based image reconstruction from unevenly sparse projection views in this work. Methods: The investigation is carried out using the FORBILD and an anthropomorphic head phantoms. In the study, 82 views, which are evenly sorted out from a full (360°) axial CT scan consisting of 984 views, form sub-scan I. Another 82 views are sorted out in a similar manner to form sub-scan II. As such, a CT scan with sparse (164) views at 1:6 ratio are formed. By shifting the two sub-scans relatively in view angulation, a CT scan with unevenly distributed sparse (164) views at 1:6 ratio are formed. An optimization-based method is implemented to reconstruct images from the unevenly distributed views. By taking the FBP reconstruction from the full scan (984 views) as the reference, the root mean square (RMS) between the reference and the optimization-based reconstruction is used to evaluate the performance quantitatively. Results: In visual inspection, the optimization-based method outperforms the FBP substantially in the reconstruction from unevenly distributed, which are quantitatively verified by the RMS gauged globally and in ROIs in both the FORBILD and anthropomorphic head phantoms. The RMS increases with increasing severity in the uneven angular distribution, especially in the case of anthropomorphic head phantom. Conclusion: The optimization-based image reconstruction can save radiation dose up to 12-fold while providing acceptable image quality

  18. Dustfall design of open coal yard in the power plant-a case study on the closed reconstruction project of coal storage yard in shengli power plant

    Science.gov (United States)

    Wang, Kunpeng; Ji, Weidong; Zhang, Feifei; Yu, Wei; Zheng, Runqing

    2018-02-01

    This thesis, based on the closed reconstruction project of the coal storage yard of Shengli Power Plant which is affiliated to Sinopec Shengli Petroleum Administration, first makes an analysis on the significance of current dustfall reconstruction of open coal yard, then summarizes the methods widely adopted in the dustfall of large-scale open coal storage yard of current thermal power plant as well as their advantages and disadvantages, and finally focuses on this project, aiming at providing some reference and assistance to the future closed reconstruction project of open coal storage yard in thermal power plant.

  19. An FDK-like cone-beam SPECT reconstruction algorithm for non-uniform attenuated projections acquired using a circular trajectory

    International Nuclear Information System (INIS)

    Huang, Q; Zeng, G L; You, J; Gullberg, G T

    2005-01-01

    In this paper, Novikov's inversion formula of the attenuated two-dimensional (2D) Radon transform is applied to the reconstruction of attenuated fan-beam projections acquired with equal detector spacing and of attenuated cone-beam projections acquired with a flat planar detector and circular trajectory. The derivation of the fan-beam algorithm is obtained by transformation from parallel-beam coordinates to fan-beam coordinates. The cone-beam reconstruction algorithm is an extension of the fan-beam reconstruction algorithm using Feldkamp-Davis-Kress's (FDK) method. Computer simulations indicate that the algorithm is efficient and is accurate in reconstructing slices close to the central slice of the cone-beam orbit plane. When the attenuation map is set to zero the implementation is equivalent to the FDK method. Reconstructed images are also shown for noise corrupted projections

  20. Comparison of pure and hybrid iterative reconstruction techniques with conventional filtered back projection: Image quality assessment in the cervicothoracic region

    International Nuclear Information System (INIS)

    Katsura, Masaki; Sato, Jiro; Akahane, Masaaki; Matsuda, Izuru; Ishida, Masanori; Yasaka, Koichiro; Kunimatsu, Akira; Ohtomo, Kuni

    2013-01-01

    Objectives: To evaluate the impact on image quality of three different image reconstruction techniques in the cervicothoracic region: model-based iterative reconstruction (MBIR), adaptive statistical iterative reconstruction (ASIR), and filtered back projection (FBP). Methods: Forty-four patients underwent unenhanced standard-of-care clinical computed tomography (CT) examinations which included the cervicothoracic region with a 64-row multidetector CT scanner. Images were reconstructed with FBP, 50% ASIR-FBP blending (ASIR50), and MBIR. Two radiologists assessed the cervicothoracic region in a blinded manner for streak artifacts, pixilated blotchy appearances, critical reproduction of visually sharp anatomical structures (thyroid gland, common carotid artery, and esophagus), and overall diagnostic acceptability. Objective image noise was measured in the internal jugular vein. Data were analyzed using the sign test and pair-wise Student's t-test. Results: MBIR images had significant lower quantitative image noise (8.88 ± 1.32) compared to ASIR images (18.63 ± 4.19, P 0.9 for ASIR vs. FBP for both readers). MBIR images were all diagnostically acceptable. Unique features of MBIR images included pixilated blotchy appearances, which did not adversely affect diagnostic acceptability. Conclusions: MBIR significantly improves image noise and streak artifacts of the cervicothoracic region over ASIR and FBP. MBIR is expected to enhance the value of CT examinations for areas where image noise and streak artifacts are problematic

  1. Effect of number of of projections on inverse radon transform based image reconstruction by using filtered back-projection for parallel beam transmission tomography

    International Nuclear Information System (INIS)

    Qureshi, S.A.; Mirza, S.M.; Arif, M.

    2007-01-01

    This paper present the effect of number of projections on inverse Radon transform (IRT) estimation using filtered back-projection (FBP) technique for parallel beam transmission tomography. The head phantom and the lung phantom have been used in this work. Various filters used in this study include Ram-Lak, Shepp-Logan, Cosin, Hamming and Hanning filters. The slices have been reconstructed by increasing the number of projections through parallel beam transmission tomography keeping the projections uniformly distributed. The Euclidean and Mean Squared errors and peak signal-to-noise ratio (PSNR) have been analyzed for their sensitiveness as functions of number of projections. It has found that image quality improves with the number of projections but at the cost of the computer time. The error has been minimized to get the best approximation of inverse Radon transform (IRT) as the number of projections is enhanced. The value of PSNR has been found to increase from 8.20 to 24.53 dB as the number of projections is raised from 5 to 180 for head phantom. (author)

  2. Novel Fourier-based iterative reconstruction for sparse fan projection using alternating direction total variation minimization

    International Nuclear Information System (INIS)

    Jin Zhao; Zhang Han-Ming; Yan Bin; Li Lei; Wang Lin-Yuan; Cai Ai-Long

    2016-01-01

    Sparse-view x-ray computed tomography (CT) imaging is an interesting topic in CT field and can efficiently decrease radiation dose. Compared with spatial reconstruction, a Fourier-based algorithm has advantages in reconstruction speed and memory usage. A novel Fourier-based iterative reconstruction technique that utilizes non-uniform fast Fourier transform (NUFFT) is presented in this work along with advanced total variation (TV) regularization for a fan sparse-view CT. The proposition of a selective matrix contributes to improve reconstruction quality. The new method employs the NUFFT and its adjoin to iterate back and forth between the Fourier and image space. The performance of the proposed algorithm is demonstrated through a series of digital simulations and experimental phantom studies. Results of the proposed algorithm are compared with those of existing TV-regularized techniques based on compressed sensing method, as well as basic algebraic reconstruction technique. Compared with the existing TV-regularized techniques, the proposed Fourier-based technique significantly improves convergence rate and reduces memory allocation, respectively. (paper)

  3. Projected potential profiles across interfaces obtained by reconstructing the exit face wave function from through focal series

    International Nuclear Information System (INIS)

    Bhattacharyya, Somnath; Koch, Christoph T.; Ruehle, Manfred

    2006-01-01

    An iterative method for reconstructing the exit face wave function from a through focal series of transmission electron microscopy image line profiles across an interface is presented. Apart from high-resolution images recorded with small changes in defocus, this method works also well for a large defocus range as used for Fresnel imaging. Using the phase-object approximation the projected electrostatic as well as the absorptive potential profiles across an interface are determined from this exit face wave function. A new experimental image alignment procedure was developed in order to align images with large relative defocus shift. The performance of this procedure is shown to be superior to other image alignment procedures existing in the literature. The reconstruction method is applied to both simulated and experimental images

  4. Reconstruction of tomographic images from projections of a small number of views by means of mathematical programming

    International Nuclear Information System (INIS)

    Kobayashi, Fujio; Yamaguchi, Shoichiro

    1985-01-01

    Fundamental studies have been made on the application of mathematical programming to the reconstruction of tomographic images from projections of a small number of views without requiring any circular symmetry nor periodicity. Linear programming and quadratic programming were applied to minimize the quadratic sum of the residue and to finally obtain optimized reconstruction images. The mathematical algorithms were verified by the method of computer simulation, and the relationship between the number of picture elements and the number of iterations necessary for convergence was also investigated. The methods of linear programming and quadratic programming require fairly simple mathematical procedures, and strict solutions can be obtained within a finite number of iterations. Their only draw back is the requirement of a large quantity of computer memory. But this problem will be desolved by the advent of large fast memory devices in the near future. (Aoki, K.)

  5. MR-guided PET motion correction in LOR space using generic projection data for image reconstruction with PRESTO

    International Nuclear Information System (INIS)

    Scheins, J.; Ullisch, M.; Tellmann, L.; Weirich, C.; Rota Kops, E.; Herzog, H.; Shah, N.J.

    2013-01-01

    The BrainPET scanner from Siemens, designed as hybrid MR/PET system for simultaneous acquisition of both modalities, provides high-resolution PET images with an optimum resolution of 3 mm. However, significant head motion often compromises the achievable image quality, e.g. in neuroreceptor studies of human brain. This limitation can be omitted when tracking the head motion and accurately correcting measured Lines-of-Response (LORs). For this purpose, we present a novel method, which advantageously combines MR-guided motion tracking with the capabilities of the reconstruction software PRESTO (PET Reconstruction Software Toolkit) to convert motion-corrected LORs into highly accurate generic projection data. In this way, the high-resolution PET images achievable with PRESTO can also be obtained in presence of severe head motion

  6. Building credibility in public studies: Lessons learned from the Hanford environmental Dose Reconstruction project may apply to all public studies

    International Nuclear Information System (INIS)

    Till, J.E.

    1995-01-01

    This article describes the process by which the author came to recognize the importance of openness to the public in environmental studies, during the Hanford Environmental Dose Reconstruction Project. Using the Dose reconstruction public involvement, the article goes on to describe a general guide to the construction of a new, positive framework for conducting future public studies. The steps include the following: putting the public in the study; building credibility into a public study (1 -search for proof in historical records; 2-define the domain and the exposed population; 3-characterize the material released; 4-identify key materials, pathways and receptors; 5-encouraging public participation; 6 -explaining the meaning of the results) and reconciling scientific and public issues

  7. Building credibility in public studies: Lessons learned from the Hanford environmental Dose Reconstruction project may apply to all public studies

    Energy Technology Data Exchange (ETDEWEB)

    Till, J.E. [Radiological Assessment Corp., Neeses, SC (United States)

    1995-09-01

    This article describes the process by which the author came to recognize the importance of openness to the public in environmental studies, during the Hanford Environmental Dose Reconstruction Project. Using the Dose reconstruction public involvement, the article goes on to describe a general guide to the construction of a new, positive framework for conducting future public studies. The steps include the following: putting the public in the study; building credibility into a public study (1 -search for proof in historical records; 2-define the domain and the exposed population; 3-characterize the material released; 4-identify key materials, pathways and receptors; 5-encouraging public participation; 6 -explaining the meaning of the results) and reconciling scientific and public issues.

  8. A PET reconstruction formulation that enforces non-negativity in projection space for bias reduction in Y-90 imaging

    Science.gov (United States)

    Lim, Hongki; Dewaraja, Yuni K.; Fessler, Jeffrey A.

    2018-02-01

    Most existing PET image reconstruction methods impose a nonnegativity constraint in the image domain that is natural physically, but can lead to biased reconstructions. This bias is particularly problematic for Y-90 PET because of the low probability positron production and high random coincidence fraction. This paper investigates a new PET reconstruction formulation that enforces nonnegativity of the projections instead of the voxel values. This formulation allows some negative voxel values, thereby potentially reducing bias. Unlike the previously reported NEG-ML approach that modifies the Poisson log-likelihood to allow negative values, the new formulation retains the classical Poisson statistical model. To relax the non-negativity constraint embedded in the standard methods for PET reconstruction, we used an alternating direction method of multipliers (ADMM). Because choice of ADMM parameters can greatly influence convergence rate, we applied an automatic parameter selection method to improve the convergence speed. We investigated the methods using lung to liver slices of XCAT phantom. We simulated low true coincidence count-rates with high random fractions corresponding to the typical values from patient imaging in Y-90 microsphere radioembolization. We compared our new methods with standard reconstruction algorithms and NEG-ML and a regularized version thereof. Both our new method and NEG-ML allow more accurate quantification in all volumes of interest while yielding lower noise than the standard method. The performance of NEG-ML can degrade when its user-defined parameter is tuned poorly, while the proposed algorithm is robust to any count level without requiring parameter tuning.

  9. In-process 3D geometry reconstruction of objects produced by direct light projection

    DEFF Research Database (Denmark)

    Andersen, Ulrik Vølcker; Pedersen, David Bue; Hansen, Hans Nørgaard

    2013-01-01

    al. 2011), this method has shown its potential with 3D printing (3DP) and selective laser sintering additive manufacturing processes, where it is possible to directly capture the geometrical features of each individual layer during a build job using a digital camera. When considering the process...... equipment such as coordinate measuring machines cannot be verified easily. This problem is addressed by developing an in-line reverse engineering and 3D reconstruction method that allows a true-to-scale reconstruction of a part being additively manufactured. In earlier works (Pedersen et al. 2010; Hansen et...

  10. Multi-sheet surface rebinning methods for reconstruction from asymmetrically truncated cone beam projections: I. Approximation and optimality

    International Nuclear Information System (INIS)

    Betcke, Marta M; Lionheart, William R B

    2013-01-01

    The mechanical motion of the gantry in conventional cone beam CT scanners restricts the speed of data acquisition in applications with near real time requirements. A possible resolution of this problem is to replace the moving source detector assembly with static parts that are electronically activated. An example of such a system is the Rapiscan Systems RTT80 real time tomography scanner, with a static ring of sources and axially offset static cylinder of detectors. A consequence of such a design is asymmetrical axial truncation of the cone beam projections resulting, in the sense of integral geometry, in severely incomplete data. In particular we collect data only in a fraction of the Tam–Danielsson window, hence the standard cone beam reconstruction techniques do not apply. In this work we propose a family of multi-sheet surface rebinning methods for reconstruction from such truncated projections. The proposed methods combine analytical and numerical ideas utilizing linearity of the ray transform to reconstruct data on multi-sheet surfaces, from which the volumetric image is obtained through deconvolution. In this first paper in the series, we discuss the rebinning to multi-sheet surfaces. In particular we concentrate on the underlying transforms on multi-sheet surfaces and their approximation with data collected by offset multi-source scanning geometries like the RTT. The optimal multi-sheet surface and the corresponding rebinning function are found as a solution of a variational problem. In the case of the quadratic objective, the variational problem for the optimal rebinning pair can be solved by a globally convergent iteration. Examples of optimal rebinning pairs are computed for different trajectories. We formulate the axial deconvolution problem for the recovery of the volumetric image from the reconstructions on multi-sheet surfaces. Efficient and stable solution of the deconvolution problem is the subject of the second paper in this series (Betcke and

  11. WE-G-207-02: Full Sequential Projection Onto Convex Sets (FS-POCS) for X-Ray CT Reconstruction

    International Nuclear Information System (INIS)

    Liu, L; Han, Y; Jin, M

    2015-01-01

    Purpose: To develop an iterative reconstruction method for X-ray CT, in which the reconstruction can quickly converge to the desired solution with much reduced projection views. Methods: The reconstruction is formulated as a convex feasibility problem, i.e. the solution is an intersection of three convex sets: 1) data fidelity (DF) set – the L2 norm of the difference of observed projections and those from the reconstructed image is no greater than an error bound; 2) non-negativity of image voxels (NN) set; and 3) piecewise constant (PC) set - the total variation (TV) of the reconstructed image is no greater than an upper bound. The solution can be found by applying projection onto convex sets (POCS) sequentially for these three convex sets. Specifically, the algebraic reconstruction technique and setting negative voxels as zero are used for projection onto the DF and NN sets, respectively, while the projection onto the PC set is achieved by solving a standard Rudin, Osher, and Fatemi (ROF) model. The proposed method is named as full sequential POCS (FS-POCS), which is tested using the Shepp-Logan phantom and the Catphan600 phantom and compared with two similar algorithms, TV-POCS and CP-TV. Results: Using the Shepp-Logan phantom, the root mean square error (RMSE) of reconstructed images changing along with the number of iterations is used as the convergence measurement. In general, FS- POCS converges faster than TV-POCS and CP-TV, especially with fewer projection views. FS-POCS can also achieve accurate reconstruction of cone-beam CT of the Catphan600 phantom using only 54 views, comparable to that of FDK using 364 views. Conclusion: We developed an efficient iterative reconstruction for sparse-view CT using full sequential POCS. The simulation and physical phantom data demonstrated the computational efficiency and effectiveness of FS-POCS

  12. A sparsity-based iterative algorithm for reconstruction of micro-CT images from highly undersampled projection datasets obtained with a synchrotron X-ray source

    Science.gov (United States)

    Melli, S. Ali; Wahid, Khan A.; Babyn, Paul; Cooper, David M. L.; Gopi, Varun P.

    2016-12-01

    Synchrotron X-ray Micro Computed Tomography (Micro-CT) is an imaging technique which is increasingly used for non-invasive in vivo preclinical imaging. However, it often requires a large number of projections from many different angles to reconstruct high-quality images leading to significantly high radiation doses and long scan times. To utilize this imaging technique further for in vivo imaging, we need to design reconstruction algorithms that reduce the radiation dose and scan time without reduction of reconstructed image quality. This research is focused on using a combination of gradient-based Douglas-Rachford splitting and discrete wavelet packet shrinkage image denoising methods to design an algorithm for reconstruction of large-scale reduced-view synchrotron Micro-CT images with acceptable quality metrics. These quality metrics are computed by comparing the reconstructed images with a high-dose reference image reconstructed from 1800 equally spaced projections spanning 180°. Visual and quantitative-based performance assessment of a synthetic head phantom and a femoral cortical bone sample imaged in the biomedical imaging and therapy bending magnet beamline at the Canadian Light Source demonstrates that the proposed algorithm is superior to the existing reconstruction algorithms. Using the proposed reconstruction algorithm to reduce the number of projections in synchrotron Micro-CT is an effective way to reduce the overall radiation dose and scan time which improves in vivo imaging protocols.

  13. Active Fragment of Veronica ciliata Fisch. Attenuates t-BHP-Induced Oxidative Stress Injury in HepG2 Cells through Antioxidant and Antiapoptosis Activities

    Directory of Open Access Journals (Sweden)

    Yiran Sun

    2017-01-01

    Full Text Available Excessive amounts of reactive oxygen species (ROS in the body are a key factor in the development of hepatopathies such as hepatitis. The aim of this study was to assess the antioxidation effect in vitro and hepatoprotective activity of the active fragment of Veronica ciliata Fisch. (VCAF. Antioxidant assays (DPPH, superoxide, and hydroxyl radicals scavenging were conducted, and hepatoprotective effects through the application of tert-butyl hydroperoxide- (t-BHP- induced oxidative stress injury in HepG2 cells were evaluated. VCAF had high phenolic and flavonoid contents and strong antioxidant activity. From the perspective of hepatoprotection, VCAF exhibited a significant protective effect on t-BHP-induced HepG2 cell injury, as indicated by reductions in cytotoxicity and the levels of ROS, 8-hydroxydeoxyguanosine (8-OHdG, and protein carbonyls. Further study demonstrated that VCAF attenuated the apoptosis of t-BHP-treated HepG2 cells by suppressing the activation of caspase-3 and caspase-8. Moreover, it significantly decreased the levels of ALT and AST, increased the activities of acetyl cholinesterase (AChE, glutathione (GSH, superoxide dismutase (SOD, and catalase (CAT, and increased total antioxidative capability (T-AOC. Collectively, we concluded that VCAF may be a considerable candidate for protecting against liver injury owing to its excellent antioxidant and antiapoptosis properties.

  14. Protective Effects of Cultivated Ginseng, Cultivated Wild Ginseng of Korean and Chinese Against CCl4 and t-BHP Induced Acute Hepatotoxicity in ICR Mice

    Directory of Open Access Journals (Sweden)

    Kim, Young-Jin

    2007-02-01

    Full Text Available Objectives : This study was aimed at investigating live protection mechanism of Cultivated Ginseng and Cultivated Wild Ginseng of Korean and Chinese by inducing liver toxicity through and t-BHP in mice and evaluated serological findings. Methods : Experiment groups was categorized into untreated normal group, treated control group, and orally administered Cultivated Ginseng and Cultivated Wild Ginseng of Korean and Chinese experimental groups. At the termination of experiment, gross examination of the liver as well as Total bilirubin, AST, and ALT contents in the serum were evaluated. Results : 1. In the induced acute hepatotoxicity test, total bilirubin, AST and ALT didn't show significant differences between the control and experimental groups. 2. In the t-BHP induced acute hepatotoxicity test, total bilirubin, AST and ALT didn't show significant differences between the control and experimental groups. Conclusion : Taken together, Cultivated Ginseng and Cultivated Wild Ginseng of Korean and Chinese cannot be effectively used for recovering the liver functions in acute hepatotoxicity tests using and t-BHP. Further researches, for example treated long period, must be tried to verify the efficacies.

  15. Adaptive statistical iterative reconstruction versus filtered back projection in the same patient: 64 channel liver CT image quality and patient radiation dose

    International Nuclear Information System (INIS)

    Mitsumori, Lee M.; Shuman, William P.; Busey, Janet M.; Kolokythas, Orpheus; Koprowicz, Kent M.

    2012-01-01

    To compare routine dose liver CT reconstructed with filtered back projection (FBP) versus low dose images reconstructed with FBP and adaptive statistical iterative reconstruction (ASIR). In this retrospective study, patients had a routine dose protocol reconstructed with FBP, and again within 17 months (median 6.1 months), had a low dose protocol reconstructed twice, with FBP and ASIR. These reconstructions were compared for noise, image quality, and radiation dose. Nineteen patients were included. (12 male, mean age 58). Noise was significantly lower in low dose images reconstructed with ASIR compared to routine dose images reconstructed with FBP (liver: p <.05, aorta: p < 0.001). Low dose FBP images were scored significantly lower for subjective image quality than low dose ASIR (2.1 ± 0.5, 3.2 ± 0.8, p < 0.001). There was no difference in subjective image quality scores between routine dose FBP images and low dose ASIR images (3.6 ± 0.5, 3.2 ± 0.8, NS).Radiation dose was 41% less for the low dose protocol (4.4 ± 2.4 mSv versus 7.5 ± 5.5 mSv, p < 0.05). Our initial results suggest low dose CT images reconstructed with ASIR may have lower measured noise, similar image quality, yet significantly less radiation dose compared with higher dose images reconstructed with FBP. (orig.)

  16. Adaptive statistical iterative reconstruction versus filtered back projection in the same patient: 64 channel liver CT image quality and patient radiation dose

    Energy Technology Data Exchange (ETDEWEB)

    Mitsumori, Lee M.; Shuman, William P.; Busey, Janet M.; Kolokythas, Orpheus; Koprowicz, Kent M. [University of Washington School of Medicine, Department of Radiology, Seattle, WA (United States)

    2012-01-15

    To compare routine dose liver CT reconstructed with filtered back projection (FBP) versus low dose images reconstructed with FBP and adaptive statistical iterative reconstruction (ASIR). In this retrospective study, patients had a routine dose protocol reconstructed with FBP, and again within 17 months (median 6.1 months), had a low dose protocol reconstructed twice, with FBP and ASIR. These reconstructions were compared for noise, image quality, and radiation dose. Nineteen patients were included. (12 male, mean age 58). Noise was significantly lower in low dose images reconstructed with ASIR compared to routine dose images reconstructed with FBP (liver: p <.05, aorta: p < 0.001). Low dose FBP images were scored significantly lower for subjective image quality than low dose ASIR (2.1 {+-} 0.5, 3.2 {+-} 0.8, p < 0.001). There was no difference in subjective image quality scores between routine dose FBP images and low dose ASIR images (3.6 {+-} 0.5, 3.2 {+-} 0.8, NS).Radiation dose was 41% less for the low dose protocol (4.4 {+-} 2.4 mSv versus 7.5 {+-} 5.5 mSv, p < 0.05). Our initial results suggest low dose CT images reconstructed with ASIR may have lower measured noise, similar image quality, yet significantly less radiation dose compared with higher dose images reconstructed with FBP. (orig.)

  17. Estimation of 1945 to 1957 food consumption. Hanford Environmental Dose Reconstruction Project: Draft

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, D.M.; Bates, D.J.; Marsh, T.L.

    1993-03-01

    This report details the methods used and the results of the study on the estimated historic levels of food consumption by individuals in the Hanford Environmental Dose Reconstruction (HEDR) study area from 1945--1957. This period includes the time of highest releases from Hanford and is the period for which data are being collected in the Hanford Thyroid Disease Study. These estimates provide the food-consumption inputs for the HEDR database of individual diets. This database will be an input file in the Hanford Environmental Dose Reconstruction Integrated Code (HEDRIC) computer model that will be used to calculate the radiation dose. The report focuses on fresh milk, eggs, lettuce, and spinach. These foods were chosen because they have been found to be significant contributors to radiation dose based on the Technical Steering Panel dose decision level.

  18. Estimation of 1945 to 1957 food consumption. Hanford Environmental Dose Reconstruction Project

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, D.M.; Bates, D.J.; Marsh, T.L.

    1993-07-01

    This report details the methods used and the results of the study on the estimated historic levels of food consumption by individuals in the Hanford Environmental Dose Reconstruction (HEDR) study area from 1945--1957. This period includes the time of highest releases from Hanford and is the period for which data are being collected in the Hanford Thyroid Disease Study. These estimates provide the food-consumption inputs for the HEDR database of individual diets. This database will be an input file in the Hanford Environmental Dose Reconstruction Integrated Code (HEDRIC) computer model that will be used to calculate the radiation dose. The report focuses on fresh milk, eggs, lettuce, and spinach. These foods were chosen because they have been found to be significant contributors to radiation dose based on the Technical Steering Panel dose decision level.

  19. Techniques for the reconstruction of two-dimensional images from projections

    International Nuclear Information System (INIS)

    Sauthoff, N.R.; Von Goeler, S.

    1978-08-01

    Several plasma diagnostics techniques measure the line integrals of quantities such as densities and optical, ultraviolet, and X-ray emission. Some approaches for reconstructing the local quantities from their line integrals, based on methods utilized in computerized tomography, electron microscopy, holographic interferometry, and radio astromony, are derived and presented. Results for the special cases with source functions posessing helical symmetry--ranging from DNA to MHD--are emphasized

  20. Comparison of pure and hybrid iterative reconstruction techniques with conventional filtered back projection: Image quality assessment in the cervicothoracic region

    Energy Technology Data Exchange (ETDEWEB)

    Katsura, Masaki, E-mail: mkatsura-tky@umin.ac.jp [Department of Radiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan); Sato, Jiro; Akahane, Masaaki; Matsuda, Izuru; Ishida, Masanori; Yasaka, Koichiro; Kunimatsu, Akira; Ohtomo, Kuni [Department of Radiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan)

    2013-02-15

    Objectives: To evaluate the impact on image quality of three different image reconstruction techniques in the cervicothoracic region: model-based iterative reconstruction (MBIR), adaptive statistical iterative reconstruction (ASIR), and filtered back projection (FBP). Methods: Forty-four patients underwent unenhanced standard-of-care clinical computed tomography (CT) examinations which included the cervicothoracic region with a 64-row multidetector CT scanner. Images were reconstructed with FBP, 50% ASIR-FBP blending (ASIR50), and MBIR. Two radiologists assessed the cervicothoracic region in a blinded manner for streak artifacts, pixilated blotchy appearances, critical reproduction of visually sharp anatomical structures (thyroid gland, common carotid artery, and esophagus), and overall diagnostic acceptability. Objective image noise was measured in the internal jugular vein. Data were analyzed using the sign test and pair-wise Student's t-test. Results: MBIR images had significant lower quantitative image noise (8.88 ± 1.32) compared to ASIR images (18.63 ± 4.19, P < 0.01) and FBP images (26.52 ± 5.8, P < 0.01). Significant improvements in streak artifacts of the cervicothoracic region were observed with the use of MBIR (P < 0.001 each for MBIR vs. the other two image data sets for both readers), while no significant difference was observed between ASIR and FBP (P > 0.9 for ASIR vs. FBP for both readers). MBIR images were all diagnostically acceptable. Unique features of MBIR images included pixilated blotchy appearances, which did not adversely affect diagnostic acceptability. Conclusions: MBIR significantly improves image noise and streak artifacts of the cervicothoracic region over ASIR and FBP. MBIR is expected to enhance the value of CT examinations for areas where image noise and streak artifacts are problematic.

  1. Methods of X-ray CT image reconstruction from few projections; Methodes de reconstruction d'images a partir d'un faible nombre de projections en tomographie par rayons X

    Energy Technology Data Exchange (ETDEWEB)

    Wang, H.

    2011-10-24

    To improve the safety (low dose) and the productivity (fast acquisition) of a X-ray CT system, we want to reconstruct a high quality image from a small number of projections. The classical reconstruction algorithms generally fail since the reconstruction procedure is unstable and suffers from artifacts. A new approach based on the recently developed 'Compressed Sensing' (CS) theory assumes that the unknown image is in some sense 'sparse' or 'compressible', and the reconstruction is formulated through a non linear optimization problem (TV/l1 minimization) by enhancing the sparsity. Using the pixel (or voxel in 3D) as basis, to apply the CS framework in CT one usually needs a 'sparsifying' transform, and combines it with the 'X-ray projector' which applies on the pixel image. In this thesis, we have adapted a 'CT-friendly' radial basis of Gaussian family called 'blob' to the CS-CT framework. The blob has better space-frequency localization properties than the pixel, and many operations, such as the X-ray transform, can be evaluated analytically and are highly parallelizable (on GPU platform). Compared to the classical Kaisser-Bessel blob, the new basis has a multi-scale structure: an image is the sum of dilated and translated radial Mexican hat functions. The typical medical objects are compressible under this basis, so the sparse representation system used in the ordinary CS algorithms is no more needed. 2D simulations show that the existing TV and l1 algorithms are more efficient and the reconstructions have better visual quality than the equivalent approach based on the pixel or wavelet basis. The new approach has also been validated on 2D experimental data, where we have observed that in general the number of projections can be reduced to about 50%, without compromising the image quality. (author) [French] Afin d'ameliorer la surete (faible dose) et la productivite (acquisition rapide) du

  2. Demonstration of a forward iterative method to reconstruct brachytherapy seed configurations from x-ray projections

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, Martin J; Todor, Dorin A [Department of Radiation Oncology, Virginia Commonwealth University, Richmond VA 23298 (United States)

    2005-06-07

    By monitoring brachytherapy seed placement and determining the actual configuration of the seeds in vivo, one can optimize the treatment plan during the process of implantation. Two or more radiographic images from different viewpoints can in principle allow one to reconstruct the configuration of implanted seeds uniquely. However, the reconstruction problem is complicated by several factors: (1) the seeds can overlap and cluster in the images; (2) the images can have distortion that varies with viewpoint when a C-arm fluoroscope is used; (3) there can be uncertainty in the imaging viewpoints; (4) the angular separation of the imaging viewpoints can be small owing to physical space constraints; (5) there can be inconsistency in the number of seeds detected in the images; and (6) the patient can move while being imaged. We propose and conceptually demonstrate a novel reconstruction method that handles all of these complications and uncertainties in a unified process. The method represents the three-dimensional seed and camera configurations as parametrized models that are adjusted iteratively to conform to the observed radiographic images. The morphed model seed configuration that best reproduces the appearance of the seeds in the radiographs is the best estimate of the actual seed configuration. All of the information needed to establish both the seed configuration and the camera model is derived from the seed images without resort to external calibration fixtures. Furthermore, by comparing overall image content rather than individual seed coordinates, the process avoids the need to establish correspondence between seed identities in the several images. The method has been shown to work robustly in simulation tests that simultaneously allow for unknown individual seed positions, uncertainties in the imaging viewpoints and variable image distortion.

  3. Demons Registration of CT Volume and CBCT Projections for Adaptive Radiotherapy: Avoiding CBCT Reconstruction

    DEFF Research Database (Denmark)

    Bjerre, Troels; Aznar, M.; Munck af Rosenschöld, P.

    2012-01-01

    with adaptive fluidity (smoothing kernel width). For forward/back-projection, the separable footprints algorithm with trapezoid functions was applied. The similarity between the simulated and measured projections was measured as the SSD. Results: The figure shows a slice of; the CT volume (reference), the CT...

  4. Adaptive algebraic reconstruction technique

    International Nuclear Information System (INIS)

    Lu Wenkai; Yin Fangfang

    2004-01-01

    Algebraic reconstruction techniques (ART) are iterative procedures for reconstructing objects from their projections. It is proven that ART can be computationally efficient by carefully arranging the order in which the collected data are accessed during the reconstruction procedure and adaptively adjusting the relaxation parameters. In this paper, an adaptive algebraic reconstruction technique (AART), which adopts the same projection access scheme in multilevel scheme algebraic reconstruction technique (MLS-ART), is proposed. By introducing adaptive adjustment of the relaxation parameters during the reconstruction procedure, one-iteration AART can produce reconstructions with better quality, in comparison with one-iteration MLS-ART. Furthermore, AART outperforms MLS-ART with improved computational efficiency

  5. Why do commercial CT scanners still employ traditional, filtered back-projection for image reconstruction?

    International Nuclear Information System (INIS)

    Pan, Xiaochuan; Sidky, Emil Y; Vannier, Michael

    2009-01-01

    Despite major advances in x-ray sources, detector arrays, gantry mechanical design and especially computer performance, one component of computed tomography (CT) scanners has remained virtually constant for the past 25 years—the reconstruction algorithm. Fundamental advances have been made in the solution of inverse problems, especially tomographic reconstruction, but these works have not been translated into clinical and related practice. The reasons are not obvious and seldom discussed. This review seeks to examine the reasons for this discrepancy and provides recommendations on how it can be resolved. We take the example of field of compressive sensing (CS), summarizing this new area of research from the eyes of practical medical physicists and explaining the disconnection between theoretical and application-oriented research. Using a few issues specific to CT, which engineers have addressed in very specific ways, we try to distill the mathematical problem underlying each of these issues with the hope of demonstrating that there are interesting mathematical problems of general importance that can result from in depth analysis of specific issues. We then sketch some unconventional CT-imaging designs that have the potential to impact on CT applications, if the link between applied mathematicians and engineers/physicists were stronger. Finally, we close with some observations on how the link could be strengthened. There is, we believe, an important opportunity to rapidly improve the performance of CT and related tomographic imaging techniques by addressing these issues. (topical review)

  6. Image quality in thoracic 4D cone-beam CT: A sensitivity analysis of respiratory signal, binning method, reconstruction algorithm, and projection angular spacing

    OpenAIRE

    Shieh, Chun-Chien; Kipritidis, John; O’Brien, Ricky T.; Kuncic, Zdenka; Keall, Paul J.

    2014-01-01

    Purpose: Respiratory signal, binning method, and reconstruction algorithm are three major controllable factors affecting image quality in thoracic 4D cone-beam CT (4D-CBCT), which is widely used in image guided radiotherapy (IGRT). Previous studies have investigated each of these factors individually, but no integrated sensitivity analysis has been performed. In addition, projection angular spacing is also a key factor in reconstruction, but how it affects image quality is not obvious. An inv...

  7. Optimized image acquisition for breast tomosynthesis in projection and reconstruction space

    OpenAIRE

    Chawla, Amarpreet S.; Lo, Joseph Y.; Baker, Jay A.; Samei, Ehsan

    2009-01-01

    Breast tomosynthesis has been an exciting new development in the field of breast imaging. While the diagnostic improvement via tomosynthesis is notable, the full potential of tomosynthesis has not yet been realized. This may be attributed to the dependency of the diagnostic quality of tomosynthesis on multiple variables, each of which needs to be optimized. Those include dose, number of angular projections, and the total angular span of those projections. In this study, the authors investigat...

  8. Image quality in thoracic 4D cone-beam CT: A sensitivity analysis of respiratory signal, binning method, reconstruction algorithm, and projection angular spacing

    International Nuclear Information System (INIS)

    Shieh, Chun-Chien; Kipritidis, John; O’Brien, Ricky T.; Keall, Paul J.; Kuncic, Zdenka

    2014-01-01

    Purpose: Respiratory signal, binning method, and reconstruction algorithm are three major controllable factors affecting image quality in thoracic 4D cone-beam CT (4D-CBCT), which is widely used in image guided radiotherapy (IGRT). Previous studies have investigated each of these factors individually, but no integrated sensitivity analysis has been performed. In addition, projection angular spacing is also a key factor in reconstruction, but how it affects image quality is not obvious. An investigation of the impacts of these four factors on image quality can help determine the most effective strategy in improving 4D-CBCT for IGRT. Methods: Fourteen 4D-CBCT patient projection datasets with various respiratory motion features were reconstructed with the following controllable factors: (i) respiratory signal (real-time position management, projection image intensity analysis, or fiducial marker tracking), (ii) binning method (phase, displacement, or equal-projection-density displacement binning), and (iii) reconstruction algorithm [Feldkamp–Davis–Kress (FDK), McKinnon–Bates (MKB), or adaptive-steepest-descent projection-onto-convex-sets (ASD-POCS)]. The image quality was quantified using signal-to-noise ratio (SNR), contrast-to-noise ratio, and edge-response width in order to assess noise/streaking and blur. The SNR values were also analyzed with respect to the maximum, mean, and root-mean-squared-error (RMSE) projection angular spacing to investigate how projection angular spacing affects image quality. Results: The choice of respiratory signals was found to have no significant impact on image quality. Displacement-based binning was found to be less prone to motion artifacts compared to phase binning in more than half of the cases, but was shown to suffer from large interbin image quality variation and large projection angular gaps. Both MKB and ASD-POCS resulted in noticeably improved image quality almost 100% of the time relative to FDK. In addition, SNR

  9. Image quality in thoracic 4D cone-beam CT: A sensitivity analysis of respiratory signal, binning method, reconstruction algorithm, and projection angular spacing

    Energy Technology Data Exchange (ETDEWEB)

    Shieh, Chun-Chien [Radiation Physics Laboratory, Sydney Medical School, University of Sydney, NSW 2006, Australia and Institute of Medical Physics, School of Physics, University of Sydney, NSW 2006 (Australia); Kipritidis, John; O’Brien, Ricky T.; Keall, Paul J., E-mail: paul.keall@sydney.edu.au [Radiation Physics Laboratory, Sydney Medical School, University of Sydney, NSW 2006 (Australia); Kuncic, Zdenka [Institute of Medical Physics, School of Physics, University of Sydney, NSW 2006 (Australia)

    2014-04-15

    Purpose: Respiratory signal, binning method, and reconstruction algorithm are three major controllable factors affecting image quality in thoracic 4D cone-beam CT (4D-CBCT), which is widely used in image guided radiotherapy (IGRT). Previous studies have investigated each of these factors individually, but no integrated sensitivity analysis has been performed. In addition, projection angular spacing is also a key factor in reconstruction, but how it affects image quality is not obvious. An investigation of the impacts of these four factors on image quality can help determine the most effective strategy in improving 4D-CBCT for IGRT. Methods: Fourteen 4D-CBCT patient projection datasets with various respiratory motion features were reconstructed with the following controllable factors: (i) respiratory signal (real-time position management, projection image intensity analysis, or fiducial marker tracking), (ii) binning method (phase, displacement, or equal-projection-density displacement binning), and (iii) reconstruction algorithm [Feldkamp–Davis–Kress (FDK), McKinnon–Bates (MKB), or adaptive-steepest-descent projection-onto-convex-sets (ASD-POCS)]. The image quality was quantified using signal-to-noise ratio (SNR), contrast-to-noise ratio, and edge-response width in order to assess noise/streaking and blur. The SNR values were also analyzed with respect to the maximum, mean, and root-mean-squared-error (RMSE) projection angular spacing to investigate how projection angular spacing affects image quality. Results: The choice of respiratory signals was found to have no significant impact on image quality. Displacement-based binning was found to be less prone to motion artifacts compared to phase binning in more than half of the cases, but was shown to suffer from large interbin image quality variation and large projection angular gaps. Both MKB and ASD-POCS resulted in noticeably improved image quality almost 100% of the time relative to FDK. In addition, SNR

  10. Three-dimensional optical reconstruction of vocal fold kinematics using high-speed video with a laser projection system

    Science.gov (United States)

    Luegmair, Georg; Mehta, Daryush D.; Kobler, James B.; Döllinger, Michael

    2015-01-01

    Vocal fold kinematics and its interaction with aerodynamic characteristics play a primary role in acoustic sound production of the human voice. Investigating the temporal details of these kinematics using high-speed videoendoscopic imaging techniques has proven challenging in part due to the limitations of quantifying complex vocal fold vibratory behavior using only two spatial dimensions. Thus, we propose an optical method of reconstructing the superior vocal fold surface in three spatial dimensions using a high-speed video camera and laser projection system. Using stereo-triangulation principles, we extend the camera-laser projector method and present an efficient image processing workflow to generate the three-dimensional vocal fold surfaces during phonation captured at 4000 frames per second. Initial results are provided for airflow-driven vibration of an ex vivo vocal fold model in which at least 75% of visible laser points contributed to the reconstructed surface. The method captures the vertical motion of the vocal folds at a high accuracy to allow for the computation of three-dimensional mucosal wave features such as vibratory amplitude, velocity, and asymmetry. PMID:26087485

  11. Conversion and correction factors for historical measurements of iodine-131 in Hanford-area vegetation, 1945--1947. Hanford Environmental Dose Reconstruction Project

    Energy Technology Data Exchange (ETDEWEB)

    Mart, E.I.; Denham, D.H.; Thiede, M.E.

    1993-12-01

    This report is a result of the Hanford Environmental Dose Reconstruction (HEDR) Project whose goal is to estimate the radiation dose that individuals could have received from emissions since 1944 at the U.S. Department of Energy`s (DOE) Hanford Site near Richland, Washington. The HEDR Project is conducted by Battelle, Pacific Northwest Laboratories (BNW). One of the radionuclides emitted that would affect the radiation dose was iodine-131. This report describes in detail the reconstructed conversion and correction factors for historical measurements of iodine-131 in Hanford-area vegetation which was collected from the beginning of October 1945 through the end of December 1947.

  12. Reconstructing Masculinity in the Locker Room: The Mentors in Violence Prevention Project.

    Science.gov (United States)

    Katz, Jackson

    1995-01-01

    The Mentors in Violence Prevention Project seeks to reduce violence against women by inspiring male athletes and other models of traditional masculinity to challenge norms that equate strength in men with dominance over women and to use their influence for positive behavior change. (SK)

  13. Reconstruction of implanted marker trajectories from cone-beam CT projection images using interdimensional correlation modeling

    International Nuclear Information System (INIS)

    Chung, Hyekyun; Poulsen, Per Rugaard; Keall, Paul J.; Cho, Seungryong; Cho, Byungchul

    2016-01-01

    Purpose: Cone-beam CT (CBCT) is a widely used imaging modality for image-guided radiotherapy. Most vendors provide CBCT systems that are mounted on a linac gantry. Thus, CBCT can be used to estimate the actual 3-dimensional (3D) position of moving respiratory targets in the thoracic/abdominal region using 2D projection images. The authors have developed a method for estimating the 3D trajectory of respiratory-induced target motion from CBCT projection images using interdimensional correlation modeling. Methods: Because the superior–inferior (SI) motion of a target can be easily analyzed on projection images of a gantry-mounted CBCT system, the authors investigated the interdimensional correlation of the SI motion with left–right and anterior–posterior (AP) movements while the gantry is rotating. A simple linear model and a state-augmented model were implemented and applied to the interdimensional correlation analysis, and their performance was compared. The parameters of the interdimensional correlation models were determined by least-square estimation of the 2D error between the actual and estimated projected target position. The method was validated using 160 3D tumor trajectories from 46 thoracic/abdominal cancer patients obtained during CyberKnife treatment. The authors’ simulations assumed two application scenarios: (1) retrospective estimation for the purpose of moving tumor setup used just after volumetric matching with CBCT; and (2) on-the-fly estimation for the purpose of real-time target position estimation during gating or tracking delivery, either for full-rotation volumetric-modulated arc therapy (VMAT) in 60 s or a stationary six-field intensity-modulated radiation therapy (IMRT) with a beam delivery time of 20 s. Results: For the retrospective CBCT simulations, the mean 3D root-mean-square error (RMSE) for all 4893 trajectory segments was 0.41 mm (simple linear model) and 0.35 mm (state-augmented model). In the on-the-fly simulations, prior

  14. Reconstruction of implanted marker trajectories from cone-beam CT projection images using interdimensional correlation modeling

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Hyekyun [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, South Korea and Department of Radiation Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 138-736 (Korea, Republic of); Poulsen, Per Rugaard [Department of Oncology, Aarhus University Hospital, Nørrebrogade 44, 8000 Aarhus C (Denmark); Keall, Paul J. [Radiation Physics Laboratory, Sydney Medical School, University of Sydney, NSW 2006 (Australia); Cho, Seungryong [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141 (Korea, Republic of); Cho, Byungchul, E-mail: cho.byungchul@gmail.com, E-mail: bcho@amc.seoul.kr [Department of Radiation Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505 (Korea, Republic of)

    2016-08-15

    Purpose: Cone-beam CT (CBCT) is a widely used imaging modality for image-guided radiotherapy. Most vendors provide CBCT systems that are mounted on a linac gantry. Thus, CBCT can be used to estimate the actual 3-dimensional (3D) position of moving respiratory targets in the thoracic/abdominal region using 2D projection images. The authors have developed a method for estimating the 3D trajectory of respiratory-induced target motion from CBCT projection images using interdimensional correlation modeling. Methods: Because the superior–inferior (SI) motion of a target can be easily analyzed on projection images of a gantry-mounted CBCT system, the authors investigated the interdimensional correlation of the SI motion with left–right and anterior–posterior (AP) movements while the gantry is rotating. A simple linear model and a state-augmented model were implemented and applied to the interdimensional correlation analysis, and their performance was compared. The parameters of the interdimensional correlation models were determined by least-square estimation of the 2D error between the actual and estimated projected target position. The method was validated using 160 3D tumor trajectories from 46 thoracic/abdominal cancer patients obtained during CyberKnife treatment. The authors’ simulations assumed two application scenarios: (1) retrospective estimation for the purpose of moving tumor setup used just after volumetric matching with CBCT; and (2) on-the-fly estimation for the purpose of real-time target position estimation during gating or tracking delivery, either for full-rotation volumetric-modulated arc therapy (VMAT) in 60 s or a stationary six-field intensity-modulated radiation therapy (IMRT) with a beam delivery time of 20 s. Results: For the retrospective CBCT simulations, the mean 3D root-mean-square error (RMSE) for all 4893 trajectory segments was 0.41 mm (simple linear model) and 0.35 mm (state-augmented model). In the on-the-fly simulations, prior

  15. PROJECTS PORTOFOLIO FOR ECOLOGICAL RECONSTRUCTION OF THE IER VALLEZ AND THEIR FUNDING

    Directory of Open Access Journals (Sweden)

    Doru Ioan Ardelean

    2013-12-01

    Full Text Available The Ier Valley has been taken into the survey as it is drained by a polluted river and strongly affected by sewerages and inning, with the aim to establish ecological reabilitation measures. In this view, a SWOT analysis was carried out, which highlighted a number of weaknessess regarding the ecological status of the river, and in order to remove them, a portofolio of 14 environment projects was drawn. Their implementation would require over than 40 millions lei that means in a proportion of 91% other resources, especially European Funds. The environment investment projects were evaluated at a total economical value of about 40 millions lei. Their funding was conceived in partnership terms and accessing funds from several sources, mainly on short term.

  16. The developing human connectome project: A minimal processing pipeline for neonatal cortical surface reconstruction.

    Science.gov (United States)

    Makropoulos, Antonios; Robinson, Emma C; Schuh, Andreas; Wright, Robert; Fitzgibbon, Sean; Bozek, Jelena; Counsell, Serena J; Steinweg, Johannes; Vecchiato, Katy; Passerat-Palmbach, Jonathan; Lenz, Gregor; Mortari, Filippo; Tenev, Tencho; Duff, Eugene P; Bastiani, Matteo; Cordero-Grande, Lucilio; Hughes, Emer; Tusor, Nora; Tournier, Jacques-Donald; Hutter, Jana; Price, Anthony N; Teixeira, Rui Pedro A G; Murgasova, Maria; Victor, Suresh; Kelly, Christopher; Rutherford, Mary A; Smith, Stephen M; Edwards, A David; Hajnal, Joseph V; Jenkinson, Mark; Rueckert, Daniel

    2018-06-01

    The Developing Human Connectome Project (dHCP) seeks to create the first 4-dimensional connectome of early life. Understanding this connectome in detail may provide insights into normal as well as abnormal patterns of brain development. Following established best practices adopted by the WU-MINN Human Connectome Project (HCP), and pioneered by FreeSurfer, the project utilises cortical surface-based processing pipelines. In this paper, we propose a fully automated processing pipeline for the structural Magnetic Resonance Imaging (MRI) of the developing neonatal brain. This proposed pipeline consists of a refined framework for cortical and sub-cortical volume segmentation, cortical surface extraction, and cortical surface inflation, which has been specifically designed to address considerable differences between adult and neonatal brains, as imaged using MRI. Using the proposed pipeline our results demonstrate that images collected from 465 subjects ranging from 28 to 45 weeks post-menstrual age (PMA) can be processed fully automatically; generating cortical surface models that are topologically correct, and correspond well with manual evaluations of tissue boundaries in 85% of cases. Results improve on state-of-the-art neonatal tissue segmentation models and significant errors were found in only 2% of cases, where these corresponded to subjects with high motion. Downstream, these surfaces will enhance comparisons of functional and diffusion MRI datasets, supporting the modelling of emerging patterns of brain connectivity. Copyright © 2018 Elsevier Inc. All rights reserved.

  17. Effective noise-suppressed and artifact-reduced reconstruction of SPECT data using a preconditioned alternating projection algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Li, Si; Xu, Yuesheng, E-mail: yxu06@syr.edu [Guangdong Provincial Key Laboratory of Computational Science, School of Mathematics and Computational Sciences, Sun Yat-sen University, Guangzhou 510275 (China); Zhang, Jiahan; Lipson, Edward [Department of Physics, Syracuse University, Syracuse, New York 13244 (United States); Krol, Andrzej; Feiglin, David [Department of Radiology, SUNY Upstate Medical University, Syracuse, New York 13210 (United States); Schmidtlein, C. Ross [Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, New York 10065 (United States); Vogelsang, Levon [Carestream Health, Rochester, New York 14608 (United States); Shen, Lixin [Guangdong Provincial Key Laboratory of Computational Science, School of Mathematics and Computational Sciences, Sun Yat-sen University, Guangzhou 510275, China and Department of Mathematics, Syracuse University, Syracuse, New York 13244 (United States)

    2015-08-15

    Purpose: The authors have recently developed a preconditioned alternating projection algorithm (PAPA) with total variation (TV) regularizer for solving the penalized-likelihood optimization model for single-photon emission computed tomography (SPECT) reconstruction. This algorithm belongs to a novel class of fixed-point proximity methods. The goal of this work is to investigate how PAPA performs while dealing with realistic noisy SPECT data, to compare its performance with more conventional methods, and to address issues with TV artifacts by proposing a novel form of the algorithm invoking high-order TV regularization, denoted as HOTV-PAPA, which has been explored and studied extensively in the present work. Methods: Using Monte Carlo methods, the authors simulate noisy SPECT data from two water cylinders; one contains lumpy “warm” background and “hot” lesions of various sizes with Gaussian activity distribution, and the other is a reference cylinder without hot lesions. The authors study the performance of HOTV-PAPA and compare it with PAPA using first-order TV regularization (TV-PAPA), the Panin–Zeng–Gullberg one-step-late method with TV regularization (TV-OSL), and an expectation–maximization algorithm with Gaussian postfilter (GPF-EM). The authors select penalty-weights (hyperparameters) by qualitatively balancing the trade-off between resolution and image noise separately for TV-PAPA and TV-OSL. However, the authors arrived at the same penalty-weight value for both of them. The authors set the first penalty-weight in HOTV-PAPA equal to the optimal penalty-weight found for TV-PAPA. The second penalty-weight needed for HOTV-PAPA is tuned by balancing resolution and the severity of staircase artifacts. The authors adjust the Gaussian postfilter to approximately match the local point spread function of GPF-EM and HOTV-PAPA. The authors examine hot lesion detectability, study local spatial resolution, analyze background noise properties, estimate mean

  18. Effective noise-suppressed and artifact-reduced reconstruction of SPECT data using a preconditioned alternating projection algorithm

    International Nuclear Information System (INIS)

    Li, Si; Xu, Yuesheng; Zhang, Jiahan; Lipson, Edward; Krol, Andrzej; Feiglin, David; Schmidtlein, C. Ross; Vogelsang, Levon; Shen, Lixin

    2015-01-01

    Purpose: The authors have recently developed a preconditioned alternating projection algorithm (PAPA) with total variation (TV) regularizer for solving the penalized-likelihood optimization model for single-photon emission computed tomography (SPECT) reconstruction. This algorithm belongs to a novel class of fixed-point proximity methods. The goal of this work is to investigate how PAPA performs while dealing with realistic noisy SPECT data, to compare its performance with more conventional methods, and to address issues with TV artifacts by proposing a novel form of the algorithm invoking high-order TV regularization, denoted as HOTV-PAPA, which has been explored and studied extensively in the present work. Methods: Using Monte Carlo methods, the authors simulate noisy SPECT data from two water cylinders; one contains lumpy “warm” background and “hot” lesions of various sizes with Gaussian activity distribution, and the other is a reference cylinder without hot lesions. The authors study the performance of HOTV-PAPA and compare it with PAPA using first-order TV regularization (TV-PAPA), the Panin–Zeng–Gullberg one-step-late method with TV regularization (TV-OSL), and an expectation–maximization algorithm with Gaussian postfilter (GPF-EM). The authors select penalty-weights (hyperparameters) by qualitatively balancing the trade-off between resolution and image noise separately for TV-PAPA and TV-OSL. However, the authors arrived at the same penalty-weight value for both of them. The authors set the first penalty-weight in HOTV-PAPA equal to the optimal penalty-weight found for TV-PAPA. The second penalty-weight needed for HOTV-PAPA is tuned by balancing resolution and the severity of staircase artifacts. The authors adjust the Gaussian postfilter to approximately match the local point spread function of GPF-EM and HOTV-PAPA. The authors examine hot lesion detectability, study local spatial resolution, analyze background noise properties, estimate mean

  19. Prediction of optimal deployment projection for transcatheter aortic valve replacement: angiographic 3-dimensional reconstruction of the aortic root versus multidetector computed tomography.

    OpenAIRE

    Binder Ronald K; Leipsic Jonathon; Wood David; Moore Teri; Toggweiler Stefan; Willson Alex; Gurvitch Ronen; Freeman Melanie; Webb John G

    2012-01-01

    BACKGROUND Identifying the optimal fluoroscopic projection of the aortic valve is important for successful transcatheter aortic valve replacement (TAVR). Various imaging modalities including multidetector computed tomography (MDCT) have been proposed for prediction of the optimal deployment projection. We evaluated a method that provides 3 dimensional angiographic reconstructions (3DA) of the aortic root for prediction of the optimal deployment angle and compared it with MDCT. METHODS AND RES...

  20. Real-time volumetric image reconstruction and 3D tumor localization based on a single x-ray projection image for lung cancer radiotherapy.

    Science.gov (United States)

    Li, Ruijiang; Jia, Xun; Lewis, John H; Gu, Xuejun; Folkerts, Michael; Men, Chunhua; Jiang, Steve B

    2010-06-01

    To develop an algorithm for real-time volumetric image reconstruction and 3D tumor localization based on a single x-ray projection image for lung cancer radiotherapy. Given a set of volumetric images of a patient at N breathing phases as the training data, deformable image registration was performed between a reference phase and the other N-1 phases, resulting in N-1 deformation vector fields (DVFs). These DVFs can be represented efficiently by a few eigenvectors and coefficients obtained from principal component analysis (PCA). By varying the PCA coefficients, new DVFs can be generated, which, when applied on the reference image, lead to new volumetric images. A volumetric image can then be reconstructed from a single projection image by optimizing the PCA coefficients such that its computed projection matches the measured one. The 3D location of the tumor can be derived by applying the inverted DVF on its position in the reference image. The algorithm was implemented on graphics processing units (GPUs) to achieve real-time efficiency. The training data were generated using a realistic and dynamic mathematical phantom with ten breathing phases. The testing data were 360 cone beam projections corresponding to one gantry rotation, simulated using the same phantom with a 50% increase in breathing amplitude. The average relative image intensity error of the reconstructed volumetric images is 6.9% +/- 2.4%. The average 3D tumor localization error is 0.8 +/- 0.5 mm. On an NVIDIA Tesla C1060 GPU card, the average computation time for reconstructing a volumetric image from each projection is 0.24 s (range: 0.17 and 0.35 s). The authors have shown the feasibility of reconstructing volumetric images and localizing tumor positions in 3D in near real-time from a single x-ray image.

  1. Fast backprojection-based reconstruction of spectral-spatial EPR images from projections with the constant sweep of a magnetic field.

    Science.gov (United States)

    Komarov, Denis A; Hirata, Hiroshi

    2017-08-01

    In this paper, we introduce a procedure for the reconstruction of spectral-spatial EPR images using projections acquired with the constant sweep of a magnetic field. The application of a constant field-sweep and a predetermined data sampling rate simplifies the requirements for EPR imaging instrumentation and facilitates the backprojection-based reconstruction of spectral-spatial images. The proposed approach was applied to the reconstruction of a four-dimensional numerical phantom and to actual spectral-spatial EPR measurements. Image reconstruction using projections with a constant field-sweep was three times faster than the conventional approach with the application of a pseudo-angle and a scan range that depends on the applied field gradient. Spectral-spatial EPR imaging with a constant field-sweep for data acquisition only slightly reduces the signal-to-noise ratio or functional resolution of the resultant images and can be applied together with any common backprojection-based reconstruction algorithm. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. A simple method for 3D lesion reconstruction from two projected angiographic images: implementation to a stereotactic radiotherapy treatment planning system

    International Nuclear Information System (INIS)

    Theodorou, K.; Kappas, C.; Gaboriaud, G.; Mazal, A.D.; Petrascu, O.; Rosenwald, J.C.

    1997-01-01

    Introduction: The most used imaging modality for diagnosis and localisation of arteriovenous malformations (AVMs) treated with stereotactic radiotherapy is angiography. The fact that the angiographic images are projected images imposes the need of the 3D reconstruction of the lesion. This, together with the 3D head anatomy from CT images could provide all the necessary information for stereotactic treatment planning. We have developed a method to combine the complementary information provided by angiography and 2D computerized tomography, matching the reconstructed AVM structure with the reconstructed head of the patient. Materials and methods: The ISIS treatment planning system, developed at Institute Curie, has been used for image acquisition, stereotactic localisation and 3D visualisation. A series of CT slices are introduced in the system as well as two orthogonal angiographic projected images of the lesion. A simple computer program has been developed for the 3D reconstruction of the lesion and for the superposition of the target contour on the CT slices of the head. Results and conclusions: In our approach we consider that the reconstruction can be made if the AVM is approximated with a number of adjacent ellipses. We assessed the method comparing the values of the reconstructed and the actual volumes of the target using linear regression analysis. For treatment planning purposes we overlapped the reconstructed AVM on the CT slices of the head. The above feature is to our knowledge a feature that the majority of the commercial stereotactic radiotherapy treatment planning system could not provide. The implementation of the method into ISIS TPS shows that we can reliably approximate and visualize the target volume

  3. Characterization of masses in digital breast tomosynthesis: comparison of machine learning in projection views and reconstructed slices.

    Science.gov (United States)

    Chan, Heang-Ping; Wu, Yi-Ta; Sahiner, Berkman; Wei, Jun; Helvie, Mark A; Zhang, Yiheng; Moore, Richard H; Kopans, Daniel B; Hadjiiski, Lubomir; Way, Ted

    2010-07-01

    In digital breast tomosynthesis (DBT), quasi-three-dimensional (3D) structural information is reconstructed from a small number of 2D projection view (PV) mammograms acquired over a limited angular range. The authors developed preliminary computer-aided diagnosis (CADx) methods for classification of malignant and benign masses and compared the effectiveness of analyzing lesion characteristics in the reconstructed DBT slices and in the PVs. A data set of MLO view DBT of 99 patients containing 107 masses (56 malignant and 51 benign) was collected at the Massachusetts General Hospital with IRB approval. The DBTs were obtained with a GE prototype system which acquired 11 PVs over a 50 degree arc. The authors reconstructed the DBTs at 1 mm slice interval using a simultaneous algebraic reconstruction technique. The region of interest (ROI) containing the mass was marked by a radiologist in the DBT volume and the corresponding ROIs on the PVs were derived based on the imaging geometry. The subsequent processes were fully automated. For classification of masses using the DBT-slice approach, the mass on each slice was segmented by an active contour model initialized with adaptive k-means clustering. A spiculation likelihood map was generated by analysis of the gradient directions around the mass margin and spiculation features were extracted from the map. The rubber band straightening transform (RBST) was applied to a band of pixels around the segmented mass boundary. The RBST image was enhanced by Sobel filtering in the horizontal and vertical directions, from which run-length statistics texture features were extracted. Morphological features including those from the normalized radial length were designed to describe the mass shape. A feature space composed of the spiculation features, texture features, and morphological features extracted from the central slice alone and seven feature spaces obtained by averaging the corresponding features from three to 19 slices centered

  4. Characterization of masses in digital breast tomosynthesis: Comparison of machine learning in projection views and reconstructed slices

    International Nuclear Information System (INIS)

    Chan, Heang-Ping; Wu Yita; Sahiner, Berkman; Wei, Jun; Helvie, Mark A.; Zhang Yiheng; Moore, Richard H.; Kopans, Daniel B.; Hadjiiski, Lubomir; Way, Ted

    2010-01-01

    Purpose: In digital breast tomosynthesis (DBT), quasi-three-dimensional (3D) structural information is reconstructed from a small number of 2D projection view (PV) mammograms acquired over a limited angular range. The authors developed preliminary computer-aided diagnosis (CADx) methods for classification of malignant and benign masses and compared the effectiveness of analyzing lesion characteristics in the reconstructed DBT slices and in the PVs. Methods: A data set of MLO view DBT of 99 patients containing 107 masses (56 malignant and 51 benign) was collected at the Massachusetts General Hospital with IRB approval. The DBTs were obtained with a GE prototype system which acquired 11 PVs over a 50 deg. arc. The authors reconstructed the DBTs at 1 mm slice interval using a simultaneous algebraic reconstruction technique. The region of interest (ROI) containing the mass was marked by a radiologist in the DBT volume and the corresponding ROIs on the PVs were derived based on the imaging geometry. The subsequent processes were fully automated. For classification of masses using the DBT-slice approach, the mass on each slice was segmented by an active contour model initialized with adaptive k-means clustering. A spiculation likelihood map was generated by analysis of the gradient directions around the mass margin and spiculation features were extracted from the map. The rubber band straightening transform (RBST) was applied to a band of pixels around the segmented mass boundary. The RBST image was enhanced by Sobel filtering in the horizontal and vertical directions, from which run-length statistics texture features were extracted. Morphological features including those from the normalized radial length were designed to describe the mass shape. A feature space composed of the spiculation features, texture features, and morphological features extracted from the central slice alone and seven feature spaces obtained by averaging the corresponding features from three to 19

  5. Polynomial reconstruction of radial catalyst concentration distribution in an experimental type FCC riser for a low number of transversal projections in gamma ray tomography

    International Nuclear Information System (INIS)

    Melo, Silvio B.; Simoes, Francisco P.M.; Oliveira, Eric F. de; Santos, Maria das Gracas dos; Dantas, Carlos C.

    2007-01-01

    In the FCC - Fluid Catalytic Cracking process the Riser is an opaque cylinder, so that, in order to investigate the catalyst concentration inside, a gamma- ray based tomography is employed. Each section is submitted to a parallel beam and by means of the Beer-Lambert transmission is calculated. This tomography session is repeated from different angles, in manual tomographic experiments where the source/detector pair is rotated, producing in each direction what we called a transversal projection. In order to reconstruct the concentration of the present catalyst in a given moment some methods use successfully the inverse Radon transform through the filtered back-projection algorithm. The results are fully satisfactory for a large number of projections, widely seen as better than those produced by the algebraic methods. For a low number of projections, however, the algebraic methods become more competitive. In practice, simple experimental set-ups work with less than 10 projections, due to the time taken by the whole process. In this work, we present an investigation of polynomial reconstructions by using Bezier surfaces of arbitrary degree, adjusted to the experimental data through a least squares method. A computational algorithm was developed to implement the mathematical reconstruction for the 3D graphics presentation. (author)

  6. 3D RECONSTRUCTION AND MODELING OF SUBTERRANEAN LANDSCAPES IN COLLABORATIVE MINING ARCHEOLOGY PROJECTS: TECHNIQUES, APPLICATIONS AND EXPERIENCES

    Directory of Open Access Journals (Sweden)

    A. Arles

    2013-07-01

    Full Text Available Mining and underground archaeology are two domains of expertise where three-dimensional data take an important part in the associated researches. Up to now, archaeologists study mines and underground networks from line-plot surveys, cross-section of galleries, and from tool marks surveys. All this kind of information can be clearly recorded back from the field from threedimensional models with a more cautious and extensive approach. Besides, the volumes of the underground structures that are very important data to explain the mining activities are difficult to evaluate from "traditional" hand-made recordings. They can now be calculated more accurately from a 3D model. Finally, reconstructed scenes are a powerful tool as thinking aid to look back again to a structure in the office or in future times. And the recorded models, rendered photo-realistically, can also be used for cultural heritage documentation presenting inaccessible and sometimes dangerous places to the public. Nowadays, thanks to modern computer technologies and highly developed software tools paired with sophisticated digital camera equipment, complex photogrammetric processes are available for moderate costs for research teams. Recognizing these advantages the authors develop and utilize image-based workflows in order to document ancient mining monuments and underground sites as a basis for further historical and archaeological researches, performed in collaborative partnership during recent projects on medieval silver mines and preventive excavations of undergrounds in France.

  7. A Dynamic Multi-Projection-Contour Approximating Framework for the 3D Reconstruction of Buildings by Super-Generalized Optical Stereo-Pairs.

    Science.gov (United States)

    Yan, Yiming; Su, Nan; Zhao, Chunhui; Wang, Liguo

    2017-09-19

    In this paper, a novel framework of the 3D reconstruction of buildings is proposed, focusing on remote sensing super-generalized stereo-pairs (SGSPs). As we all know, 3D reconstruction cannot be well performed using nonstandard stereo pairs, since reliable stereo matching could not be achieved when the image-pairs are collected at a great difference of views, and we always failed to obtain dense 3D points for regions of buildings, and cannot do further 3D shape reconstruction. We defined SGSPs as two or more optical images collected in less constrained views but covering the same buildings. It is even more difficult to reconstruct the 3D shape of a building by SGSPs using traditional frameworks. As a result, a dynamic multi-projection-contour approximating (DMPCA) framework was introduced for SGSP-based 3D reconstruction. The key idea is that we do an optimization to find a group of parameters of a simulated 3D model and use a binary feature-image that minimizes the total differences between projection-contours of the building in the SGSPs and that in the simulated 3D model. Then, the simulated 3D model, defined by the group of parameters, could approximate the actual 3D shape of the building. Certain parameterized 3D basic-unit-models of typical buildings were designed, and a simulated projection system was established to obtain a simulated projection-contour in different views. Moreover, the artificial bee colony algorithm was employed to solve the optimization. With SGSPs collected by the satellite and our unmanned aerial vehicle, the DMPCA framework was verified by a group of experiments, which demonstrated the reliability and advantages of this work.

  8. Isolation of major phenolics from Launaea spinosa and their protective effect on HepG2 cells damaged with t-BHP.

    Science.gov (United States)

    Abdallah, Hossam; Farag, Mohamed; Osman, Samir; Kim, Da hye; Kang, Kyungsu; Pan, Cheol-Ho; Abdel-Sattar, Essam

    2016-01-01

    Some Launaea species (Asteraceae) are used traditionally to treat liver oxidative stress. The present study investigates the protective effects of isolated compounds from Launaea spinosa Sch. Bip. (Asteraceae) against oxidative stress on t-BHP-induced HepG2 cells. Major phenolic content from flowering aerial parts of L. spinosa was isolated and identified. The protective effects of isolated compounds (10 and 20 μM) against oxidative stress induced by tert-butyl hydroperoxide (t-BHP) in HepG2 cells were investigated through the measurement of aspartate aminotransferase (AST), alanine transaminase (ALT), and superoxide dismutase (SOD) levels. A new phenolic compound identified as 2,3-diferulyl R,R-(+) methyl tartrate (6), in addition to five known metabolites, esculetin (1), esculetin-7-O-d-glucoside (cichoriin) (2), fertaric acid (3), acacetin-7-O-d-glucoside (4), and acacetin-7-O-d-glucuronic acid (5), were isolated. Oxidant-induced damage by 200 μM t-BHP in HepG2 cells was inhibited by compounds 1, 4, and 5 (10 and 20 μM), or quercetin (10 μM; positive control). The protective effects of compounds 1, 4, and 5 were associated with decreasing in AST, ALT, and SOD levels. Compound 4 (20 μM) decreased the AST level from 128.5 ± 13.9 to 7.9 ±1.8 U/mL. Meanwhile, compound 1 (20 μM) decreased ALT activity from 20.3 ± 7.0 to 7.6 ± 2.4 U/mL, while compound 5 decreased SOD levels from 41.6 ± 9.0 to 28.3 ± 3.4 mU/mg. The major phenolic compounds isolated from L. spinosa displayed a significant cytoprotective effect against oxidative stress, leading to maintenance of the normal redox status of the cell.

  9. Transverse Position Reconstruction in a Liquid Argon Time Projection Chamber using Principal Component Analysis and Multi-Dimensional Fitting

    Science.gov (United States)

    Watson, Andrew William

    2017-08-01

    One of the most enduring questions in modern physics is the dark matter problem. Measurements of galactic rotation curves taken in the middle of the twentieth century suggest that there are large spherical halos of unseen matter permeating and surrounding most galaxies, stretching far beyond their visible extents. Although some of this mass discrepancy can be attributed to sources like primordial black holes or Massive Astrophysical Compact Halo Objects (MACHOs), these theories can only explain a small percentage of this "missing matter". One approach which could account for the entirety of this missing mass is the theory of Weakly Interacting Massive Particles, or "WIMPs". As their name suggests, WIMPs interact only through the weak nuclear force and gravity and are quite massive (100 GeV/c2 to 1 TeV/c2). These particles have very small cross sections ( ≈ 10-39 cm2) with nucleons and therefore interact only very rarely with "normal" baryonic matter. To directly detect a dark matter particle, one needs to overcome this small cross-section barrier. In many experiments, this is achieved by utilizing detectors filled with liquid noble elements, which have excellent particle identification capabilities and are very low-background, allowing potential WIMP signals to be more easily distinguished from detector noise. These experiments also often apply uniform electric fields across their liquid volumes, turning the apparatus into Time Projection Chambers or "TPCs". TPCs can accurately determine the location of an interaction in the liquid volume (often simply called an "event") along the direction of the electric field. In DarkSide-50 ("DS-50" for short), the electric field is aligned antiparallel to the z-axis of the detector, and so the depth of an event can be determined to a considerable degree of accuracy by measuring the time between the first and second scintillation signals ("S1" and "S2"), which are generated at the interaction point itself and in a small gas

  10. Virtual patient 3D dose reconstruction using in air EPID measurements and a back-projection algorithm for IMRT and VMAT treatments.

    Science.gov (United States)

    Olaciregui-Ruiz, Igor; Rozendaal, Roel; van Oers, René F M; Mijnheer, Ben; Mans, Anton

    2017-05-01

    At our institute, a transit back-projection algorithm is used clinically to reconstruct in vivo patient and in phantom 3D dose distributions using EPID measurements behind a patient or a polystyrene slab phantom, respectively. In this study, an extension to this algorithm is presented whereby in air EPID measurements are used in combination with CT data to reconstruct 'virtual' 3D dose distributions. By combining virtual and in vivo patient verification data for the same treatment, patient-related errors can be separated from machine, planning and model errors. The virtual back-projection algorithm is described and verified against the transit algorithm with measurements made behind a slab phantom, against dose measurements made with an ionization chamber and with the OCTAVIUS 4D system, as well as against TPS patient data. Virtual and in vivo patient dose verification results are also compared. Virtual dose reconstructions agree within 1% with ionization chamber measurements. The average γ-pass rate values (3% global dose/3mm) in the 3D dose comparison with the OCTAVIUS 4D system and the TPS patient data are 98.5±1.9%(1SD) and 97.1±2.9%(1SD), respectively. For virtual patient dose reconstructions, the differences with the TPS in median dose to the PTV remain within 4%. Virtual patient dose reconstruction makes pre-treatment verification based on deviations of DVH parameters feasible and eliminates the need for phantom positioning and re-planning. Virtual patient dose reconstructions have additional value in the inspection of in vivo deviations, particularly in situations where CBCT data is not available (or not conclusive). Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  11. Lico A Enhances Nrf2-Mediated Defense Mechanisms against t-BHP-Induced Oxidative Stress and Cell Death via Akt and ERK Activation in RAW 264.7 Cells

    Directory of Open Access Journals (Sweden)

    Hongming Lv

    2015-01-01

    Full Text Available Licochalcone A (Lico A exhibits various biological properties, including anti-inflammatory and antioxidant activities. In this study, we investigated the antioxidative potential and mechanisms of Lico A against tert-butyl hydroperoxide- (t-BHP- induced oxidative damage in RAW 264.7 cells. Our results indicated that Lico A significantly inhibited t-BHP-induced cytotoxicity, apoptosis, and reactive oxygen species (ROS generation and reduced glutathione (GSH depletion but increased the glutamate-cysteine ligase modifier (GCLM subunit and the glutamate-cysteine ligase catalytic (GCLC subunit genes expression. Additionally, Lico A dramatically upregulated the antioxidant enzyme heme oxygenase 1 (HO-1 and nuclear factor erythroid 2-related factor 2 (Nrf2, which were associated with inducing Nrf2 nuclear translocation, decreasing Keap1 protein expression and increasing antioxidant response element (ARE promoter activity. Lico A also obviously induced the activation of serine/threonine kinase (Akt and extracellular signal-regulated kinase (ERK, but PI3K/Akt and ERK inhibitors treatment displayed clearly decreased levels of LicoA-induced Nrf2 nuclear translocation and HO-1 expression, respectively. Furthermore, Lico A treatment markedly attenuated t-BHP-induced oxidative damage, which was reduced by treatment with PI3K/Akt, ERK, and HO-1 inhibitors. Therefore, Lico A might have a protective role against t-BHP-induced cytotoxicity by modulating HO-1 and by scavenging ROS via the activation of the PI3K/Akt and ERK/Nrf2 signaling pathways.

  12. The Tragedy of the Krenak People for the Death of the Doce / Uatu River, in the Disaster Of Samarco / Vale / BHP, Brazil

    Directory of Open Access Journals (Sweden)

    Thiago Henrique Fiorott

    2017-09-01

    Full Text Available In 2015, Brazil witnessed the biggest environmental disaster of its history - the rupture of the Samarco / Vale / BHP mining dam in Mariana-MG. The impacts of this tragedy have brought environmental, social, and economic damages, among others. One of the most exploited peoples was the Krenak - whose lands are located on the banks of the river, which they call Uatu (Rio Grande / Rio Doce. The objective of the article is to describe the impacts of the disaster on the sustainability of the Krenak people. It was a qualitative research, case study, which used primary and secondary data. The results demonstrate the death of fish, and other animals, important for a traditional Krenak food safety. As families were left without drinking water, that made impossible social activities, education, health, culture, religion, economy and leisure. In the view of the Krenak people, the major consequence was the death of Uatu, subtracting an important element of their identity, territoriality and sustainability.

  13. Design and implementation of a control system to improve the quality of the combustion gases in the fire-tube boiler of 5 BHP

    Directory of Open Access Journals (Sweden)

    Carlos Alfredo Pérez Albán

    2016-06-01

    Full Text Available The goal of this paper is the design and implementation of a system for controlling the quality of the combustion gases in a fire-tube boiler of 5 BHP. Based on the percentage of O2 present in the combustion gases, measured by a lambda sensor, the percentage of CO2 emitted into the atmosphere is determined. PID proportional control is responsible for the automatic regulation of the entry of air to the boiler by an actuator, according to the percentage of the oxygen concentration in the combustion gases. The control system has an HMI display and a modular PLC. The results achieved ensure pollutant gases emissions within the parameters established by current environmental standards, achieving the required quality of combustion gases and reducing the fuel consumption of the boiler.

  14. WE-EF-207-08: Improve Cone Beam CT Using a Synchronized Moving Grid, An Inter-Projection Sensor Fusion and a Probability Total Variation Reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, H; Kong, V; Jin, J [Georgia Regents University Cancer Center, Augusta, GA (Georgia); Ren, L; Zhang, Y; Giles, W [Duke University Medical Center, Durham, NC (United States)

    2015-06-15

    Purpose: To present a cone beam computed tomography (CBCT) system, which uses a synchronized moving grid (SMOG) to reduce and correct scatter, an inter-projection sensor fusion (IPSF) algorithm to estimate the missing information blocked by the grid, and a probability total variation (pTV) algorithm to reconstruct the CBCT image. Methods: A prototype SMOG-equipped CBCT system was developed, and was used to acquire gridded projections with complimentary grid patterns in two neighboring projections. Scatter was reduced by the grid, and the remaining scatter was corrected by measuring it under the grid. An IPSF algorithm was used to estimate the missing information in a projection from data in its 2 neighboring projections. Feldkamp-Davis-Kress (FDK) algorithm was used to reconstruct the initial CBCT image using projections after IPSF processing for pTV. A probability map was generated depending on the confidence of estimation in IPSF for the regions of missing data and penumbra. pTV was finally used to reconstruct the CBCT image for a Catphan, and was compared to conventional CBCT image without using SMOG, images without using IPSF (SMOG + FDK and SMOG + mask-TV), and image without using pTV (SMOG + IPSF + FDK). Results: The conventional CBCT without using SMOG shows apparent scatter-induced cup artifacts. The approaches with SMOG but without IPSF show severe (SMOG + FDK) or additional (SMOG + TV) artifacts, possibly due to using projections of missing data. The 2 approaches with SMOG + IPSF removes the cup artifacts, and the pTV approach is superior than the FDK by substantially reducing the noise. Using the SMOG also reduces half of the imaging dose. Conclusion: The proposed technique is promising in improving CBCT image quality while reducing imaging dose.

  15. Prediction of optimal deployment projection for transcatheter aortic valve replacement: angiographic 3-dimensional reconstruction of the aortic root versus multidetector computed tomography.

    Science.gov (United States)

    Binder, Ronald K; Leipsic, Jonathon; Wood, David; Moore, Teri; Toggweiler, Stefan; Willson, Alex; Gurvitch, Ronen; Freeman, Melanie; Webb, John G

    2012-04-01

    Identifying the optimal fluoroscopic projection of the aortic valve is important for successful transcatheter aortic valve replacement (TAVR). Various imaging modalities, including multidetector computed tomography (MDCT), have been proposed for prediction of the optimal deployment projection. We evaluated a method that provides 3-dimensional angiographic reconstructions (3DA) of the aortic root for prediction of the optimal deployment angle and compared it with MDCT. Forty patients undergoing transfemoral TAVR at St Paul's Hospital, Vancouver, Canada, were evaluated. All underwent preimplant 3DA and 68% underwent preimplant MDCT. Three-dimensional angiographic reconstructions were generated from images of a C-arm rotational aortic root angiogram during breath-hold, rapid ventricular pacing, and injection of 32 mL contrast medium at 8 mL/s. Two independent operators prospectively predicted perpendicular valve projections. The implant angle was chosen at the discretion of the physician performing TAVR. The angles from 3DA, from MDCT, the implant angle, and the postdeployment perpendicular prosthesis view were compared. The shortest distance from the postdeployment perpendicular prosthesis projection to the regression line of predicted perpendicular projections was calculated. All but 1 patient had adequate image quality for reproducible angle predictions. There was a significant correlation between 3DA and MDCT for prediction of perpendicular valve projections (r=0.682, Pregression line of predicted angles to the postdeployment prosthesis view was 5.1±4.6° for 3DA and 7.9±4.9° for MDCT (P=0.01). Three-dimensional angiographic reconstructions and MDCT are safe, practical, and accurate imaging modalities for identifying the optimal perpendicular valve deployment projection during TAVR.

  16. WE-EF-207-08: Improve Cone Beam CT Using a Synchronized Moving Grid, An Inter-Projection Sensor Fusion and a Probability Total Variation Reconstruction

    International Nuclear Information System (INIS)

    Zhang, H; Kong, V; Jin, J; Ren, L; Zhang, Y; Giles, W

    2015-01-01

    Purpose: To present a cone beam computed tomography (CBCT) system, which uses a synchronized moving grid (SMOG) to reduce and correct scatter, an inter-projection sensor fusion (IPSF) algorithm to estimate the missing information blocked by the grid, and a probability total variation (pTV) algorithm to reconstruct the CBCT image. Methods: A prototype SMOG-equipped CBCT system was developed, and was used to acquire gridded projections with complimentary grid patterns in two neighboring projections. Scatter was reduced by the grid, and the remaining scatter was corrected by measuring it under the grid. An IPSF algorithm was used to estimate the missing information in a projection from data in its 2 neighboring projections. Feldkamp-Davis-Kress (FDK) algorithm was used to reconstruct the initial CBCT image using projections after IPSF processing for pTV. A probability map was generated depending on the confidence of estimation in IPSF for the regions of missing data and penumbra. pTV was finally used to reconstruct the CBCT image for a Catphan, and was compared to conventional CBCT image without using SMOG, images without using IPSF (SMOG + FDK and SMOG + mask-TV), and image without using pTV (SMOG + IPSF + FDK). Results: The conventional CBCT without using SMOG shows apparent scatter-induced cup artifacts. The approaches with SMOG but without IPSF show severe (SMOG + FDK) or additional (SMOG + TV) artifacts, possibly due to using projections of missing data. The 2 approaches with SMOG + IPSF removes the cup artifacts, and the pTV approach is superior than the FDK by substantially reducing the noise. Using the SMOG also reduces half of the imaging dose. Conclusion: The proposed technique is promising in improving CBCT image quality while reducing imaging dose

  17. Influence of different chemical agents (H2O2, t-BHP and MMS) on the activity of antioxidant enzymes in human HepG2 and hamster V79 cells; relationship to cytotoxicity and genotoxicity.

    Science.gov (United States)

    Slamenova, D; Kozics, K; Melusova, M; Horvathova, E

    2015-01-01

    We investigated activities of antioxidant enzymes (AEs), superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) in human HepG2 and hamster V79 cells treated with a scale of concentrations of hydrogen peroxide (H2O2), tert-butyl hydroperoxide (t-BHP) and methyl methanesulfonate (MMS). Cytotoxicity and genotoxicity of these substances were evaluated simultaneously. We have found out that H2O2, t-BHP and MMS predictably induce significant concentration-dependent increase of DNA lesions in both cell lines. Cytotoxicity detected in V79 cells with help of PE test was in a good conformity with the level of DNA damage. MTT test has proved unsuitable, except for MMS-treated V79 cells. Compared with human cells HepG2, hamster cells V79 manifested approximately similar levels of SOD and CAT but ten times higher activity of GPx. Across all concentrations tested the most significant increase of activity of the enzyme CAT was found in H2O2- and t-BHP-treated HepG2 cells, of the enzyme SOD in t-BHP- and MMS-treated V79 cells, and of the enzyme GPx in H2O2-treated V79 cells. We suggest that stimulation of enzyme activity by the relevant chemical compounds may result from transcriptional or post-transcriptional regulation of the expression of the genes CAT, SOD and GPx. Several authors suggest that moderate levels of toxic reactants can induce increase of AEs activities, while very high levels of reactants can induce their decrease, as a consequence of damage of the molecular machinery required to induce AEs. Based on a great amount of experiments, which were done and described within this paper, we can say that the above mentioned principle does not apply in general. Only the reactions of t-BHP affected HepG2 cells were consistent with this idea.

  18. Vascular diameter measurement in CT angiography: comparison of model-based iterative reconstruction and standard filtered back projection algorithms in vitro.

    Science.gov (United States)

    Suzuki, Shigeru; Machida, Haruhiko; Tanaka, Isao; Ueno, Eiko

    2013-03-01

    The purpose of this study was to evaluate the performance of model-based iterative reconstruction (MBIR) in measurement of the inner diameter of models of blood vessels and compare performance between MBIR and a standard filtered back projection (FBP) algorithm. Vascular models with wall thicknesses of 0.5, 1.0, and 1.5 mm were scanned with a 64-MDCT unit and densities of contrast material yielding 275, 396, and 542 HU. Images were reconstructed images by MBIR and FBP, and the mean diameter of each model vessel was measured by software automation. Twenty separate measurements were repeated for each vessel, and variance among the repeated measures was analyzed for determination of measurement error. For all nine model vessels, CT attenuation profiles were compared along a line passing through the luminal center on axial images reconstructed with FBP and MBIR, and the 10-90% edge rise distances at the boundary between the vascular wall and the lumen were evaluated. For images reconstructed with FBP, measurement errors were smallest for models with 1.5-mm wall thickness, except those filled with 275-HU contrast material, and errors grew as the density of the contrast material decreased. Measurement errors with MBIR were comparable to or less than those with FBP. In CT attenuation profiles of images reconstructed with MBIR, the 10-90% edge rise distances at the boundary between the lumen and vascular wall were relatively short for each vascular model compared with those of the profile curves of FBP images. MBIR is better than standard FBP for reducing reconstruction blur and improving the accuracy of diameter measurement at CT angiography.

  19. Complementary frame reconstruction: a low-biased dynamic PET technique for low count density data in projection space

    International Nuclear Information System (INIS)

    Hong, Inki; Cho, Sanghee; Michel, Christian J; Casey, Michael E; Schaefferkoetter, Joshua D

    2014-01-01

    A new data handling method is presented for improving the image noise distribution and reducing bias when reconstructing very short frames from low count dynamic PET acquisition. The new method termed ‘Complementary Frame Reconstruction’ (CFR) involves the indirect formation of a count-limited emission image in a short frame through subtraction of two frames with longer acquisition time, where the short time frame data is excluded from the second long frame data before the reconstruction. This approach can be regarded as an alternative to the AML algorithm recently proposed by Nuyts et al, as a method to reduce the bias for the maximum likelihood expectation maximization (MLEM) reconstruction of count limited data. CFR uses long scan emission data to stabilize the reconstruction and avoids modification of algorithms such as MLEM. The subtraction between two long frame images, naturally allows negative voxel values and significantly reduces bias introduced in the final image. Simulations based on phantom and clinical data were used to evaluate the accuracy of the reconstructed images to represent the true activity distribution. Applicability to determine the arterial input function in human and small animal studies is also explored. In situations with limited count rate, e.g. pediatric applications, gated abdominal, cardiac studies, etc., or when using limited doses of short-lived isotopes such as 15 O-water, the proposed method will likely be preferred over independent frame reconstruction to address bias and noise issues. (paper)

  20. Comparison of the effects of model-based iterative reconstruction and filtered back projection algorithms on software measurements in pulmonary subsolid nodules.

    Science.gov (United States)

    Cohen, Julien G; Kim, Hyungjin; Park, Su Bin; van Ginneken, Bram; Ferretti, Gilbert R; Lee, Chang Hyun; Goo, Jin Mo; Park, Chang Min

    2017-08-01

    To evaluate the differences between filtered back projection (FBP) and model-based iterative reconstruction (MBIR) algorithms on semi-automatic measurements in subsolid nodules (SSNs). Unenhanced CT scans of 73 SSNs obtained using the same protocol and reconstructed with both FBP and MBIR algorithms were evaluated by two radiologists. Diameter, mean attenuation, mass and volume of whole nodules and their solid components were measured. Intra- and interobserver variability and differences between FBP and MBIR were then evaluated using Bland-Altman method and Wilcoxon tests. Longest diameter, volume and mass of nodules and those of their solid components were significantly higher using MBIR (p algorithms with respect to the diameter, volume and mass of nodules and their solid components. There were no significant differences in intra- or interobserver variability between FBP and MBIR (p > 0.05). Semi-automatic measurements of SSNs significantly differed between FBP and MBIR; however, the differences were within the range of measurement variability. • Intra- and interobserver reproducibility of measurements did not differ between FBP and MBIR. • Differences in SSNs' semi-automatic measurement induced by reconstruction algorithms were not clinically significant. • Semi-automatic measurement may be conducted regardless of reconstruction algorithm. • SSNs' semi-automated classification agreement (pure vs. part-solid) did not significantly differ between algorithms.

  1. 3D computed tomography using a microfocus X-ray source: Analysis of artifact formation in the reconstructed images using simulated as well as experimental projection data

    International Nuclear Information System (INIS)

    Krimmel, S.; Stephan, J.; Baumann, J.

    2005-01-01

    The scope of this contribution is to identify and to quantify the influence of different parameters on the formation of image artifacts in X-ray computed tomography (CT) resulting for example, from beam hardening or from partial lack of information using 3D cone beam CT. In general, the reconstructed image quality depends on a number of acquisition parameters concerning the X-ray source (e.g. X-ray spectrum), the geometrical setup (e.g. cone beam angle), the sample properties (e.g. absorption characteristics) and the detector properties. While it is difficult to distinguish the influence of different effects clearly in experimental projection data, they can be selected individually with the help of simulated projection data by varying the parameter set. The reconstruction of the 3D data set is performed with the filtered back projection algorithm according to Feldkamp, Davis and Kress for experimental as well as for simulated projection data. The experimental data are recorded with an industrial microfocus CT system which features a focal spot size of a few micrometers and uses a digital flat panel detector for data acquisition

  2. Comparison of iterative model, hybrid iterative, and filtered back projection reconstruction techniques in low-dose brain CT: impact of thin-slice imaging

    Energy Technology Data Exchange (ETDEWEB)

    Nakaura, Takeshi; Iyama, Yuji; Kidoh, Masafumi; Yokoyama, Koichi [Amakusa Medical Center, Diagnostic Radiology, Amakusa, Kumamoto (Japan); Kumamoto University, Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto (Japan); Oda, Seitaro; Yamashita, Yasuyuki [Kumamoto University, Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto (Japan); Tokuyasu, Shinichi [Philips Electronics, Kumamoto (Japan); Harada, Kazunori [Amakusa Medical Center, Department of Surgery, Kumamoto (Japan)

    2016-03-15

    The purpose of this study was to evaluate the utility of iterative model reconstruction (IMR) in brain CT especially with thin-slice images. This prospective study received institutional review board approval, and prior informed consent to participate was obtained from all patients. We enrolled 34 patients who underwent brain CT and reconstructed axial images with filtered back projection (FBP), hybrid iterative reconstruction (HIR) and IMR with 1 and 5 mm slice thicknesses. The CT number, image noise, contrast, and contrast noise ratio (CNR) between the thalamus and internal capsule, and the rate of increase of image noise in 1 and 5 mm thickness images between the reconstruction methods, were assessed. Two independent radiologists assessed image contrast, image noise, image sharpness, and overall image quality on a 4-point scale. The CNRs in 1 and 5 mm slice thickness were significantly higher with IMR (1.2 ± 0.6 and 2.2 ± 0.8, respectively) than with FBP (0.4 ± 0.3 and 1.0 ± 0.4, respectively) and HIR (0.5 ± 0.3 and 1.2 ± 0.4, respectively) (p < 0.01). The mean rate of increasing noise from 5 to 1 mm thickness images was significantly lower with IMR (1.7 ± 0.3) than with FBP (2.3 ± 0.3) and HIR (2.3 ± 0.4) (p < 0.01). There were no significant differences in qualitative analysis of unfamiliar image texture between the reconstruction techniques. IMR offers significant noise reduction and higher contrast and CNR in brain CT, especially for thin-slice images, when compared to FBP and HIR. (orig.)

  3. The use of 3D contrast-enhanced CT reconstructions to project images of vascular rings and coarctation of the aorta.

    Science.gov (United States)

    Di Sessa, Thomas G; Di Sessa, Peter; Gregory, Bill; Vranicar, Mark

    2009-01-01

    Aortic arch and pulmonary artery anomalies make up a group of vascular structures that have complex three-dimensional (3D) shapes. Tortuosity as well as hypoplasia or atresia of segments of the aortic arch or pulmonary artery makes the conventional two-dimensional (2D) imaging difficult. Nine patients with native coarctation or recoarctation and 4 patients with a vascular ring had a CT scan as a part of their clinical evaluation. There were 7 males. The mean age was 11.7 years. (range 19 days to 29 years) The mean weight was 22.7 kg (range 3.3-139.0 kg). The dicom data from contrast CT scans were converted by the Amira software package into a 3D image. The areas of interest were selected. The images were then projected in 3D on a standard video monitor and could be rotated 360 degrees in any dimension. Adequate CT scans and 3D reconstructions were obtained in 12 of 13 patients. There were 85-1,044 slices obtained in the adequate studies. We could not reconstruct a 3D image from a patient's CT scan that had only 22 slices. The anatomy defined by 3D was compared to 2D CT imaging and confirmed by cardiac catheterization or direct visualization in the operating room in the 12 patients with adequate 3D reconstructions. In 5 of 12 patients, 3D reconstructions provided valuable spatial information not observed in the conventional 2D scans. We believe that 3D reconstruction of contrast-enhanced CT scans of these complex structures provides additional valuable information that is helpful in the decision-making process.

  4. Literature and data review for the surface-water pathway: Columbia River and adjacent coastal areas. Hanford Environmental Dose Reconstruction Project

    Energy Technology Data Exchange (ETDEWEB)

    Walters, W.H.; Dirkes, R.L.; Napier, B.A.

    1992-11-01

    As part of the Hanford Environmental Dose Reconstruction (HEDR) Project, Battelle, Pacific Northwest Laboratories reviewed literature and data on radionuclide concentrations and distribution in the water, sediment, and biota of the Columbia River and adjacent coastal areas. Over 600 documents were reviewed including Hanford reports, reports by offsite agencies, journal articles, and graduate theses. Radionuclide concentration data were used in preliminary estimates of individual dose for the period 1964 through 1966. This report summarizes the literature and database reviews and the results of the preliminary dose estimates.

  5. Projections onto Convex Sets Super-Resolution Reconstruction Based on Point Spread Function Estimation of Low-Resolution Remote Sensing Images

    Directory of Open Access Journals (Sweden)

    Chong Fan

    2017-02-01

    Full Text Available To solve the problem on inaccuracy when estimating the point spread function (PSF of the ideal original image in traditional projection onto convex set (POCS super-resolution (SR reconstruction, this paper presents an improved POCS SR algorithm based on PSF estimation of low-resolution (LR remote sensing images. The proposed algorithm can improve the spatial resolution of the image and benefit agricultural crop visual interpolation. The PSF of the highresolution (HR image is unknown in reality. Therefore, analysis of the relationship between the PSF of the HR image and the PSF of the LR image is important to estimate the PSF of the HR image by using multiple LR images. In this study, the linear relationship between the PSFs of the HR and LR images can be proven. In addition, the novel slant knife-edge method is employed, which can improve the accuracy of the PSF estimation of LR images. Finally, the proposed method is applied to reconstruct airborne digital sensor 40 (ADS40 three-line array images and the overlapped areas of two adjacent GF-2 images by embedding the estimated PSF of the HR image to the original POCS SR algorithm. Experimental results show that the proposed method yields higher quality of reconstructed images than that produced by the blind SR method and the bicubic interpolation method.

  6. Summer Student Project Report. Parallelization of the path reconstruction algorithm for the inner detector of the ATLAS experiment.

    CERN Document Server

    Maldonado Puente, Bryan Patricio

    2014-01-01

    The inner detector of the ATLAS experiment has two types of silicon detectors used for tracking: Pixel Detector and SCT (semiconductor tracker). Once a proton-proton collision occurs, the result- ing particles pass through these detectors and these are recorded as hits on the detector surfaces. A medium to high energy particle passes through seven different surfaces of the two detectors, leaving seven hits, while lower energy particles can leave many more hits as they circle through the detector. For a typical event during the expected operational conditions, there are 30 000 hits in average recorded by the sensors. Only high energy particles are of interest for physics analysis and are taken into account for the path reconstruction; thus, a filtering process helps to discard the low energy particles produced in the collision. The following report presents a solution for increasing the speed of the filtering process in the path reconstruction algorithm.

  7. 3D reconstruction of coronary arteries from 2D angiographic projections using non-uniform rational basis splines (NURBS for accurate modelling of coronary stenoses.

    Directory of Open Access Journals (Sweden)

    Francesca Galassi

    Full Text Available Assessment of coronary stenosis severity is crucial in clinical practice. This study proposes a novel method to generate 3D models of stenotic coronary arteries, directly from 2D coronary images, and suitable for immediate assessment of the stenosis severity.From multiple 2D X-ray coronary arteriogram projections, 2D vessels were extracted. A 3D centreline was reconstructed as intersection of surfaces from corresponding branches. Next, 3D luminal contours were generated in a two-step process: first, a Non-Uniform Rational B-Spline (NURBS circular contour was designed and, second, its control points were adjusted to interpolate computed 3D boundary points. Finally, a 3D surface was generated as an interpolation across the control points of the contours and used in the analysis of the severity of a lesion. To evaluate the method, we compared 3D reconstructed lesions with Optical Coherence Tomography (OCT, an invasive imaging modality that enables high-resolution endoluminal visualization of lesion anatomy.Validation was performed on routine clinical data. Analysis of paired cross-sectional area discrepancies indicated that the proposed method more closely represented OCT contours than conventional approaches in luminal surface reconstruction, with overall root-mean-square errors ranging from 0.213mm2 to 1.013mm2, and maximum error of 1.837mm2. Comparison of volume reduction due to a lesion with corresponding FFR measurement suggests that the method may help in estimating the physiological significance of a lesion.The algorithm accurately reconstructed 3D models of lesioned arteries and enabled quantitative assessment of stenoses. The proposed method has the potential to allow immediate analysis of the stenoses in clinical practice, thereby providing incremental diagnostic and prognostic information to guide treatments in real time and without the need for invasive techniques.

  8. Renal Cyst Pseudoenhancement: Intraindividual Comparison Between Virtual Monochromatic Spectral Images and Conventional Polychromatic 120-kVp Images Obtained During the Same CT Examination and Comparisons Among Images Reconstructed Using Filtered Back Projection, Adaptive Statistical Iterative Reconstruction, and Model-Based Iterative Reconstruction

    Science.gov (United States)

    Yamada, Yoshitake; Yamada, Minoru; Sugisawa, Koichi; Akita, Hirotaka; Shiomi, Eisuke; Abe, Takayuki; Okuda, Shigeo; Jinzaki, Masahiro

    2015-01-01

    Abstract The purpose of this study was to compare renal cyst pseudoenhancement between virtual monochromatic spectral (VMS) and conventional polychromatic 120-kVp images obtained during the same abdominal computed tomography (CT) examination and among images reconstructed using filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), and model-based iterative reconstruction (MBIR). Our institutional review board approved this prospective study; each participant provided written informed consent. Thirty-one patients (19 men, 12 women; age range, 59–85 years; mean age, 73.2 ± 5.5 years) with renal cysts underwent unenhanced 120-kVp CT followed by sequential fast kVp-switching dual-energy (80/140 kVp) and 120-kVp abdominal enhanced CT in the nephrographic phase over a 10-cm scan length with a random acquisition order and 4.5-second intervals. Fifty-one renal cysts (maximal diameter, 18.0 ± 14.7 mm [range, 4–61 mm]) were identified. The CT attenuation values of the cysts as well as of the kidneys were measured on the unenhanced images, enhanced VMS images (at 70 keV) reconstructed using FBP and ASIR from dual-energy data, and enhanced 120-kVp images reconstructed using FBP, ASIR, and MBIR. The results were analyzed using the mixed-effects model and paired t test with Bonferroni correction. The attenuation increases (pseudoenhancement) of the renal cysts on the VMS images reconstructed using FBP/ASIR (least square mean, 5.0/6.0 Hounsfield units [HU]; 95% confidence interval, 2.6–7.4/3.6–8.4 HU) were significantly lower than those on the conventional 120-kVp images reconstructed using FBP/ASIR/MBIR (least square mean, 12.1/12.8/11.8 HU; 95% confidence interval, 9.8–14.5/10.4–15.1/9.4–14.2 HU) (all P < .001); on the other hand, the CT attenuation values of the kidneys on the VMS images were comparable to those on the 120-kVp images. Regardless of the reconstruction algorithm, 70-keV VMS images showed

  9. A research project with students of Information and Communication Technology in obligatory secondary education: virtual reconstruction of the thermal area of the roman villa of Balazote (Albacete

    Directory of Open Access Journals (Sweden)

    Pilar Mediano Serrano

    2016-10-01

    Full Text Available The optional subject Information and Communication Technology (ICT in obligatory secondary education is fundamentally about how to use applications. The software related to this subject is based on: photo editing programs, 3D constructions, sound editing and video editing. These can be viewed in isolation and independently or as a part of a comprehensive project in which students have to handle all of them at once. This article will explain a project with students: the virtual reconstruction of the thermal area of the roman villa of Balazote (Albacete. The goal was to improve student motivation and get actively involved in their learning process. Students used computers and classes of the course to conduct such research. First, the necessary information was sought, and then, based on that information and using different software about virtual reconstruction and recording and editing films: Gimp, SketchUP, Movie Maker, etc., our film was made. The result of this work is a film consisting of a virtual tour inside the roman villa.

  10. Total Variation-Based Reduction of Streak Artifacts, Ring Artifacts and Noise in 3D Reconstruction from Optical Projection Tomography

    Czech Academy of Sciences Publication Activity Database

    Michálek, Jan

    2015-01-01

    Roč. 21, č. 6 (2015), s. 1602-1615 ISSN 1431-9276 R&D Projects: GA MŠk(CZ) LH13028; GA ČR(CZ) GA13-12412S Institutional support: RVO:67985823 Keywords : optical projection tomography * microscopy * artifacts * total variation * data mismatch Subject RIV: EA - Cell Biology Impact factor: 1.730, year: 2015

  11. Parameters used in the environmental pathways (DESCARTES) and radiological dose (CIDER) modules of the Hanford Environmental Dose Reconstruction Integrated Codes (HEDRIC) for the air pathway. Hanford Environmental Dose Reconstruction Project

    Energy Technology Data Exchange (ETDEWEB)

    Snyder, S.F.; Farris, W.T.; Napier, B.A.; Ikenberry, T.A.; Gilbert, R.O.

    1992-09-01

    This letter report is a description of work performed for the Hanford Environmental Dose Reconstruction (HEDR) Project. The HEDR Project was established to estimate the radiation doses to individuals resulting from releases of radionuclides from the Hanford Site since 1944. This work is being done by staff at Battelle, Pacific Northwest Laboratories (Battelle) under a contract with the Centers for Disease Control (CDC) with technical direction provided by an independent Technical Steering Panel (TSP). The objective of this report is to-document the environmental accumulation and dose-assessment parameters that will be used to estimate the impacts of past Hanford Site airborne releases. During 1993, dose estimates made by staff at Battelle will be used by the Fred Hutchinson Cancer Research Center as part of the Hanford Thyroid Disease Study (HTDS). This document contains information on parameters that are specific to the airborne release of the radionuclide iodine-131. Future versions of this document will include parameter information pertinent to other pathways and radionuclides.

  12. Clinical evaluation of image quality and radiation dose reduction in upper abdominal computed tomography using model-based iterative reconstruction; comparison with filtered back projection and adaptive statistical iterative reconstruction

    International Nuclear Information System (INIS)

    Nakamoto, Atsushi; Kim, Tonsok; Hori, Masatoshi; Onishi, Hiromitsu; Tsuboyama, Takahiro; Sakane, Makoto; Tatsumi, Mitsuaki; Tomiyama, Noriyuki

    2015-01-01

    Highlights: • MBIR significantly improves objective image quality. • MBIR reduces the radiation dose by 87.5% without increasing objective image noise. • A half dose will be needed to maintain the subjective image quality. - Abstract: Purpose: To evaluate the image quality of upper abdominal CT images reconstructed with model-based iterative reconstruction (MBIR) in comparison with filtered back projection (FBP) and adaptive statistical iterative reconstruction (ASIR) on scans acquired with various radiation exposure dose protocols. Materials and methods: This prospective study was approved by our institutional review board, and informed consent was obtained from all 90 patients who underwent both control-dose (CD) and reduced-dose (RD) CT of the upper abdomen (unenhanced: n = 45, contrast-enhanced: n = 45). The RD scan protocol was randomly selected from three protocols; Protocol A: 12.5% dose, Protocol B: 25% dose, Protocol C: 50% dose. Objective image noise, signal-to-noise (SNR) ratio for the liver parenchyma, visual image score and lesion conspicuity were compared among CD images of FBP and RD images of FBP, ASIR and MBIR. Results: RD images of MBIR yielded significantly lower objective image noise and higher SNR compared with RD images of FBP and ASIR for all protocols (P < .01) and CD images of FBP for Protocol C (P < .05). Although the subjective image quality of RD images of MBIR was almost acceptable for Protocol C, it was inferior to that of CD images of FBP for Protocols A and B (P < .0083). The conspicuity of the small lesions in RD images of MBIR tended to be superior to that in RD images of FBP and ASIR and inferior to that in CD images for Protocols A and B, although the differences were not significant (P > .0083). Conclusion: Although 12.5%-dose MBIR images (mean size-specific dose estimates [SSDE] of 1.13 mGy) yielded objective image noise and SNR comparable to CD-FBP images, at least a 50% dose (mean SSDE of 4.63 mGy) would be needed to

  13. Clinical evaluation of image quality and radiation dose reduction in upper abdominal computed tomography using model-based iterative reconstruction; comparison with filtered back projection and adaptive statistical iterative reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Nakamoto, Atsushi, E-mail: a-nakamoto@radiol.med.osaka-u.ac.jp; Kim, Tonsok, E-mail: kim@radiol.med.osaka-u.ac.jp; Hori, Masatoshi, E-mail: mhori@radiol.med.osaka-u.ac.jp; Onishi, Hiromitsu, E-mail: h-onishi@radiol.med.osaka-u.ac.jp; Tsuboyama, Takahiro, E-mail: t-tsuboyama@radiol.med.osaka-u.ac.jp; Sakane, Makoto, E-mail: m-sakane@radiol.med.osaka-u.ac.jp; Tatsumi, Mitsuaki, E-mail: m-tatsumi@radiol.med.osaka-u.ac.jp; Tomiyama, Noriyuki, E-mail: tomiyama@radiol.med.osaka-u.ac.jp

    2015-09-15

    Highlights: • MBIR significantly improves objective image quality. • MBIR reduces the radiation dose by 87.5% without increasing objective image noise. • A half dose will be needed to maintain the subjective image quality. - Abstract: Purpose: To evaluate the image quality of upper abdominal CT images reconstructed with model-based iterative reconstruction (MBIR) in comparison with filtered back projection (FBP) and adaptive statistical iterative reconstruction (ASIR) on scans acquired with various radiation exposure dose protocols. Materials and methods: This prospective study was approved by our institutional review board, and informed consent was obtained from all 90 patients who underwent both control-dose (CD) and reduced-dose (RD) CT of the upper abdomen (unenhanced: n = 45, contrast-enhanced: n = 45). The RD scan protocol was randomly selected from three protocols; Protocol A: 12.5% dose, Protocol B: 25% dose, Protocol C: 50% dose. Objective image noise, signal-to-noise (SNR) ratio for the liver parenchyma, visual image score and lesion conspicuity were compared among CD images of FBP and RD images of FBP, ASIR and MBIR. Results: RD images of MBIR yielded significantly lower objective image noise and higher SNR compared with RD images of FBP and ASIR for all protocols (P < .01) and CD images of FBP for Protocol C (P < .05). Although the subjective image quality of RD images of MBIR was almost acceptable for Protocol C, it was inferior to that of CD images of FBP for Protocols A and B (P < .0083). The conspicuity of the small lesions in RD images of MBIR tended to be superior to that in RD images of FBP and ASIR and inferior to that in CD images for Protocols A and B, although the differences were not significant (P > .0083). Conclusion: Although 12.5%-dose MBIR images (mean size-specific dose estimates [SSDE] of 1.13 mGy) yielded objective image noise and SNR comparable to CD-FBP images, at least a 50% dose (mean SSDE of 4.63 mGy) would be needed to

  14. Image quality and radiation dose of low dose coronary CT angiography in obese patients: Sinogram affirmed iterative reconstruction versus filtered back projection

    International Nuclear Information System (INIS)

    Wang, Rui; Schoepf, U. Joseph; Wu, Runze; Reddy, Ryan P.; Zhang, Chuanchen; Yu, Wei; Liu, Yi; Zhang, Zhaoqi

    2012-01-01

    Purpose: To investigate the image quality and radiation dose of low radiation dose CT coronary angiography (CTCA) using sinogram affirmed iterative reconstruction (SAFIRE) compared with standard dose CTCA using filtered back-projection (FBP) in obese patients. Materials and methods: Seventy-eight consecutive obese patients were randomized into two groups and scanned using a prospectively ECG-triggered step-and-shot (SAS) CTCA protocol on a dual-source CT scanner. Thirty-nine patients (protocol A) were examined using a routine radiation dose protocol at 120 kV and images were reconstructed with FBP (protocol A). Thirty-nine patients (protocol B) were examined using a low dose protocol at 100 kV and images were reconstructed with SAFIRE. Two blinded observers independently assessed the image quality of each coronary segment using a 4-point scale (1 = non-diagnostic, 4 = excellent) and measured the objective parameters image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). Radiation dose was calculated. Results: The coronary artery image quality scores, image noise, SNR and CNR were not significantly different between protocols A and B (all p > 0.05), with image quality scores of 3.51 ± 0.70 versus 3.55 ± 0.47, respectively. The effective radiation dose was significantly lower in protocol B (4.41 ± 0.83 mSv) than that in protocol A (8.83 ± 1.74 mSv, p < 0.01). Conclusion: Compared with standard dose CTCA using FBP, low dose CTCA using SAFIRE can maintain diagnostic image quality with 50% reduction of radiation dose.

  15. Measurement of vascular wall attenuation: Comparison of CT angiography using model-based iterative reconstruction with standard filtered back-projection algorithm CT in vitro

    International Nuclear Information System (INIS)

    Suzuki, Shigeru; Machida, Haruhiko; Tanaka, Isao; Ueno, Eiko

    2012-01-01

    Objectives: To compare the performance of model-based iterative reconstruction (MBIR) with that of standard filtered back projection (FBP) for measuring vascular wall attenuation. Study design: After subjecting 9 vascular models (actual attenuation value of wall, 89 HU) with wall thickness of 0.5, 1.0, or 1.5 mm that we filled with contrast material of 275, 396, or 542 HU to scanning using 64-detector computed tomography (CT), we reconstructed images using MBIR and FBP (Bone, Detail kernels) and measured wall attenuation at the center of the wall for each model. We performed attenuation measurements for each model and additional supportive measurements by a differentiation curve. We analyzed statistics using analyzes of variance with repeated measures. Results: Using the Bone kernel, standard deviation of the measurement exceeded 30 HU in most conditions. In measurements at the wall center, the attenuation values obtained using MBIR were comparable to or significantly closer to the actual wall attenuation than those acquired using Detail kernel. Using differentiation curves, we could measure attenuation for models with walls of 1.0- or 1.5-mm thickness using MBIR but only those of 1.5-mm thickness using Detail kernel. We detected no significant differences among the attenuation values of the vascular walls of either thickness (MBIR, P = 0.1606) or among the 3 densities of intravascular contrast material (MBIR, P = 0.8185; Detail kernel, P = 0.0802). Conclusions: Compared with FBP, MBIR reduces both reconstruction blur and image noise simultaneously, facilitates recognition of vascular wall boundaries, and can improve accuracy in measuring wall attenuation.

  16. Measurement of vascular wall attenuation: comparison of CT angiography using model-based iterative reconstruction with standard filtered back-projection algorithm CT in vitro.

    Science.gov (United States)

    Suzuki, Shigeru; Machida, Haruhiko; Tanaka, Isao; Ueno, Eiko

    2012-11-01

    To compare the performance of model-based iterative reconstruction (MBIR) with that of standard filtered back projection (FBP) for measuring vascular wall attenuation. After subjecting 9 vascular models (actual attenuation value of wall, 89 HU) with wall thickness of 0.5, 1.0, or 1.5 mm that we filled with contrast material of 275, 396, or 542 HU to scanning using 64-detector computed tomography (CT), we reconstructed images using MBIR and FBP (Bone, Detail kernels) and measured wall attenuation at the center of the wall for each model. We performed attenuation measurements for each model and additional supportive measurements by a differentiation curve. We analyzed statistics using analyzes of variance with repeated measures. Using the Bone kernel, standard deviation of the measurement exceeded 30 HU in most conditions. In measurements at the wall center, the attenuation values obtained using MBIR were comparable to or significantly closer to the actual wall attenuation than those acquired using Detail kernel. Using differentiation curves, we could measure attenuation for models with walls of 1.0- or 1.5-mm thickness using MBIR but only those of 1.5-mm thickness using Detail kernel. We detected no significant differences among the attenuation values of the vascular walls of either thickness (MBIR, P=0.1606) or among the 3 densities of intravascular contrast material (MBIR, P=0.8185; Detail kernel, P=0.0802). Compared with FBP, MBIR reduces both reconstruction blur and image noise simultaneously, facilitates recognition of vascular wall boundaries, and can improve accuracy in measuring wall attenuation. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  17. Comparison of the effects of model-based iterative reconstruction and filtered back projection algorithms on software measurements in pulmonary subsolid nodules

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Julien G. [Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Seoul National University Medical Research Center, Institute of Radiation Medicine, Seoul (Korea, Republic of); Centre Hospitalier Universitaire de Grenoble, Clinique Universitaire de Radiologie et Imagerie Medicale (CURIM), Universite Grenoble Alpes, Grenoble Cedex 9 (France); Kim, Hyungjin; Park, Su Bin [Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Seoul National University Medical Research Center, Institute of Radiation Medicine, Seoul (Korea, Republic of); Ginneken, Bram van [Radboud University Nijmegen Medical Center, Department of Radiology and Nuclear Medicine, Nijmegen (Netherlands); Ferretti, Gilbert R. [Centre Hospitalier Universitaire de Grenoble, Clinique Universitaire de Radiologie et Imagerie Medicale (CURIM), Universite Grenoble Alpes, Grenoble Cedex 9 (France); Institut A Bonniot, INSERM U 823, La Tronche (France); Lee, Chang Hyun [Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Goo, Jin Mo; Park, Chang Min [Seoul National University College of Medicine, Department of Radiology, Seoul (Korea, Republic of); Seoul National University Medical Research Center, Institute of Radiation Medicine, Seoul (Korea, Republic of); Seoul National University College of Medicine, Cancer Research Institute, Seoul (Korea, Republic of)

    2017-08-15

    To evaluate the differences between filtered back projection (FBP) and model-based iterative reconstruction (MBIR) algorithms on semi-automatic measurements in subsolid nodules (SSNs). Unenhanced CT scans of 73 SSNs obtained using the same protocol and reconstructed with both FBP and MBIR algorithms were evaluated by two radiologists. Diameter, mean attenuation, mass and volume of whole nodules and their solid components were measured. Intra- and interobserver variability and differences between FBP and MBIR were then evaluated using Bland-Altman method and Wilcoxon tests. Longest diameter, volume and mass of nodules and those of their solid components were significantly higher using MBIR (p < 0.05) with mean differences of 1.1% (limits of agreement, -6.4 to 8.5%), 3.2% (-20.9 to 27.3%) and 2.9% (-16.9 to 22.7%) and 3.2% (-20.5 to 27%), 6.3% (-51.9 to 64.6%), 6.6% (-50.1 to 63.3%), respectively. The limits of agreement between FBP and MBIR were within the range of intra- and interobserver variability for both algorithms with respect to the diameter, volume and mass of nodules and their solid components. There were no significant differences in intra- or interobserver variability between FBP and MBIR (p > 0.05). Semi-automatic measurements of SSNs significantly differed between FBP and MBIR; however, the differences were within the range of measurement variability. (orig.)

  18. Local detection of prostate cancer by positron emission tomography with 2-fluorodeoxyglucose comparison of filtered back projection and iterative reconstruction with segmented attenuation correction

    International Nuclear Information System (INIS)

    Turlakow, A.; Larson, S. M.; Coakley, F.; Akhurst, T.; Macapinlac, H. A.; Hricak, H.; Gonen, M.; Kelly, W.; Scher, H.; Leibel, S.; Humm, J.; Scardino, P.

    2001-01-01

    To compare filtered back projection (FBP) and iterative reconstruction with segmented attenuation correction (IRSAC) in the local imaging of prostate cancer by positron emission tomography with 2-fluorodeoxyglucose (FDG-PET). 13 patients with primary (n=7) or recurrent (n=6) prostate cancer who had increased uptake in the prostate on FDG-PET performed without urinary catheterization, contemporaneous biopsy confirming the presence of active tumor in the prostate, were retrospectively identified. Two independent nuclear medicine physicians separately rated FBP and IRSAC images for visualization of prostatic activity on a 4-point scale. Results were compared using biopsy and cross-sectional imaging findings as the standard of reference. IRSAC images were significantly better that FBP in terms of visualization of prostatic activity in 12 of 13 patients, and were equivalent in 1 patient (p<0.001, Wilcoxon signed ranks test). In particular, 2 foci of tumor activity in 2 different patients seen on IRSAC images were not visible on FBP images. In 11 patients who had a gross tumor mass evident on cross-sectional imaging, there was good agreement between PET and cross-sectional anatomic imaging with respect to tumor localization. In selected patients, cancer can be imaged within the prostate using FDG-PET, and IRSAC is superior to FBP in image reconstruction for local tumor visualization

  19. Comparing reconstructed past variations and future projections of the Baltic Sea ecosystem—first results from multi-model ensemble simulations

    DEFF Research Database (Denmark)

    Meier, H E Markus; Andersson, Helén C; Arheimer, Berit

    2012-01-01

    Multi-model ensemble simulations for the marine biogeochemistry and food web of the Baltic Sea were performed for the period 1850–2098, and projected changes in the future climate were compared with the past climate environment. For the past period 1850–2006, atmospheric, hydrological and nutrient...... forcings were reconstructed, based on historical measurements. For the future period 1961–2098, scenario simulations were driven by regionalized global general circulation model (GCM) data and forced by various future greenhouse gas emission and air- and riverborne nutrient load scenarios (ranging from...... a pessimistic ‘business-as-usual’ to the most optimistic case). To estimate uncertainties, different models for the various parts of the Earth system were applied. Assuming the IPCC greenhouse gas emission scenarios A1B or A2, we found that water temperatures at the end of this century may be higher...

  20. Entropy and transverse section reconstruction

    International Nuclear Information System (INIS)

    Gullberg, G.T.

    1976-01-01

    A new approach to the reconstruction of a transverse section using projection data from multiple views incorporates the concept of maximum entropy. The principle of maximizing information entropy embodies the assurance of minimizing bias or prejudice in the reconstruction. Using maximum entropy is a necessary condition for the reconstructed image. This entropy criterion is most appropriate for 3-D reconstruction of objects from projections where the system is underdetermined or the data are limited statistically. This is the case in nuclear medicine time limitations in patient studies do not yield sufficient projections

  1. Tomographic reconstruction of binary fields

    International Nuclear Information System (INIS)

    Roux, Stéphane; Leclerc, Hugo; Hild, François

    2012-01-01

    A novel algorithm is proposed for reconstructing binary images from their projection along a set of different orientations. Based on a nonlinear transformation of the projection data, classical back-projection procedures can be used iteratively to converge to the sought image. A multiscale implementation allows for a faster convergence. The algorithm is tested on images up to 1 Mb definition, and an error free reconstruction is achieved with a very limited number of projection data, saving a factor of about 100 on the number of projections required for classical reconstruction algorithms.

  2. Atmospheric showers reconstruction and air fluorescence measurement for the study of ultra-energetic cosmic rays in the framework of EUSO project

    International Nuclear Information System (INIS)

    Colin, Pierre

    2005-01-01

    The EUSO project (Extreme Universe Space Observatory) is an innovative concept to measure the UHECR (Ultra High Energy Cosmic ray) spectrum by observing from space the light (air fluorescence and Cerenkov radiation) produced in the atmosphere by EAS (Extensive Air Shower). After an overview of the scientific context and an EUSO project description, a reconstruction method of EAS seen from space is presented. This new method enable one to reconstruct the UHECR parameters (Energy, direction, X_m_a_x) using only the fluorescence signal shape (without extra information). This method is very efficient for the horizontal EAS. The second part of this thesis deals with the study and the measurement of the air fluorescence with the MACFLY experiment (Measurement of Air Cerenkov and Fluorescence Light Yield). After a state of the art on the air fluorescence knowledge, a model of FLY (Florescence Light Yield) proportional to the Energy released in air is proposed. The experiment MACFLY and the data analysis method are described in detail. The experiment is composed of two devices. The first (Macfly1) which measures the fluorescence produced by only one particle measure the FLY of electron of 1.5 MeV (radioactive source), 20 GeV and 50 GeV (CERN test beam). The second (Macfly2) which measure the fluorescence produced by an electromagnetic shower, was the first experiment to measure the shower age dependence of the FLY. The pressure dependence was also measured by the two devices. Thanks to a GEANT4 simulation program, we compare our measurements with the FLY models. The assumption of the proportionality between the FLY and the energy deposited has been checked. One finds the same result with Macfly1 and Macfly2. In the air at 950 hPa, 23 deg. C and 0% of moisture one obtains: FLY=19 ± 4 photons/MeV. (author) [fr

  3. Glacial evolution in King George and Livingston Islands (Antarctica) since the Last Glacial Maximum based on cosmogenic nuclide dating and glacier surface reconstruction - CRONOANTAR project

    Science.gov (United States)

    Ruiz Fernández, Jesús; Oliva, Marc; Fernández Menéndez, Susana del Carmen; García Hernández, Cristina; Menéndez Duarte, Rosa Ana; Pellitero Ondicol, Ramón; Pérez Alberti, Augusto; Schimmelpfennig, Irene

    2017-04-01

    CRONOANTAR brings together researchers from Spain, Portugal, France and United Kingdom with the objective of spatially and temporally reconstruct the deglaciation process at the two largest islands in the South Shetlands Archipelago (Maritime Antarctica), since the Global Last Glacial Maximum. Glacier retreat in polar areas has major implications at a local, regional and even planetary scale. Global average sea level rise is the most obvious and socio-economically relevant, but there are others such as the arrival of new fauna to deglaciated areas, plant colonisation or permafrost formation and degradation. This project will study the ice-free areas in Byers and Hurd peninsulas (Livingston Island) and Fildes and Potter peninsulas (King George Island). Ice-cap glacier retreat chronology will be revealed by the use of cosmogenic isotopes (mainly 36Cl) on glacially originated sedimentary and erosive records. Cosmogenic dating will be complemented by other dating methods (C14 and OSL), which will permit the validation of these methods in regions with cold-based glaciers. Given the geomorphological evidences and the obtained ages, a deglaciation calendar will be proposed and we will use a GIS methodology to reconstruct the glacier extent and the ice thickness. The results emerging from this project will allow to assess whether the high glacier retreat rates observed during the last decades were registered in the past, or if they are conversely the consequence (and evidence) of the Global Change in Antarctica. Acknowledgements This work has been funded by the Spanish Ministry of Economy, Industry and Competitiveness (Reference: CTM2016-77878-P).

  4. Quaternary glaciation and hydrologic variation in the South American tropics as reconstructed from the Lake Titicaca drilling project

    Science.gov (United States)

    Fritz, Sherilyn C.; Baker, Paul A.; Seltzer, Geoffrey O.; Ballantyne, Ashley; Tapia, Pedro; Cheng, Hai; Edwards, R. Lawrence

    2007-11-01

    A 136-m-long drill core of sediments was recovered from tropical high-altitude Lake Titicaca, Bolivia-Peru, enabling a reconstruction of past climate that spans four cycles of regional glacial advance and retreat and that is estimated to extend continuously over the last 370,000 yr. Within the errors of the age model, the periods of regional glacial advance and retreat are concordant respectively with global glacial and interglacial stages. Periods of ice advance in the southern tropical Andes generally were periods of positive water balance, as evidenced by deeper and fresher conditions in Lake Titicaca. Conversely, reduced glaciation occurred during periods of negative water balance and shallow closed-basin conditions in the lake. The apparent coincidence of positive water balance of Lake Titicaca and glacial growth in the adjacent Andes with Northern Hemisphere ice sheet expansion implies that regional water balance and glacial mass balance are strongly influenced by global-scale temperature changes, as well as by precessional forcing of the South American summer monsoon.

  5. Changes in Soil Dissolved Organic Carbon Affect Reconstructed History and Projected Future Trends in Surface Water Acidification

    Czech Academy of Sciences Publication Activity Database

    Hruška, Jakub; Krám, Pavel; Moldan, Filip; Oulehle, Filip; Evans, C. D.; Wright, R. F.; Cosby, B. J.; Kopáček, Jiří

    2014-01-01

    Roč. 225, č. 7 (2014), s. 2015 ISSN 0049-6979 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073 Institutional support: RVO:67179843 ; RVO:60077344 Keywords : acidification * surface waters * soils * dissolved organic carbon * magic model * preindustrial water chemistry Subject RIV: EH - Ecology, Behaviour; DA - Hydrology ; Limnology (BC-A) Impact factor: 1.554, year: 2014

  6. Overview of image reconstruction

    International Nuclear Information System (INIS)

    Marr, R.B.

    1980-04-01

    Image reconstruction (or computerized tomography, etc.) is any process whereby a function, f, on R/sup n/ is estimated from empirical data pertaining to its integrals, ∫f(x) dx, for some collection of hyperplanes of dimension k < n. The paper begins with background information on how image reconstruction problems have arisen in practice, and describes some of the application areas of past or current interest; these include radioastronomy, optics, radiology and nuclear medicine, electron microscopy, acoustical imaging, geophysical tomography, nondestructive testing, and NMR zeugmatography. Then the various reconstruction algorithms are discussed in five classes: summation, or simple back-projection; convolution, or filtered back-projection; Fourier and other functional transforms; orthogonal function series expansion; and iterative methods. Certain more technical mathematical aspects of image reconstruction are considered from the standpoint of uniqueness, consistency, and stability of solution. The paper concludes by presenting certain open problems. 73 references

  7. CT imaging of bronchus related to solitary pulmonary lesion: comparison of minimum intensity projection and multi-planar reconstruction

    International Nuclear Information System (INIS)

    Zhou Jun; Shan Fei; Zhang Zhiyong; Yang Shan; Zhang Xingwei; Wu Dong; Zhan Songhua

    2011-01-01

    Objective: To investigate the clinical value of 64-slice computed tomography with MinIP and MPR for imaging the bronchus related to a solitary pulmonary lesion (SPL). Methods: Seventy-five subjects with solitary pulmonary lesions underwent chest 64-slice CT and their bronchi were analyzed retrospectively. All images of thin-section (0.625 mm) were reconstructed with MPR and MinIP into images of 1, 2, 3, and 5 mm thickness and 1 mm gap in two orthogonal planes along the long axis of bronchus related to the SPL. The image quality of four series of MinIP and MPR images was evaluated in the aspect of bronchus visibility and pulmonary vascular masking. One-way ANOVA with Bonferroni correction and interclass correlation coefficient were used in the statistical analysis. Results: (1) The mean scores of display of the bronchi on MinIP images of four series (4.85, 4.77 and 4.84, 4.63 and 4.67, 4.25 and 4.28, in 1, 2, 3, and 5 mm thickness, respectively) and on MPR images of 1 or 2 mm thickness (4.77 and 4.76, 4.04 and 4.27, in 1 and 2 mm thickness, respectively) were good or excellent. MPR images of 1 mm thickness and MinIP images of 1-3 mm thickness showed no significant differences (t=0.318, P> 0.05 for all), but they were superior to MinIP images of 5 mm thickness (t=6.318 and 6.610, P 0.05). (2) The effect of suppression of pulmonary vascular markings on MinIP images was better with the increase of slice thickness (F= 45.312 and 40.415, P<0.01). The mean scores of MinIP images of 3 mm and 5 mm thickness (4.67 and 4.64, 5.00 and 4.97, for 3 and 5 mm thickness, respectively) were good or excellent, but MinIP images of 2 mm thickness were just acceptable. Conclusion: MinIP images of 3 mm thickness may display the bronchus related to SPL more clearly. (authors)

  8. Image Reconstruction. Chapter 13

    Energy Technology Data Exchange (ETDEWEB)

    Nuyts, J. [Department of Nuclear Medicine and Medical Imaging Research Center, Katholieke Universiteit Leuven, Leuven (Belgium); Matej, S. [Medical Image Processing Group, Department of Radiology, University of Pennsylvania, Philadelphia, PA (United States)

    2014-12-15

    This chapter discusses how 2‑D or 3‑D images of tracer distribution can be reconstructed from a series of so-called projection images acquired with a gamma camera or a positron emission tomography (PET) system [13.1]. This is often called an ‘inverse problem’. The reconstruction is the inverse of the acquisition. The reconstruction is called an inverse problem because making software to compute the true tracer distribution from the acquired data turns out to be more difficult than the ‘forward’ direction, i.e. making software to simulate the acquisition. There are basically two approaches to image reconstruction: analytical reconstruction and iterative reconstruction. The analytical approach is based on mathematical inversion, yielding efficient, non-iterative reconstruction algorithms. In the iterative approach, the reconstruction problem is reduced to computing a finite number of image values from a finite number of measurements. That simplification enables the use of iterative instead of mathematical inversion. Iterative inversion tends to require more computer power, but it can cope with more complex (and hopefully more accurate) models of the acquisition process.

  9. [THE RESULTS OF IMPLEMENTATION OF THE INTERNATIONAL BANK FOR RECONSTRUCTION AND DEVELOPMENT LOAN PROJECT "PREVENTION, DIAGNOSIS, AND TREATMENT OF TUBERCULOSIS AND AIDS", A "TUBERCULOSIS" COMPONENT].

    Science.gov (United States)

    2010-01-01

    Due to the implementation of the International Bank for Reconstruction and Development (IBRD) loan project "Prevention, diagnosis, treatment of tuberculosis and AIDS", a "Tuberculosis" component that is an addition to the national tuberculosis control program in 15 subjects of the Russian Federation, followed up by the Central Research Institute of Tuberculosis, Russian Academy of Medical Sciences, the 2005-2008 measures stipulated by the Project have caused substantial changes in the organization of tuberculosis control: implementation of Orders Nos. 109, 50, and 690 and supervision of their implementation; modernization of the laboratories of the general medical network and antituberbulosis service (404 kits have been delivered for clinical diagnostic laboratories and 12 for bacteriological laboratories, including BACTEC 960 that has been provided in 6 areas); 91 training seminars have been held at the federal and regional levels; 1492 medical workers have been trained in the detection, diagnosis, and treatment of patients with tuberculosis; 8 manuals and guidelines have been prepared and sent to all areas. In the period 2005-2008, the tuberculosis morbidity and mortality rates in the followed-up areas reduced by 1.2 and 18.6%, respectively. The analysis of patient cohorts in 2007 and 2005 revealed that the therapeutic efficiency evaluated from sputum smear microscopy increased by 16.3%; there were reductions in the proportion of patients having ineffective chemotherapy (from 16.1 to 11.1%), patients who died from tuberculosis (from 11.6 to 9.9%), and those who interrupted therapy ahead of time (from 11.8 to 7.8%). Implementation of the IBR project has contributed to the improvement of the national strategy and the enhancement of the efficiency of tuberculosis control.

  10. Segmentation-DrivenTomographic Reconstruction

    DEFF Research Database (Denmark)

    Kongskov, Rasmus Dalgas

    such that the segmentation subsequently can be carried out by use of a simple segmentation method, for instance just a thresholding method. We tested the advantages of going from a two-stage reconstruction method to a one stage segmentation-driven reconstruction method for the phase contrast tomography reconstruction......The tomographic reconstruction problem is concerned with creating a model of the interior of an object from some measured data, typically projections of the object. After reconstructing an object it is often desired to segment it, either automatically or manually. For computed tomography (CT...

  11. Comparison of applied dose and image quality in staging CT of neuroendocrine tumor patients using standard filtered back projection and adaptive statistical iterative reconstruction

    International Nuclear Information System (INIS)

    Böning, G.; Schäfer, M.; Grupp, U.; Kaul, D.; Kahn, J.; Pavel, M.; Maurer, M.; Denecke, T.; Hamm, B.; Streitparth, F.

    2015-01-01

    Highlights: • Iterative reconstruction (IR) in staging CT provides equal objective image quality compared to filtered back projection (FBP). • IR delivers excellent subjective quality and reduces effective dose compared to FBP. • In patients with neuroendocrine tumor (NET) or may other hypervascular abdominal tumors IR can be used without scarifying diagnostic confidence. - Abstract: Objective: To investigate whether dose reduction via adaptive statistical iterative reconstruction (ASIR) affects image quality and diagnostic accuracy in neuroendocrine tumor (NET) staging. Methods: A total of 28 NET patients were enrolled in the study. Inclusion criteria were histologically proven NET and visible tumor in abdominal computed tomography (CT). In an intraindividual study design, the patients underwent a baseline CT (filtered back projection, FBP) and follow-up CT (ASIR 40%) using matched scan parameters. Image quality was assessed subjectively using a 5-grade scoring system and objectively by determining signal-to-noise ratio (SNR) and contrast-to-noise ratios (CNRs). Applied volume computed tomography dose index (CTDI vol ) of each scan was taken from the dose report. Results: ASIR 40% significantly reduced CTDI vol (10.17 ± 3.06 mGy [FBP], 6.34 ± 2.25 mGy [ASIR] (p < 0.001) by 37.6% and significantly increased CNRs (complete tumor-to-liver, 2.76 ± 1.87 [FBP], 3.2 ± 2.32 [ASIR]) (p < 0.05) (complete tumor-to-muscle, 2.74 ± 2.67 [FBP], 4.31 ± 4.61 [ASIR]) (p < 0.05) compared to FBP. Subjective scoring revealed no significant changes for diagnostic confidence (5.0 ± 0 [FBP], 5.0 ± 0 [ASIR]), visibility of suspicious lesion (4.8 ± 0.5 [FBP], 4.8 ± 0.5 [ASIR]) and artifacts (5.0 ± 0 [FBP], 5.0 ± 0 [ASIR]). ASIR 40% significantly decreased scores for noise (4.3 ± 0.6 [FBP], 4.0 ± 0.8 [ASIR]) (p < 0.05), contrast (4.4 ± 0.6 [FBP], 4.1 ± 0.8 [ASIR]) (p < 0.001) and visibility of small structures (4.5 ± 0.7 [FBP], 4.3 ± 0.8 [ASIR]) (p < 0

  12. Comparison of applied dose and image quality in staging CT of neuroendocrine tumor patients using standard filtered back projection and adaptive statistical iterative reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Böning, G., E-mail: georg.boening@charite.de [Department of Radiology, Charité, Humboldt-University Medical School, Charitéplatz 1, 10117 Berlin (Germany); Schäfer, M.; Grupp, U. [Department of Radiology, Charité, Humboldt-University Medical School, Charitéplatz 1, 10117 Berlin (Germany); Kaul, D. [Department of Radiation Oncology, Charité, Humboldt-University Medical School, Charitéplatz 1, 10117 Berlin (Germany); Kahn, J. [Department of Radiology, Charité, Humboldt-University Medical School, Charitéplatz 1, 10117 Berlin (Germany); Pavel, M. [Department of Gastroenterology, Charité, Humboldt-University Medical School, Charitéplatz 1, 10117 Berlin (Germany); Maurer, M.; Denecke, T.; Hamm, B.; Streitparth, F. [Department of Radiology, Charité, Humboldt-University Medical School, Charitéplatz 1, 10117 Berlin (Germany)

    2015-08-15

    Highlights: • Iterative reconstruction (IR) in staging CT provides equal objective image quality compared to filtered back projection (FBP). • IR delivers excellent subjective quality and reduces effective dose compared to FBP. • In patients with neuroendocrine tumor (NET) or may other hypervascular abdominal tumors IR can be used without scarifying diagnostic confidence. - Abstract: Objective: To investigate whether dose reduction via adaptive statistical iterative reconstruction (ASIR) affects image quality and diagnostic accuracy in neuroendocrine tumor (NET) staging. Methods: A total of 28 NET patients were enrolled in the study. Inclusion criteria were histologically proven NET and visible tumor in abdominal computed tomography (CT). In an intraindividual study design, the patients underwent a baseline CT (filtered back projection, FBP) and follow-up CT (ASIR 40%) using matched scan parameters. Image quality was assessed subjectively using a 5-grade scoring system and objectively by determining signal-to-noise ratio (SNR) and contrast-to-noise ratios (CNRs). Applied volume computed tomography dose index (CTDI{sub vol}) of each scan was taken from the dose report. Results: ASIR 40% significantly reduced CTDI{sub vol} (10.17 ± 3.06 mGy [FBP], 6.34 ± 2.25 mGy [ASIR] (p < 0.001) by 37.6% and significantly increased CNRs (complete tumor-to-liver, 2.76 ± 1.87 [FBP], 3.2 ± 2.32 [ASIR]) (p < 0.05) (complete tumor-to-muscle, 2.74 ± 2.67 [FBP], 4.31 ± 4.61 [ASIR]) (p < 0.05) compared to FBP. Subjective scoring revealed no significant changes for diagnostic confidence (5.0 ± 0 [FBP], 5.0 ± 0 [ASIR]), visibility of suspicious lesion (4.8 ± 0.5 [FBP], 4.8 ± 0.5 [ASIR]) and artifacts (5.0 ± 0 [FBP], 5.0 ± 0 [ASIR]). ASIR 40% significantly decreased scores for noise (4.3 ± 0.6 [FBP], 4.0 ± 0.8 [ASIR]) (p < 0.05), contrast (4.4 ± 0.6 [FBP], 4.1 ± 0.8 [ASIR]) (p < 0.001) and visibility of small structures (4.5 ± 0.7 [FBP], 4.3 ± 0.8 [ASIR]) (p < 0

  13. ICDP project DeepCHALLA: reconstructing East African climate change and environmental history over the past 250,000 years

    Science.gov (United States)

    Verschuren, Dirk; Van Daele, Maarten; Wolff, Christian; Waldmann, Nicolas; Meyer, Inka; Ombori, Titus; Peterse, Francien; O'Grady, Ryan; Schnurrenberger, Doug; Olago, Daniel

    2017-04-01

    Sediments on the bottom of Lake Challa, a 92-meter deep crater lake on the border of Kenya and Tanzania near Mt. Kilimanjaro, contain a uniquely long and continuous record of past climate and environmental change. The near-equatorial location and exceptional quality of this natural archive provide great opportunities to study tropical climate variability at both short (inter-annual to decadal) and long (glacial-interglacial) time scales; and the influence of this climate variability on the region's freshwater resources, the functioning of terrestrial ecosystems, and the history of the East African landscape in which modern humans (our species, Homo sapiens) evolved and have lived ever since. Supported in part by the International Continental Scientific Drilling Programme (ICDP), the DeepCHALLA project has now recovered the sediment record of Lake Challa down to 214.8 meter below the lake floor, with almost certain 100% cover of the uppermost 121.3 meter (ca.150,000 year BP to present) and estimated 85% cover over the lower part of the sequence, down to the lowermost distinct reflector in the available seismic stratigraphy. This reflector represents a 2 meter thick layer of volcanic sand and silt deposited ca.250,000 years ago, and overlies still older silty lacustrine clays deposited during early lake development. Down-hole logging produced continuous profiles of in-situ sediment composition that confer an absolute depth scale to both the recovered cores and their three-dimensional representation in seismic stratigraphy. As readily observed through the transparent core liners, Lake Challa sediments are finely laminated throughout most of the recovered sequence. Combined with the great time span, the exquisite temporal resolution of these sediments promises to greatly increase our understanding of tropical climate and ecosystem dynamics, and create a long-awaited equatorial counterpart to the high-latitude climate records extracted from the ice sheets of Greenland

  14. Radioactive contamination of fish, shellfish, and waterfowl exposed to Hanford effluents: Annual summaries, 1945--1972. Hanford Environmental Dose Reconstruction Project

    Energy Technology Data Exchange (ETDEWEB)

    Hanf, R.W.; Dirkes, R.L.; Duncan, J.P.

    1992-07-01

    The objective of the Hanford Environmental Dose Reconstruction Project (HEDR) is to estimate the potential radiation doses received by people living within the sphere of influence of the Hanford Site. A potential critical pathway for human radiation exposure is through the consumption of waterfowl that frequent onsite waste-water ponds or through eating of fish, shellfish, and waterfowl that reside in/on the Columbia River and its tributaries downstream of the reactors. This document summarizes information on fish, shellfish, and waterfowl radiation contamination for samples collected by Hanford monitoring personnel and offsite agencies for the period 1945 to 1972. Specific information includes the types of organisms sampled, the kinds of tissues and organs analyzed, the sampling locations, and the radionuclides reported. Some tissue concentrations are also included. We anticipate that these yearly summaries will be helpful to individuals and organizations interested in evaluating aquatic pathway information for locations impacted by Hanford operations and will be useful for planning the direction of future HEDR studies.

  15. Classification of cryo electron microscopy images, noisy tomographic images recorded with unknown projection directions, by simultaneously estimating reconstructions and application to an assembly mutant of Cowpea Chlorotic Mottle Virus and portals of the bacteriophage P22

    Science.gov (United States)

    Lee, Junghoon; Zheng, Yili; Yin, Zhye; Doerschuk, Peter C.; Johnson, John E.

    2010-08-01

    Cryo electron microscopy is frequently used on biological specimens that show a mixture of different types of object. Because the electron beam rapidly destroys the specimen, the beam current is minimized which leads to noisy images (SNR substantially less than 1) and only one projection image per object (with an unknown projection direction) is collected. For situations where the objects can reasonably be described as coming from a finite set of classes, an approach based on joint maximum likelihood estimation of the reconstruction of each class and then use of the reconstructions to label the class of each image is described and demonstrated on two challenging problems: an assembly mutant of Cowpea Chlorotic Mottle Virus and portals of the bacteriophage P22.

  16. Comparing reconstructed past variations and future projections of the Baltic Sea ecosystem—first results from multi-model ensemble simulations

    International Nuclear Information System (INIS)

    Meier, H E Markus; Andersson, Helén C; Arheimer, Berit; Donnelly, Chantal; Eilola, Kari; Höglund, Anders; Kuznetsov, Ivan; Blenckner, Thorsten; Gustafsson, Bo G; Müller-Karulis, Bärbel; Niiranen, Susa; Chubarenko, Boris; Hansson, Anders; Havenhand, Jonathan; MacKenzie, Brian R; Neumann, Thomas; Piwowarczyk, Joanna; Raudsepp, Urmas; Reckermann, Marcus; Ruoho-Airola, Tuija

    2012-01-01

    Multi-model ensemble simulations for the marine biogeochemistry and food web of the Baltic Sea were performed for the period 1850–2098, and projected changes in the future climate were compared with the past climate environment. For the past period 1850–2006, atmospheric, hydrological and nutrient forcings were reconstructed, based on historical measurements. For the future period 1961–2098, scenario simulations were driven by regionalized global general circulation model (GCM) data and forced by various future greenhouse gas emission and air- and riverborne nutrient load scenarios (ranging from a pessimistic ‘business-as-usual’ to the most optimistic case). To estimate uncertainties, different models for the various parts of the Earth system were applied. Assuming the IPCC greenhouse gas emission scenarios A1B or A2, we found that water temperatures at the end of this century may be higher and salinities and oxygen concentrations may be lower than ever measured since 1850. There is also a tendency of increased eutrophication in the future, depending on the nutrient load scenario. Although cod biomass is mainly controlled by fishing mortality, climate change together with eutrophication may result in a biomass decline during the latter part of this century, even when combined with lower fishing pressure. Despite considerable shortcomings of state-of-the-art models, this study suggests that the future Baltic Sea ecosystem may unprecedentedly change compared to the past 150 yr. As stakeholders today pay only little attention to adaptation and mitigation strategies, more information is needed to raise public awareness of the possible impacts of climate change on marine ecosystems. (letter)

  17. Dose reduction in chest CT: Comparison of the adaptive iterative dose reduction 3D, adaptive iterative dose reduction, and filtered back projection reconstruction techniques

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Yoshitake, E-mail: yamada@rad.med.keio.ac.jp [Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582 (Japan); Jinzaki, Masahiro, E-mail: jinzaki@rad.med.keio.ac.jp [Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582 (Japan); Hosokawa, Takahiro, E-mail: hosokawa@rad.med.keio.ac.jp [Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582 (Japan); Tanami, Yutaka, E-mail: tanami@rad.med.keio.ac.jp [Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582 (Japan); Sugiura, Hiroaki, E-mail: hsugiura@rad.med.keio.ac.jp [Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582 (Japan); Abe, Takayuki, E-mail: tabe@z5.keio.jp [Center for Clinical Research, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582 (Japan); Kuribayashi, Sachio, E-mail: skuribay@a5.keio.jp [Department of Diagnostic Radiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582 (Japan)

    2012-12-15

    Objectives: To assess the effectiveness of adaptive iterative dose reduction (AIDR) and AIDR 3D in improving the image quality in low-dose chest CT (LDCT). Materials and methods: Fifty patients underwent standard-dose chest CT (SDCT) and LDCT simultaneously, performed under automatic exposure control with noise index of 19 and 38 (for a 2-mm slice thickness), respectively. The SDCT images were reconstructed with filtered back projection (SDCT-FBP images), and the LDCT images with FBP, AIDR and AIDR 3D (LDCT-FBP, LDCT-AIDR and LDCT-AIDR 3D images, respectively). On all the 200 lung and 200 mediastinal image series, objective image noise and signal-to-noise ratio (SNR) were measured in several regions, and two blinded radiologists independently assessed the subjective image quality. Wilcoxon's signed rank sum test with Bonferroni's correction was used for the statistical analyses. Results: The mean dose reduction in LDCT was 64.2% as compared with the dose in SDCT. LDCT-AIDR 3D images showed significantly reduced objective noise and significantly increased SNR in all regions as compared to the SDCT-FBP, LDCT-FBP and LDCT-AIDR images (all, P ≤ 0.003). In all assessments of the image quality, LDCT-AIDR 3D images were superior to LDCT-AIDR and LDCT-FBP images. The overall diagnostic acceptability of both the lung and mediastinal LDCT-AIDR 3D images was comparable to that of the lung and mediastinal SDCT-FBP images. Conclusions: AIDR 3D is superior to AIDR. Intra-individual comparisons between SDCT and LDCT suggest that AIDR 3D allows a 64.2% reduction of the radiation dose as compared to SDCT, by substantially reducing the objective image noise and increasing the SNR, while maintaining the overall diagnostic acceptability.

  18. Myocardial perfusion magnetic resonance imaging using sliding-window conjugate-gradient highly constrained back-projection reconstruction for detection of coronary artery disease.

    Science.gov (United States)

    Ma, Heng; Yang, Jun; Liu, Jing; Ge, Lan; An, Jing; Tang, Qing; Li, Han; Zhang, Yu; Chen, David; Wang, Yong; Liu, Jiabin; Liang, Zhigang; Lin, Kai; Jin, Lixin; Bi, Xiaoming; Li, Kuncheng; Li, Debiao

    2012-04-15

    Myocardial perfusion magnetic resonance imaging (MRI) with sliding-window conjugate-gradient highly constrained back-projection reconstruction (SW-CG-HYPR) allows whole left ventricular coverage, improved temporal and spatial resolution and signal/noise ratio, and reduced cardiac motion-related image artifacts. The accuracy of this technique for detecting coronary artery disease (CAD) has not been determined in a large number of patients. We prospectively evaluated the diagnostic performance of myocardial perfusion MRI with SW-CG-HYPR in patients with suspected CAD. A total of 50 consecutive patients who were scheduled for coronary angiography with suspected CAD underwent myocardial perfusion MRI with SW-CG-HYPR at 3.0 T. The perfusion defects were interpreted qualitatively by 2 blinded observers and were correlated with x-ray angiographic stenoses ≥50%. The prevalence of CAD was 56%. In the per-patient analysis, the sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of SW-CG-HYPR was 96% (95% confidence interval 82% to 100%), 82% (95% confidence interval 60% to 95%), 87% (95% confidence interval 70% to 96%), 95% (95% confidence interval 74% to100%), and 90% (95% confidence interval 82% to 98%), respectively. In the per-vessel analysis, the corresponding values were 98% (95% confidence interval 91% to 100%), 89% (95% confidence interval 80% to 94%), 86% (95% confidence interval 76% to 93%), 99% (95% confidence interval 93% to 100%), and 93% (95% confidence interval 89% to 97%), respectively. In conclusion, myocardial perfusion MRI using SW-CG-HYPR allows whole left ventricular coverage and high resolution and has high diagnostic accuracy in patients with suspected CAD. Copyright © 2012 Elsevier Inc. All rights reserved.

  19. Comparison of applied dose and image quality in staging CT of neuroendocrine tumor patients using standard filtered back projection and adaptive statistical iterative reconstruction.

    Science.gov (United States)

    Böning, G; Schäfer, M; Grupp, U; Kaul, D; Kahn, J; Pavel, M; Maurer, M; Denecke, T; Hamm, B; Streitparth, F

    2015-08-01

    To investigate whether dose reduction via adaptive statistical iterative reconstruction (ASIR) affects image quality and diagnostic accuracy in neuroendocrine tumor (NET) staging. A total of 28 NET patients were enrolled in the study. Inclusion criteria were histologically proven NET and visible tumor in abdominal computed tomography (CT). In an intraindividual study design, the patients underwent a baseline CT (filtered back projection, FBP) and follow-up CT (ASIR 40%) using matched scan parameters. Image quality was assessed subjectively using a 5-grade scoring system and objectively by determining signal-to-noise ratio (SNR) and contrast-to-noise ratios (CNRs). Applied volume computed tomography dose index (CTDIvol) of each scan was taken from the dose report. ASIR 40% significantly reduced CTDIvol (10.17±3.06mGy [FBP], 6.34±2.25mGy [ASIR] (pASIR]) (pASIR]) (pASIR]), visibility of suspicious lesion (4.8±0.5 [FBP], 4.8±0.5 [ASIR]) and artifacts (5.0±0 [FBP], 5.0±0 [ASIR]). ASIR 40% significantly decreased scores for noise (4.3±0.6 [FBP], 4.0±0.8 [ASIR]) (pASIR]) (pASIR]) (pASIR can be used to reduce radiation dose without sacrificing image quality and diagnostic confidence in staging CT of NET patients. This may be beneficial for patients with frequent follow-up and significant cumulative radiation exposure. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  20. Climate Reconstructions

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Paleoclimatology Program archives reconstructions of past climatic conditions derived from paleoclimate proxies, in addition to the Program's large holdings...

  1. Projectables

    DEFF Research Database (Denmark)

    Rasmussen, Troels A.; Merritt, Timothy R.

    2017-01-01

    CNC cutting machines have become essential tools for designers and architects enabling rapid prototyping, model-building and production of high quality components. Designers often cut from new materials, discarding the irregularly shaped remains. We introduce ProjecTables, a visual augmented...... reality system for interactive packing of model parts onto sheet materials. ProjecTables enables designers to (re)use scrap materials for CNC cutting that would have been previously thrown away, at the same time supporting aesthetic choices related to wood grain, avoiding surface blemishes, and other...... relevant material properties. We conducted evaluations of ProjecTables with design students from Aarhus School of Architecture, demonstrating that participants could quickly and easily place and orient model parts reducing material waste. Contextual interviews and ideation sessions led to a deeper...

  2. Impact of hybrid iterative reconstruction on Agatston coronary artery calcium scores in comparison to filtered back projection in native cardiac CT; Einfluss der hybriden iterativen Rekonstruktion bei der nativen CT des Herzens auf die Agatston-Kalziumscores der Koronararterien

    Energy Technology Data Exchange (ETDEWEB)

    Obmann, V.C.; Heverhagen, J.T. [Inselspital - University Hospital Bern (Switzerland). University Inst. for Diagnostic, Interventional and Pediatric Radiology; Klink, T. [Wuerzburg Univ. (Germany). Inst. of Diagnostic and Interventional Radiology; Stork, A.; Begemann, P.G.C. [Roentgeninstitut Duesseldorf, Duesseldorf (Germany); Laqmani, A.; Adam, G. [University Medical Center Hamburg-Eppendorf, Hamburg (Germany). Dept. of Diagnostic and Interventional Radiology

    2015-05-15

    To investigate whether the effects of hybrid iterative reconstruction (HIR) on coronary artery calcium (CAC) measurements using the Agatston score lead to changes in assignment of patients to cardiovascular risk groups compared to filtered back projection (FBP). 68 patients (mean age 61.5 years; 48 male; 20 female) underwent prospectively ECG-gated, non-enhanced, cardiac 256-MSCT for coronary calcium scoring. Scanning parameters were as follows: Tube voltage, 120 kV; Mean tube current time-product 63.67 mAs (50 - 150 mAs); collimation, 2 x 128 x 0.625 mm. Images were reconstructed with FBP and with HIR at all levels (L1 to L7). Two independent readers measured Agatston scores of all reconstructions and assigned patients to cardiovascular risk groups. Scores of HIR and FBP reconstructions were correlated (Spearman). Interobserver agreement and variability was assessed with k-statistics and Bland-Altmann-Plots. Agatston scores of HIR reconstructions were closely correlated with FBP reconstructions (L1, R = 0.9996; L2, R = 0.9995; L3, R = 0.9991; L4, R = 0.986; L5, R = 0.9986; L6, R = 0.9987; and L7, R = 0.9986). In comparison to FBP, HIR led to reduced Agatston scores between 97% (L1) and 87.4% (L7) of the FBP values. Using HIR iterations L1-L3, all patients were assigned to identical risk groups as after FPB reconstruction. In 5.4% of patients the risk group after HIR with the maximum iteration level was different from the group after FBP reconstruction. There was an excellent correlation of Agatston scores after HIR and FBP with identical risk group assignment at levels 1 - 3 for all patients. Hence it appears that the application of HIR in routine calcium scoring does not entail any disadvantages. Thus, future studies are needed to demonstrate whether HIR is a reliable method for reducing radiation dose in coronary calcium scoring.

  3. Vaginal reconstruction

    International Nuclear Information System (INIS)

    Lesavoy, M.A.

    1985-01-01

    Vaginal reconstruction can be an uncomplicated and straightforward procedure when attention to detail is maintained. The Abbe-McIndoe procedure of lining the neovaginal canal with split-thickness skin grafts has become standard. The use of the inflatable Heyer-Schulte vaginal stent provides comfort to the patient and ease to the surgeon in maintaining approximation of the skin graft. For large vaginal and perineal defects, myocutaneous flaps such as the gracilis island have been extremely useful for correction of radiation-damaged tissue of the perineum or for the reconstruction of large ablative defects. Minimal morbidity and scarring ensue because the donor site can be closed primarily. With all vaginal reconstruction, a compliant patient is a necessity. The patient must wear a vaginal obturator for a minimum of 3 to 6 months postoperatively and is encouraged to use intercourse as an excellent obturator. In general, vaginal reconstruction can be an extremely gratifying procedure for both the functional and emotional well-being of patients

  4. ACL Reconstruction

    Science.gov (United States)

    ... in moderate exercise and recreational activities, or play sports that put less stress on the knees. ACL reconstruction is generally recommended if: You're an athlete and want to continue in your sport, especially if the sport involves jumping, cutting or ...

  5. DNA Protecting Activities of Nymphaea nouchali (Burm. f Flower Extract Attenuate t-BHP-Induced Oxidative Stress Cell Death through Nrf2-Mediated Induction of Heme Oxygenase-1 Expression by Activating MAP-Kinases

    Directory of Open Access Journals (Sweden)

    Md Badrul Alam

    2017-09-01

    Full Text Available This study was performed to investigate the antioxidant activities of Nymphaea nouchali flower (NNF extract and the underlying mechanism using RAW 264.7 cells. The presence of gallic acid, catechin, epicatechin, epigallocatechin, epicatechin gallate, caffeic acid, quercetin, and apigenin in the NNF was confirmed by high-performance liquid chromatography (HPLC. The extract had a very potent capacity to scavenge numerous free radicals. NNF extract was also able to prevent DNA damage and quench cellular reactive oxygen species (ROS generation induced by tert-Butyl hydroperoxide (t-BHP with no signs of toxicity. The NNF extract was able to augment the expression of both primary and phase II detoxifying enzyme, resulting in combat the oxidative stress. This is accomplished by phosphorylation of mitogen-activated protein kinase (MAP kinase (p38 kinase and extracellular signal-regulated kinase (ERK followed by enhancing the nuclear translocation of the nuclear factor erythroid 2-related factor 2 (Nrf2. This attenuates cellular ROS generation and confers protection from cell death. Altogether, the results of current study revealed that Nymphaea nouchali flower could be a source of natural phytochemicals that could lead to the development of new therapeutic agents for preventing oxidative stress associated diseases and attenuating disease progression.

  6. Iterative reconstruction technique vs filter back projection: utility for quantitative bronchial assessment on low-dose thin-section MDCT in patients with/without chronic obstructive pulmonary disease

    Energy Technology Data Exchange (ETDEWEB)

    Koyama, Hisanobu; Seki, Shinichiro; Sugimura, Kazuro [Kobe University Graduate School of Medicine, Division of Radiology, Department of Radiology, Kobe, Hyogo (Japan); Ohno, Yoshiharu; Nishio, Mizuho; Matsumoto, Sumiaki; Yoshikawa, Takeshi [Kobe University Graduate School of Medicine, Advanced Biomedical Imaging Research Centre, Kobe (Japan); Kobe University Graduate School of Medicine, Division of Functional and Diagnostic Imaging Research, Department of Radiology, Kobe (Japan); Sugihara, Naoki [Toshiba Medical Systems Corporation, Ohtawara, Tochigi (Japan)

    2014-08-15

    The aim of this study was to evaluate the utility of the iterative reconstruction (IR) technique for quantitative bronchial assessment during low-dose computed tomography (CT) as a substitute for standard-dose CT in patients with/without chronic obstructive pulmonary disease. Fifty patients (mean age, 69.2; mean % predicted FEV1, 79.4) underwent standard-dose CT (150mAs) and low-dose CT (25mAs). Except for tube current, the imaging parameters were identical for both protocols. Standard-dose CT was reconstructed using filtered back-projection (FBP), and low-dose CT was reconstructed using IR and FBP. For quantitative bronchial assessment, the wall area percentage (WA%) of the sub-segmental bronchi and the airway luminal volume percentage (LV%) from the main bronchus to the peripheral bronchi were acquired in each dataset. The correlation and agreement of WA% and LV% between standard-dose CT and both low-dose CTs were statistically evaluated. WA% and LV% between standard-dose CT and both low-dose CTs were significant correlated (r > 0.77, p < 0.00001); however, only the LV% agreement between SD-CT and low-dose CT reconstructed with IR was moderate (concordance correlation coefficient = 0.93); the other agreement was poor (concordance correlation coefficient <0.90). Quantitative bronchial assessment via low-dose CT has potential as a substitute for standard-dose CT by using IR and airway luminal volumetry techniques. circle Quantitative bronchial assessment of COPD using low-dose CT is possible. (orig.)

  7. Maxillary reconstruction

    Directory of Open Access Journals (Sweden)

    Brown James

    2007-12-01

    Full Text Available This article aims to discuss the various defects that occur with maxillectomy with a full review of the literature and discussion of the advantages and disadvantages of the various techniques described. Reconstruction of the maxilla can be relatively simple for the standard low maxillectomy that does not involve the orbital floor (Class 2. In this situation the structure of the face is less damaged and the there are multiple reconstructive options for the restoration of the maxilla and dental alveolus. If the maxillectomy includes the orbit (Class 4 then problems involving the eye (enopthalmos, orbital dystopia, ectropion and diplopia are avoided which simplifies the reconstruction. Most controversy is associated with the maxillectomy that involves the orbital floor and dental alveolus (Class 3. A case is made for the use of the iliac crest with internal oblique as an ideal option but there are other methods, which may provide a similar result. A multidisciplinary approach to these patients is emphasised which should include a prosthodontist with a special expertise for these defects.

  8. Jini service to reconstruct tomographic data

    Science.gov (United States)

    Knoll, Peter; Mirzaei, S.; Koriska, K.; Koehn, H.

    2002-06-01

    A number of imaging systems rely on the reconstruction of a 3- dimensional model from its projections through the process of computed tomography (CT). In medical imaging, for example magnetic resonance imaging (MRI), positron emission tomography (PET), and Single Computer Tomography (SPECT) acquire two-dimensional projections of a three dimensional projections of a three dimensional object. In order to calculate the 3-dimensional representation of the object, i.e. its voxel distribution, several reconstruction algorithms have been developed. Currently, mainly two reconstruct use: the filtered back projection(FBP) and iterative methods. Although the quality of iterative reconstructed SPECT slices is better than that of FBP slices, such iterative algorithms are rarely used for clinical routine studies because of their low availability and increased reconstruction time. We used Jini and a self-developed iterative reconstructions algorithm to design and implement a Jini reconstruction service. With this service, the physician selects the patient study from a database and a Jini client automatically discovers the registered Jini reconstruction services in the department's Intranet. After downloading the proxy object the this Jini service, the SPECT acquisition data are reconstructed. The resulting transaxial slices are visualized using a Jini slice viewer, which can be used for various imaging modalities.

  9. Fast Tomographic Reconstruction From Limited Data Using Artificial Neural Networks

    NARCIS (Netherlands)

    D.M. Pelt (Daniël); K.J. Batenburg (Joost)

    2013-01-01

    htmlabstractImage reconstruction from a small number of projections is a challenging problem in tomography. Advanced algorithms that incorporate prior knowledge can sometimes produce accurate reconstructions, but they typically require long computation times. Furthermore, the required prior

  10. Dosimetric comparison of different dose prescription systems with CT based intracavitary brachytherapy and manual back projection technique to reconstruct the applicator

    International Nuclear Information System (INIS)

    Oinam, A.S.; Dubey, S.; Kehwar, T.S.; Rout, Sanjaya K.; Patel, F.D.; Sharma, S.C.; Goyal, D.R.; Narayan, P.

    2002-01-01

    Intracavitary brachytherapy is one of the well-established techniques for the treatment of carcinoma of cervix. The prediction of late effect of normal tissue like rectum and bladder needs the defining of the volume of the bladder and rectum in situ. In the normal planning of intracavitary and interstitial implants, simulated radiograph films are used to reconstruct the applicator geometry and dose points to represent the dose to critical organs. CT based brachytherapy can define such volume instead of defining dose points, which represent the dose to these critical organs

  11. MO-G-17A-07: Improved Image Quality in Brain F-18 FDG PET Using Penalized-Likelihood Image Reconstruction Via a Generalized Preconditioned Alternating Projection Algorithm: The First Patient Results

    Energy Technology Data Exchange (ETDEWEB)

    Schmidtlein, CR; Beattie, B; Humm, J [Memorial Sloan Kettering Cancer Center, New York, NY (United States); Li, S; Wu, Z; Xu, Y [Sun Yat-sen University, Guangzhou, Guangdong (China); Zhang, J; Shen, L [Syracuse University, Syracuse, NY (United States); Vogelsang, L [VirtualScopics, Rochester, NY (United States); Feiglin, D; Krol, A [SUNY Upstate Medical University, Syracuse, NY (United States)

    2014-06-15

    Purpose: To investigate the performance of a new penalized-likelihood PET image reconstruction algorithm using the 1{sub 1}-norm total-variation (TV) sum of the 1st through 4th-order gradients as the penalty. Simulated and brain patient data sets were analyzed. Methods: This work represents an extension of the preconditioned alternating projection algorithm (PAPA) for emission-computed tomography. In this new generalized algorithm (GPAPA), the penalty term is expanded to allow multiple components, in this case the sum of the 1st to 4th order gradients, to reduce artificial piece-wise constant regions (“staircase” artifacts typical for TV) seen in PAPA images penalized with only the 1st order gradient. Simulated data were used to test for “staircase” artifacts and to optimize the penalty hyper-parameter in the root-mean-squared error (RMSE) sense. Patient FDG brain scans were acquired on a GE D690 PET/CT (370 MBq at 1-hour post-injection for 10 minutes) in time-of-flight mode and in all cases were reconstructed using resolution recovery projectors. GPAPA images were compared PAPA and RMSE-optimally filtered OSEM (fully converged) in simulations and to clinical OSEM reconstructions (3 iterations, 32 subsets) with 2.6 mm XYGaussian and standard 3-point axial smoothing post-filters. Results: The results from the simulated data show a significant reduction in the 'staircase' artifact for GPAPA compared to PAPA and lower RMSE (up to 35%) compared to optimally filtered OSEM. A simple power-law relationship between the RMSE-optimal hyper-parameters and the noise equivalent counts (NEC) per voxel is revealed. Qualitatively, the patient images appear much sharper and with less noise than standard clinical images. The convergence rate is similar to OSEM. Conclusions: GPAPA reconstructions using the 1{sub 1}-norm total-variation sum of the 1st through 4th-order gradients as the penalty show great promise for the improvement of image quality over that

  12. MO-G-17A-07: Improved Image Quality in Brain F-18 FDG PET Using Penalized-Likelihood Image Reconstruction Via a Generalized Preconditioned Alternating Projection Algorithm: The First Patient Results

    International Nuclear Information System (INIS)

    Schmidtlein, CR; Beattie, B; Humm, J; Li, S; Wu, Z; Xu, Y; Zhang, J; Shen, L; Vogelsang, L; Feiglin, D; Krol, A

    2014-01-01

    Purpose: To investigate the performance of a new penalized-likelihood PET image reconstruction algorithm using the 1 1 -norm total-variation (TV) sum of the 1st through 4th-order gradients as the penalty. Simulated and brain patient data sets were analyzed. Methods: This work represents an extension of the preconditioned alternating projection algorithm (PAPA) for emission-computed tomography. In this new generalized algorithm (GPAPA), the penalty term is expanded to allow multiple components, in this case the sum of the 1st to 4th order gradients, to reduce artificial piece-wise constant regions (“staircase” artifacts typical for TV) seen in PAPA images penalized with only the 1st order gradient. Simulated data were used to test for “staircase” artifacts and to optimize the penalty hyper-parameter in the root-mean-squared error (RMSE) sense. Patient FDG brain scans were acquired on a GE D690 PET/CT (370 MBq at 1-hour post-injection for 10 minutes) in time-of-flight mode and in all cases were reconstructed using resolution recovery projectors. GPAPA images were compared PAPA and RMSE-optimally filtered OSEM (fully converged) in simulations and to clinical OSEM reconstructions (3 iterations, 32 subsets) with 2.6 mm XYGaussian and standard 3-point axial smoothing post-filters. Results: The results from the simulated data show a significant reduction in the 'staircase' artifact for GPAPA compared to PAPA and lower RMSE (up to 35%) compared to optimally filtered OSEM. A simple power-law relationship between the RMSE-optimal hyper-parameters and the noise equivalent counts (NEC) per voxel is revealed. Qualitatively, the patient images appear much sharper and with less noise than standard clinical images. The convergence rate is similar to OSEM. Conclusions: GPAPA reconstructions using the 1 1 -norm total-variation sum of the 1st through 4th-order gradients as the penalty show great promise for the improvement of image quality over that currently

  13. Road Construction Safety Audit for Interstate Reconstruction. Volume 1.

    Science.gov (United States)

    1998-10-01

    Traffic control alternatives associated with reconstruction projects on a rural interstate have been investigated in this research. Slab replacement projects, milling/resurfacing projects, and traffic controls in the vicinity of interstate ramps were...

  14. Road Construction Safety Audit for Interstate Reconstruction. Volume 2.

    Science.gov (United States)

    1998-10-01

    Traffic control alternatives associated with reconstruction projects on a rural interstate have been investigated in this research. Slab replacement projects, milling/resurfacing projects, and traffic controls in the vicinity of interstate ramps were...

  15. Algorithms for reconstructing images for industrial applications

    International Nuclear Information System (INIS)

    Lopes, R.T.; Crispim, V.R.

    1986-01-01

    Several algorithms for reconstructing objects from their projections are being studied in our Laboratory, for industrial applications. Such algorithms are useful locating the position and shape of different composition of materials in the object. A Comparative study of two algorithms is made. The two investigated algorithsm are: The MART (Multiplicative - Algebraic Reconstruction Technique) and the Convolution Method. The comparison are carried out from the point view of the quality of the image reconstructed, number of views and cost. (Author) [pt

  16. Minerals and energy: major development projects - April 2006 listing

    Energy Technology Data Exchange (ETDEWEB)

    William Mollard [Australian Bureau of Agricultural and Resource Economics (ABARE), Canberra, ACT (Australia)

    2006-06-15

    ABARE's project list, released around May and November each year, lists completed and committed projects in the minerals and energy sector in Australia. Santos' $200 million Casino gas field project in Bass Strait will produce natural gas and condensate while output from Berwyndale South will be coal seam methane. Five coal projects were completed in the six months to April 2006. The largest of these was Xstrata's Newlands Northern underground mine. In the same region, BMA's (BHP Billiton Mitsubishi Alliance) $102 million Broadmeadow underground mine and BHP/Mitsui Coal's $50 million Poitrel opencut mine, both near Moranbah, were brought into production. In New South Wales, two projects a new mine and a mine infrastructure development, both near Singletonwere commissioned. Xstrata's new Ravensworth West opencut mine will produce up to 1.5 million tonnes a year of thermal coal. Excel Coal's $73 million Wambo Rail project involved building a rail loop and loading facilities at its Wambo operation. Queensland coal mine projects and coal infrastructure developments account for 19 per cent (or $6.3 billion) of the estimated capital cost of $34 billion for all advanced projects. The largest coal mine development is the $1 billion Dawson mine expansion which is expected to add around 12 million tonnes of coking and thermal coal capacity, commencing in early 2007. Anglo Coal/Mitsui is also developing the large new Lake Lindsay opencut mine. Rio Tinto is developing its $440 million Clermont opencut mine. Twelve other advanced coal mine developments in Queensland are expected to raise coal production capacity by around 30 million tonnes a year by 2008. 10 figs., 4 tabs.

  17. Establishment of a cohort for the long-term clinical follow-up with dose reconstruction under the joint medical research project conducted by Sasakawa Memorial Health Foundation (Japan) and the Research Institute of Radiation Hygiene (Russia)

    International Nuclear Information System (INIS)

    Konstantinov, Y.O.; Bruk, G.Y.; Ershov, E.B.

    2000-01-01

    The cohort of children in the western districts of the Bryansk Region of Russia exposed to radiation following the Chernobyl accident is described in this paper. The cohort was selected under the Joint Medical Research Project on Dosimetry Associated with the Chernobyl Accident conducted by Sasakawa Memorial Health Foundation (SMHF, Japan) and the Research Institute of Radiation Hygiene (RIRH, Russia). The subjects of the Research Project are those people residing in the most contaminated areas of Russia who was 0 to 10 years old at the time of exposure. At the moment the cohort comprises 1210 subjects, though this number may slightly decrease in course of a follow-up in view of migration of population. Most of cohort subjects were examined on their health status within the framework of the Chernobyl Sasakawa Health and Medical Cooperation Project (CSHMCP) from 1991-1996. In view of the main findings of studies in CSHMCP were thyroid abnormalities, selection of subjects was conducted on the basis of the credible estimates of thyroid dose. Preference for subjects to be included into the cohort was defined by the availability of health examination data from previous study (1991-1996) and individual dosimetry, environmental and social data that may prove useful for reconstruction of individual dose. The primary data analyzed for subjects selection are measurements of iodine-131 in the thyroid in May-June 1986, questionnaire data on individual food habits and early measurements of radiocesium in the body of subjects made by RIRH from May to September 1986. Plausible analytical models were applied to calculate thyroid dose from available data. Previously worked out methods of thyroid dose reconstruction using early measurement data of radiocesium content in the body and questionnaire data on individual consumption of locally produced milk were reevaluated. Basing on these analytical procedures, the individual thyroid dose was ascribed to each member of the cohort. The

  18. Comparison of image quality and visibility of normal and abnormal findings at submillisievert chest CT using filtered back projection, iterative model reconstruction (IMR) and iDose{sup 4}™

    Energy Technology Data Exchange (ETDEWEB)

    Laqmani, Azien, E-mail: a.laqmani@uke.de [Department of Diagnostic and Interventional Radiology and Nuclear Medicine, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg (Germany); Avanesov, Maxim; Butscheidt, Sebastian; Kurfürst, Maximilian [Department of Diagnostic and Interventional Radiology and Nuclear Medicine, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg (Germany); Sehner, Susanne [Department of Medical Biometry and Epidemiology, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg (Germany); Schmidt-Holtz, Jakob; Derlin, Thorsten; Behzadi, Cyrus [Department of Diagnostic and Interventional Radiology and Nuclear Medicine, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg (Germany); Nagel, Hans D. [Science & Technology for Radiology, Fritz-Reuter-Weg 5f, 21244 Buchholz, Germany, (Germany); Adam, Gerhard; Regier, Marc [Department of Diagnostic and Interventional Radiology and Nuclear Medicine, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg (Germany)

    2016-11-15

    Objective: To compare both image quality and visibility of normal and abnormal findings at submillisievert chest CT (smSv-CT) using filtered back projection (FBP) and the two different iterative reconstruction (IR) techniques iterative model reconstruction (IMR) and iDose{sup 4}™. Materials and methods: This institutional review board approved study was based on retrospective interpretation of clinically indicated acquired data. The requirement to obtain informed consent was waived. 81 patients with suspected pneumonia underwent smSv-CT (Brilliance iCT, Philips Healthcare; mean effective dose: 0.86 ± 0.2 mSv). Data were reconstructed using FBP and two different IR techniques iDose{sup 4}™ and IMR (Philips Healthcare) at various iteration levels. Objective image noise (OIN) was measured. Two experienced readers independently assessed all images for image noise, image appearance and visibility of normal anatomic and abnormal findings. A random intercept model was used for statistical analysis. Results: Compared to FBP and iDose{sup 4}™, IMR reduced OIN up to 88% and 72%, respectively (p < 0.001). A mild blotchy image appearance was seen in IMR images, affecting diagnostic confidence. iDose{sup 4}™ images provided satisfactory to good image quality for visibility of normal and abnormal findings and were superior to FBP (p < 0.001). IMR images were significantly inferior for visibility of normal structures compared to iDose{sup 4}™, while being superior for visibility of abnormal findings except for reticular pattern (p < 0.001). Conclusion: IMR results for visibility of normal and abnormal lung findings are heterogeneous, indicating that IMR may not represent a priority technique for clinical routine. iDose{sup 4}™ represents a suitable method for evaluation of lung tissue at submillisievert chest CT.

  19. The Algebraic Reconstruction Technique (ART)

    International Nuclear Information System (INIS)

    Raparia, D.; Alessi, J.; Kponou, A.

    1997-01-01

    Projections of charged particle beam current density (profiles) are frequently used as a measure of beam position and size. In conventional practice only two projections, usually horizontal and vertical, are measured. This puts a severe limit on the detail of information that can be achieved. A third projection provides a significant improvement. The Algebraic Reconstruction Technique (ART) uses three or more projections to reconstruct 3-dimensional density profiles. At the 200 MeV H-linac, we have used this technique to measure beam density, and it has proved very helpful, especially in helping determine if there is any coupling present in x-y phase space. We will present examples of measurements of current densities using this technique

  20. Four new bass strait platforms -a project manager's view

    Energy Technology Data Exchange (ETDEWEB)

    Power, J.W.

    1982-05-01

    The offshore development by Esso/BHP of the West Kingfish, Cobia, Fortescue and Flounder oil fields in the Gippsland Basin is one of the significant undertakings by the petroleum industry during the 1980s. Production from the fields will help sustain the current level of production from Bass Strait into the latter part of this decade. This paper examines some of the principal project management issues and actions involved in the planning and execution of the design and construction phases of the platforms and pipelines associated with each of these fields.

  1. Impact of model-based iterative reconstruction on low-contrast lesion detection and image quality in abdominal CT: a 12-reader-based comparative phantom study with filtered back projection at different tube voltages

    Energy Technology Data Exchange (ETDEWEB)

    Euler, Andre; Stieltjes, Bram; Eichenberger, Reto; Reisinger, Clemens; Hirschmann, Anna; Zaehringer, Caroline; Kircher, Achim; Streif, Matthias; Bucher, Sabine; Buergler, David; D' Errico, Luigia; Kopp, Sebastien; Wilhelm, Markus [University Hospital Basel, Clinic of Radiology and Nuclear Medicine, Basel (Switzerland); Szucs-Farkas, Zsolt [Hospital Centre of Biel, Institute of Radiology, Biel (Switzerland); Schindera, Sebastian T. [University Hospital Basel, Clinic of Radiology and Nuclear Medicine, Basel (Switzerland); Cantonal Hospital Aarau, Institute of Radiology, Aarau (Switzerland)

    2017-12-15

    To evaluate the impact of model-based iterative reconstruction (MBIR) on image quality and low-contrast lesion detection compared with filtered back projection (FBP) in abdominal computed tomography (CT) of simulated medium and large patients at different tube voltages. A phantom with 45 hypoattenuating lesions was placed in two water containers and scanned at 70, 80, 100, and 120 kVp. The 120-kVp protocol served as reference, and the volume CT dose index (CTDI{sub vol}) was kept constant for all protocols. The datasets were reconstructed with MBIR and FBP. Image noise and contrast-to-noise-ratio (CNR) were assessed. Low-contrast lesion detectability was evaluated by 12 radiologists. MBIR decreased the image noise by 24% and 27%, and increased the CNR by 30% and 29% for the medium and large phantoms, respectively. Lower tube voltages increased the CNR by 58%, 46%, and 16% at 70, 80, and 100 kVp, respectively, compared with 120 kVp in the medium phantom and by 9%, 18% and 12% in the large phantom. No significant difference in lesion detection rate was observed (medium: 79-82%; large: 57-65%; P > 0.37). Although MBIR improved quantitative image quality compared with FBP, it did not result in increased low-contrast lesion detection in abdominal CT at different tube voltages in simulated medium and large patients. (orig.)

  2. PET reconstruction

    International Nuclear Information System (INIS)

    O'Sullivan, F.; Pawitan, Y.; Harrison, R.L.; Lewellen, T.K.

    1990-01-01

    In statistical terms, filtered backprojection can be viewed as smoothed Least Squares (LS). In this paper, the authors report on improvement in LS resolution by: incorporating locally adaptive smoothers, imposing positivity and using statistical methods for optimal selection of the resolution parameter. The resulting algorithm has high computational efficiency relative to more elaborate Maximum Likelihood (ML) type techniques (i.e. EM with sieves). Practical aspects of the procedure are discussed in the context of PET and illustrations with computer simulated and real tomograph data are presented. The relative recovery coefficients for a 9mm sphere in a computer simulated hot-spot phantom range from .3 to .6 when the number of counts ranges from 10,000 to 640,000 respectively. The authors will also present results illustrating the relative efficacy of ML and LS reconstruction techniques

  3. SU-F-T-191: 4D Dose Reconstruction of Intensity Modulated Proton Therapy (IMPT) Based On Breathing Probability Density Function (PDF) From 4D Cone Beam Projection Images: A Study for Lung Treatment

    International Nuclear Information System (INIS)

    Zhou, J; Ding, X; Liang, J; Zhang, J; Wang, Y; Yan, D

    2016-01-01

    Purpose: With energy repainting in lung IMPT, the dose delivered is approximate to the convolution of dose in each phase with corresponding breathing PDF. This study is to compute breathing PDF weighted 4D dose in lung IMPT treatment and compare to its initial robust plan. Methods: Six lung patients were evaluated in this study. Amsterdam shroud image were generated from pre-treatment 4D cone-beam projections. Diaphragm motion curve was extract from the shroud image and the breathing PDF was generated. Each patient was planned to 60 Gy (12GyX5). In initial plans, ITV density on average CT was overridden with its maximum value for planning, using two IMPT beams with robust optimization (5mm uncertainty in patient position and 3.5% range uncertainty). The plan was applied to all 4D CT phases. The dose in each phase was deformed to a reference phase. 4D dose is reconstructed by summing all these doses based on corresponding weighting from the PDF. Plan parameters, including maximum dose (Dmax), ITV V100, homogeneity index (HI=D2/D98), R50 (50%IDL/ITV), and the lung-GTV’s V12.5 and V5 were compared between the reconstructed 4D dose to initial plans. Results: The Dmax is significantly less dose in the reconstructed 4D dose, 68.12±3.5Gy, vs. 70.1±4.3Gy in the initial plans (p=0.015). No significant difference is found for the ITV V100, HI, and R50, 92.2%±15.4% vs. 96.3%±2.5% (p=0.565), 1.033±0.016 vs. 1.038±0.017 (p=0.548), 19.2±12.1 vs. 18.1±11.6 (p=0.265), for the 4D dose and initial plans, respectively. The lung-GTV V12.5 and V5 are significantly high in the 4D dose, 13.9%±4.8% vs. 13.0%±4.6% (p=0.021) and 17.6%±5.4% vs. 16.9%±5.2% (p=0.011), respectively. Conclusion: 4D dose reconstruction based on phase PDF can be used to evaluate the dose received by the patient. A robust optimization based on the phase PDF may even further improve patient care.

  4. Basic surveys for joint execution, etc. of the heat and power plant reconstruction project for the corporation 'Yuzhmash', Dnepropetrovsk, Ukraine. Ukraine 'Yuzhmash' feasibility study report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    This project, for the execution of joint implementations set forth in the protocol of the Third Session of the Conference of the Parties to the United Nations Framework Convention on Climate Change, aims to replace the existing plant with a new combined cycle thermal power system which will achieve CO2 emission reduction, environmental preservation, and energy conservation. The project will save energy by 103,731 toe/year. The total project cost will be 9-billion yen, and cost performance will be 87,000-yen/toe or 3,400-yen/toe in a 25-year period. Greenhouse gas emissions will be reduced by 242,424 tons/year, and cost performance will be 37,000-yen/t-CO2 or 1,500-yen/t-CO2 in a 25-year period. Profitability EIRR (economic internal rate of return) is calculated on the assumption of an exchange rate of 4.91UHA/US$ (as of February 2000). When emission trading is carried out at US$/t-CO2=0.0, 5.0, 14.0, or 60.0, EIRR will be 7.363, 8.112, 9.939, or 15.155%, respectively. The price of Ukrainian natural gas affects profitability. A profitability goal to justify project execution will be achieved only when the price of CO2 emission right of 60.00US$/ton or more is realized. Advantageous fund procurement is also necessary. (NEDO)

  5. Optimal reconstruction angles

    International Nuclear Information System (INIS)

    Cook, G.O. Jr.; Knight, L.

    1979-07-01

    The question of optimal projection angles has recently become of interest in the field of reconstruction from projections. Here, studies are concentrated on the n x n pixel space, where literative algorithms such as ART and direct matrix techniques due to Katz are considered. The best angles are determined in a Gauss--Markov statistical sense as well as with respect to a function-theoretical error bound. The possibility of making photon intensity a function of angle is also examined. Finally, the best angles to use in an ART-like algorithm are studied. A certain set of unequally spaced angles was found to be preferred in several contexts. 15 figures, 6 tables

  6. Tomographic image reconstruction using Artificial Neural Networks

    International Nuclear Information System (INIS)

    Paschalis, P.; Giokaris, N.D.; Karabarbounis, A.; Loudos, G.K.; Maintas, D.; Papanicolas, C.N.; Spanoudaki, V.; Tsoumpas, Ch.; Stiliaris, E.

    2004-01-01

    A new image reconstruction technique based on the usage of an Artificial Neural Network (ANN) is presented. The most crucial factor in designing such a reconstruction system is the network architecture and the number of the input projections needed to reconstruct the image. Although the training phase requires a large amount of input samples and a considerable CPU time, the trained network is characterized by simplicity and quick response. The performance of this ANN is tested using several image patterns. It is intended to be used together with a phantom rotating table and the γ-camera of IASA for SPECT image reconstruction

  7. Reconstruction of pollution history of organic contaminants in the upper Gulf of Thailand by using sediment cores: first report from Tropical Asia Core (TACO) project.

    Science.gov (United States)

    Boonyatumanond, Ruchaya; Wattayakorn, Gullaya; Amano, Atsuko; Inouchi, Yoshio; Takada, Hideshige

    2007-05-01

    This paper reports the first reconstruction of a pollution history in tropical Asia from sediment cores. Four sediment core samples were collected from an offshore transect in the upper Gulf of Thailand and were analyzed for organic micropollutants. The cores were dated by measurement of (137)Cs and geochronometric molecular markers (linear alkylbenzenes, LABs; and tetrapropylene-type alkylbenzenes, TABs). Polychlorinated biphenyl (PCB) concentrations showed a subsurface maximum in layers corresponding to the 1970s, indicating the effectiveness of regulation of PCBs in Thailand. LAB concentrations increased over time, indicating the increase in input of sewage into the Gulf during the last 30 years. Hopanes, biomarkers of petroleum pollution, also increased over time, indicating that the inputs of automobile-derived hydrocarbons to the coastal zone has been increasing owing to the increased number of cars in Thailand since the 1950s. Polycyclic aromatic hydrocarbons (PAHs) increased in the layers corresponding to the 1950s and 1960s, probably because of the increased inputs of automobile-derived PAHs. PAH concentrations in the upper layers corresponding to the 1970s and later remained constant or increased. The absence of a subsurface maximum of PAHs contrasts with results observed in industrialized countries. This can be explained by the facts that the Thai economy did not depend on coal as an energy source in the 1960s and that economic growth has continued since the 1970s to the present. The deposition flux of PAHs and hopanes showed a dramatic offshore decrease, whereas that of LABs was uniform.

  8. Reconstruction of pollution history of organic contaminants in the upper Gulf of Thailand by using sediment cores: First report from Tropical Asia Core (TACO) project

    International Nuclear Information System (INIS)

    Boonyatumanond, Ruchaya; Wattayakorn, Gullaya; Amano, Atsuko; Inouchi, Yoshio; Takada, Hideshige

    2007-01-01

    This paper reports the first reconstruction of a pollution history in tropical Asia from sediment cores. Four sediment core samples were collected from an offshore transect in the upper Gulf of Thailand and were analyzed for organic micropollutants. The cores were dated by measurement of 137 Cs and geochronometric molecular markers (linear alkylbenzenes, LABs; and tetrapropylene-type alkylbenzenes, TABs). Polychlorinated biphenyl (PCB) concentrations showed a subsurface maximum in layers corresponding to the 1970s, indicating the effectiveness of regulation of PCBs in Thailand. LAB concentrations increased over time, indicating the increase in input of sewage into the Gulf during the last 30 years. Hopanes, biomarkers of petroleum pollution, also increased over time, indicating that the inputs of automobile-derived hydrocarbons to the coastal zone has been increasing owing to the increased number of cars in Thailand since the 1950s. Polycyclic aromatic hydrocarbons (PAHs) increased in the layers corresponding to the 1950s and 1960s, probably because of the increased inputs of automobile-derived PAHs. PAH concentrations in the upper layers corresponding to the 1970s and later remained constant or increased. The absence of a subsurface maximum of PAHs contrasts with results observed in industrialized countries. This can be explained by the facts that the Thai economy did not depend on coal as an energy source in the 1960s and that economic growth has continued since the 1970s to the present. The deposition flux of PAHs and hopanes showed a dramatic offshore decrease, whereas that of LABs was uniform

  9. Breast Reconstruction After Mastectomy

    Science.gov (United States)

    ... Cancer Prevention Genetics of Breast & Gynecologic Cancers Breast Cancer Screening Research Breast Reconstruction After Mastectomy On This Page What is breast reconstruction? How do surgeons use implants to reconstruct a woman’s breast? How do surgeons ...

  10. Breast reconstruction - implants

    Science.gov (United States)

    Breast implants surgery; Mastectomy - breast reconstruction with implants; Breast cancer - breast reconstruction with implants ... harder to find a tumor if your breast cancer comes back. Getting breast implants does not take as long as breast reconstruction ...

  11. Simulation and Track Reconstruction for Beam Telescopes

    CERN Document Server

    Maqbool, Salman

    2017-01-01

    Beam telescopes are an important tool to test new detectors under development in a particle beam. To test these novel detectors and determine their properties, the particle tracks need to be reconstructed from the known detectors in the telescope. Based on the reconstructed track, its predicted position on the Device under Test (DUT) are compared with the actual hits on the DUT. Several methods exist for track reconstruction, but most of them do not account for the effects of multiple scattering. General Broken Lines is one such algorithm which incorporates these effects during reconstruction. The aim of this project was to simulate the beam telescope and extend the track reconstruction framework for the FE-I4 telescope, which takes these effects into account. Section 1 introduces the problem, while section 2 focuses on beam telescopes. This is followed by the Allpix2 simulation framework in Section 3. And finally, Section 4 introduces the Proteus track reconstruction framework along with the General Broken ...

  12. Rational approximations for tomographic reconstructions

    International Nuclear Information System (INIS)

    Reynolds, Matthew; Beylkin, Gregory; Monzón, Lucas

    2013-01-01

    We use optimal rational approximations of projection data collected in x-ray tomography to improve image resolution. Under the assumption that the object of interest is described by functions with jump discontinuities, for each projection we construct its rational approximation with a small (near optimal) number of terms for a given accuracy threshold. This allows us to augment the measured data, i.e., double the number of available samples in each projection or, equivalently, extend (double) the domain of their Fourier transform. We also develop a new, fast, polar coordinate Fourier domain algorithm which uses our nonlinear approximation of projection data in a natural way. Using augmented projections of the Shepp–Logan phantom, we provide a comparison between the new algorithm and the standard filtered back-projection algorithm. We demonstrate that the reconstructed image has improved resolution without additional artifacts near sharp transitions in the image. (paper)

  13. The EASTNET Project: Extending the Network of Climate-Sensitive Tree-Ring Chronologies From the Eastern United States for Reconstructing the Spatio-Temporal Characteristics of Climate and Drought Over the Past Millennium

    Science.gov (United States)

    Buckley, B. M.; Cook, E. R.

    2002-12-01

    Recently, a network of gridded PDSI reconstructions for the contiguous United States was produced, based on the available network of drought-sensitive tree-ring chronologies (Cook et al. 1999). Analyses were constrained to the common period of 1700 - 1979 due to the limitations of the available tree-ring data. While several chronologies from the western U.S. span 1,000 years or more, very few chronologies from the eastern U.S. covered even the past 500 years. The objective of this project, funded by the National Science Foundation's ESH program, is to extend the tree-ring chronology network from the eastern U.S. with chronologies spanning the past 500-1,000 years. This aim is being achieved by sampling in areas that have escaped the effects of development, logging and major disturbance such as fire. The two main target species are Thuja occidentalis (eastern white cedar) and Juniperus virginiana (eastern red cedar). The primary terrain types are on cliffs, rocky outcrops, and other areas that have been difficult to access. We have already developed chronologies from Wisconsin, New Hampshire, Pennsylvania, West Virginia, and Virginia that span from 500 to 1500 years. The temporal depth of these chronologies is being extended through the exploitation of "sub-fossil" wood found at these sites, in the form of standing-dead stems and downed and buried logs. We are also currently pursuing leads in Maine, Vermont, Massachusetts, Connecticut, New York, New Jersey Pennsylvania, Kentucky and North Carolina where old cedar trees have either been reported or where terrain types match criteria developed for this project. In this paper we discuss the current status of the network, and explore the spatio-temporal characteristics of climate and drought across the eastern US for the past 500 years and more. We use our preliminary network to explore the regional expression of climate anomalies such as drought. Our analyses so far demonstrates multicentennial variability suggestive

  14. Kesiapan Implementasi Badan Hukum Pendidikan (BHP

    Directory of Open Access Journals (Sweden)

    Etty Nurbayani

    2012-06-01

    Full Text Available A change in format of state university to education legal entity allows the existence of autonomous. Thus, a rector is more creative and no longer bounded by structure and bureaucratic mechanism. The autonomous in academic, finance, administration, personnel, etc., followed by a possible optimal accountability where every year the rector must give a responsibility report to senate, assembly of guardian trustful, external auditor, public accountant, and Finance Minister also Minister of National Education.

  15. Investigation of various reconstruction parameters for algebraic reconstruction technique in a newly developed chest digital tomosynthesis

    International Nuclear Information System (INIS)

    Lee, H.; Choi, S.; Kim, Y.-S.; Park, H.-S.; Seo, C.-W.; Kim, H.-J.; Lee, D.; Lee, Y.

    2017-01-01

    Chest digital tomosynthesis (CDT) is a promising new modality that provides 3D information by reconstructing limited projection views. CDT systems have been developed to improve the limitations of conventional radiography such as image degradation and low sensitivity. However, the development of reconstruction methods is challenging because of the limited projection views within various angular ranges. Optimization of reconstruction parameters for various reconsturction methods in CDT system also is needed. The purpose of this study was to investigate the feasibility of algebraic reconstruction technique (ART) method, and to evaluate the effect of the reconstruction parameters for our newly developed CDT system. We designed ART method with 41 projection views over an angular range of ±20°. To investigate the effect of reconstruction parameters, we measured the contrast-to-noise ratio (CNR), artifact spread function (ASF), and quality factor (QF) using LUNGMAN phantom included tumors. We found that the proper choice of reconstruction parameters such as relaxation parameter, initial guess, and number of iterations improved the quality of reconstructed images from the same projection views. Optimal values of ART relaxation parameter with uniform (UI) and back-projection (BP) initial guesses were 0.4 and 0.6, respectively. BP initial guess improved image quality in comparison with UI initial guess, in terms of providing a higher CNR and QF values with a faster speed. CNR and QF values improved with increasing number of iteration. Particularly, ART method with BP initial guess (when β = 0.6) after 3-terations provide satisfactory reconstructed image. In conclusion, the use of ART method with proper reconstruction parameters provided better image quality than FBP method as well as conventional radiography. These results indicated that the ART method with optimal reconstruction parameters could improve image quality for nodule detection using the CDT system.

  16. Investigation of various reconstruction parameters for algebraic reconstruction technique in a newly developed chest digital tomosynthesis

    Science.gov (United States)

    Lee, H.; Choi, S.; Lee, D.; Kim, Y.-s.; Park, H.-S.; Lee, Y.; Seo, C.-W.; Kim, H.-J.

    2017-08-01

    Chest digital tomosynthesis (CDT) is a promising new modality that provides 3D information by reconstructing limited projection views. CDT systems have been developed to improve the limitations of conventional radiography such as image degradation and low sensitivity. However, the development of reconstruction methods is challenging because of the limited projection views within various angular ranges. Optimization of reconstruction parameters for various reconsturction methods in CDT system also is needed. The purpose of this study was to investigate the feasibility of algebraic reconstruction technique (ART) method, and to evaluate the effect of the reconstruction parameters for our newly developed CDT system. We designed ART method with 41 projection views over an angular range of ±20°. To investigate the effect of reconstruction parameters, we measured the contrast-to-noise ratio (CNR), artifact spread function (ASF), and quality factor (QF) using LUNGMAN phantom included tumors. We found that the proper choice of reconstruction parameters such as relaxation parameter, initial guess, and number of iterations improved the quality of reconstructed images from the same projection views. Optimal values of ART relaxation parameter with uniform (UI) and back-projection (BP) initial guesses were 0.4 and 0.6, respectively. BP initial guess improved image quality in comparison with UI initial guess, in terms of providing a higher CNR and QF values with a faster speed. CNR and QF values improved with increasing number of iteration. Particularly, ART method with BP initial guess (when β = 0.6) after 3-terations provide satisfactory reconstructed image. In conclusion, the use of ART method with proper reconstruction parameters provided better image quality than FBP method as well as conventional radiography. These results indicated that the ART method with optimal reconstruction parameters could improve image quality for nodule detection using the CDT system.

  17. Parallel CT image reconstruction based on GPUs

    International Nuclear Information System (INIS)

    Flores, Liubov A.; Vidal, Vicent; Mayo, Patricia; Rodenas, Francisco; Verdú, Gumersindo

    2014-01-01

    In X-ray computed tomography (CT) iterative methods are more suitable for the reconstruction of images with high contrast and precision in noisy conditions from a small number of projections. However, in practice, these methods are not widely used due to the high computational cost of their implementation. Nowadays technology provides the possibility to reduce effectively this drawback. It is the goal of this work to develop a fast GPU-based algorithm to reconstruct high quality images from under sampled and noisy projection data. - Highlights: • We developed GPU-based iterative algorithm to reconstruct images. • Iterative algorithms are capable to reconstruct images from under sampled set of projections. • The computer cost of the implementation of the developed algorithm is low. • The efficiency of the algorithm increases for the large scale problems

  18. Computed tomography of the cervical spine: comparison of image quality between a standard-dose and a low-dose protocol using filtered back-projection and iterative reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Becce, Fabio [University of Lausanne, Department of Diagnostic and Interventional Radiology, Centre Hospitalier Universitaire Vaudois, Lausanne (Switzerland); Universite Catholique Louvain, Department of Radiology, Cliniques Universitaires Saint-Luc, Brussels (Belgium); Ben Salah, Yosr; Berg, Bruno C. vande; Lecouvet, Frederic E.; Omoumi, Patrick [Universite Catholique Louvain, Department of Radiology, Cliniques Universitaires Saint-Luc, Brussels (Belgium); Verdun, Francis R. [University of Lausanne, Institute of Radiation Physics, Centre Hospitalier Universitaire Vaudois, Lausanne (Switzerland); Meuli, Reto [University of Lausanne, Department of Diagnostic and Interventional Radiology, Centre Hospitalier Universitaire Vaudois, Lausanne (Switzerland)

    2013-07-15

    To compare image quality of a standard-dose (SD) and a low-dose (LD) cervical spine CT protocol using filtered back-projection (FBP) and iterative reconstruction (IR). Forty patients investigated by cervical spine CT were prospectively randomised into two groups: SD (120 kVp, 275 mAs) and LD (120 kVp, 150 mAs), both applying automatic tube current modulation. Data were reconstructed using both FBP and sinogram-affirmed IR. Image noise, signal-to-noise (SNR) and contrast-to-noise (CNR) ratios were measured. Two radiologists independently and blindly assessed the following anatomical structures at C3-C4 and C6-C7 levels, using a four-point scale: intervertebral disc, content of neural foramina and dural sac, ligaments, soft tissues and vertebrae. They subsequently rated overall image quality using a ten-point scale. For both protocols and at each disc level, IR significantly decreased image noise and increased SNR and CNR, compared with FBP. SNR and CNR were statistically equivalent in LD-IR and SD-FBP protocols. Regardless of the dose and disc level, the qualitative scores with IR compared with FBP, and with LD-IR compared with SD-FBP, were significantly higher or not statistically different for intervertebral discs, neural foramina and ligaments, while significantly lower or not statistically different for soft tissues and vertebrae. The overall image quality scores were significantly higher with IR compared with FBP, and with LD-IR compared with SD-FBP. LD-IR cervical spine CT provides better image quality for intervertebral discs, neural foramina and ligaments, and worse image quality for soft tissues and vertebrae, compared with SD-FBP, while reducing radiation dose by approximately 40 %. (orig.)

  19. Computed tomography of the cervical spine: comparison of image quality between a standard-dose and a low-dose protocol using filtered back-projection and iterative reconstruction

    International Nuclear Information System (INIS)

    Becce, Fabio; Ben Salah, Yosr; Berg, Bruno C. vande; Lecouvet, Frederic E.; Omoumi, Patrick; Verdun, Francis R.; Meuli, Reto

    2013-01-01

    To compare image quality of a standard-dose (SD) and a low-dose (LD) cervical spine CT protocol using filtered back-projection (FBP) and iterative reconstruction (IR). Forty patients investigated by cervical spine CT were prospectively randomised into two groups: SD (120 kVp, 275 mAs) and LD (120 kVp, 150 mAs), both applying automatic tube current modulation. Data were reconstructed using both FBP and sinogram-affirmed IR. Image noise, signal-to-noise (SNR) and contrast-to-noise (CNR) ratios were measured. Two radiologists independently and blindly assessed the following anatomical structures at C3-C4 and C6-C7 levels, using a four-point scale: intervertebral disc, content of neural foramina and dural sac, ligaments, soft tissues and vertebrae. They subsequently rated overall image quality using a ten-point scale. For both protocols and at each disc level, IR significantly decreased image noise and increased SNR and CNR, compared with FBP. SNR and CNR were statistically equivalent in LD-IR and SD-FBP protocols. Regardless of the dose and disc level, the qualitative scores with IR compared with FBP, and with LD-IR compared with SD-FBP, were significantly higher or not statistically different for intervertebral discs, neural foramina and ligaments, while significantly lower or not statistically different for soft tissues and vertebrae. The overall image quality scores were significantly higher with IR compared with FBP, and with LD-IR compared with SD-FBP. LD-IR cervical spine CT provides better image quality for intervertebral discs, neural foramina and ligaments, and worse image quality for soft tissues and vertebrae, compared with SD-FBP, while reducing radiation dose by approximately 40 %. (orig.)

  20. Differences in Services and Fees for Management and Administration of Iraq Reconstruction Contracts

    National Research Council Canada - National Science Library

    Warren, David; Childress, David; Salvatierra, George; Thompson, Chuck; Williams, Roger M

    2008-01-01

    ...), a field operating agency of the Air Force Civil Engineer, are two primary organizations providing project management and contract administration services for major Iraq reconstruction projects...

  1. Simulated annealing image reconstruction for positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Sundermann, E; Lemahieu, I; Desmedt, P [Department of Electronics and Information Systems, University of Ghent, St. Pietersnieuwstraat 41, B-9000 Ghent, Belgium (Belgium)

    1994-12-31

    In Positron Emission Tomography (PET) images have to be reconstructed from moisy projection data. The noise on the PET data can be modeled by a Poison distribution. In this paper, we present the results of using the simulated annealing technique to reconstruct PET images. Various parameter settings of the simulated annealing algorithm are discussed and optimized. The reconstructed images are of good quality and high contrast, in comparison to other reconstruction techniques. (authors). 11 refs., 2 figs.

  2. Simulated annealing image reconstruction for positron emission tomography

    International Nuclear Information System (INIS)

    Sundermann, E.; Lemahieu, I.; Desmedt, P.

    1994-01-01

    In Positron Emission Tomography (PET) images have to be reconstructed from moisy projection data. The noise on the PET data can be modeled by a Poison distribution. In this paper, we present the results of using the simulated annealing technique to reconstruct PET images. Various parameter settings of the simulated annealing algorithm are discussed and optimized. The reconstructed images are of good quality and high contrast, in comparison to other reconstruction techniques. (authors)

  3. Reconstructing Normality

    DEFF Research Database (Denmark)

    Gildberg, Frederik Alkier; Bradley, Stephen K.; Fristed, Peter Billeskov

    2012-01-01

    Forensic psychiatry is an area of priority for the Danish Government. As the field expands, this calls for increased knowledge about mental health nursing practice, as this is part of the forensic psychiatry treatment offered. However, only sparse research exists in this area. The aim of this study...... was to investigate the characteristics of forensic mental health nursing staff interaction with forensic mental health inpatients and to explore how staff give meaning to these interactions. The project included 32 forensic mental health staff members, with over 307 hours of participant observations, 48 informal....... The intention is to establish a trusting relationship to form behaviour and perceptual-corrective care, which is characterized by staff's endeavours to change, halt, or support the patient's behaviour or perception in relation to staff's perception of normality. The intention is to support and teach the patient...

  4. Superiority of CT imaging reconstruction on Linux OS

    International Nuclear Information System (INIS)

    Lin Shaochun; Yan Xufeng; Wu Tengfang; Luo Xiaomei; Cai Huasong

    2010-01-01

    Objective: To compare the speed of CT reconstruction using the Linux and Windows OS. Methods: Shepp-Logan head phantom in different pixel size was projected to obtain the sinogram by using the inverse Fourier transformation, filtered back projection and Radon transformation on both Linux and Windows OS. Results: CT image reconstruction using the Linux operating system was significantly better and more efficient than Windows. Conclusion: CT image reconstruction using the Linux operating system is more efficient. (authors)

  5. Improving Filtered Backprojection Reconstruction by Data-Dependent Filtering

    NARCIS (Netherlands)

    D.M. Pelt (Daniël); K.J. Batenburg (Joost)

    2014-01-01

    htmlabstractFiltered backprojection, one of the most widely used reconstruction methods in tomography, requires a large number of low-noise projections to yield accurate reconstructions. In many applications of tomography, complete projection data of high quality cannot be obtained, because of

  6. ICDP Project DeepCHALLA: Reconstructing 250,000 Years of Climate Change and Environmental History on the East African Equator

    Science.gov (United States)

    Wolff, C.; Verschuren, D.; Van Daele, M. E.; Waldmann, N.; Meyer, I.; Lane, C. S.; Van der Meeren, T.; Ombori, T.; Kasanzu, C.; Olago, D.

    2017-12-01

    Sediments on the bottom of Lake Challa, a 92-m deep crater lake on the border of Kenya and Tanzania near Mt. Kilimanjaro, contain a uniquely long and continuous record of past climate and environmental change in easternmost equatorial Africa. Supported in part by the International Continental Scientific Drilling Programme (ICDP), the DeepCHALLA project has now recovered this sediment record down to 214.8 m below the lake floor, with 100% recovery of the uppermost 121.3 m (the last 160 kyr BP) and ca.85% recovery of the older part of the sequence, down to the lowermost distinct reflector identified in seismic stratigraphy. This acoustic basement represents a ca.2-m thick layer of coarsely laminated, diatom-rich organic mud mixed with volcanic sand and silt deposited 250 kyr ago, overlying an estimated 20-30 m of unsampled lacustrine deposits representing the earliest phase of lake development. Down-hole logging produced profiles of in-situ sediment composition that confer an absolute depth- scale to both the recovered cores and the seismic stratigraphy. An estimated 74% of the recovered sequence is finely laminated (varved), and continuously so over the upper 72.3 m (the last 90 kyr). All other sections display at least cm-scale lamination, demonstrating persistence of a tranquil, profundal depositional environment throughout lake history. The sequence is interrupted only by 32 visible tephra layers 2 to 9 mm thick; and by several dozen fine-grained turbidites up to 108 cm thick, most of which are clearly bracketed between a non-erosive base and a diatom-laden cap. Tie points between sediment markers and the corresponding seismic reflectors support a preliminary age model inferring a near-constant rate of sediment accumulation over at least the last glacial cycle (140 kyr BP to present). This great time span combined with the exquisite temporal resolution of the Lake Challa sediments provides great opportunities to study past tropical climate dynamics at both short

  7. Clinical applications of iterative reconstruction

    International Nuclear Information System (INIS)

    Eberl, S.

    1998-01-01

    Expectation maximisation (EM) reconstruction largely eliminates the hot and cold streaking artifacts characteristic of filtered-back projection (FBP) reconstruction around localised hot areas, such as the bladder. It also substantially reduces the problem of decreased inferior wall counts in MIBI myocardial perfusion studies due to ''streaking'' from high liver uptake. Non-uniform attenuation and scatter correction, resolution recovery, anatomical information, e.g. from MRI or CT tracer kinetic modelling, can all be built into the EM reconstruction imaging model. The properties of ordered subset EM (OSEM) have also been used to correct for known patient motion as part of the reconstruction process. These uses of EM are elaborated more fully in some of the other abstracts of this meeting. Currently we use OSEM routinely for: (i) studies where streaking is a problem, including all MIBI myocardial perfusion studies, to avoid hot liver inferior wall artifact, (ii) all whole body FDG PET, all lung V/Q SPECT (which have a short acquisition time) and all gated 201 TI myocardial perfusion studies due to improved noise characteristics of OSEM in these studies; (iii) studies with measured, non-uniform attenuation correction. With the accelerated OSEM algorithm, iterative reconstruction is practical for routine clinical applications and we have found OSEM to provide clearly superior reconstructions for the areas listed above and are investigating its application to other studies. In clinical use, we have not found OSEM to introduce artifacts which would not also occur with FBP, e.g. uncorrected patient motion will cause artifacts with both OSEM and FBP

  8. Software Architecture Reconstruction Method, a Survey

    OpenAIRE

    Zainab Nayyar; Nazish Rafique

    2014-01-01

    Architecture reconstruction belongs to a reverse engineering process, in which we move from code to architecture level for reconstructing architecture. Software architectures are the blue prints of projects which depict the external overview of the software system. Mostly maintenance and testing cause the software to deviate from its original architecture, because sometimes for enhancing the functionality of a system the software deviates from its documented specifications, some new modules a...

  9. Reconstructing weak values without weak measurements

    International Nuclear Information System (INIS)

    Johansen, Lars M.

    2007-01-01

    I propose a scheme for reconstructing the weak value of an observable without the need for weak measurements. The post-selection in weak measurements is replaced by an initial projector measurement. The observable can be measured using any form of interaction, including projective measurements. The reconstruction is effected by measuring the change in the expectation value of the observable due to the projector measurement. The weak value may take nonclassical values if the projector measurement disturbs the expectation value of the observable

  10. Vertex Reconstruction for AEGIS’ FACT Detector

    CERN Document Server

    Themistokleous, Neofytos

    2017-01-01

    My project dealt with the development of a vertex reconstruction technique to discriminate antihydrogen from background signals in the AEGIS apparatus. It involved the creation of a Toy Monte-Carlo to simulate particle annihilation events, and a vertex reconstruction utility based on the Bayesian theory of probability. The first results based on 107 generated events with single track in the detector are encouraging. For such events, the algorithm can reconstruct the z-coordinate accurately , while for the r-coordinate the result is less accurate.

  11. Breast reconstruction - natural tissue

    Science.gov (United States)

    ... flap; TRAM; Latissimus muscle flap with a breast implant; DIEP flap; DIEAP flap; Gluteal free flap; Transverse upper gracilis flap; TUG; Mastectomy - breast reconstruction with natural tissue; Breast cancer - breast reconstruction with natural tissue

  12. Breast reconstruction after mastectomy

    Directory of Open Access Journals (Sweden)

    Daniel eSchmauss

    2016-01-01

    Full Text Available Breast cancer is the leading cause of cancer death in women worldwide. Its surgical approach has become less and less mutilating in the last decades. However, the overall number of breast reconstructions has significantly increased lately. Nowadays breast reconstruction should be individualized at its best, first of all taking into consideration oncological aspects of the tumor, neo-/adjuvant treatment and genetic predisposition, but also its timing (immediate versus delayed breast reconstruction, as well as the patient’s condition and wish. This article gives an overview over the various possibilities of breast reconstruction, including implant- and expander-based reconstruction, flap-based reconstruction (vascularized autologous tissue, the combination of implant and flap, reconstruction using non-vascularized autologous fat, as well as refinement surgery after breast reconstruction.

  13. Feasible Dose Reduction in Routine Chest Computed Tomography Maintaining Constant Image Quality Using the Last Three Scanner Generations: From Filtered Back Projection to Sinogram-affirmed Iterative Reconstruction and Impact of the Novel Fully Integrated Detector Design Minimizing Electronic Noise

    Directory of Open Access Journals (Sweden)

    Lukas Ebner

    2014-01-01

    Full Text Available Objective:The aim of the present study was to evaluate a dose reduction in contrast-enhanced chest computed tomography (CT by comparing the three latest generations of Siemens CT scanners used in clinical practice. We analyzed the amount of radiation used with filtered back projection (FBP and an iterative reconstruction (IR algorithm to yield the same image quality. Furthermore, the influence on the radiation dose of the most recent integrated circuit detector (ICD; Stellar detector, Siemens Healthcare, Erlangen, Germany was investigated. Materials and Methods: 136 Patients were included. Scan parameters were set to a thorax routine: SOMATOM Sensation 64 (FBP, SOMATOM Definition Flash (IR, and SOMATOM Definition Edge (ICD and IR. Tube current was set constantly to the reference level of 100 mA automated tube current modulation using reference milliamperes. Care kV was used on the Flash and Edge scanner, while tube potential was individually selected between 100 and 140 kVp by the medical technologists at the SOMATOM Sensation. Quality assessment was performed on soft-tissue kernel reconstruction. Dose was represented by the dose length product. Results: Dose-length product (DLP with FBP for the average chest CT was 308 mGycm ± 99.6. In contrast, the DLP for the chest CT with IR algorithm was 196.8 mGycm ± 68.8 (P = 0.0001. Further decline in dose can be noted with IR and the ICD: DLP: 166.4 mGycm ± 54.5 (P = 0.033. The dose reduction compared to FBP was 36.1% with IR and 45.6% with IR/ICD. Signal-to-noise ratio (SNR was favorable in the aorta, bone, and soft tissue for IR/ICD in combination compared to FBP (the P values ranged from 0.003 to 0.048. Overall contrast-to-noise ratio (CNR improved with declining DLP. Conclusion: The most recent technical developments, namely IR in combination with integrated circuit detectors, can significantly lower radiation dose in chest CT examinations.

  14. Iterative CT reconstruction via minimizing adaptively reweighted total variation.

    Science.gov (United States)

    Zhu, Lei; Niu, Tianye; Petrongolo, Michael

    2014-01-01

    Iterative reconstruction via total variation (TV) minimization has demonstrated great successes in accurate CT imaging from under-sampled projections. When projections are further reduced, over-smoothing artifacts appear in the current reconstruction especially around the structure boundaries. We propose a practical algorithm to improve TV-minimization based CT reconstruction on very few projection data. Based on the theory of compressed sensing, the L-0 norm approach is more desirable to further reduce the projection views. To overcome the computational difficulty of the non-convex optimization of the L-0 norm, we implement an adaptive weighting scheme to approximate the solution via a series of TV minimizations for practical use in CT reconstruction. The weight on TV is initialized as uniform ones, and is automatically changed based on the gradient of the reconstructed image from the previous iteration. The iteration stops when a small difference between the weighted TV values is observed on two consecutive reconstructed images. We evaluate the proposed algorithm on both a digital phantom and a physical phantom. Using 20 equiangular projections, our method reduces reconstruction errors in the conventional TV minimization by a factor of more than 5, with improved spatial resolution. By adaptively reweighting TV in iterative CT reconstruction, we successfully further reduce the projection number for the same or better image quality.

  15. Biologic Collagen Cylinder with Skate Flap Technique for Nipple Reconstruction

    Directory of Open Access Journals (Sweden)

    Brian P. Tierney

    2014-01-01

    Full Text Available A surgical technique using local tissue skate flaps combined with cylinders made from a naturally derived biomaterial has been used effectively for nipple reconstruction. A retrospective review of patients who underwent nipple reconstruction using this technique was performed. Comorbidities and type of breast reconstruction were collected. Outcome evaluation included complications, surgical revisions, and nipple projection. There were 115 skate flap reconstructions performed in 83 patients between July 2009 and January 2013. Patients ranged from 32 to 73 years old. Average body mass index was 28.0. The most common comorbidities were hypertension (39.8% and smoking (16.9%. After breast reconstruction, 68.7% of the patients underwent chemotherapy and 20.5% underwent radiation. Seventy-one patients had immediate breast reconstruction with expanders and 12 had delayed reconstruction. The only reported complications were extrusions (3.5%. Six nipples (5.2% in 5 patients required surgical revision due to loss of projection; two patients had minor loss of projection but did not require surgical revision. Nipple projection at time of surgery ranged from 6 to 7 mm and average projection at 6 months was 3–5 mm. A surgical technique for nipple reconstruction using a skate flap with a graft material is described. Complications are infrequent and short-term projection measurements are encouraging.

  16. Biologic collagen cylinder with skate flap technique for nipple reconstruction.

    Science.gov (United States)

    Tierney, Brian P; Hodde, Jason P; Changkuon, Daniela I

    2014-01-01

    A surgical technique using local tissue skate flaps combined with cylinders made from a naturally derived biomaterial has been used effectively for nipple reconstruction. A retrospective review of patients who underwent nipple reconstruction using this technique was performed. Comorbidities and type of breast reconstruction were collected. Outcome evaluation included complications, surgical revisions, and nipple projection. There were 115 skate flap reconstructions performed in 83 patients between July 2009 and January 2013. Patients ranged from 32 to 73 years old. Average body mass index was 28.0. The most common comorbidities were hypertension (39.8%) and smoking (16.9%). After breast reconstruction, 68.7% of the patients underwent chemotherapy and 20.5% underwent radiation. Seventy-one patients had immediate breast reconstruction with expanders and 12 had delayed reconstruction. The only reported complications were extrusions (3.5%). Six nipples (5.2%) in 5 patients required surgical revision due to loss of projection; two patients had minor loss of projection but did not require surgical revision. Nipple projection at time of surgery ranged from 6 to 7 mm and average projection at 6 months was 3-5 mm. A surgical technique for nipple reconstruction using a skate flap with a graft material is described. Complications are infrequent and short-term projection measurements are encouraging.

  17. Distance weighting for improved tomographic reconstructions

    International Nuclear Information System (INIS)

    Koeppe, R.A.; Holden, J.E.

    1984-01-01

    An improved method for the reconstruction of emission computed axial tomography images has been developed. The method is a modification of filtered back-projection, where the back projected values are weighted to reflect the loss of formation, with distance from the camera, which is inherent in gamma camera imaging. This information loss is a result of: loss of spatial resolution with distance, attenuation, and scatter. The weighting scheme can best be described by considering the contributions of any two opposing views to the reconstruction image pixels. The weight applied to the projections of one view is set to equal the relative amount of the original activity that was initially received in that projection, assuming a uniform attenuating medium. This yields a weighting value which is a function of distance into the image with a value of one for pixels ''near the camera'', a value of .5 at the image center, and a value of zero on the opposite side. Tomographic reconstructions produced with this method show improved spatial resolution when compared to conventional 360 0 reconstructions. The improvement is in the tangential direction, where simulations have indicated a FWHM improvement of 1 to 1.5 millimeters. The resolution in the radial direction is essentially the same for both methods. Visual inspection of the reconstructed images show improved resolution and contrast

  18. Fiscal 1999 report on basic research for promotion of joint implementation programs. Heat and power plant reconstruction project for Yuzhmash Company co-generating plant, Donepropetrovsk City, the Ukraine; 1999 nendo Donepropetrovsk shi Yuzhmansh sha Heat and Power Plant Reconstruction Project chosa hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    This project complies with the COP3 (Third Session of the Conference of the Parties to the United Nations Framework Convention on Climate Change) protocol. To be newly installed are three gas turbine power generators (rating: 26MW, main fuel: natural gas), three waste heat recovery boilers (additionally fired boilers, 2-pressure natural circulation type), and one 40MW water circulation type mixed pressure steam turbine power generator (including a bleeder for co-generation). Greenhouse gases will be reduced by 242,424 tons/year in terms of CO2. The project will cost 9-billion yen in total, with improvement on cost performance expected to be 37,000 yen/ton/year in terms of CO2 and 1,500 yen/ton/25 years. Profitability is assessed using EIRR (economic internal rate of return) when the exchange rate is set at 4.91 UHA/US dollar (as of February 2000). Provided that the emission trading rate in US dollar/ton in CO2 is 0.0, 5.00, 14.0, or 60.00, the economic rate of return will be 7.363, 8.112, 9.399, or 15.155%, respectively. To realize an internal rate of return of 15% which the project wants to achieve, the emission trading rate needs to be 60 US dollars/ton in CO2 or higher. (NEDO)

  19. Direct computation of harmonic moments for tomographic reconstruction

    International Nuclear Information System (INIS)

    Nara, Takaaki; Ito, Nobutaka; Takamatsu, Tomonori; Sakurai, Tetsuya

    2007-01-01

    A novel algorithm to compute harmonic moments of a density function from its projections is presented for tomographic reconstruction. For projection p(r, θ), we define harmonic moments of projection by ∫ π 0 ∫ ∞ -∞ p(r,θ)(re iθ ) n drd θ and show that it coincides with the harmonic moments of the density function except a constant. Furthermore, we show that the harmonic moment of projection of order n can be exactly computed by using n+ 1 projection directions, which leads to an efficient algorithm to reconstruct the vertices of a polygon from projections.

  20. Fast parallel algorithm for CT image reconstruction.

    Science.gov (United States)

    Flores, Liubov A; Vidal, Vicent; Mayo, Patricia; Rodenas, Francisco; Verdú, Gumersindo

    2012-01-01

    In X-ray computed tomography (CT) the X rays are used to obtain the projection data needed to generate an image of the inside of an object. The image can be generated with different techniques. Iterative methods are more suitable for the reconstruction of images with high contrast and precision in noisy conditions and from a small number of projections. Their use may be important in portable scanners for their functionality in emergency situations. However, in practice, these methods are not widely used due to the high computational cost of their implementation. In this work we analyze iterative parallel image reconstruction with the Portable Extensive Toolkit for Scientific computation (PETSc).

  1. Accelerated Compressed Sensing Based CT Image Reconstruction.

    Science.gov (United States)

    Hashemi, SayedMasoud; Beheshti, Soosan; Gill, Patrick R; Paul, Narinder S; Cobbold, Richard S C

    2015-01-01

    In X-ray computed tomography (CT) an important objective is to reduce the radiation dose without significantly degrading the image quality. Compressed sensing (CS) enables the radiation dose to be reduced by producing diagnostic images from a limited number of projections. However, conventional CS-based algorithms are computationally intensive and time-consuming. We propose a new algorithm that accelerates the CS-based reconstruction by using a fast pseudopolar Fourier based Radon transform and rebinning the diverging fan beams to parallel beams. The reconstruction process is analyzed using a maximum-a-posterior approach, which is transformed into a weighted CS problem. The weights involved in the proposed model are calculated based on the statistical characteristics of the reconstruction process, which is formulated in terms of the measurement noise and rebinning interpolation error. Therefore, the proposed method not only accelerates the reconstruction, but also removes the rebinning and interpolation errors. Simulation results are shown for phantoms and a patient. For example, a 512 × 512 Shepp-Logan phantom when reconstructed from 128 rebinned projections using a conventional CS method had 10% error, whereas with the proposed method the reconstruction error was less than 1%. Moreover, computation times of less than 30 sec were obtained using a standard desktop computer without numerical optimization.

  2. Accelerated Compressed Sensing Based CT Image Reconstruction

    Directory of Open Access Journals (Sweden)

    SayedMasoud Hashemi

    2015-01-01

    Full Text Available In X-ray computed tomography (CT an important objective is to reduce the radiation dose without significantly degrading the image quality. Compressed sensing (CS enables the radiation dose to be reduced by producing diagnostic images from a limited number of projections. However, conventional CS-based algorithms are computationally intensive and time-consuming. We propose a new algorithm that accelerates the CS-based reconstruction by using a fast pseudopolar Fourier based Radon transform and rebinning the diverging fan beams to parallel beams. The reconstruction process is analyzed using a maximum-a-posterior approach, which is transformed into a weighted CS problem. The weights involved in the proposed model are calculated based on the statistical characteristics of the reconstruction process, which is formulated in terms of the measurement noise and rebinning interpolation error. Therefore, the proposed method not only accelerates the reconstruction, but also removes the rebinning and interpolation errors. Simulation results are shown for phantoms and a patient. For example, a 512 × 512 Shepp-Logan phantom when reconstructed from 128 rebinned projections using a conventional CS method had 10% error, whereas with the proposed method the reconstruction error was less than 1%. Moreover, computation times of less than 30 sec were obtained using a standard desktop computer without numerical optimization.

  3. Low dose reconstruction algorithm for differential phase contrast imaging.

    Science.gov (United States)

    Wang, Zhentian; Huang, Zhifeng; Zhang, Li; Chen, Zhiqiang; Kang, Kejun; Yin, Hongxia; Wang, Zhenchang; Marco, Stampanoni

    2011-01-01

    Differential phase contrast imaging computed tomography (DPCI-CT) is a novel x-ray inspection method to reconstruct the distribution of refraction index rather than the attenuation coefficient in weakly absorbing samples. In this paper, we propose an iterative reconstruction algorithm for DPCI-CT which benefits from the new compressed sensing theory. We first realize a differential algebraic reconstruction technique (DART) by discretizing the projection process of the differential phase contrast imaging into a linear partial derivative matrix. In this way the compressed sensing reconstruction problem of DPCI reconstruction can be transformed to a resolved problem in the transmission imaging CT. Our algorithm has the potential to reconstruct the refraction index distribution of the sample from highly undersampled projection data. Thus it can significantly reduce the dose and inspection time. The proposed algorithm has been validated by numerical simulations and actual experiments.

  4. DART: a practical reconstruction algorithm for discrete tomography.

    Science.gov (United States)

    Batenburg, Kees Joost; Sijbers, Jan

    2011-09-01

    In this paper, we present an iterative reconstruction algorithm for discrete tomography, called discrete algebraic reconstruction technique (DART). DART can be applied if the scanned object is known to consist of only a few different compositions, each corresponding to a constant gray value in the reconstruction. Prior knowledge of the gray values for each of the compositions is exploited to steer the current reconstruction towards a reconstruction that contains only these gray values. Based on experiments with both simulated CT data and experimental μCT data, it is shown that DART is capable of computing more accurate reconstructions from a small number of projection images, or from a small angular range, than alternative methods. It is also shown that DART can deal effectively with noisy projection data and that the algorithm is robust with respect to errors in the estimation of the gray values.

  5. Iterative reconstruction reduces abdominal CT dose

    International Nuclear Information System (INIS)

    Martinsen, Anne Catrine Trægde; Sæther, Hilde Kjernlie; Hol, Per Kristian; Olsen, Dag Rune; Skaane, Per

    2012-01-01

    Objective: In medical imaging, lowering radiation dose from computed tomography scanning, without reducing diagnostic performance is a desired achievement. Iterative image reconstruction may be one tool to achieve dose reduction. This study reports the diagnostic performance using a blending of 50% statistical iterative reconstruction (ASIR) and filtered back projection reconstruction (FBP) compared to standard FBP image reconstruction at different dose levels for liver phantom examinations. Methods: An anthropomorphic liver phantom was scanned at 250, 185, 155, 140, 120 and 100 mA s, on a 64-slice GE Lightspeed VCT scanner. All scans were reconstructed with ASIR and FBP. Four readers evaluated independently on a 5-point scale 21 images, each containing 32 test sectors. In total 672 areas were assessed. ROC analysis was used to evaluate the differences. Results: There was a difference in AUC between the 250 mA s FBP images and the 120 and 100 mA s FBP images. ASIR reconstruction gave a significantly higher diagnostic performance compared to standard reconstruction at 100 mA s. Conclusion: A blending of 50–90% ASIR and FBP may improve image quality of low dose CT examinations of the liver, and thus give a potential for reducing radiation dose.

  6. Maximum Likelihood Reconstruction for Magnetic Resonance Fingerprinting.

    Science.gov (United States)

    Zhao, Bo; Setsompop, Kawin; Ye, Huihui; Cauley, Stephen F; Wald, Lawrence L

    2016-08-01

    This paper introduces a statistical estimation framework for magnetic resonance (MR) fingerprinting, a recently proposed quantitative imaging paradigm. Within this framework, we present a maximum likelihood (ML) formalism to estimate multiple MR tissue parameter maps directly from highly undersampled, noisy k-space data. A novel algorithm, based on variable splitting, the alternating direction method of multipliers, and the variable projection method, is developed to solve the resulting optimization problem. Representative results from both simulations and in vivo experiments demonstrate that the proposed approach yields significantly improved accuracy in parameter estimation, compared to the conventional MR fingerprinting reconstruction. Moreover, the proposed framework provides new theoretical insights into the conventional approach. We show analytically that the conventional approach is an approximation to the ML reconstruction; more precisely, it is exactly equivalent to the first iteration of the proposed algorithm for the ML reconstruction, provided that a gridding reconstruction is used as an initialization.

  7. Medical image reconstruction. A conceptual tutorial

    International Nuclear Information System (INIS)

    Zeng, Gengsheng Lawrence

    2010-01-01

    ''Medical Image Reconstruction: A Conceptual Tutorial'' introduces the classical and modern image reconstruction technologies, such as two-dimensional (2D) parallel-beam and fan-beam imaging, three-dimensional (3D) parallel ray, parallel plane, and cone-beam imaging. This book presents both analytical and iterative methods of these technologies and their applications in X-ray CT (computed tomography), SPECT (single photon emission computed tomography), PET (positron emission tomography), and MRI (magnetic resonance imaging). Contemporary research results in exact region-of-interest (ROI) reconstruction with truncated projections, Katsevich's cone-beam filtered backprojection algorithm, and reconstruction with highly undersampled data with l 0 -minimization are also included. (orig.)

  8. Direct iterative reconstruction of computed tomography trajectories (DIRECTT)

    International Nuclear Information System (INIS)

    Lange, A.; Hentschel, M.P.; Schors, J.

    2004-01-01

    The direct reconstruction approach employs an iterative procedure by selection of and angular averaging over projected trajectory data of volume elements. This avoids the blur effects of the classical Fourier method due to the sampling theorem. But longer computing time is required. The reconstructed tomographic images reveal at least the spatial resolution of the radiation detector. Any set of projection angles may be selected for the measurements. Limited rotation of the object yields still good reconstruction of details. Projections of a partial region of the object can be reconstructed without additional artifacts thus reducing the overall radiation dose. Noisy signal data from low dose irradiation have low impact on spatial resolution. The image quality is monitored during all iteration steps and is pre-selected according to the specific requirements. DIRECTT can be applied independently from the measurement equipment in addition to conventional reconstruction or as a refinement filter. (author)

  9. Iterative concurrent reconstruction algorithms for emission computed tomography

    International Nuclear Information System (INIS)

    Brown, J.K.; Hasegawa, B.H.; Lang, T.F.

    1994-01-01

    Direct reconstruction techniques, such as those based on filtered backprojection, are typically used for emission computed tomography (ECT), even though it has been argued that iterative reconstruction methods may produce better clinical images. The major disadvantage of iterative reconstruction algorithms, and a significant reason for their lack of clinical acceptance, is their computational burden. We outline a new class of ''concurrent'' iterative reconstruction techniques for ECT in which the reconstruction process is reorganized such that a significant fraction of the computational processing occurs concurrently with the acquisition of ECT projection data. These new algorithms use the 10-30 min required for acquisition of a typical SPECT scan to iteratively process the available projection data, significantly reducing the requirements for post-acquisition processing. These algorithms are tested on SPECT projection data from a Hoffman brain phantom acquired with a 2 x 10 5 counts in 64 views each having 64 projections. The SPECT images are reconstructed as 64 x 64 tomograms, starting with six angular views. Other angular views are added to the reconstruction process sequentially, in a manner that reflects their availability for a typical acquisition protocol. The results suggest that if T s of concurrent processing are used, the reconstruction processing time required after completion of the data acquisition can be reduced by at least 1/3 T s. (Author)

  10. Application of iterative reconstruction in dynamic studies

    International Nuclear Information System (INIS)

    Meikle, S.R.

    1998-01-01

    Full text: The conventional approach to analysing dynamic tomographic data (SPECT or PET) is to reconstruct projections corresponding to each time interval separately and then fit a suitable tracer kinetic model to the dynamic sequence (method 1 ) . This approach assumes that the tracer distribution remains static during any given time interval and, for practical reasons, filtered back-projection (FBP) is the preferred reconstruction algorithm. However, alternative approaches exist which lend themselves to iterative algorithms, such as EM. One approach is to fit the model directly to the projection data, followed by EM reconstruction of the parameter estimates (method 2). This requires that the tracer model can be expressed as a linear function of the unknown model parameters. A third alternative is to incorporate the tracer model into the reconstruction algorithm (method 3). Such an extension was described during the early development of the EM algorithm, referred to as the EM parametric image reconstruction algorithm (EM-PIRA). We have investigated these various strategies for analysing dynamic data and their relative pros and cons. Tracer modelling was performed using a general model, referred to as spectral analysis, which makes no restriction on the number of physiological compartments and satisfies the linearity requirement of method 2. A kinetic software phantom was created and used to test the convergence and noise properties of the different approaches. In summary, method 2 is the most practical as it reduces the number of reconstructions by at least an order of magnitude and provides improved signal-to-noise ratios compared with method 1. EM-PIRA allows greater flexibility in the choice of parametric images and appears to have a regularising effect on convergence. Methods 2 and 3 are also better suited to dynamic scanning with a rotating camera, as they can potentially account for changes in tracer distribution between projections

  11. Apparatus and method for reconstructing data

    International Nuclear Information System (INIS)

    1981-01-01

    A method and apparatus is described for constructing a two-dimensional picture of an object slice from linear projections of radiation not absorbed or scattered by the object, using convolution methods of data reconstruction, useful in the fields of medical radiology, microscopy, and non-destructive testing. (U.K.)

  12. Diffusion of particles adsorbed on reconstructive surface

    Czech Academy of Sciences Publication Activity Database

    Tarasenko A., Nataliya; Tarasenko, Alexander; Jastrabík, Lubomír

    2005-01-01

    Roč. 11, č. 1 (2005), s. 485-489 ISSN 0929-5607 R&D Projects: GA MŠk LN00A015 Institutional research plan: CEZ:AV0Z10100522 Keywords : lattice gas * surface reconstruction * surface diffusion * phase transitions Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.323, year: 2005

  13. Virtual Reconstruction of Cultural Heritage Artifacts

    Czech Academy of Sciences Publication Activity Database

    Haindl, Michal; Sedláček, Matěj; Vávra, Radomír

    2015-01-01

    Roč. 2015, č. 103 (2015), s. 12-13 ISSN 0926-4981 R&D Projects: GA ČR(CZ) GA14-10911S Institutional support: RVO:67985556 Keywords : virtual reconstruction * shape modeling * surface modeling * bidirectional texture function Subject RIV: BD - Theory of Information http:// library .utia.cas.cz/separaty/2015/RO/haindl-0447984.pdf

  14. Update on orbital reconstruction.

    Science.gov (United States)

    Chen, Chien-Tzung; Chen, Yu-Ray

    2010-08-01

    Orbital trauma is common and frequently complicated by ocular injuries. The recent literature on orbital fracture is analyzed with emphasis on epidemiological data assessment, surgical timing, method of approach and reconstruction materials. Computed tomographic (CT) scan has become a routine evaluation tool for orbital trauma, and mobile CT can be applied intraoperatively if necessary. Concomitant serious ocular injury should be carefully evaluated preoperatively. Patients presenting with nonresolving oculocardiac reflex, 'white-eyed' blowout fracture, or diplopia with a positive forced duction test and CT evidence of orbital tissue entrapment require early surgical repair. Otherwise, enophthalmos can be corrected by late surgery with a similar outcome to early surgery. The use of an endoscope-assisted approach for orbital reconstruction continues to grow, offering an alternative method. Advances in alloplastic materials have improved surgical outcome and shortened operating time. In this review of modern orbital reconstruction, several controversial issues such as surgical indication, surgical timing, method of approach and choice of reconstruction material are discussed. Preoperative fine-cut CT image and thorough ophthalmologic examination are key elements to determine surgical indications. The choice of surgical approach and reconstruction materials much depends on the surgeon's experience and the reconstruction area. Prefabricated alloplastic implants together with image software and stereolithographic models are significant advances that help to more accurately reconstruct the traumatized orbit. The recent evolution of orbit reconstruction improves functional and aesthetic results and minimizes surgical complications.

  15. Spiral scan long object reconstruction through PI line reconstruction

    International Nuclear Information System (INIS)

    Tam, K C; Hu, J; Sourbelle, K

    2004-01-01

    The response of a point object in a cone beam (CB) spiral scan is analysed. Based on the result, a reconstruction algorithm for long object imaging in spiral scan cone beam CT is developed. A region-of-interest (ROI) of the long object is scanned with a detector smaller than the ROI, and a portion of it can be reconstructed without contamination from overlaying materials. The top and bottom surfaces of the ROI are defined by two sets of PI lines near the two ends of the spiral path. With this novel definition of the top and bottom ROI surfaces and through the use of projective geometry, it is straightforward to partition the cone beam image into regions corresponding to projections of the ROI, the overlaying objects or both. This also simplifies computation at source positions near the spiral ends, and makes it possible to reduce radiation exposure near the spiral ends substantially through simple hardware collimation. Simulation results to validate the algorithm are presented

  16. Permutationally invariant state reconstruction

    DEFF Research Database (Denmark)

    Moroder, Tobias; Hyllus, Philipp; Tóth, Géza

    2012-01-01

    Feasible tomography schemes for large particle numbers must possess, besides an appropriate data acquisition protocol, an efficient way to reconstruct the density operator from the observed finite data set. Since state reconstruction typically requires the solution of a nonlinear large-scale opti...... optimization, which has clear advantages regarding speed, control and accuracy in comparison to commonly employed numerical routines. First prototype implementations easily allow reconstruction of a state of 20 qubits in a few minutes on a standard computer.......-scale optimization problem, this is a major challenge in the design of scalable tomography schemes. Here we present an efficient state reconstruction scheme for permutationally invariant quantum state tomography. It works for all common state-of-the-art reconstruction principles, including, in particular, maximum...

  17. Neutrino Event Reconstruction in a Liquid Argon TPC

    Energy Technology Data Exchange (ETDEWEB)

    Barker, Gary, E-mail: G.J.Barker@Warwick.ac.uk [Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL (United Kingdom)

    2011-07-25

    We present some preliminary findings and results from activities in Europe and the USA working towards an automated, algorithmic, reconstruction of particle interactions in liquid argon time projection chambers.

  18. Simulation and track reconstruction for beam telescopes

    CERN Document Server

    Maqbool, Salman

    2017-01-01

    Beam telescopes are used for testing new detectors under development. Sensors are placed and a particle beam is passed through them. To test these novel detectors and determine their properties, the particle tracks need to be reconstructed from the known detectors in the telescope. Based on the reconstructed track, it’s predicted hits on the Device under Test (DUT) are compared with the actual hits on the DUT. Several methods exist for track reconstruction, but most of them don’t account for the effects of multiple scattering. General Broken Lines is one such algorithm which incorporates these effects during reconstruction. The aim of this project was to simulate the beam telescope and extend the track reconstruction framework for the FE-I4 telescope, which takes these effects into account. Section 1 introduces the problem, while section 2 focuses on beam telescopes. This is followed by the Allpix2 simulation framework in Section 3. And finally, Section 4 introduces the Proteus track reconstruction framew...

  19. A Statistical Approach to Motion Compensated Cone Beam Reconstruction

    DEFF Research Database (Denmark)

    Lyksborg, Mark; Hansen, Mads Fogtmann; Larsen, Rasmus

    2010-01-01

    number of projections to be adequate. Since the patients are breathing freely during a scan, the number of projections with similar respiration may be to low. In the following we use an iterative reconstruction combined with the simultaneous estimation of the motion field, to improve reconstruction...... in these situations. Using a simulated dataset we demonstrate that this combination outperforms the FDK but due to ill possessedness of the motion estimation it is only on par with the sole iterative method....

  20. Benefits of sinogram-affirmed iterative reconstruction in 0.4 mSv ultra-low-dose CT of the upper abdomen following transarterial chemoembolisation: comparison to low-dose and standard-dose CT and filtered back projection technique

    International Nuclear Information System (INIS)

    Bodelle, B.; Isler, S.; Scholtz, J.-E.; Frellesen, C.; Luboldt, W.; Vogl, T.J.; Beeres, M.

    2016-01-01

    Aim: To evaluate the advantage of sinogram-affirmed iterative reconstruction (SIR) compared to filtered back projection (FBP) in upper abdomen computed tomography (CT) after transarterial chemoembolisation (TACE) at different tube currents. Materials and methods: The study was approved by the institutional review board. Written informed consent was obtained from all patients. Post-TACE CT was performed with different tube currents successively varied in four steps (180, 90, 45 and 23 mAs) with 40 patients per group (mean age: 60±12 years, range: 23–85 years, sex: 70 female, 90 male). The data were reconstructed with standard FBP and five different SIR strengths. Image quality was independently rated by two readers on a five-point scale. High (Lipiodol-to-liver) as well as low (liver-to-fat) contrast-to-noise ratios (CNRs) were intra-individually compared within one dose to determine the optimal strength (S1–S5) and inter-individually between different doses to determine the possibility of dose reduction using the Kruskal–Wallis test. Results: Subjective image quality and objective CNR analysis were concordant: intra-individually, SIR was significantly (p<0.001) superior to FBP. Inter-individually, regarding different doses (180 versus 23 ref mAs), there was no significant (p=1.00) difference when using S5 SIR at 23 mAs instead of FBP. Conclusion: SIR allows for an 88% dose reduction from 3.43 to 0.4 mSv in unenhanced CT of the liver following TACE without subjective or objective loss in image quality. - Highlights: • Diagnostic image quality and radiation dose of ultra-low-dose CT of the upper abdomen using sinogram affirmed iterative reconstruction following transarterial chemoembolization in comparison to low-dose and standard dose CT and filtered back projection technique. • Ultra-low dose CT of the upper abdomen using sinogram affirmed iterative reconstruction allows for significant dose reduction by 88%. • Ultra-low dose CT of the upper abdomen

  1. Total Variation and Tomographic Imaging from Projections

    DEFF Research Database (Denmark)

    Hansen, Per Christian; Jørgensen, Jakob Heide

    2011-01-01

    or 3D reconstruction from noisy projections. We demonstrate that for a small signal-to-noise ratio, this new approach allows us to compute better (i.e., more reliable) reconstructions than those obtained by classical methods. This is possible due to the use of the TV reconstruction model, which...

  2. Hybrid spectral CT reconstruction.

    Directory of Open Access Journals (Sweden)

    Darin P Clark

    Full Text Available Current photon counting x-ray detector (PCD technology faces limitations associated with spectral fidelity and photon starvation. One strategy for addressing these limitations is to supplement PCD data with high-resolution, low-noise data acquired with an energy-integrating detector (EID. In this work, we propose an iterative, hybrid reconstruction technique which combines the spectral properties of PCD data with the resolution and signal-to-noise characteristics of EID data. Our hybrid reconstruction technique is based on an algebraic model of data fidelity which substitutes the EID data into the data fidelity term associated with the PCD reconstruction, resulting in a joint reconstruction problem. Within the split Bregman framework, these data fidelity constraints are minimized subject to additional constraints on spectral rank and on joint intensity-gradient sparsity measured between the reconstructions of the EID and PCD data. Following a derivation of the proposed technique, we apply it to the reconstruction of a digital phantom which contains realistic concentrations of iodine, barium, and calcium encountered in small-animal micro-CT. The results of this experiment suggest reliable separation and detection of iodine at concentrations ≥ 5 mg/ml and barium at concentrations ≥ 10 mg/ml in 2-mm features for EID and PCD data reconstructed with inherent spatial resolutions of 176 μm and 254 μm, respectively (point spread function, FWHM. Furthermore, hybrid reconstruction is demonstrated to enhance spatial resolution within material decomposition results and to improve low-contrast detectability by as much as 2.6 times relative to reconstruction with PCD data only. The parameters of the simulation experiment are based on an in vivo micro-CT experiment conducted in a mouse model of soft-tissue sarcoma. Material decomposition results produced from this in vivo data demonstrate the feasibility of distinguishing two K-edge contrast agents with

  3. Hybrid spectral CT reconstruction

    Science.gov (United States)

    Clark, Darin P.

    2017-01-01

    Current photon counting x-ray detector (PCD) technology faces limitations associated with spectral fidelity and photon starvation. One strategy for addressing these limitations is to supplement PCD data with high-resolution, low-noise data acquired with an energy-integrating detector (EID). In this work, we propose an iterative, hybrid reconstruction technique which combines the spectral properties of PCD data with the resolution and signal-to-noise characteristics of EID data. Our hybrid reconstruction technique is based on an algebraic model of data fidelity which substitutes the EID data into the data fidelity term associated with the PCD reconstruction, resulting in a joint reconstruction problem. Within the split Bregman framework, these data fidelity constraints are minimized subject to additional constraints on spectral rank and on joint intensity-gradient sparsity measured between the reconstructions of the EID and PCD data. Following a derivation of the proposed technique, we apply it to the reconstruction of a digital phantom which contains realistic concentrations of iodine, barium, and calcium encountered in small-animal micro-CT. The results of this experiment suggest reliable separation and detection of iodine at concentrations ≥ 5 mg/ml and barium at concentrations ≥ 10 mg/ml in 2-mm features for EID and PCD data reconstructed with inherent spatial resolutions of 176 μm and 254 μm, respectively (point spread function, FWHM). Furthermore, hybrid reconstruction is demonstrated to enhance spatial resolution within material decomposition results and to improve low-contrast detectability by as much as 2.6 times relative to reconstruction with PCD data only. The parameters of the simulation experiment are based on an in vivo micro-CT experiment conducted in a mouse model of soft-tissue sarcoma. Material decomposition results produced from this in vivo data demonstrate the feasibility of distinguishing two K-edge contrast agents with a spectral

  4. Multichannel algorithm for fast 3D reconstruction

    International Nuclear Information System (INIS)

    Rodet, Thomas; Grangeat, Pierre; Desbat, Laurent

    2002-01-01

    Some recent medical imaging applications such as functional imaging (PET and SPECT) or interventional imaging (CT fluoroscopy) involve increasing amounts of data. In order to reduce the image reconstruction time, we develop a new fast 3D reconstruction algorithm based on a divide and conquer approach. The proposed multichannel algorithm performs an indirect frequential subband decomposition of the image f to be reconstructed (f=Σf j ) through the filtering of the projections Rf. The subband images f j are reconstructed on a downsampled grid without information suppression. In order to reduce the computation time, we do not backproject the null filtered projections and we downsample the number of projections according to the Shannon conditions associated with the subband image. Our algorithm is based on filtering and backprojection operators. Using the same algorithms for these basic operators, our approach is three and a half times faster than a classical FBP algorithm for a 2D image 512x512 and six times faster for a 3D image 32x512x512. (author)

  5. Tensor-based Dictionary Learning for Dynamic Tomographic Reconstruction

    Science.gov (United States)

    Tan, Shengqi; Zhang, Yanbo; Wang, Ge; Mou, Xuanqin; Cao, Guohua; Wu, Zhifang; Yu, Hengyong

    2015-01-01

    In dynamic computed tomography (CT) reconstruction, the data acquisition speed limits the spatio-temporal resolution. Recently, compressed sensing theory has been instrumental in improving CT reconstruction from far few-view projections. In this paper, we present an adaptive method to train a tensor-based spatio-temporal dictionary for sparse representation of an image sequence during the reconstruction process. The correlations among atoms and across phases are considered to capture the characteristics of an object. The reconstruction problem is solved by the alternating direction method of multipliers. To recover fine or sharp structures such as edges, the nonlocal total variation is incorporated into the algorithmic framework. Preclinical examples including a sheep lung perfusion study and a dynamic mouse cardiac imaging demonstrate that the proposed approach outperforms the vectorized dictionary-based CT reconstruction in the case of few-view reconstruction. PMID:25779991

  6. Evaluation of proxy-based millennial reconstruction methods

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Terry C.K.; Tsao, Min [University of Victoria, Department of Mathematics and Statistics, Victoria, BC (Canada); Zwiers, Francis W. [Environment Canada, Climate Research Division, Toronto, ON (Canada)

    2008-08-15

    A range of existing statistical approaches for reconstructing historical temperature variations from proxy data are compared using both climate model data and real-world paleoclimate proxy data. We also propose a new method for reconstruction that is based on a state-space time series model and Kalman filter algorithm. The state-space modelling approach and the recently developed RegEM method generally perform better than their competitors when reconstructing interannual variations in Northern Hemispheric mean surface air temperature. On the other hand, a variety of methods are seen to perform well when reconstructing surface air temperature variability on decadal time scales. An advantage of the new method is that it can incorporate additional, non-temperature, information into the reconstruction, such as the estimated response to external forcing, thereby permitting a simultaneous reconstruction and detection analysis as well as future projection. An application of these extensions is also demonstrated in the paper. (orig.)

  7. Tensor-based dictionary learning for dynamic tomographic reconstruction

    International Nuclear Information System (INIS)

    Tan, Shengqi; Wu, Zhifang; Zhang, Yanbo; Mou, Xuanqin; Wang, Ge; Cao, Guohua; Yu, Hengyong

    2015-01-01

    In dynamic computed tomography (CT) reconstruction, the data acquisition speed limits the spatio-temporal resolution. Recently, compressed sensing theory has been instrumental in improving CT reconstruction from far few-view projections. In this paper, we present an adaptive method to train a tensor-based spatio-temporal dictionary for sparse representation of an image sequence during the reconstruction process. The correlations among atoms and across phases are considered to capture the characteristics of an object. The reconstruction problem is solved by the alternating direction method of multipliers. To recover fine or sharp structures such as edges, the nonlocal total variation is incorporated into the algorithmic framework. Preclinical examples including a sheep lung perfusion study and a dynamic mouse cardiac imaging demonstrate that the proposed approach outperforms the vectorized dictionary-based CT reconstruction in the case of few-view reconstruction. (paper)

  8. Improving head and neck CTA with hybrid and model-based iterative reconstruction techniques

    NARCIS (Netherlands)

    Niesten, J. M.; van der Schaaf, I. C.; Vos, P. C.; Willemink, MJ; Velthuis, B. K.

    2015-01-01

    AIM: To compare image quality of head and neck computed tomography angiography (CTA) reconstructed with filtered back projection (FBP), hybrid iterative reconstruction (HIR) and model-based iterative reconstruction (MIR) algorithms. MATERIALS AND METHODS: The raw data of 34 studies were

  9. Electro-optical system for the high speed reconstruction of computed tomography images

    International Nuclear Information System (INIS)

    Tresp, V.

    1989-01-01

    An electro-optical system for the high-speed reconstruction of computed tomography (CT) images has been built and studied. The system is capable of reconstructing high-contrast and high-resolution images at video rate (30 images per second), which is more than two orders of magnitude faster than the reconstruction rate achieved by special purpose digital computers used in commercial CT systems. The filtered back-projection algorithm which was implemented in the reconstruction system requires the filtering of all projections with a prescribed filter function. A space-integrating acousto-optical convolver, a surface acoustic wave filter and a digital finite-impulse response filter were used for this purpose and their performances were compared. The second part of the reconstruction, the back projection of the filtered projections, is computationally very expensive. An optical back projector has been built which maps the filtered projections onto the two-dimensional image space using an anamorphic lens system and a prism image rotator. The reconstructed image is viewed by a video camera, routed through a real-time image-enhancement system, and displayed on a TV monitor. The system reconstructs parallel-beam projection data, and in a modified version, is also capable of reconstructing fan-beam projection data. This extension is important since the latter are the kind of projection data actually acquired in high-speed X-ray CT scanners. The reconstruction system was tested by reconstructing precomputed projection data of phantom images. These were stored in a special purpose projection memory and transmitted to the reconstruction system as an electronic signal. In this way, a projection measurement system that acquires projections sequentially was simulated

  10. Quantitative tomography simulations and reconstruction algorithms

    International Nuclear Information System (INIS)

    Martz, H.E.; Aufderheide, M.B.; Goodman, D.; Schach von Wittenau, A.; Logan, C.; Hall, J.; Jackson, J.; Slone, D.

    2000-01-01

    X-ray, neutron and proton transmission radiography and computed tomography (CT) are important diagnostic tools that are at the heart of LLNL's effort to meet the goals of the DOE's Advanced Radiography Campaign. This campaign seeks to improve radiographic simulation and analysis so that radiography can be a useful quantitative diagnostic tool for stockpile stewardship. Current radiographic accuracy does not allow satisfactory separation of experimental effects from the true features of an object's tomographically reconstructed image. This can lead to difficult and sometimes incorrect interpretation of the results. By improving our ability to simulate the whole radiographic and CT system, it will be possible to examine the contribution of system components to various experimental effects, with the goal of removing or reducing them. In this project, we are merging this simulation capability with a maximum-likelihood (constrained-conjugate-gradient-CCG) reconstruction technique yielding a physics-based, forward-model image-reconstruction code. In addition, we seek to improve the accuracy of computed tomography from transmission radiographs by studying what physics is needed in the forward model. During FY 2000, an improved version of the LLNL ray-tracing code called HADES has been coupled with a recently developed LLNL CT algorithm known as CCG. The problem of image reconstruction is expressed as a large matrix equation relating a model for the object being reconstructed to its projections (radiographs). Using a constrained-conjugate-gradient search algorithm, a maximum likelihood solution is sought. This search continues until the difference between the input measured radiographs or projections and the simulated or calculated projections is satisfactorily small

  11. The evolving breast reconstruction

    DEFF Research Database (Denmark)

    Thomsen, Jørn Bo; Gunnarsson, Gudjon Leifur

    2014-01-01

    The aim of this editorial is to give an update on the use of the propeller thoracodorsal artery perforator flap (TAP/TDAP-flap) within the field of breast reconstruction. The TAP-flap can be dissected by a combined use of a monopolar cautery and a scalpel. Microsurgical instruments are generally...... not needed. The propeller TAP-flap can be designed in different ways, three of these have been published: (I) an oblique upwards design; (II) a horizontal design; (III) an oblique downward design. The latissimus dorsi-flap is a good and reliable option for breast reconstruction, but has been criticized...... for oncoplastic and reconstructive breast surgery and will certainly become an invaluable addition to breast reconstructive methods....

  12. Forging Provincial Reconstruction Teams

    National Research Council Canada - National Science Library

    Honore, Russel L; Boslego, David V

    2007-01-01

    The Provincial Reconstruction Team (PRT) training mission completed by First U.S. Army in April 2006 was a joint Service effort to meet a requirement from the combatant commander to support goals in Afghanistan...

  13. Breast Reconstruction with Implants

    Science.gov (United States)

    ... your surgical options and discuss the advantages and disadvantages of implant-based reconstruction, and may show you ... Policy Notice of Privacy Practices Notice of Nondiscrimination Advertising Mayo Clinic is a not-for-profit organization ...

  14. Ultra-Fast Image Reconstruction of Tomosynthesis Mammography Using GPU.

    Science.gov (United States)

    Arefan, D; Talebpour, A; Ahmadinejhad, N; Kamali Asl, A

    2015-06-01

    Digital Breast Tomosynthesis (DBT) is a technology that creates three dimensional (3D) images of breast tissue. Tomosynthesis mammography detects lesions that are not detectable with other imaging systems. If image reconstruction time is in the order of seconds, we can use Tomosynthesis systems to perform Tomosynthesis-guided Interventional procedures. This research has been designed to study ultra-fast image reconstruction technique for Tomosynthesis Mammography systems using Graphics Processing Unit (GPU). At first, projections of Tomosynthesis mammography have been simulated. In order to produce Tomosynthesis projections, it has been designed a 3D breast phantom from empirical data. It is based on MRI data in its natural form. Then, projections have been created from 3D breast phantom. The image reconstruction algorithm based on FBP was programmed with C++ language in two methods using central processing unit (CPU) card and the Graphics Processing Unit (GPU). It calculated the time of image reconstruction in two kinds of programming (using CPU and GPU).

  15. A combinational fast algorithm for image reconstruction

    International Nuclear Information System (INIS)

    Wu Zhongquan

    1987-01-01

    A combinational fast algorithm has been developed in order to increase the speed of reconstruction. First, an interpolation method based on B-spline functions is used in image reconstruction. Next, the influence of the boundary conditions assumed here on the interpolation of filtered projections and on the image reconstruction is discussed. It is shown that this boundary condition has almost no influence on the image in the central region of the image space, because the error of interpolation rapidly decreases by a factor of ten in shifting two pixels from the edge toward the center. In addition, a fast algorithm for computing the detecting angle has been used with the mentioned interpolation algorithm, and the cost for detecting angle computaton is reduced by a factor of two. The implementation results show that in the same subjective and objective fidelity, the computational cost for the interpolation using this algorithm is about one-twelfth of the conventional algorithm

  16. Image reconstruction methods in positron tomography

    International Nuclear Information System (INIS)

    Townsend, D.W.; Defrise, M.

    1993-01-01

    In the two decades since the introduction of the X-ray scanner into radiology, medical imaging techniques have become widely established as essential tools in the diagnosis of disease. As a consequence of recent technological and mathematical advances, the non-invasive, three-dimensional imaging of internal organs such as the brain and the heart is now possible, not only for anatomical investigations using X-ray but also for studies which explore the functional status of the body using positron-emitting radioisotopes. This report reviews the historical and physical basis of medical imaging techniques using positron-emitting radioisotopes. Mathematical methods which enable three-dimensional distributions of radioisotopes to be reconstructed from projection data (sinograms) acquired by detectors suitably positioned around the patient are discussed. The extension of conventional two-dimensional tomographic reconstruction algorithms to fully three-dimensional reconstruction is described in detail. (orig.)

  17. European bank for reconstruction and development

    Directory of Open Access Journals (Sweden)

    Kastratović Radovan

    2015-01-01

    Full Text Available European Bank for Reconstruction and Development - EBRD was established in the year 1991 and commenced operations in 1991. The objective of the Bank was to instigate market oriented approach to business in the countries of Central and Eastern Europe. This comprises support offered to structural reforms, privatisation, and development of entrepreneurship and legal system through financing of project conducive to the achievement of the aimed targets. The Bank approves loans both to the nation states and to the private sector. European Bank for Reconstruction and Development often appears in the role of investor. In addition, the Bank has also its consultative function. Owners of the European Bank for Reconstruction and Development are the developed countries and those that participate in the distribution of the Bank's profit. The Bank invests in the countries of Central, Eastern and South-East Europe, but also in those of Central Asia and Southern Mediterranean. The importance that the European Bank for Reconstruction and Development has for our country is best illustrated by the fact that this Bank is our largest institutional investor, with investments exceeding 3.5 billion EUR. This work begins with presentation of general information on the work of the European Bank for Reconstruction and Development, its objectives, activities, background history, ownership and organisational structure. It proceeds by giving relevant data on the Bank's business operations - the manner of project financing, the Bank's funds distribution per geographic criteria and activities, and the operative and financial results of the Bank's business activities. Brief description is also offered of the cooperation that the European Bank has with other international financial institutions. Finally, data is given bearing witness on the importance that the European Bank for Reconstruction and Development has for Serbia.

  18. Fully 3D GPU PET reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Herraiz, J.L., E-mail: joaquin@nuclear.fis.ucm.es [Grupo de Fisica Nuclear, Departmento Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid (Spain); Espana, S. [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Cal-Gonzalez, J. [Grupo de Fisica Nuclear, Departmento Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid (Spain); Vaquero, J.J. [Departmento de Bioingenieria e Ingenieria Espacial, Universidad Carlos III, Madrid (Spain); Desco, M. [Departmento de Bioingenieria e Ingenieria Espacial, Universidad Carlos III, Madrid (Spain); Unidad de Medicina y Cirugia Experimental, Hospital General Universitario Gregorio Maranon, Madrid (Spain); Udias, J.M. [Grupo de Fisica Nuclear, Departmento Fisica Atomica, Molecular y Nuclear, Universidad Complutense de Madrid (Spain)

    2011-08-21

    Fully 3D iterative tomographic image reconstruction is computationally very demanding. Graphics Processing Unit (GPU) has been proposed for many years as potential accelerators in complex scientific problems, but it has not been used until the recent advances in the programmability of GPUs that the best available reconstruction codes have started to be implemented to be run on GPUs. This work presents a GPU-based fully 3D PET iterative reconstruction software. This new code may reconstruct sinogram data from several commercially available PET scanners. The most important and time-consuming parts of the code, the forward and backward projection operations, are based on an accurate model of the scanner obtained with the Monte Carlo code PeneloPET and they have been massively parallelized on the GPU. For the PET scanners considered, the GPU-based code is more than 70 times faster than a similar code running on a single core of a fast CPU, obtaining in both cases the same images. The code has been designed to be easily adapted to reconstruct sinograms from any other PET scanner, including scanner prototypes.

  19. Fully 3D GPU PET reconstruction

    International Nuclear Information System (INIS)

    Herraiz, J.L.; Espana, S.; Cal-Gonzalez, J.; Vaquero, J.J.; Desco, M.; Udias, J.M.

    2011-01-01

    Fully 3D iterative tomographic image reconstruction is computationally very demanding. Graphics Processing Unit (GPU) has been proposed for many years as potential accelerators in complex scientific problems, but it has not been used until the recent advances in the programmability of GPUs that the best available reconstruction codes have started to be implemented to be run on GPUs. This work presents a GPU-based fully 3D PET iterative reconstruction software. This new code may reconstruct sinogram data from several commercially available PET scanners. The most important and time-consuming parts of the code, the forward and backward projection operations, are based on an accurate model of the scanner obtained with the Monte Carlo code PeneloPET and they have been massively parallelized on the GPU. For the PET scanners considered, the GPU-based code is more than 70 times faster than a similar code running on a single core of a fast CPU, obtaining in both cases the same images. The code has been designed to be easily adapted to reconstruct sinograms from any other PET scanner, including scanner prototypes.

  20. Distributed 3-D iterative reconstruction for quantitative SPECT

    International Nuclear Information System (INIS)

    Ju, Z.W.; Frey, E.C.; Tsui, B.M.W.

    1995-01-01

    The authors describe a distributed three dimensional (3-D) iterative reconstruction library for quantitative single-photon emission computed tomography (SPECT). This library includes 3-D projector-backprojector pairs (PBPs) and distributed 3-D iterative reconstruction algorithms. The 3-D PBPs accurately and efficiently model various combinations of the image degrading factors including attenuation, detector response and scatter response. These PBPs were validated by comparing projection data computed using the projectors with that from direct Monte Carlo (MC) simulations. The distributed 3-D iterative algorithms spread the projection-backprojection operations for all the projection angles over a heterogeneous network of single or multi-processor computers to reduce the reconstruction time. Based on a master/slave paradigm, these distributed algorithms provide dynamic load balancing and fault tolerance. The distributed algorithms were verified by comparing images reconstructed using both the distributed and non-distributed algorithms. Computation times for distributed 3-D reconstructions running on up to 4 identical processors were reduced by a factor approximately 80--90% times the number of the processors participating, compared to those for non-distributed 3-D reconstructions running on a single processor. When combined with faster affordable computers, this library provides an efficient means for implementing accurate reconstruction and compensation methods to improve quality and quantitative accuracy in SPECT images

  1. Industrial dynamic tomographic reconstruction

    International Nuclear Information System (INIS)

    Oliveira, Eric Ferreira de

    2016-01-01

    The state of the art methods applied to industrial processes is currently based on the principles of classical tomographic reconstructions developed for tomographic patterns of static distributions, or is limited to cases of low variability of the density distribution function of the tomographed object. Noise and motion artifacts are the main problems caused by a mismatch in the data from views acquired in different instants. All of these add to the known fact that using a limited amount of data can result in the presence of noise, artifacts and some inconsistencies with the distribution under study. One of the objectives of the present work is to discuss the difficulties that arise from implementing reconstruction algorithms in dynamic tomography that were originally developed for static distributions. Another objective is to propose solutions that aim at reducing a temporal type of information loss caused by employing regular acquisition systems to dynamic processes. With respect to dynamic image reconstruction it was conducted a comparison between different static reconstruction methods, like MART and FBP, when used for dynamic scenarios. This comparison was based on a MCNPx simulation as well as an analytical setup of an aluminum cylinder that moves along the section of a riser during the process of acquisition, and also based on cross section images from CFD techniques. As for the adaptation of current tomographic acquisition systems for dynamic processes, this work established a sequence of tomographic views in a just-in-time fashion for visualization purposes, a form of visually disposing density information as soon as it becomes amenable to image reconstruction. A third contribution was to take advantage of the triple color channel necessary to display colored images in most displays, so that, by appropriately scaling the acquired values of each view in the linear system of the reconstruction, it was possible to imprint a temporal trace into the regularly

  2. Analytical inversion formula for uniformly attenuated fan-beam projections

    International Nuclear Information System (INIS)

    Weng, Y.; Zeng, G.L.; Gullberg, G.T.

    1997-01-01

    In deriving algorithms to reconstruct single photon emission computed tomography (SPECT) projection data, it is important that the algorithm compensates for photon attenuation in order to obtain quantitative reconstruction results. A convolution backprojection algorithm was derived by Tretiak and Metz to reconstruct two-dimensional (2-D) transaxial slices from uniformly attenuated parallel-beam projections. Using transformation of coordinates, this algorithm can be modified to obtain a formulation useful to reconstruct uniformly attenuated fan-beam projections. Unlike that for parallel-beam projections, this formulation does not produce a filtered backprojection reconstruction algorithm but instead has a formulation that is an inverse integral operator with a spatially varying kernel. This algorithm thus requires more computation time than does the filtered backprojection reconstruction algorithm for the uniformly attenuated parallel-beam case. However, the fan-beam reconstructions demonstrate the same image quality as that of parallel-beam reconstructions

  3. Alternative reconstruction after pancreaticoduodenectomy

    Directory of Open Access Journals (Sweden)

    Cooperman Avram M

    2008-01-01

    Full Text Available Abstract Background Pancreaticoduodenectomy is the procedure of choice for tumors of the head of the pancreas and periampulla. Despite advances in surgical technique and postoperative care, the procedure continues to carry a high morbidity rate. One of the most common morbidities is delayed gastric emptying with rates of 15%–40%. Following two prolonged cases of delayed gastric emptying, we altered our reconstruction to avoid this complication altogether. Subsequently, our patients underwent a classic pancreaticoduodenectomy with an undivided Roux-en-Y technique for reconstruction. Methods We reviewed the charts of our last 13 Whipple procedures evaluating them for complications, specifically delayed gastric emptying. We compared the outcomes of those patients to a control group of 15 patients who underwent the Whipple procedure with standard reconstruction. Results No instances of delayed gastric emptying occurred in patients who underwent an undivided Roux-en-Y technique for reconstruction. There was 1 wound infection (8%, 1 instance of pneumonia (8%, and 1 instance of bleeding from the gastrojejunal staple line (8%. There was no operative mortality. Conclusion Use of the undivided Roux-en-Y technique for reconstruction following the Whipple procedure may decrease the incidence of delayed gastric emptying. In addition, it has the added benefit of eliminating bile reflux gastritis. Future randomized control trials are recommended to further evaluate the efficacy of the procedure.

  4. Optimisation of the ATLAS Track Reconstruction Software for Run-2

    CERN Document Server

    Salzburger, Andreas; The ATLAS collaboration

    2015-01-01

    Track reconstruction is one of the most complex element of the reconstruction of events recorded by ATLAS from collisions delivered by the LHC. It is the most time consuming reconstruction component in high luminosity environments. The flat budget projections for computing resources for Run-2 of the LHC together with the demands of reconstructing higher pile-up collision data at rates more than double those in Run-1 (an increase from 400 Hz to 1 kHz in trigger output) have put stringent requirements on the track reconstruction software. The ATLAS experiment has performed a two year long software campaign which aimed to reduce the reconstruction rate by a factor of three to meet the resource limitations for Run-2: the majority of the changes to achieve this were improvements to the track reconstruction software. The CPU processing time of ATLAS track reconstruction was reduced by more than a factor of three during this campaign without any loss of output information of the track reconstruction. We present the ...

  5. Neural Network for Sparse Reconstruction

    Directory of Open Access Journals (Sweden)

    Qingfa Li

    2014-01-01

    Full Text Available We construct a neural network based on smoothing approximation techniques and projected gradient method to solve a kind of sparse reconstruction problems. Neural network can be implemented by circuits and can be seen as an important method for solving optimization problems, especially large scale problems. Smoothing approximation is an efficient technique for solving nonsmooth optimization problems. We combine these two techniques to overcome the difficulties of the choices of the step size in discrete algorithms and the item in the set-valued map of differential inclusion. In theory, the proposed network can converge to the optimal solution set of the given problem. Furthermore, some numerical experiments show the effectiveness of the proposed network in this paper.

  6. Reconstruction of emission coefficients for a non-axisymmetric coupling arc by algebraic reconstruction technique

    International Nuclear Information System (INIS)

    Zhang Guangjun; Xiong Jun; Gao Hongming; Wu Lin

    2011-01-01

    A preliminary investigation of tomographic reconstruction of an asymmetric arc plasma has been carried out. The objective of this work aims at reconstructing emission coefficients of a non-axisymmetric coupling arc from measured intensities by means of an algebraic reconstruction technique (ART). In order to define the optimal experimental scheme for good quality with limited views, the dependence of the reconstruction quality on three configurations (four, eight, ten projection angles) are presented and discussed via a displaced Gaussian model. Then, the emission coefficients of a free burning arc are reconstructed by the ART with the ten-view configuration and an Abel inversion, respectively, and good agreement is obtained. Finally, the emission coefficient profiles of the coupling arc are successfully achieved with the ten-view configuration. The results show that the distribution of emission coefficient for the coupling arc is different from centrosymmetric shape. The ART is perfectly suitable for reconstructing emission coefficients of the coupling arc with the ten-view configuration, proving the feasibility and utility of the ART to characterize an asymmetric arc.

  7. Reconstructing random media

    International Nuclear Information System (INIS)

    Yeong, C.L.; Torquato, S.

    1998-01-01

    We formulate a procedure to reconstruct the structure of general random heterogeneous media from limited morphological information by extending the methodology of Rintoul and Torquato [J. Colloid Interface Sci. 186, 467 (1997)] developed for dispersions. The procedure has the advantages that it is simple to implement and generally applicable to multidimensional, multiphase, and anisotropic structures. Furthermore, an extremely useful feature is that it can incorporate any type and number of correlation functions in order to provide as much morphological information as is necessary for accurate reconstruction. We consider a variety of one- and two-dimensional reconstructions, including periodic and random arrays of rods, various distribution of disks, Debye random media, and a Fontainebleau sandstone sample. We also use our algorithm to construct heterogeneous media from specified hypothetical correlation functions, including an exponentially damped, oscillating function as well as physically unrealizable ones. copyright 1998 The American Physical Society

  8. Delayed breast implant reconstruction

    DEFF Research Database (Denmark)

    Hvilsom, Gitte B.; Hölmich, Lisbet R.; Steding-Jessen, Marianne

    2012-01-01

    We evaluated the association between radiation therapy and severe capsular contracture or reoperation after 717 delayed breast implant reconstruction procedures (288 1- and 429 2-stage procedures) identified in the prospective database of the Danish Registry for Plastic Surgery of the Breast during...... of radiation therapy was associated with a non-significantly increased risk of reoperation after both 1-stage (HR = 1.4; 95% CI: 0.7-2.5) and 2-stage (HR = 1.6; 95% CI: 0.9-3.1) procedures. Reconstruction failure was highest (13.2%) in the 2-stage procedures with a history of radiation therapy. Breast...... reconstruction approaches other than implants should be seriously considered among women who have received radiation therapy....

  9. Image reconstruction in computerized tomography using the convolution method

    International Nuclear Information System (INIS)

    Oliveira Rebelo, A.M. de.

    1984-03-01

    In the present work an algoritin was derived, using the analytical convolution method (filtered back-projection) for two-dimensional or three-dimensional image reconstruction in computerized tomography applied to non-destructive testing and to the medical use. This mathematical model is based on the analytical Fourier transform method for image reconstruction. This model consists of a discontinuous system formed by an NxN array of cells (pixels). The attenuation in the object under study of a colimated gamma ray beam has been determined for various positions and incidence angles (projections) in terms of the interaction of the beam with the intercepted pixels. The contribution of each pixel to beam attenuation was determined using the weight function W ij which was used for simulated tests. Simulated tests using standard objects with attenuation coefficients in the range of 0,2 to 0,7 cm -1 were carried out using cell arrays of up to 25x25. One application was carried out in the medical area simulating image reconstruction of an arm phantom with attenuation coefficients in the range of 0,2 to 0,5 cm -1 using cell arrays of 41x41. The simulated results show that, in objects with a great number of interfaces and great variations of attenuation coefficients at these interfaces, a good reconstruction is obtained with the number of projections equal to the reconstruction matrix dimension. A good reconstruction is otherwise obtained with fewer projections. (author) [pt

  10. HEEL BONE RECONSTRUCTIVE OSTEOSYNTHESIS

    Directory of Open Access Journals (Sweden)

    A. N. Svetashov

    2010-01-01

    Full Text Available To detect the most appropriate to heel bone injury severity variants of reconstructive osteosynthesis it was analyzed treatment results of 56 patients. In 15 (26.8% patients classic methods of surgical service were applied, in 41 (73.2% cases to restore the defect porous implants were used. Osteosynthesis without heel bone plastic restoration accomplishment was ineffective in 60% patients from control group. Reconstructive osteosynthesis method ensures long-term good functional effect of rehabilitation in 96.4% patients from the basic group.

  11. Vertex reconstruction in CMS

    International Nuclear Information System (INIS)

    Chabanat, E.; D'Hondt, J.; Estre, N.; Fruehwirth, R.; Prokofiev, K.; Speer, T.; Vanlaer, P.; Waltenberger, W.

    2005-01-01

    Due to the high track multiplicity in the final states expected in proton collisions at the LHC experiments, novel vertex reconstruction algorithms are required. The vertex reconstruction problem can be decomposed into a pattern recognition problem ('vertex finding') and an estimation problem ('vertex fitting'). Starting from least-squares methods, robustifications of the classical algorithms are discussed and the statistical properties of the novel methods are shown. A whole set of different approaches for the vertex finding problem is presented and compared in relevant physics channels

  12. Vertex Reconstruction in CMS

    CERN Document Server

    Chabanat, E; D'Hondt, J; Vanlaer, P; Prokofiev, K; Speer, T; Frühwirth, R; Waltenberger, W

    2005-01-01

    Because of the high track multiplicity in the final states expected in proton collisions at the LHC experiments, novel vertex reconstruction algorithms are required. The vertex reconstruction problem can be decomposed into a pattern recognition problem ("vertex finding") and an estimation problem ("vertex fitting"). Starting from least-square methods, ways to render the classical algorithms more robust are discussed and the statistical properties of the novel methods are shown. A whole set of different approaches for the vertex finding problem is presented and compared in relevant physics channels.

  13. Iterative reconstruction: how it works, how to apply it

    Energy Technology Data Exchange (ETDEWEB)

    Seibert, James Anthony [University of California Davis Medical Center, Department of Radiology, Sacramento, CA (United States)

    2014-10-15

    Computed tomography acquires X-ray projection data from multiple angles though an object to generate a tomographic rendition of its attenuation characteristics. Filtered back projection is a fast, closed analytical solution to the reconstruction process, whereby all projections are equally weighted, but is prone to deliver inadequate image quality when the dose levels are reduced. Iterative reconstruction is an algorithmic method that uses statistical and geometric models to variably weight the image data in a process that can be solved iteratively to independently reduce noise and preserve resolution and image quality. Applications of this technology in a clinical setting can result in lower dose on the order of 20-40% compared to a standard filtered back projection reconstruction for most exams. A carefully planned implementation strategy and methodological approach is necessary to achieve the goals of lower dose with uncompromised image quality. (orig.)

  14. Rapidly 3D Texture Reconstruction Based on Oblique Photography

    Directory of Open Access Journals (Sweden)

    ZHANG Chunsen

    2015-07-01

    Full Text Available This paper proposes a city texture fast reconstruction method based on aerial tilt image for reconstruction of three-dimensional city model. Based on the photogrammetry and computer vision theory and using the city building digital surface model obtained by prior treatment, through collinear equation calculation geometric projection of object and image space, to obtain the three-dimensional information and texture information of the structure and through certain the optimal algorithm selecting the optimal texture on the surface of the object, realize automatic extraction of the building side texture and occlusion handling of the dense building texture. The real image texture reconstruction results show that: the method to the 3D city model texture reconstruction has the characteristics of high degree of automation, vivid effect and low cost and provides a means of effective implementation for rapid and widespread real texture rapid reconstruction of city 3D model.

  15. ADART: an adaptive algebraic reconstruction algorithm for discrete tomography.

    Science.gov (United States)

    Maestre-Deusto, F Javier; Scavello, Giovanni; Pizarro, Joaquín; Galindo, Pedro L

    2011-08-01

    In this paper we suggest an algorithm based on the Discrete Algebraic Reconstruction Technique (DART) which is capable of computing high quality reconstructions from substantially fewer projections than required for conventional continuous tomography. Adaptive DART (ADART) goes a step further than DART on the reduction of the number of unknowns of the associated linear system achieving a significant reduction in the pixel error rate of reconstructed objects. The proposed methodology automatically adapts the border definition criterion at each iteration, resulting in a reduction of the number of pixels belonging to the border, and consequently of the number of unknowns in the general algebraic reconstruction linear system to be solved, being this reduction specially important at the final stage of the iterative process. Experimental results show that reconstruction errors are considerably reduced using ADART when compared to original DART, both in clean and noisy environments.

  16. High resolution x-ray CMT: Reconstruction methods

    Energy Technology Data Exchange (ETDEWEB)

    Brown, J.K.

    1997-02-01

    This paper qualitatively discusses the primary characteristics of methods for reconstructing tomographic images from a set of projections. These reconstruction methods can be categorized as either {open_quotes}analytic{close_quotes} or {open_quotes}iterative{close_quotes} techniques. Analytic algorithms are derived from the formal inversion of equations describing the imaging process, while iterative algorithms incorporate a model of the imaging process and provide a mechanism to iteratively improve image estimates. Analytic reconstruction algorithms are typically computationally more efficient than iterative methods; however, analytic algorithms are available for a relatively limited set of imaging geometries and situations. Thus, the framework of iterative reconstruction methods is better suited for high accuracy, tomographic reconstruction codes.

  17. ACTS: from ATLAS software towards a common track reconstruction software

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00349786; The ATLAS collaboration; Salzburger, Andreas; Kiehn, Moritz; Hrdinka, Julia; Calace, Noemi

    2017-01-01

    Reconstruction of charged particles' trajectories is a crucial task for most particle physics experiments. The high instantaneous luminosity achieved at the LHC leads to a high number of proton-proton collisions per bunch crossing, which has put the track reconstruction software of the LHC experiments through a thorough test. Preserving track reconstruction performance under increasingly difficult experimental conditions, while keeping the usage of computational resources at a reasonable level, is an inherent problem for many HEP experiments. Exploiting concurrent algorithms and using multivariate techniques for track identification are the primary strategies to achieve that goal. Starting from current ATLAS software, the ACTS project aims to encapsulate track reconstruction software into a generic, framework- and experiment-independent software package. It provides a set of high-level algorithms and data structures for performing track reconstruction tasks as well as fast track simulation. The software is de...

  18. Optimization of reconstruction algorithms using Monte Carlo simulation

    International Nuclear Information System (INIS)

    Hanson, K.M.

    1989-01-01

    A method for optimizing reconstruction algorithms is presented that is based on how well a specified task can be performed using the reconstructed images. Task performance is numerically assessed by a Monte Carlo simulation of the complete imaging process including the generation of scenes appropriate to the desired application, subsequent data taking, reconstruction, and performance of the stated task based on the final image. The use of this method is demonstrated through the optimization of the Algebraic Reconstruction Technique (ART), which reconstructs images from their projections by an iterative procedure. The optimization is accomplished by varying the relaxation factor employed in the updating procedure. In some of the imaging situations studied, it is found that the optimization of constrained ART, in which a non-negativity constraint is invoked, can vastly increase the detectability of objects. There is little improvement attained for unconstrained ART. The general method presented may be applied to the problem of designing neutron-diffraction spectrometers. (author)

  19. Direct cone beam SPECT reconstruction with camera tilt

    International Nuclear Information System (INIS)

    Jianying Li; Jaszczak, R.J.; Greer, K.L.; Coleman, R.E.; Zongjian Cao; Tsui, B.M.W.

    1993-01-01

    A filtered backprojection (FBP) algorithm is derived to perform cone beam (CB) single-photon emission computed tomography (SPECT) reconstruction with camera tilt using circular orbits. This algorithm reconstructs the tilted angle CB projection data directly by incorporating the tilt angle into it. When the tilt angle becomes zero, this algorithm reduces to that of Feldkamp. Experimentally acquired phantom studies using both a two-point source and the three-dimensional Hoffman brain phantom have been performed. The transaxial tilted cone beam brain images and profiles obtained using the new algorithm are compared with those without camera tilt. For those slices which have approximately the same distance from the detector in both tilt and non-tilt set-ups, the two transaxial reconstructions have similar profiles. The two-point source images reconstructed from this new algorithm and the tilted cone beam brain images are also compared with those reconstructed from the existing tilted cone beam algorithm. (author)

  20. A modified discrete algebraic reconstruction technique for multiple grey image reconstruction for limited angle range tomography.

    Science.gov (United States)

    Liang, Zhiting; Guan, Yong; Liu, Gang; Chen, Xiangyu; Li, Fahu; Guo, Pengfei; Tian, Yangchao

    2016-03-01

    The `missing wedge', which is due to a restricted rotation range, is a major challenge for quantitative analysis of an object using tomography. With prior knowledge of the grey levels, the discrete algebraic reconstruction technique (DART) is able to reconstruct objects accurately with projections in a limited angle range. However, the quality of the reconstructions declines as the number of grey levels increases. In this paper, a modified DART (MDART) was proposed, in which each independent region of homogeneous material was chosen as a research object, instead of the grey values. The grey values of each discrete region were estimated according to the solution of the linear projection equations. The iterative process of boundary pixels updating and correcting the grey values of each region was executed alternately. Simulation experiments of binary phantoms as well as multiple grey phantoms show that MDART is capable of achieving high-quality reconstructions with projections in a limited angle range. The interesting advancement of MDART is that neither prior knowledge of the grey values nor the number of grey levels is necessary.

  1. Reconstructing Neutrino Mass Spectrum

    OpenAIRE

    Smirnov, A. Yu.

    1999-01-01

    Reconstruction of the neutrino mass spectrum and lepton mixing is one of the fundamental problems of particle physics. In this connection we consider two central topics: (i) the origin of large lepton mixing, (ii) possible existence of new (sterile) neutrino states. We discuss also possible relation between large mixing and existence of sterile neutrinos.

  2. Position reconstruction in LUX

    Science.gov (United States)

    Akerib, D. S.; Alsum, S.; Araújo, H. M.; Bai, X.; Bailey, A. J.; Balajthy, J.; Beltrame, P.; Bernard, E. P.; Bernstein, A.; Biesiadzinski, T. P.; Boulton, E. M.; Brás, P.; Byram, D.; Cahn, S. B.; Carmona-Benitez, M. C.; Chan, C.; Currie, A.; Cutter, J. E.; Davison, T. J. R.; Dobi, A.; Druszkiewicz, E.; Edwards, B. N.; Fallon, S. R.; Fan, A.; Fiorucci, S.; Gaitskell, R. J.; Genovesi, J.; Ghag, C.; Gilchriese, M. G. D.; Hall, C. R.; Hanhardt, M.; Haselschwardt, S. J.; Hertel, S. A.; Hogan, D. P.; Horn, M.; Huang, D. Q.; Ignarra, C. M.; Jacobsen, R. G.; Ji, W.; Kamdin, K.; Kazkaz, K.; Khaitan, D.; Knoche, R.; Larsen, N. A.; Lenardo, B. G.; Lesko, K. T.; Lindote, A.; Lopes, M. I.; Manalaysay, A.; Mannino, R. L.; Marzioni, M. F.; McKinsey, D. N.; Mei, D.-M.; Mock, J.; Moongweluwan, M.; Morad, J. A.; Murphy, A. St. J.; Nehrkorn, C.; Nelson, H. N.; Neves, F.; O'Sullivan, K.; Oliver-Mallory, K. C.; Palladino, K. J.; Pease, E. K.; Rhyne, C.; Shaw, S.; Shutt, T. A.; Silva, C.; Solmaz, M.; Solovov, V. N.; Sorensen, P.; Sumner, T. J.; Szydagis, M.; Taylor, D. J.; Taylor, W. C.; Tennyson, B. P.; Terman, P. A.; Tiedt, D. R.; To, W. H.; Tripathi, M.; Tvrznikova, L.; Uvarov, S.; Velan, V.; Verbus, J. R.; Webb, R. C.; White, J. T.; Whitis, T. J.; Witherell, M. S.; Wolfs, F. L. H.; Xu, J.; Yazdani, K.; Young, S. K.; Zhang, C.

    2018-02-01

    The (x, y) position reconstruction method used in the analysis of the complete exposure of the Large Underground Xenon (LUX) experiment is presented. The algorithm is based on a statistical test that makes use of an iterative method to recover the photomultiplier tube (PMT) light response directly from the calibration data. The light response functions make use of a two dimensional functional form to account for the photons reflected on the inner walls of the detector. To increase the resolution for small pulses, a photon counting technique was employed to describe the response of the PMTs. The reconstruction was assessed with calibration data including 83mKr (releasing a total energy of 41.5 keV) and 3H (β- with Q = 18.6 keV) decays, and a deuterium-deuterium (D-D) neutron beam (2.45 MeV) . Within the detector's fiducial volume, the reconstruction has achieved an (x, y) position uncertainty of σ = 0.82 cm and σ = 0.17 cm for events of only 200 and 4,000 detected electroluminescence photons respectively. Such signals are associated with electron recoils of energies ~0.25 keV and ~10 keV, respectively. The reconstructed position of the smallest events with a single electron emitted from the liquid surface (22 detected photons) has a horizontal (x, y) uncertainty of 2.13 cm.

  3. Adaptive multiresolution method for MAP reconstruction in electron tomography

    Energy Technology Data Exchange (ETDEWEB)

    Acar, Erman, E-mail: erman.acar@tut.fi [Department of Signal Processing, Tampere University of Technology, P.O. Box 553, FI-33101 Tampere (Finland); BioMediTech, Tampere University of Technology, Biokatu 10, 33520 Tampere (Finland); Peltonen, Sari; Ruotsalainen, Ulla [Department of Signal Processing, Tampere University of Technology, P.O. Box 553, FI-33101 Tampere (Finland); BioMediTech, Tampere University of Technology, Biokatu 10, 33520 Tampere (Finland)

    2016-11-15

    3D image reconstruction with electron tomography holds problems due to the severely limited range of projection angles and low signal to noise ratio of the acquired projection images. The maximum a posteriori (MAP) reconstruction methods have been successful in compensating for the missing information and suppressing noise with their intrinsic regularization techniques. There are two major problems in MAP reconstruction methods: (1) selection of the regularization parameter that controls the balance between the data fidelity and the prior information, and (2) long computation time. One aim of this study is to provide an adaptive solution to the regularization parameter selection problem without having additional knowledge about the imaging environment and the sample. The other aim is to realize the reconstruction using sequences of resolution levels to shorten the computation time. The reconstructions were analyzed in terms of accuracy and computational efficiency using a simulated biological phantom and publically available experimental datasets of electron tomography. The numerical and visual evaluations of the experiments show that the adaptive multiresolution method can provide more accurate results than the weighted back projection (WBP), simultaneous iterative reconstruction technique (SIRT), and sequential MAP expectation maximization (sMAPEM) method. The method is superior to sMAPEM also in terms of computation time and usability since it can reconstruct 3D images significantly faster without requiring any parameter to be set by the user. - Highlights: • An adaptive multiresolution reconstruction method is introduced for electron tomography. • The method provides more accurate results than the conventional reconstruction methods. • The missing wedge and noise problems can be compensated by the method efficiently.

  4. GPU accelerated CT reconstruction for clinical use: quality driven performance

    Science.gov (United States)

    Vaz, Michael S.; Sneyders, Yuri; McLin, Matthew; Ricker, Alan; Kimpe, Tom

    2007-03-01

    We present performance and quality analysis of GPU accelerated FDK filtered backprojection for cone beam computed tomography (CBCT) reconstruction. Our implementation of the FDK CT reconstruction algorithm does not compromise fidelity at any stage and yields a result that is within 1 HU of a reference C++ implementation. Our streaming implementation is able to perform reconstruction as the images are acquired; it addresses low latency as well as fast throughput, which are key considerations for a "real-time" design. Further, it is scaleable to multiple GPUs for increased performance. The implementation does not place any constraints on image acquisition; it works effectively for arbitrary angular coverage with arbitrary angular spacing. As such, this GPU accelerated CT reconstruction solution may easily be used with scanners that are already deployed. We are able to reconstruct a 512 x 512 x 340 volume from 625 projections, each sized 1024 x 768, in less than 50 seconds. The quoted 50 second timing encompasses the entire reconstruction using bilinear interpolation and includes filtering on the CPU, uploading the filtered projections to the GPU, and also downloading the reconstructed volume from GPU memory to system RAM.

  5. Interval-based reconstruction for uncertainty quantification in PET

    Science.gov (United States)

    Kucharczak, Florentin; Loquin, Kevin; Buvat, Irène; Strauss, Olivier; Mariano-Goulart, Denis

    2018-02-01

    A new directed interval-based tomographic reconstruction algorithm, called non-additive interval based expectation maximization (NIBEM) is presented. It uses non-additive modeling of the forward operator that provides intervals instead of single-valued projections. The detailed approach is an extension of the maximum likelihood—expectation maximization algorithm based on intervals. The main motivation for this extension is that the resulting intervals have appealing properties for estimating the statistical uncertainty associated with the reconstructed activity values. After reviewing previously published theoretical concepts related to interval-based projectors, this paper describes the NIBEM algorithm and gives examples that highlight the properties and advantages of this interval valued reconstruction.

  6. Liquid Argon TPC Signal Formation, Signal Processing and Hit Reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Baller, Bruce [Fermilab

    2017-03-11

    This document describes the early stage of the reconstruction chain that was developed for the ArgoNeuT and MicroBooNE experiments at Fermilab. These experiments study accelerator neutrino interactions that occur in a Liquid Argon Time Projection Chamber. Reconstructing the properties of particles produced in these interactions requires knowledge of the micro-physics processes that affect the creation and transport of ionization electrons to the readout system. A wire signal deconvolution technique was developed to convert wire signals to a standard form for hit reconstruction, to remove artifacts in the electronics chain and to remove coherent noise.

  7. High spatial resolution CT image reconstruction using parallel computing

    International Nuclear Information System (INIS)

    Yin Yin; Liu Li; Sun Gongxing

    2003-01-01

    Using the PC cluster system with 16 dual CPU nodes, we accelerate the FBP and OR-OSEM reconstruction of high spatial resolution image (2048 x 2048). Based on the number of projections, we rewrite the reconstruction algorithms into parallel format and dispatch the tasks to each CPU. By parallel computing, the speedup factor is roughly equal to the number of CPUs, which can be up to about 25 times when 25 CPUs used. This technique is very suitable for real-time high spatial resolution CT image reconstruction. (authors)

  8. Radiation fields, dosimetry, biokinetics and biophysical models for cancer induction by ionising radiation 1996-1999. Dose reconstruction. Final report

    International Nuclear Information System (INIS)

    Jacob, P.; Aragno, D.; Bailiff, I.K.

    2000-01-01

    The project Dose Reconstruction was conducted within the five work packages: - EPR with teeth, - Chromosome painting (FISH) in lymphocytes, - Luminescence methods, - Modelling, and - Evaluation. (orig.)

  9. Evaluating low pass filters on SPECT reconstructed cardiac orientation estimation

    Science.gov (United States)

    Dwivedi, Shekhar

    2009-02-01

    Low pass filters can affect the quality of clinical SPECT images by smoothing. Appropriate filter and parameter selection leads to optimum smoothing that leads to a better quantification followed by correct diagnosis and accurate interpretation by the physician. This study aims at evaluating the low pass filters on SPECT reconstruction algorithms. Criteria for evaluating the filters are estimating the SPECT reconstructed cardiac azimuth and elevation angle. Low pass filters studied are butterworth, gaussian, hamming, hanning and parzen. Experiments are conducted using three reconstruction algorithms, FBP (filtered back projection), MLEM (maximum likelihood expectation maximization) and OSEM (ordered subsets expectation maximization), on four gated cardiac patient projections (two patients with stress and rest projections). Each filter is applied with varying cutoff and order for each reconstruction algorithm (only butterworth used for MLEM and OSEM). The azimuth and elevation angles are calculated from the reconstructed volume and the variation observed in the angles with varying filter parameters is reported. Our results demonstrate that behavior of hamming, hanning and parzen filter (used with FBP) with varying cutoff is similar for all the datasets. Butterworth filter (cutoff > 0.4) behaves in a similar fashion for all the datasets using all the algorithms whereas with OSEM for a cutoff < 0.4, it fails to generate cardiac orientation due to oversmoothing, and gives an unstable response with FBP and MLEM. This study on evaluating effect of low pass filter cutoff and order on cardiac orientation using three different reconstruction algorithms provides an interesting insight into optimal selection of filter parameters.

  10. Apparatus and method for reconstructing data

    International Nuclear Information System (INIS)

    Pavkovich, J.M.

    1977-01-01

    The apparatus and method for reconstructing data are described. A fan beam of radiation is passed through an object, the beam lying in the same quasi-plane as the object slice to be examined. Radiation not absorbed in the object slice is recorded on oppositely situated detectors aligned with the source of radiation. Relative rotation is provided between the source-detector configuration and the object. Reconstruction means are coupled to the detector means, and may comprise a general purpose computer, a special purpose computer, and control logic for interfacing between said computers and controlling the respective functioning thereof for performing a convolution and back projection based upon non-absorbed radiation detected by said detector means, whereby the reconstruction means converts values of the non-absorbed radiation into values of absorbed radiation at each of an arbitrarily large number of points selected within the object slice. Display means are coupled to the reconstruction means for providing a visual or other display or representation of the quantities of radiation absorbed at the points considered in the object. (Auth.)

  11. Interactive reconstruction in single-photon tomography

    International Nuclear Information System (INIS)

    Miller, T.R.; Wallis, J.W.; Wilson, A.D.

    1989-01-01

    A new method is described to allow interactive selection of the reconstruction filter at the time of interpretation of images from single-photon tomography. In the filtered back projection algorithm, the only part of the reconstruction process requiring user interaction is the selection of the window function. Since the ramp and window filters have different purposes, they can be separated, placing the window at the end of the reconstruction process as a three-dimensional filter. All stages of reconstruction except the window filtering are performed before the physician begins to interpret the study. The three-dimensional filtering is performed very rapidly with use of the Chebyshev convolution algorithm. A 64 x 64 x 64 pixel cube of data is filtered in 13-33 s using filters of 3-11 lengths. Smaller volumes of image data can be filtered in less than 1 s; thus, the user can interactively choose any desired filter for a given tomographic study at the time of interpretation of the images. (orig.)

  12. Algebraic reconstruction techniques for spectral reconstruction in diffuse optical tomography

    International Nuclear Information System (INIS)

    Brendel, Bernhard; Ziegler, Ronny; Nielsen, Tim

    2008-01-01

    Reconstruction in diffuse optical tomography (DOT) necessitates solving the diffusion equation, which is nonlinear with respect to the parameters that have to be reconstructed. Currently applied solving methods are based on the linearization of the equation. For spectral three-dimensional reconstruction, the emerging equation system is too large for direct inversion, but the application of iterative methods is feasible. Computational effort and speed of convergence of these iterative methods are crucial since they determine the computation time of the reconstruction. In this paper, the iterative methods algebraic reconstruction technique (ART) and conjugated gradients (CGs) as well as a new modified ART method are investigated for spectral DOT reconstruction. The aim of the modified ART scheme is to speed up the convergence by considering the specific conditions of spectral reconstruction. As a result, it converges much faster to favorable results than conventional ART and CG methods

  13. Bayesian tomographic reconstruction of microsystems

    International Nuclear Information System (INIS)

    Salem, Sofia Fekih; Vabre, Alexandre; Mohammad-Djafari, Ali

    2007-01-01

    The microtomography by X ray transmission plays an increasingly dominating role in the study and the understanding of microsystems. Within this framework, an experimental setup of high resolution X ray microtomography was developed at CEA-List to quantify the physical parameters related to the fluids flow in microsystems. Several difficulties rise from the nature of experimental data collected on this setup: enhanced error measurements due to various physical phenomena occurring during the image formation (diffusion, beam hardening), and specificities of the setup (limited angle, partial view of the object, weak contrast).To reconstruct the object we must solve an inverse problem. This inverse problem is known to be ill-posed. It therefore needs to be regularized by introducing prior information. The main prior information we account for is that the object is composed of a finite known number of different materials distributed in compact regions. This a priori information is introduced via a Gauss-Markov field for the contrast distributions with a hidden Potts-Markov field for the class materials in the Bayesian estimation framework. The computations are done by using an appropriate Markov Chain Monte Carlo (MCMC) technique.In this paper, we present first the basic steps of the proposed algorithms. Then we focus on one of the main steps in any iterative reconstruction method which is the computation of forward and adjoint operators (projection and backprojection). A fast implementation of these two operators is crucial for the real application of the method. We give some details on the fast computation of these steps and show some preliminary results of simulations

  14. A New Local Flap Nipple Reconstruction Technique Using Dermal Bridge and Preoperatively Designed Tattoo

    Science.gov (United States)

    Iwahira, Yoshiko

    2017-01-01

    Background: Nipple–areolar reconstruction is the final step in breast reconstruction. Reconstruction using local flaps and tattooing is useful in cases of bilateral reconstruction, a small nipple–areolar complex (NAC) as the donor site, and avoiding disturbance of the normal side and other body parts. However, this method can cause projection loss and color fading of the nipple. Moreover, the breast mound is reconstructed with an implant. Methods: We performed nipple–areolar reconstruction of 90 nipples using clover-designed flaps oriented at 120 degrees and tattooing after breast silicone implantation in 64 women. The tattoo was designed before flap operation and stained darker. Following donor site closure, a dermal flap was made as a bridge for nipple support. The nipple space was separated by the dermal flap from the breast mound and was filled with subcutaneous tissue. The size of the reconstructed nipple projection was measured postoperatively and 1 year later. The projection maintenance rate was calculated. Results: The heights of the nipple projection were 11.3 ± 1.8 mm (95% confidence interval [CI]: 10.9–11.7) just after the operation and 6.09 ± 2.4 mm (95% CI: 5.6–6.6) 1 year later. The actual range of nipple projection between these 2 heights was 5.2 ± 2.4 mm (95% CI: 4.7–5.7). The maintenance rate of the reconstructed nipple projection after 12 months was 54.1 ± 20.9 (95% CI: 49.7–58.5). The nipple color was maintained for over a year. Conclusions: Our nipple–areolar reconstruction technique could maintain the projection and color of the reconstructed nipple for a long period. Good outcomes were obtained in this implant-based breast reconstruction. PMID:28507843

  15. Arctic Sea Level Reconstruction

    DEFF Research Database (Denmark)

    Svendsen, Peter Limkilde

    Reconstruction of historical Arctic sea level is very difficult due to the limited coverage and quality of tide gauge and altimetry data in the area. This thesis addresses many of these issues, and discusses strategies to help achieve a stable and plausible reconstruction of Arctic sea level from...... 1950 to today.The primary record of historical sea level, on the order of several decades to a few centuries, is tide gauges. Tide gauge records from around the world are collected in the Permanent Service for Mean Sea Level (PSMSL) database, and includes data along the Arctic coasts. A reasonable...... amount of data is available along the Norwegian and Russian coasts since 1950, and most published research on Arctic sea level extends cautiously from these areas. Very little tide gauge data is available elsewhere in the Arctic, and records of a length of several decades,as generally recommended for sea...

  16. Reconstructing warm inflation

    Science.gov (United States)

    Herrera, Ramón

    2018-03-01

    The reconstruction of a warm inflationary universe model from the scalar spectral index n_S(N) and the tensor to scalar ratio r( N) as a function of the number of e-folds N is studied. Under a general formalism we find the effective potential and the dissipative coefficient in terms of the cosmological parameters n_S and r considering the weak and strong dissipative stages under the slow roll approximation. As a specific example, we study the attractors for the index n_S given by nS-1∝ N^{-1} and for the ratio r∝ N^{-2}, in order to reconstruct the model of warm inflation. Here, expressions for the effective potential V(φ ) and the dissipation coefficient Γ (φ ) are obtained.

  17. Jet Vertex Charge Reconstruction

    CERN Document Server

    Nektarijevic, Snezana; The ATLAS collaboration

    2015-01-01

    A newly developed algorithm called the jet vertex charge tagger, aimed at identifying the sign of the charge of jets containing $b$-hadrons, referred to as $b$-jets, is presented. In addition to the well established track-based jet charge determination, this algorithm introduces the so-called \\emph{jet vertex charge} reconstruction, which exploits the charge information associated to the displaced vertices within the jet. Furthermore, the charge of a soft muon contained in the jet is taken into account when available. All available information is combined into a multivariate discriminator. The algorithm has been developed on jets matched to generator level $b$-hadrons provided by $t\\bar{t}$ events simulated at $\\sqrt{s}$=13~TeV using the full ATLAS detector simulation and reconstruction.

  18. Acellular dermal matrix based nipple reconstruction: A modified technique

    Directory of Open Access Journals (Sweden)

    Raghavan Vidya

    2017-09-01

    Full Text Available Nipple areolar reconstruction (NAR has evolved with the advancement in breast reconstruction and can improve self-esteem and, consequently, patient satisfaction. Although a variety of reconstruction techniques have been described in the literature varying from nipple sharing, local flaps to alloplastic and allograft augmentation, over time, loss of nipple projection remains a major problem. Acellular dermal matrices (ADM have revolutionised breast reconstruction more recently. We discuss the use of ADM to act as a base plate and strut to give support to the base and offer nipple bulk and projection in a primary procedure of NAR with a local clover shaped dermal flap in 5 breasts (4 patients. We used 5-point Likert scales (1 = highly unsatisfied, 5 = highly satisfied to assess patient satisfaction. Median age was 46 years (range: 38–55 years. Nipple projection of 8 mm, 7 mm, and 7 mms were achieved in the unilateral cases and 6 mm in the bilateral case over a median 18 month period. All patients reported at least a 4 on the Likert scale. We had no post-operative complications. It seems that nipple areolar reconstruction [NAR] using ADM can achieve nipple projection which is considered aesthetically pleasing for patients.

  19. LHCb jet reconstruction

    International Nuclear Information System (INIS)

    Francisco, Oscar; Rangel, Murilo; Barter, William; Bursche, Albert; Potterat, Cedric; Coco, Victor

    2012-01-01

    Full text: The Large Hadron Collider (LHC) is the most powerful particle accelerator in the world. It has been designed to collide proton beams at an energy up to 14 TeV in the center of mass. In 2011, the data taking was done with a center of mass energy of 7 TeV, the instant luminosity has reached values greater than 4 X 10 32 cm -2 s -1 and the integrated luminosity reached the value of 1,02fb -1 on the LHCb. The jet reconstruction is fundamental to observe events that can be used to test perturbative QCD (pQCD). It also provides a way to observe standard model channels and searches for new physics like SUSY. The anti-kt algorithm is a jet reconstruction algorithm that is based on the distance of the particles on the space ηX φ and on the transverse momentum of particles. To maximize the energy resolution all information about the trackers and the colorimeters are used on the LHCb experiment to create objects called particle flow objects that are used as input to anti-kt algorithm. The LHCb is specially interesting for jets studies because its η region is complementary to the others main experiments on LHC. We will present the first results of jet reconstruction using 2011 LHCb data. (author)

  20. LHCb jet reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Francisco, Oscar; Rangel, Murilo [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil); Barter, William [University of Cambridge, Cambridge (United Kingdom); Bursche, Albert [Universitat Zurich, Zurich (Switzerland); Potterat, Cedric [Universitat de Barcelona, Barcelona (Spain); Coco, Victor [Nikhef National Institute for Subatomic Physics, Amsterdam (Netherlands)

    2012-07-01

    Full text: The Large Hadron Collider (LHC) is the most powerful particle accelerator in the world. It has been designed to collide proton beams at an energy up to 14 TeV in the center of mass. In 2011, the data taking was done with a center of mass energy of 7 TeV, the instant luminosity has reached values greater than 4 X 10{sup 32} cm{sup -2}s{sup -1} and the integrated luminosity reached the value of 1,02fb{sup -1} on the LHCb. The jet reconstruction is fundamental to observe events that can be used to test perturbative QCD (pQCD). It also provides a way to observe standard model channels and searches for new physics like SUSY. The anti-kt algorithm is a jet reconstruction algorithm that is based on the distance of the particles on the space {eta}X {phi} and on the transverse momentum of particles. To maximize the energy resolution all information about the trackers and the colorimeters are used on the LHCb experiment to create objects called particle flow objects that are used as input to anti-kt algorithm. The LHCb is specially interesting for jets studies because its {eta} region is complementary to the others main experiments on LHC. We will present the first results of jet reconstruction using 2011 LHCb data. (author)

  1. Geometric reconstruction methods for electron tomography

    Energy Technology Data Exchange (ETDEWEB)

    Alpers, Andreas, E-mail: alpers@ma.tum.de [Zentrum Mathematik, Technische Universität München, D-85747 Garching bei München (Germany); Gardner, Richard J., E-mail: Richard.Gardner@wwu.edu [Department of Mathematics, Western Washington University, Bellingham, WA 98225-9063 (United States); König, Stefan, E-mail: koenig@ma.tum.de [Zentrum Mathematik, Technische Universität München, D-85747 Garching bei München (Germany); Pennington, Robert S., E-mail: robert.pennington@uni-ulm.de [Center for Electron Nanoscopy, Technical University of Denmark, DK-2800 Kongens Lyngby (Denmark); Boothroyd, Chris B., E-mail: ChrisBoothroyd@cantab.net [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, D-52425 Jülich (Germany); Houben, Lothar, E-mail: l.houben@fz-juelich.de [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, D-52425 Jülich (Germany); Dunin-Borkowski, Rafal E., E-mail: rdb@fz-juelich.de [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, D-52425 Jülich (Germany); Joost Batenburg, Kees, E-mail: Joost.Batenburg@cwi.nl [Centrum Wiskunde and Informatica, NL-1098XG, Amsterdam, The Netherlands and Vision Lab, Department of Physics, University of Antwerp, B-2610 Wilrijk (Belgium)

    2013-05-15

    Electron tomography is becoming an increasingly important tool in materials science for studying the three-dimensional morphologies and chemical compositions of nanostructures. The image quality obtained by many current algorithms is seriously affected by the problems of missing wedge artefacts and non-linear projection intensities due to diffraction effects. The former refers to the fact that data cannot be acquired over the full 180° tilt range; the latter implies that for some orientations, crystalline structures can show strong contrast changes. To overcome these problems we introduce and discuss several algorithms from the mathematical fields of geometric and discrete tomography. The algorithms incorporate geometric prior knowledge (mainly convexity and homogeneity), which also in principle considerably reduces the number of tilt angles required. Results are discussed for the reconstruction of an InAs nanowire. - Highlights: ► Four algorithms for electron tomography are introduced that utilize prior knowledge. ► Objects are assumed to be homogeneous; convexity and regularity is also discussed. ► We are able to reconstruct slices of a nanowire from as few as four projections. ► Algorithms should be selected based on the specific reconstruction task at hand.

  2. Geometric reconstruction methods for electron tomography

    International Nuclear Information System (INIS)

    Alpers, Andreas; Gardner, Richard J.; König, Stefan; Pennington, Robert S.; Boothroyd, Chris B.; Houben, Lothar; Dunin-Borkowski, Rafal E.; Joost Batenburg, Kees

    2013-01-01

    Electron tomography is becoming an increasingly important tool in materials science for studying the three-dimensional morphologies and chemical compositions of nanostructures. The image quality obtained by many current algorithms is seriously affected by the problems of missing wedge artefacts and non-linear projection intensities due to diffraction effects. The former refers to the fact that data cannot be acquired over the full 180° tilt range; the latter implies that for some orientations, crystalline structures can show strong contrast changes. To overcome these problems we introduce and discuss several algorithms from the mathematical fields of geometric and discrete tomography. The algorithms incorporate geometric prior knowledge (mainly convexity and homogeneity), which also in principle considerably reduces the number of tilt angles required. Results are discussed for the reconstruction of an InAs nanowire. - Highlights: ► Four algorithms for electron tomography are introduced that utilize prior knowledge. ► Objects are assumed to be homogeneous; convexity and regularity is also discussed. ► We are able to reconstruct slices of a nanowire from as few as four projections. ► Algorithms should be selected based on the specific reconstruction task at hand

  3. 3D dictionary learning based iterative cone beam CT reconstruction

    Directory of Open Access Journals (Sweden)

    Ti Bai

    2014-03-01

    Full Text Available Purpose: This work is to develop a 3D dictionary learning based cone beam CT (CBCT reconstruction algorithm on graphic processing units (GPU to improve the quality of sparse-view CBCT reconstruction with high efficiency. Methods: A 3D dictionary containing 256 small volumes (atoms of 3 × 3 × 3 was trained from a large number of blocks extracted from a high quality volume image. On the basis, we utilized cholesky decomposition based orthogonal matching pursuit algorithm to find the sparse representation of each block. To accelerate the time-consuming sparse coding in the 3D case, we implemented the sparse coding in a parallel fashion by taking advantage of the tremendous computational power of GPU. Conjugate gradient least square algorithm was adopted to minimize the data fidelity term. Evaluations are performed based on a head-neck patient case. FDK reconstruction with full dataset of 364 projections is used as the reference. We compared the proposed 3D dictionary learning based method with tight frame (TF by performing reconstructions on a subset data of 121 projections. Results: Compared to TF based CBCT reconstruction that shows good overall performance, our experiments indicated that 3D dictionary learning based CBCT reconstruction is able to recover finer structures, remove more streaking artifacts and also induce less blocky artifacts. Conclusion: 3D dictionary learning based CBCT reconstruction algorithm is able to sense the structural information while suppress the noise, and hence to achieve high quality reconstruction under the case of sparse view. The GPU realization of the whole algorithm offers a significant efficiency enhancement, making this algorithm more feasible for potential clinical application.-------------------------------Cite this article as: Bai T, Yan H, Shi F, Jia X, Lou Y, Xu Q, Jiang S, Mou X. 3D dictionary learning based iterative cone beam CT reconstruction. Int J Cancer Ther Oncol 2014; 2(2:020240. DOI: 10

  4. [Reconstructive methods after Fournier gangrene].

    Science.gov (United States)

    Wallner, C; Behr, B; Ring, A; Mikhail, B D; Lehnhardt, M; Daigeler, A

    2016-04-01

    Fournier's gangrene is a variant of the necrotizing fasciitis restricted to the perineal and genital region. It presents as an acute life-threatening disease and demands rapid surgical debridement, resulting in large soft tissue defects. Various reconstructive methods have to be applied to reconstitute functionality and aesthetics. The objective of this work is to identify different reconstructive methods in the literature and compare them to our current concepts for reconstructing defects caused by Fournier gangrene. Analysis of the current literature and our reconstructive methods on Fournier gangrene. The Fournier gangrene is an emergency requiring rapid, calculated antibiotic treatment and radical surgical debridement. After the acute phase of the disease, appropriate reconstructive methods are indicated. The planning of the reconstruction of the defect depends on many factors, especially functional and aesthetic demands. Scrotal reconstruction requires a higher aesthetic and functional reconstructive degree than perineal cutaneous wounds. In general, thorough wound hygiene, proper pre-operative planning, and careful consideration of the patient's demands are essential for successful reconstruction. In the literature, various methods for reconstruction after Fournier gangrene are described. Reconstruction with a flap is required for a good functional result in complex regions as the scrotum and penis, while cutaneous wounds can be managed through skin grafting. Patient compliance and tissue demand are crucial factors in the decision-making process.

  5. Basic surveys for joint execution, etc. of the heat and power plant reconstruction project for the corporation 'Yuzhmash', Dnepropetrovsk, Ukraine. Ukraine 'Yuzhmash' feasibility study report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    This project, for the execution of joint implementations set forth in the protocol of the Third Session of the Conference of the Parties to the United Nations Framework Convention on Climate Change, aims to replace the existing plant with a new combined cycle thermal power system which will achieve CO2 emission reduction, environmental preservation, and energy conservation. The project will save energy by 103,731 toe/year. The total project cost will be 9-billion yen, and cost performance will be 87,000-yen/toe or 3,400-yen/toe in a 25-year period. Greenhouse gas emissions will be reduced by 242,424 tons/year, and cost performance will be 37,000-yen/t-CO2 or 1,500-yen/t-CO2 in a 25-year period. Profitability EIRR (economic internal rate of return) is calculated on the assumption of an exchange rate of 4.91UHA/US$ (as of February 2000). When emission trading is carried out at US$/t-CO2=0.0, 5.0, 14.0, or 60.0, EIRR will be 7.363, 8.112, 9.939, or 15.155%, respectively. The price of Ukrainian natural gas affects profitability. A profitability goal to justify project execution will be achieved only when the price of CO2 emission right of 60.00US$/ton or more is realized. Advantageous fund procurement is also necessary. (NEDO)

  6. Practical implementation of tetrahedral mesh reconstruction in emission tomography

    Science.gov (United States)

    Boutchko, R.; Sitek, A.; Gullberg, G. T.

    2013-05-01

    This paper presents a practical implementation of image reconstruction on tetrahedral meshes optimized for emission computed tomography with parallel beam geometry. Tetrahedral mesh built on a point cloud is a convenient image representation method, intrinsically three-dimensional and with a multi-level resolution property. Image intensities are defined at the mesh nodes and linearly interpolated inside each tetrahedron. For the given mesh geometry, the intensities can be computed directly from tomographic projections using iterative reconstruction algorithms with a system matrix calculated using an exact analytical formula. The mesh geometry is optimized for a specific patient using a two stage process. First, a noisy image is reconstructed on a finely-spaced uniform cloud. Then, the geometry of the representation is adaptively transformed through boundary-preserving node motion and elimination. Nodes are removed in constant intensity regions, merged along the boundaries, and moved in the direction of the mean local intensity gradient in order to provide higher node density in the boundary regions. Attenuation correction and detector geometric response are included in the system matrix. Once the mesh geometry is optimized, it is used to generate the final system matrix for ML-EM reconstruction of node intensities and for visualization of the reconstructed images. In dynamic PET or SPECT imaging, the system matrix generation procedure is performed using a quasi-static sinogram, generated by summing projection data from multiple time frames. This system matrix is then used to reconstruct the individual time frame projections. Performance of the new method is evaluated by reconstructing simulated projections of the NCAT phantom and the method is then applied to dynamic SPECT phantom and patient studies and to a dynamic microPET rat study. Tetrahedral mesh-based images are compared to the standard voxel-based reconstruction for both high and low signal-to-noise ratio

  7. Practical implementation of tetrahedral mesh reconstruction in emission tomography

    International Nuclear Information System (INIS)

    Boutchko, R; Gullberg, G T; Sitek, A

    2013-01-01

    This paper presents a practical implementation of image reconstruction on tetrahedral meshes optimized for emission computed tomography with parallel beam geometry. Tetrahedral mesh built on a point cloud is a convenient image representation method, intrinsically three-dimensional and with a multi-level resolution property. Image intensities are defined at the mesh nodes and linearly interpolated inside each tetrahedron. For the given mesh geometry, the intensities can be computed directly from tomographic projections using iterative reconstruction algorithms with a system matrix calculated using an exact analytical formula. The mesh geometry is optimized for a specific patient using a two stage process. First, a noisy image is reconstructed on a finely-spaced uniform cloud. Then, the geometry of the representation is adaptively transformed through boundary-preserving node motion and elimination. Nodes are removed in constant intensity regions, merged along the boundaries, and moved in the direction of the mean local intensity gradient in order to provide higher node density in the boundary regions. Attenuation correction and detector geometric response are included in the system matrix. Once the mesh geometry is optimized, it is used to generate the final system matrix for ML-EM reconstruction of node intensities and for visualization of the reconstructed images. In dynamic PET or SPECT imaging, the system matrix generation procedure is performed using a quasi-static sinogram, generated by summing projection data from multiple time frames. This system matrix is then used to reconstruct the individual time frame projections. Performance of the new method is evaluated by reconstructing simulated projections of the NCAT phantom and the method is then applied to dynamic SPECT phantom and patient studies and to a dynamic microPET rat study. Tetrahedral mesh-based images are compared to the standard voxel-based reconstruction for both high and low signal-to-noise ratio

  8. Blockwise conjugate gradient methods for image reconstruction in volumetric CT.

    Science.gov (United States)

    Qiu, W; Titley-Peloquin, D; Soleimani, M

    2012-11-01

    Cone beam computed tomography (CBCT) enables volumetric image reconstruction from 2D projection data and plays an important role in image guided radiation therapy (IGRT). Filtered back projection is still the most frequently used algorithm in applications. The algorithm discretizes the scanning process (forward projection) into a system of linear equations, which must then be solved to recover images from measured projection data. The conjugate gradients (CG) algorithm and its variants can be used to solve (possibly regularized) linear systems of equations Ax=b and linear least squares problems minx∥b-Ax∥2, especially when the matrix A is very large and sparse. Their applications can be found in a general CT context, but in tomography problems (e.g. CBCT reconstruction) they have not widely been used. Hence, CBCT reconstruction using the CG-type algorithm LSQR was implemented and studied in this paper. In CBCT reconstruction, the main computational challenge is that the matrix A usually is very large, and storing it in full requires an amount of memory well beyond the reach of commodity computers. Because of these memory capacity constraints, only a small fraction of the weighting matrix A is typically used, leading to a poor reconstruction. In this paper, to overcome this difficulty, the matrix A is partitioned and stored blockwise, and blockwise matrix-vector multiplications are implemented within LSQR. This implementation allows us to use the full weighting matrix A for CBCT reconstruction without further enhancing computer standards. Tikhonov regularization can also be implemented in this fashion, and can produce significant improvement in the reconstructed images. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  9. Image reconstruction. Application to transverse axial tomography

    International Nuclear Information System (INIS)

    Aubry, Florent.

    1977-09-01

    A method of computerized tridimensional image reconstruction from their projection, especially in the computerized transverse axial tomography is suggested. First, the different techniques actually developped and presented in the literature are analyzed. Then, the equipment used is briefly described. The reconstruction algorithm developped is presented. This algorithm is based on the convolution method, well adapted to the real conditions of exploitation. It is an extension of SHEPP and LOGAN's algorithm. A correction of the self absorption and of the detector's response is proposed. Finally, the first results obtained which are satisfactory are given. The simplicity of the method which does not need a too long computation time makes possible the implementation of the algorithm on a mini-computer [fr

  10. Image reconstruction under non-Gaussian noise

    DEFF Research Database (Denmark)

    Sciacchitano, Federica

    During acquisition and transmission, images are often blurred and corrupted by noise. One of the fundamental tasks of image processing is to reconstruct the clean image from a degraded version. The process of recovering the original image from the data is an example of inverse problem. Due...... to the ill-posedness of the problem, the simple inversion of the degradation model does not give any good reconstructions. Therefore, to deal with the ill-posedness it is necessary to use some prior information on the solution or the model and the Bayesian approach. Additive Gaussian noise has been......D thesis intends to solve some of the many open questions for image restoration under non-Gaussian noise. The two main kinds of noise studied in this PhD project are the impulse noise and the Cauchy noise. Impulse noise is due to for instance the malfunctioning pixel elements in the camera sensors, errors...

  11. Photometric Lunar Surface Reconstruction

    Science.gov (United States)

    Nefian, Ara V.; Alexandrov, Oleg; Morattlo, Zachary; Kim, Taemin; Beyer, Ross A.

    2013-01-01

    Accurate photometric reconstruction of the Lunar surface is important in the context of upcoming NASA robotic missions to the Moon and in giving a more accurate understanding of the Lunar soil composition. This paper describes a novel approach for joint estimation of Lunar albedo, camera exposure time, and photometric parameters that utilizes an accurate Lunar-Lambertian reflectance model and previously derived Lunar topography of the area visualized during the Apollo missions. The method introduced here is used in creating the largest Lunar albedo map (16% of the Lunar surface) at the resolution of 10 meters/pixel.

  12. Penile surgery and reconstruction.

    Science.gov (United States)

    Perovic, Sava V; Djordjevic, Miroslav L J; Kekic, Zoran K; Djakovic, Nenad G

    2002-05-01

    This review will highlight recent advances in the field of penile reconstructive surgery in the paediatric and adult population. It is based on the work published during the year 2001. Besides the anatomical and histological studies of the penis, major contributions have been described in congenital and acquired penile anomalies. Also, a few new techniques and modifications of old procedures are described in order to improve the final functional and aesthetic outcome. The techniques for penile enlargement present a trend in the new millennium, but are still at the stage of investigation.

  13. Progressive Reconstruction: A Methodology for Stabilization and Reconstruction Operations

    National Research Council Canada - National Science Library

    Rohr, Karl C

    2006-01-01

    ... these nations in accordance with stated United States' goals. The argument follows closely current and developing United States military doctrine on stabilization, reconstruction, and counterinsurgency operations...

  14. Designing on ICT reconstruction software based on DSP techniques

    International Nuclear Information System (INIS)

    Liu Jinhui; Xiang Xincheng

    2006-01-01

    The convolution back project (CBP) algorithm is used to realize the CT image's reconstruction in ICT generally, which is finished by using PC or workstation. In order to add the ability of multi-platform operation of CT reconstruction software, a CT reconstruction method based on modern digital signal processor (DSP) technique is proposed and realized in this paper. The hardware system based on TI's C6701 DSP processor is selected to support the CT software construction. The CT reconstruction software is compiled only using assembly language related to the DSP hardware. The CT software can be run on TI's C6701 EVM board by inputting the CT data, and can get the CT Images that satisfy the real demands. (authors)

  15. IRVE-II Post-Flight Trajectory Reconstruction

    Science.gov (United States)

    O'Keefe, Stephen A.; Bose, David M.

    2010-01-01

    NASA s Inflatable Re-entry Vehicle Experiment (IRVE) II successfully demonstrated an inflatable aerodynamic decelerator after being launched aboard a sounding rocket from Wallops Flight Facility (WFF). Preliminary day of flight data compared well with pre-flight Monte Carlo analysis, and a more complete trajectory reconstruction performed with an Extended Kalman Filter (EKF) approach followed. The reconstructed trajectory and comparisons to an attitude solution provided by NASA Sounding Rocket Operations Contract (NSROC) personnel at WFF are presented. Additional comparisons are made between the reconstructed trajectory and pre and post-flight Monte Carlo trajectory predictions. Alternative observations of the trajectory are summarized which leverage flight accelerometer measurements, the pre-flight aerodynamic database, and on-board flight video. Finally, analysis of the payload separation and aeroshell deployment events are presented. The flight trajectory is reconstructed to fidelity sufficient to assess overall project objectives related to flight dynamics and overall, IRVE-II flight dynamics are in line with expectations

  16. Liquid argon TPC signal formation, signal processing and reconstruction techniques

    Science.gov (United States)

    Baller, B.

    2017-07-01

    This document describes a reconstruction chain that was developed for the ArgoNeuT and MicroBooNE experiments at Fermilab. These experiments study accelerator neutrino interactions that occur in a Liquid Argon Time Projection Chamber. Reconstructing the properties of particles produced in these interactions benefits from the knowledge of the micro-physics processes that affect the creation and transport of ionization electrons to the readout system. A wire signal deconvolution technique was developed to convert wire signals to a standard form for hit reconstruction, to remove artifacts in the electronics chain and to remove coherent noise. A unique clustering algorithm reconstructs line-like trajectories and vertices in two dimensions which are then matched to create of 3D objects. These techniques and algorithms are available to all experiments that use the LArSoft suite of software.

  17. 3D reconstruction, a new challenge in industrial radiography

    International Nuclear Information System (INIS)

    Lavayssiere, B.; Fleuet, E.; Georgel, B.

    1995-01-01

    In a NDT context, industrial radiography enables the detection of defects through their projection on a film. EDF has studied the benefit that may be brought in terms of localisation and orientation of the defects by the mean of 3D reconstruction using a very limited number of radiographs. The reconstruction issue consists of solving an integral equation of the first kind ; in a noisy context, the reconstruction belongs to the so-called ill-posed class of problem. Appropriate solutions may only be found with the help of regularization technique, by the introduction of a priori knowledge concerning the unknown solution and also by the use of a statistical modelization of the physical process which produces radiographs. Another approach simplifies the problem and reconstructs the skeleton of a defect only. All these methods coming from applied mathematical sciences enable a more precise diagnosis in non-destructive testing of thick inhomogeneous material. (authors). 4 refs., 4 figs

  18. A Kalman filter technique applied for medical image reconstruction

    International Nuclear Information System (INIS)

    Goliaei, S.; Ghorshi, S.; Manzuri, M. T.; Mortazavi, M.

    2011-01-01

    Medical images contain information about vital organic tissues inside of human body and are widely used for diagnoses of disease or for surgical purposes. Image reconstruction is essential for medical images for some applications such as suppression of noise or de-blurring the image in order to provide images with better quality and contrast. Due to vital rule of image reconstruction in medical sciences the corresponding algorithms with better efficiency and higher speed is desirable. Most algorithms in image reconstruction are operated on frequency domain such as the most popular one known as filtered back projection. In this paper we introduce a Kalman filter technique which is operated in time domain for medical image reconstruction. Results indicated that as the number of projection increases in both normal collected ray sum and the collected ray sum corrupted by noise the quality of reconstructed image becomes better in terms of contract and transparency. It is also seen that as the number of projection increases the error index decreases.

  19. Synchronized dynamic dose reconstruction

    International Nuclear Information System (INIS)

    Litzenberg, Dale W.; Hadley, Scott W.; Tyagi, Neelam; Balter, James M.; Ten Haken, Randall K.; Chetty, Indrin J.

    2007-01-01

    Variations in target volume position between and during treatment fractions can lead to measurable differences in the dose distribution delivered to each patient. Current methods to estimate the ongoing cumulative delivered dose distribution make idealized assumptions about individual patient motion based on average motions observed in a population of patients. In the delivery of intensity modulated radiation therapy (IMRT) with a multi-leaf collimator (MLC), errors are introduced in both the implementation and delivery processes. In addition, target motion and MLC motion can lead to dosimetric errors from interplay effects. All of these effects may be of clinical importance. Here we present a method to compute delivered dose distributions for each treatment beam and fraction, which explicitly incorporates synchronized real-time patient motion data and real-time fluence and machine configuration data. This synchronized dynamic dose reconstruction method properly accounts for the two primary classes of errors that arise from delivering IMRT with an MLC: (a) Interplay errors between target volume motion and MLC motion, and (b) Implementation errors, such as dropped segments, dose over/under shoot, faulty leaf motors, tongue-and-groove effect, rounded leaf ends, and communications delays. These reconstructed dose fractions can then be combined to produce high-quality determinations of the dose distribution actually received to date, from which individualized adaptive treatment strategies can be determined

  20. LHCb; LHCb Jet Reconstruction

    CERN Multimedia

    Augusto, O

    2012-01-01

    The Large Hadron Collider (LHC) is the most powerful particle accelerator in the world. It has been designed to collide proton beams at an energy up to 14 TeV in the center of mass. In 2011, the data taking was done with a center of mass energy of 7 TeV, the instant luminosity has reached values greater than $4 \\times 10^{32} cm^{-2} s^{-1}$ and the integrated luminosity reached the value of 1.02 $fb^{-1}$ on the LHCb. The jet reconstruction is fundamental to observe events that can be used to test pertubative QCD (pQCD). It also provides a way to observe standard model channels and searches for new physics like SUSY. The anti-kt algorithm is a jet reconstruction algorithm that is based on the distance of the particles on the space $\\eta \\times \\phi$ and on the transverse momentum of particles. To maximize the energy resolution all information about the trackers and the calo...

  1. Project Paleonao: How know the pattern of the rains. Spanish and Portuguese researchers reconstruct the climatic evolution of the North; Proyecto paleonao: como conocer el patron de las lluvias

    Energy Technology Data Exchange (ETDEWEB)

    Ayala, A.

    2015-07-01

    NAO, the effect of the North Atlantic oscillation, is the difference of air pressure between Iceland and the Azores, and that which governs climate variation every twelve months. To study and understand this phenomenon, which determines the arrival or not of the rains and influence on marine and terrestrial ecosystems are It launched the Paleonao Project. Based on historical weather records, its researchers use sensors natural lakes to collect data. is the case of the Penalara glacial lagoon, whose sediments they allow to know the evolution of the climate since thousands of years and to observe long-term trends of what will eventually passing in terms of precipitation and temperature changes. (Author)

  2. Three-dimensional ICT reconstruction

    International Nuclear Information System (INIS)

    Zhang Aidong; Li Ju; Chen Fa; Sun Lingxia

    2005-01-01

    The three-dimensional ICT reconstruction method is the hot topic of recent ICT technology research. In the context, qualified visual three-dimensional ICT pictures are achieved through multi-piece two-dimensional images accumulation by, combining with thresholding method and linear interpolation. Different direction and different position images of the reconstructed pictures are got by rotation and interception respectively. The convenient and quick method is significantly instructive to more complicated three-dimensional reconstruction of ICT images. (authors)

  3. Three-dimensional ICT reconstruction

    International Nuclear Information System (INIS)

    Zhang Aidong; Li Ju; Chen Fa; Sun Lingxia

    2004-01-01

    The three-dimensional ICT reconstruction method is the hot topic of recent ICT technology research. In the context qualified visual three-dimensional ICT pictures are achieved through multi-piece two-dimensional images accumulation by order, combining with thresholding method and linear interpolation. Different direction and different position images of the reconstructed pictures are got by rotation and interception respectively. The convenient and quick method is significantly instructive to more complicated three-dimensional reconstruction of ICT images. (authors)

  4. Virtual 3-D Facial Reconstruction

    Directory of Open Access Journals (Sweden)

    Martin Paul Evison

    2000-06-01

    Full Text Available Facial reconstructions in archaeology allow empathy with people who lived in the past and enjoy considerable popularity with the public. It is a common misconception that facial reconstruction will produce an exact likeness; a resemblance is the best that can be hoped for. Research at Sheffield University is aimed at the development of a computer system for facial reconstruction that will be accurate, rapid, repeatable, accessible and flexible. This research is described and prototypical 3-D facial reconstructions are presented. Interpolation models simulating obesity, ageing and ethnic affiliation are also described. Some strengths and weaknesses in the models, and their potential for application in archaeology are discussed.

  5. An iterative reconstruction method of complex images using expectation maximization for radial parallel MRI

    International Nuclear Information System (INIS)

    Choi, Joonsung; Kim, Dongchan; Oh, Changhyun; Han, Yeji; Park, HyunWook

    2013-01-01

    In MRI (magnetic resonance imaging), signal sampling along a radial k-space trajectory is preferred in certain applications due to its distinct advantages such as robustness to motion, and the radial sampling can be beneficial for reconstruction algorithms such as parallel MRI (pMRI) due to the incoherency. For radial MRI, the image is usually reconstructed from projection data using analytic methods such as filtered back-projection or Fourier reconstruction after gridding. However, the quality of the reconstructed image from these analytic methods can be degraded when the number of acquired projection views is insufficient. In this paper, we propose a novel reconstruction method based on the expectation maximization (EM) method, where the EM algorithm is remodeled for MRI so that complex images can be reconstructed. Then, to optimize the proposed method for radial pMRI, a reconstruction method that uses coil sensitivity information of multichannel RF coils is formulated. Experiment results from synthetic and in vivo data show that the proposed method introduces better reconstructed images than the analytic methods, even from highly subsampled data, and provides monotonic convergence properties compared to the conjugate gradient based reconstruction method. (paper)

  6. Accelerating image reconstruction in three-dimensional optoacoustic tomography on graphics processing units.

    Science.gov (United States)

    Wang, Kun; Huang, Chao; Kao, Yu-Jiun; Chou, Cheng-Ying; Oraevsky, Alexander A; Anastasio, Mark A

    2013-02-01

    Optoacoustic tomography (OAT) is inherently a three-dimensional (3D) inverse problem. However, most studies of OAT image reconstruction still employ two-dimensional imaging models. One important reason is because 3D image reconstruction is computationally burdensome. The aim of this work is to accelerate existing image reconstruction algorithms for 3D OAT by use of parallel programming techniques. Parallelization strategies are proposed to accelerate a filtered backprojection (FBP) algorithm and two different pairs of projection/backprojection operations that correspond to two different numerical imaging models. The algorithms are designed to fully exploit the parallel computing power of graphics processing units (GPUs). In order to evaluate the parallelization strategies for the projection/backprojection pairs, an iterative image reconstruction algorithm is implemented. Computer simulation and experimental studies are conducted to investigate the computational efficiency and numerical accuracy of the developed algorithms. The GPU implementations improve the computational efficiency by factors of 1000, 125, and 250 for the FBP algorithm and the two pairs of projection/backprojection operators, respectively. Accurate images are reconstructed by use of the FBP and iterative image reconstruction algorithms from both computer-simulated and experimental data. Parallelization strategies for 3D OAT image reconstruction are proposed for the first time. These GPU-based implementations significantly reduce the computational time for 3D image reconstruction, complementing our earlier work on 3D OAT iterative image reconstruction.

  7. Use of 3D reconstruction to correct for patient motion in SPECT

    International Nuclear Information System (INIS)

    Fulton, R.R.; Hutton, B.F.; Braun, M.; Ardekani, B.; Larkin, R.

    1994-01-01

    Patient motion occurring during data acquisition in single photon emission computed tomography (SPECT) can cause serious reconstruction artefacts. We have developed a new approach to correct for head motion in brain SPECT. Prior to motion, projections are assigned to conventional projections. When head motion occurs, it is measured by a motion monitoring system, and subsequent projection data are mapped 'virtual' projections. The appropriate position of each virtual projection is determined by applying the converse of the patient's accumulated motion to the actual camera projection. Conventional and virtual projections, taken together, form a consistent set that can be reconstructed using a three-dimensional (3D) algorithm. The technique has been tested on a range of simulated rotational movements, both within and out of the transaxial plane. For all simulated movements, the motion corrected images exhibited better agreement with a motion free reconstruction than did the uncorrected images. (Author)

  8. Effect of noise in computed tomographic reconstructions on detectability

    International Nuclear Information System (INIS)

    Hanson, K.M.

    1982-01-01

    The detectability of features in an image is ultimately limited by the random fluctuations in density or noise present in that image. The noise in CT reconstructions arising from the statistical fluctuations in the one-dimensional input projection measurements has an unusual character owing to the reconstruction procedure. Such CT image noise differs from the white noise normally found in images in its lack of low-frequency components. The noise power spectrum of CT reconstructions can be related to the effective density of x-ray quanta detected in the projection measurements, designated as NEQ (noise-equivalent quanta). The detectability of objects that are somewhat larger than the spatial resolution is directly related to NEQ. Since contrast resolution may be defined in terms of the ability to detect large, low-contrast objects, the measurement of a CT scanner's NEQ may be used to characterize its contrast sensitivity

  9. A study of transverse image reconstruction with digital subtraction angiography

    International Nuclear Information System (INIS)

    Sakamoto, Kiyoshi; Kotoura, Noriko; Terasawa, Yuuji; Oda, Masahiko; Gotou, Hiroshi; Nasada, Toshiya; Tanooka, Masao

    1995-01-01

    For digital subtraction angiography (DSA) with C-type equipment, it is possible to radiate an X-ray during rotation and to collect data at different angular settings. We tried to reconstruct transverse image from data obtained by scanning DSA images at different angular settings. 88 projection data were obtained by rotating the object at 180deg during radiation. Reconstruction was made using the convolution method with pixel value distribution for each projection. Similarly, the image quality of the reconstructed images were compared with the unsubtracted and subtracted ones. In case a part object was outside the calculating region, artifacts were generally produced. However, the artifacts were reduced by subtracting the background from the image. In addition, the cupping phenomenon caused by beam hardening was relaxed and high-quality imaging could be achieved. This method will become even more effective, if we will use it with selective angiography in which the limited area is enhanced. (author)

  10. Quantitative reconstruction from a single diffraction-enhanced image

    International Nuclear Information System (INIS)

    Paganin, D.M.; Lewis, R.A.; Kitchen, M.

    2003-01-01

    Full text: We develop an algorithm for using a single diffraction-enhanced image (DEI) to obtain a quantitative reconstruction of the projected thickness of a single-material sample which is embedded within a substrate of approximately constant thickness. This algorithm is used to quantitatively map inclusions in a breast phantom, from a single synchrotron DEI image. In particular, the reconstructed images quantitatively represent the projected thickness in the bulk of the sample, in contrast to DEI images which greatly emphasise sharp edges (high spatial frequencies). In the context of an ultimate aim of improved methods for breast cancer detection, the reconstructions are potentially of greater diagnostic value compared to the DEI data. Lastly, we point out that the methods of analysis presented here are also applicable to the quantitative analysis of differential interference contrast (DIC) images

  11. DG TOMO: A new method for tomographic reconstruction

    International Nuclear Information System (INIS)

    Freitas, D. de; Feschet, F.; Cachin, F.; Geissler, B.; Bapt, A.; Karidioula, I.; Martin, C.; Kelly, A.; Mestas, D.; Gerard, Y.; Reveilles, J.P.; Maublant, J.

    2006-01-01

    Aim: FBP and OSEM are the most popular tomographic reconstruction methods in scintigraphy. FBP is a simple method but artifacts of reconstruction are generated which corrections induce degradation of the spatial resolution. OSEM takes account of statistical fluctuations but noise strongly increases after a certain number of iterations. We compare a new method of tomographic reconstruction based on discrete geometry (DG TOMO) to FBP and OSEM. Materials and methods: Acquisitions were performed on a three-head gamma-camera (Philips) with a NEMA Phantom containing six spheres of sizes from 10 to 37 mm inner diameter, filled with around 325 MBq/l of technetium-99 m. The spheres were positioned in water containing 3 MBq/l of technetium-99 m. Acquisitions were realized during a 180 o -rotation around the phantom by 25-s steps. DG TOMO has been developed in our laboratory in order to minimize the number of projections at acquisition. Two tomographic reconstructions utilizing 32 and 16 projections with FBP, OSEM and DG TOMO were performed and transverse slices were compared. Results: FBP with 32 projections detects only the activity in the three largest spheres (diameter ≥22 mm). With 16 projections, the star effect is predominant and the contrast of the third sphere is very low. OSEM with 32 projections provides a better image but the three smallest spheres (diameter ≤17 mm) are difficult to distinguish. With 16 projections, the three smaller spheres are not detectable. The results of DG TOMO are similar to OSEM. Conclusion: Since the parameters of DG TOMO can be further optimized, this method appears as a promising alternative for tomoscintigraphy reconstruction

  12. A compressed sensing based approach on Discrete Algebraic Reconstruction Technique.

    Science.gov (United States)

    Demircan-Tureyen, Ezgi; Kamasak, Mustafa E

    2015-01-01

    Discrete tomography (DT) techniques are capable of computing better results, even using less number of projections than the continuous tomography techniques. Discrete Algebraic Reconstruction Technique (DART) is an iterative reconstruction method proposed to achieve this goal by exploiting a prior knowledge on the gray levels and assuming that the scanned object is composed from a few different densities. In this paper, DART method is combined with an initial total variation minimization (TvMin) phase to ensure a better initial guess and extended with a segmentation procedure in which the threshold values are estimated from a finite set of candidates to minimize both the projection error and the total variation (TV) simultaneously. The accuracy and the robustness of the algorithm is compared with the original DART by the simulation experiments which are done under (1) limited number of projections, (2) limited view problem and (3) noisy projections conditions.

  13. Reconstructing an Ancient Wonder.

    Science.gov (United States)

    Imhof, Christopher J.

    2001-01-01

    Describes a Montessori class project involving the building of a model of the ancient Briton monument, Stonehenge. Illustrates how the flexibility of the Montessori elementary curriculum encourages children to make their own toys and learn from the process. (JPB)

  14. Registration-based Reconstruction of Four-dimensional Cone Beam Computed Tomography

    DEFF Research Database (Denmark)

    Christoffersen, Christian; Hansen, David Christoffer; Poulsen, Per Rugaard

    2013-01-01

    We present a new method for reconstruction of four-dimensional (4D) cone beam computed tomography from an undersampled set of X-ray projections. The novelty of the proposed method lies in utilizing optical flow based registration to facilitate that each temporal phase is reconstructed from the full...

  15. Influence of iterative image reconstruction on CT-based calcium score measurements

    NARCIS (Netherlands)

    van Osch, Jochen A. C.; Mouden, Mohamed; van Dalen, Jorn A.; Timmer, Jorik R.; Reiffers, Stoffer; Knollema, Siert; Greuter, Marcel J. W.; Ottervanger, Jan Paul; Jager, Piet L.

    Iterative reconstruction techniques for coronary CT angiography have been introduced as an alternative for traditional filter back projection (FBP) to reduce image noise, allowing improved image quality and a potential for dose reduction. However, the impact of iterative reconstruction on the

  16. Comparison among tomographic reconstruction with limited data

    International Nuclear Information System (INIS)

    Oliveira, Eric F.; Dantas, Carlos C.; Vasconcelos, Daniel A.A.; Cadiz, Luis F.; Melo, Silvio B.

    2011-01-01

    Nowadays there is a continuing interest in applying computed tomography (CT) techniques in non-destructive testing and inspection of many industrial products. These applications of CT usually require a differentiated analysis when there are strong limitations in acquiring a sufficiently large amount of projection data. The use of a low number of tomographic data normally degrades the quality of the reconstructed image, highlighting the formation of artifacts and noise. This work investigates the reconstruction methods most commonly used (FBP, ART, SIRT, MART, SMART) and shows the performance of each one in this limited scenario. For this purpose, all methods were implemented and tested with a phantom of uniform density with well-known distribution, with measures of transmission of gamma radiation in a first generation CT scanner. The phantom is a concentric stainless steel tube coupled with a half - cylinder of aluminum. The measurements were made with an highest root mean square error, with the formation of visible artifacts. The artifacts are diminished but still visible in the ART and SIRT techniques, and the best performance was observed with the techniques MART and SMART. The technical superiority of these multiplicative methods is clearly seen in the reconstructed image quality, endorsing their application to situations of limited input data. (author)

  17. Strategies of reconstruction algorithms for computerized tomography

    International Nuclear Information System (INIS)

    Garderet, P.

    1984-10-01

    Image reconstruction from projections has progressively spread out over all fields of medical imaging. As the mathematical aspects of the problem become more and more comprehensively explored a great variety of numerical solutions have been developed best suited to such-and-such imaging medical application and taking into account the physical phenomena related to data collection (a priori properties for signal and noise). The purpose of that survey is to present the general mathematical frame and the fundamental assumptions of various strategies; Fourier methods approximate explicit deterministic inversion formula for the Radon transform. Algebraic reconstruction techniques set up an a priori discrete model through a series expansion approach of the solution. The numerical system to be solved is huge when a fine grid of pixels is to be reconstructed; iterative solutions may then be found. Recently some least square procedures have been shown to be tractable which avoid the use of iterative methods. Finally maximum like hood approach incorporates accurately the Poisson nature of photon noise and are well adapted to emission computed tomography. The various strategies will be analysed from both aspects of theoretical assumptions needed for suitable use and of computing facilities, actual performance and cost. In the end we take a glimpse of the extension of the algorithms from two dimensional imaging to fully three dimensional volume analysis in preparation of the future medical imaging technologies

  18. Monthly paleostreamflow reconstruction from annual tree-ring chronologies

    Science.gov (United States)

    J. H. Stagge; D. E. Rosenberg; R. J. DeRose; T. M. Rittenour

    2018-01-01

    Paleoclimate reconstructions are increasingly used to characterize annual climate variability prior to the instrumental record, to improve estimates of climate extremes, and to provide a baseline for climate change projections. To date, paleoclimate records have seen limited engineering use to estimate hydrologic risks because water systems models and managers usually...

  19. Reconstruction of the central carbon metabolism of Aspergillus niger

    DEFF Research Database (Denmark)

    David, Helga; Åkesson, Mats Fredrik; Nielsen, Jens

    2003-01-01

    database for annotation of genes identified in future genome sequencing projects on aspergilli. Based on the metabolic reconstruction, a stoichiometric model was set up that includes 284 metabolites and 335 reactions, of which 268 represent biochemical conversions and 67 represent transport processes...

  20. Precipitation reconstruction for the Czech Lands, AD 1501-2010

    Czech Academy of Sciences Publication Activity Database

    Dobrovolný, Petr; Brázdil, Rudolf; Trnka, Miroslav; Kotyza, O.; Valášek, H.

    2015-01-01

    Roč. 35, č. 1 (2015), s. 1-14 ISSN 0899-8418 R&D Projects: GA ČR GA13-04291S; GA ČR GA13-19831S Institutional support: RVO:67179843 Keywords : documentary evidence * instrumental data * precipitation * reconstruction * Czech Lands Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 3.609, year: 2015

  1. Effective Diffusivities of Gases in a Reconstructed Porous Body

    Czech Academy of Sciences Publication Activity Database

    Čapek, P.; Hejtmánek, Vladimír; Brabec, Libor; Zikánová, Arlette; Kočiřík, Milan

    2008-01-01

    Roč. 86, č. 7A (2008), s. 713-722 ISSN 0263-8762 R&D Projects: GA ČR GA203/05/0347 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z40400503 Keywords : stochastic reconstruction * random pore network * random Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.989, year: 2008

  2. Firm Elevation of Reconstructed Auricle Using Polydactyly Digit in Microtia.

    Science.gov (United States)

    Jang, Suk Yoon; Kim, Woo Seob; Kim, Han Koo; Bae, Tae Hui

    2018-03-01

    Total ear reconstruction for microtia is usually accomplished in 2 stages which is known as Nagata technique. After framework fabrication and implantation, the elevation procedure is required as a second step surgery. The authors are introducing a novel material for augmenting projection of rib cartilage framework in microtia treatment.

  3. Configurable 3D rotational X-ray reconstruction

    NARCIS (Netherlands)

    Nguyen, Xuan Huy

    2012-01-01

    This report is one of the deliverables of the project "Configurable 3D Rotational X-ray Reconstruction", carried out by the author as the final part of the Professional Doctorate in Engineering (PDEng) degree program in Software Technology provided by Eindhoven University of Technology and Stan

  4. Top Reconstruction Techniques in 0-Lepton Direct Stop Searches

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    Final presentation of my summer research into new and improved methods for identifying top quarks in 6+ jet events with missing transverse energy. Specifically, I will discuss methods I have developed to reconstruct tops, and my future plans for my project in the future.

  5. An industrial case study in reconstructing requirements views

    NARCIS (Netherlands)

    Lormans, M.; Van Deursen, A.; Gross, H.G.

    2008-01-01

    Requirements views, such as coverage and status views, are an important asset for monitoring and managing software development projects. We have developed a method that automates the process of reconstructing these views, and we have built a tool, REQANALYST, that supports this method. This paper

  6. CRUCIATE LIGAMENT RECONSTRUCTION

    Directory of Open Access Journals (Sweden)

    A. V. Korolev

    2016-01-01

    Full Text Available Purpose: To evaluate long-term results of meniscal repair during arthroscopic ACL reconstruction.Materials and methods: 45 patients who underwent meniscal repair during arthroscopic ACL reconstruction between 2007 and 2013 by the same surgeon were included in the study. In total, fifty meniscus were repaired (26 medial and 24 lateral. Procedures included use of one up to four Fast-Fix implants (Smith & Nephew. In five cases both medial and lateral meniscus were repaired. Cincinnati, IKDC and Lysholm scales were used for long-term outcome analysis.Results: 19 male and 26 female patients were included in the study aging from 15 to 59 years (mean age 33,2±1,5. Median time from injury to surgical procedure was zero months (ranging zero to one. Mean time from surgery to scale analysis was 55,9±3 months (ranged 20-102. Median Cincinnati score was 97 (ranged 90-100, with excellent results in 93% of cases (43 patients and good results in 7% (3 patients. Median IKDC score was 90,8 (ranged 86,2-95,4, with excellent outcomes in 51% of cases (23 patients, good in 33% (15 patients and satisfactory in 16% (7 patients. Median Lysholm score was 95 (ranged 90-100, with excellent outcomes in 76% of cases (34 patients and good in 24% (11 patients. Authors identified no statistical differences when comparing survey results in age, sex and time from trauma to surgery.Conclusions: Results of the present study match the data from orthopedic literature that prove meniscal repair as a safe and efficient procedure with good and excellent outcomes. All-inside meniscal repair can be used irrespectively of patients' age and is efficient even in case of delayed procedures.

  7. Value of selective MIP reconstructions of respiratory triggered 3D-TSE-MR cholangiography on a workstation versus standard MIP reconstructions and single-shot MRCP

    International Nuclear Information System (INIS)

    Schaible, R.; Textor, J.; Kreft, B.; Schild, H.; Neubrand, M.

    2001-01-01

    Comparison of anatomical visualisation and diagnostic value of selective MIP reconstructions of respiratory triggered 3D-TSE-MRCP versus standard MIP reconstructions and single-shot MRCP. Material and Methods: 50 patients with pancreaticobiliary disease were examined at 1.5 Tesla (ACS NT II, Philips Medical Systems) using a breath-hold single-shot (SS) and a respiratory triggered 3D-TSE-MRCP technique in 12 standard MIP projections. Additional selective MIP reconstructions with different slice thickness (2, 4, 10 cm) and projections were performed on a workstation. Visualization of the pancreaticobiliary system and the diagnostic value of the examinations were analysed. Results: Single-shot and 3D-TSE in standard projections showed comparable anatomical visualisation. On selective MIP reconstructions the biliary system (SS p [de

  8. Reconstruction of electric systems (ELE)

    International Nuclear Information System (INIS)

    Kohutovic, P.

    2001-01-01

    The original design of WWER-230 units consisted of a single common system EEPS (essential electric power supply system) per unit. The establishment of redundancy 2 x 100% EEPS was a global task. The task was started during the 'Small reconstruction' - MR V1, continued in 'Gradual reconstruction' and finished in the year 2000. (author)

  9. Breast Reconstruction Following Cancer Treatment.

    Science.gov (United States)

    Gerber, Bernd; Marx, Mario; Untch, Michael; Faridi, Andree

    2015-08-31

    About 8000 breast reconstructions after mastectomy are per - formed in Germany each year. It has become more difficult to advise patients because of the wide variety of heterologous and autologous techniques that are now available and because of changes in the recommendations about radiotherapy. This article is based on a review of pertinent articles (2005-2014) that were retrieved by a selective search employing the search terms "mastectomy" and "breast reconstruction." The goal of reconstruction is to achieve an oncologically safe and aestically satisfactory result for the patient over the long term. Heterologous, i.e., implant-based, breast reconstruction (IBR) and autologous breast reconstruction (ABR) are complementary techniques. Immediate reconstruction preserves the skin of the breast and its natural form and prevents the psychological trauma associated with mastectomy. If post-mastectomy radiotherapy (PMRT) is not indicated, implant-based reconstruction with or without a net/acellular dermal matrix (ADM) is a common option. Complications such as seroma formation, infection, and explantation are significantly more common when an ADM is used (15.3% vs. 5.4% ). If PMRT is performed, then the complication rate of implant-based breast reconstruction is 1 to 48% ; in particular, Baker grade III/IV capsular fibrosis occurs in 7 to 22% of patients, and the prosthesis must be explanted in 9 to 41% . Primary or, preferably, secondary autologous reconstruction is an alternative. The results of ABR are more stable over the long term, but the operation is markedly more complex. Autologous breast reconstruction after PMRT does not increase the risk of serious complications (20.5% vs. 17.9% without radiotherapy). No randomized controlled trials have yet been conducted to compare the reconstructive techniques with each other. If radiotherapy will not be performed, immediate reconstruction with an implant is recommended. On the other hand, if post-mastectomy radiotherapy

  10. Evaluation of digital breast tomosynthesis reconstruction algorithms using synchrotron radiation in standard geometry

    International Nuclear Information System (INIS)

    Bliznakova, K.; Kolitsi, Z.; Speller, R. D.; Horrocks, J. A.; Tromba, G.; Pallikarakis, N.

    2010-01-01

    Purpose: In this article, the image quality of reconstructed volumes by four algorithms for digital tomosynthesis, applied in the case of breast, is investigated using synchrotron radiation. Methods: An angular data set of 21 images of a complex phantom with heterogeneous tissue-mimicking background was obtained using the SYRMEP beamline at ELETTRA Synchrotron Light Laboratory, Trieste, Italy. The irradiated part was reconstructed using the multiple projection algorithm (MPA) and the filtered backprojection with ramp followed by hamming windows (FBR-RH) and filtered backprojection with ramp (FBP-R). Additionally, an algorithm for reducing the noise in reconstructed planes based on noise mask subtraction from the planes of the originally reconstructed volume using MPA (MPA-NM) has been further developed. The reconstruction techniques were evaluated in terms of calculations and comparison of the contrast-to-noise ratio (CNR) and artifact spread function. Results: It was found that the MPA-NM resulted in higher CNR, comparable with the CNR of FBP-RH for high contrast details. Low contrast objects are well visualized and characterized by high CNR using the simple MPA and the MPA-NM. In addition, the image quality of the reconstructed features in terms of CNR and visual appearance as a function of the initial number of projection images and the reconstruction arc was carried out. Slices reconstructed with more input projection images result in less reconstruction artifacts and higher detail CNR, while those reconstructed from projection images acquired in reduced angular range causes pronounced streak artifacts. Conclusions: Of the reconstruction algorithms implemented, the MPA-NM and MPA are a good choice for detecting low contrast objects, while the FBP-RH, FBP-R, and MPA-NM provide high CNR and well outlined edges in case of microcalcifications.

  11. Increasing Cone-beam projection usage by temporal fitting

    DEFF Research Database (Denmark)

    Lyksborg, Mark; Hansen, Mads Fogtmann; Larsen, Rasmus

    2010-01-01

    A Cone-beam CT system can be used to image the lung region. The system records 2D projections which will allow 3D reconstruction however a reconstruction based on all projections will lead to a blurred reconstruction in regions were respiratory motion occur. To avoid this the projections are typi......A Cone-beam CT system can be used to image the lung region. The system records 2D projections which will allow 3D reconstruction however a reconstruction based on all projections will lead to a blurred reconstruction in regions were respiratory motion occur. To avoid this the projections...... in [6] prior knowledge of the lung deformation estimated from the planning CT could be used to include all projections into the reconstruction. It has also been attempted to estimate both the motion and 3D volume simultaneously in [4]. Problems with motion estimation are ill-posed leading to suboptimal...... motion which in return affects the reconstruction. By directly including time into the image representation the effect of suboptimal motion fields are avoided and we are still capable of using phase neighbour projections. The 4D image model is fitted by solving a statistical cost function based...

  12. A two-step Hilbert transform method for 2D image reconstruction

    International Nuclear Information System (INIS)

    Noo, Frederic; Clackdoyle, Rolf; Pack, Jed D

    2004-01-01

    The paper describes a new accurate two-dimensional (2D) image reconstruction method consisting of two steps. In the first step, the backprojected image is formed after taking the derivative of the parallel projection data. In the second step, a Hilbert filtering is applied along certain lines in the differentiated backprojection (DBP) image. Formulae for performing the DBP step in fan-beam geometry are also presented. The advantage of this two-step Hilbert transform approach is that in certain situations, regions of interest (ROIs) can be reconstructed from truncated projection data. Simulation results are presented that illustrate very similar reconstructed image quality using the new method compared to standard filtered backprojection, and that show the capability to correctly handle truncated projections. In particular, a simulation is presented of a wide patient whose projections are truncated laterally yet for which highly accurate ROI reconstruction is obtained

  13. Iterative reconstruction with boundary detection for carbon ion computed tomography

    Science.gov (United States)

    Shrestha, Deepak; Qin, Nan; Zhang, You; Kalantari, Faraz; Niu, Shanzhou; Jia, Xun; Pompos, Arnold; Jiang, Steve; Wang, Jing

    2018-03-01

    In heavy ion radiation therapy, improving the accuracy in range prediction of the ions inside the patient’s body has become essential. Accurate localization of the Bragg peak provides greater conformity of the tumor while sparing healthy tissues. We investigated the use of carbon ions directly for computed tomography (carbon CT) to create the relative stopping power map of a patient’s body. The Geant4 toolkit was used to perform a Monte Carlo simulation of the carbon ion trajectories, to study their lateral and angular deflections and the most likely paths, using a water phantom. Geant4 was used to create carbonCT projections of a contrast and spatial resolution phantom, with a cone beam of 430 MeV/u carbon ions. The contrast phantom consisted of cranial bone, lung material, and PMMA inserts while the spatial resolution phantom contained bone and lung material inserts with line pair (lp) densities ranging from 1.67 lp cm-1 through 5 lp cm-1. First, the positions of each carbon ion on the rear and front trackers were used for an approximate reconstruction of the phantom. The phantom boundary was extracted from this approximate reconstruction, by using the position as well as angle information from the four tracking detectors, resulting in the entry and exit locations of the individual ions on the phantom surface. Subsequent reconstruction was performed by the iterative algebraic reconstruction technique coupled with total variation minimization (ART-TV) assuming straight line trajectories for the ions inside the phantom. The influence of number of projections was studied with reconstruction from five different sets of projections: 15, 30, 45, 60 and 90. Additionally, the effect of number of ions on the image quality was investigated by reducing the number of ions/projection while keeping the total number of projections at 60. An estimation of carbon ion range using the carbonCT image resulted in improved range prediction compared to the range calculated using a

  14. FUNGSI BHP SEBAGAI WALI PENGAWAS TERHADAP ANAK DI BAWAH PERWALIAN DALAM RANGKA PERLINDUNGAN ANAK (STUDI KASUS DI BHP SEMARANG

    Directory of Open Access Journals (Sweden)

    Endang Heriyani

    2016-01-01

    Full Text Available According to Article 45 paragraph (1 Regulations No 1 1974 about marriage, both of the parents have obligation to take care and educate their children as well as possible. But in fact, many events can be watched on parents who do not do their duties as parents. Children who are not in the authority of their parents, will be placed under the guardianship. According to Article 306 of the book of the civil law act in guardianship there should be a guardian which is run by the Heritage Hall. The problem rises is the existence of the Heritage Hall as the guardian watch in guardianship that can give protection to the children under the guardianship and how are the efforts to optimize the function of the Heritage Hall as the guardian watch to the children under the guardianship. This research is a normative and an empirical law research. The conclusion of this research is that the guardian's obligations and the obligations of the Heritage Hall as the guardian watch if it is executed to provide protection to the children, both the personality and the treasure. Thus, the position of Heritage Hall as the guardian watch needs to be maintained. The efforts of Heritage Hall to optimize the function of the Heritage Hall as the guardian watch can be reached by the bill of draft legislation about Heritage Hall. By maintaining the provisions of the book of civil law act or S 1872 No 166 on the instruction of Heritage Hall, which are still needed by the Heritage Hall in doing the duties.

  15. Ray tracing reconstruction investigation for C-arm tomosynthesis

    Science.gov (United States)

    Malalla, Nuhad A. Y.; Chen, Ying

    2016-04-01

    C-arm tomosynthesis is a three dimensional imaging technique. Both x-ray source and the detector are mounted on a C-arm wheeled structure to provide wide variety of movement around the object. In this paper, C-arm tomosynthesis was introduced to provide three dimensional information over a limited view angle (less than 180o) to reduce radiation exposure and examination time. Reconstruction algorithms based on ray tracing method such as ray tracing back projection (BP), simultaneous algebraic reconstruction technique (SART) and maximum likelihood expectation maximization (MLEM) were developed for C-arm tomosynthesis. C-arm tomosynthesis projection images of simulated spherical object were simulated with a virtual geometric configuration with a total view angle of 40 degrees. This study demonstrated the sharpness of in-plane reconstructed structure and effectiveness of removing out-of-plane blur for each reconstruction algorithms. Results showed the ability of ray tracing based reconstruction algorithms to provide three dimensional information with limited angle C-arm tomosynthesis.

  16. A fast sparse reconstruction algorithm for electrical tomography

    International Nuclear Information System (INIS)

    Zhao, Jia; Xu, Yanbin; Tan, Chao; Dong, Feng

    2014-01-01

    Electrical tomography (ET) has been widely investigated due to its advantages of being non-radiative, low-cost and high-speed. However, the image reconstruction of ET is a nonlinear and ill-posed inverse problem and the imaging results are easily affected by measurement noise. A sparse reconstruction algorithm based on L 1 regularization is robust to noise and consequently provides a high quality of reconstructed images. In this paper, a sparse reconstruction by separable approximation algorithm (SpaRSA) is extended to solve the ET inverse problem. The algorithm is competitive with the fastest state-of-the-art algorithms in solving the standard L 2 −L 1 problem. However, it is computationally expensive when the dimension of the matrix is large. To further improve the calculation speed of solving inverse problems, a projection method based on the Krylov subspace is employed and combined with the SpaRSA algorithm. The proposed algorithm is tested with image reconstruction of electrical resistance tomography (ERT). Both simulation and experimental results demonstrate that the proposed method can reduce the computational time and improve the noise robustness for the image reconstruction. (paper)

  17. Denoising multicriterion iterative reconstruction in emission spectral tomography

    Science.gov (United States)

    Wan, Xiong; Yin, Aihan

    2007-03-01

    In the study of optical testing, the computed tomogaphy technique has been widely adopted to reconstruct three-dimensional distributions of physical parameters of various kinds of fluid fields, such as flame, plasma, etc. In most cases, projection data are often stained by noise due to environmental disturbance, instrumental inaccuracy, and other random interruptions. To improve the reconstruction performance in noisy cases, an algorithm that combines a self-adaptive prefiltering denoising approach (SPDA) with a multicriterion iterative reconstruction (MCIR) is proposed and studied. First, the level of noise is approximately estimated with a frequency domain statistical method. Then the cutoff frequency of a Butterworth low-pass filter was established based on the evaluated noise energy. After the SPDA processing, the MCIR algorithm was adopted for limited-view optical computed tomography reconstruction. Simulated reconstruction of two test phantoms and a flame emission spectral tomography experiment were employed to evaluate the performance of SPDA-MCIR in noisy cases. Comparison with some traditional methods and experiment results showed that the SPDA-MCIR combination had obvious improvement in the case of noisy data reconstructions.

  18. Optimisation of the ATLAS Track Reconstruction Software for Run-2

    CERN Document Server

    Salzburger, Andreas; The ATLAS collaboration

    2015-01-01

    The reconstruction of particle trajectories in the tracking detectors of experiments at the Large Hadron Collider (LHC) is one of the most complex parts in analysing the collected data from beam-beam collisions. To achieve the desired integrated luminosity during Run-1 of the LHC data taking period, the number of simultaneous proton-proton interactions per beam crossing (pile-up) was steadily increased. The track reconstruction is the most time consuming reconstruction component and scales non-linear in high luminosity environments. Flat budget projections (at best) for computing resources during the upcoming Run-2 of the LHC together with the demands of reconstructing higher pile-up collision data at rates more than double compared to Run-1 have put pressure on the track reconstruction software to stay within the available computing resources. The ATLAS experiment has thus performed a two year long software campaign which led to a reduction of the reconstruction time for Run-2 conditions by a factor of four:...

  19. Novel image reconstruction algorithm for multi-phase flow tomography system using γ ray method

    International Nuclear Information System (INIS)

    Hao Kuihong; Wang Huaxiang; Gao Mei

    2007-01-01

    After analyzing the reason of image reconstructed algorithm by using the conventional back projection (IBP) is prone to produce spurious line, and considering the characteristic of multi-phase flow tomography, a novel image reconstruction algorithm is proposed, which carries out the intersection calculation using back projection data. This algorithm can obtain a perfect system point spread function, and can eliminate spurious line better. Simulating results show that the algorithm is effective for identifying multi-phase flow pattern. (authors)

  20. NCT-ART - a neutron computer tomography code based on the algebraic reconstruction technique

    International Nuclear Information System (INIS)

    Krueger, A.

    1988-01-01

    A computer code is presented, which calculates two-dimensional cuts of material assemblies from a number of neutron radiographic projections. Mathematically, the reconstruction is performed by an iterative solution of a system of linear equations. If the system is fully determined, clear pictures are obtained. Even for an underdetermined system (low number of projections) reasonable pictures are reconstructed, but then picture artefacts and convergence problems occur increasingly. (orig.) With 37 figs [de

  1. Spruce Lake Dam reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Snyder, G. [SGE Acres Ltd., Fredericton, NB (Canada); Barnard, J. [SGE Acres Ltd., St. John' s, NF (Canada); Vriezen, C. [City of Saint John, NF (Canada); Stephenson, M. [Jacques Whitford Environment Ltd., Fredericton, NB (Canada)

    2004-09-01

    Spruce Lake Dam was constructed in 1898 as part of the water supply system for Saint John, New Brunswick. The original dam was a 6 meter high, 140 meter long concrete gravity dam with an intake structure at its mid point and an overflow spillway at the left abutment. A rehabilitation project was launched in 2001 to bring the deteriorated dam into conformance with the dam safety guidelines of the Canadian Dam Association. The project criteria included minimal disruption to normal operation of water supply facilities and no negative effect on water quality. The project involved installation of a new low level outlet, removal of a gate house and water intake pipes, replacement of an access road culvert in the spillway channel, and raising the earth dam section by 1.8 meters to allow for increased water storage. The new raised section has an impervious core. The project also involved site and geotechnical investigations as well as hydrotechnical and environmental studies. This presentation described the final design of the remedial work and the environmental permitting procedures. Raising the operating level of the system proved successful as demonstrated by the fewer number of pumping days required after dam rehabilitation. The dam safety assessment under the Canadian Environmental Assessment Act began in April 2001, and the rehabilitation was completed by the end of 2002. 1 tab., 8 figs.

  2. Homotopic non-local regularized reconstruction from sparse positron emission tomography measurements

    International Nuclear Information System (INIS)

    Wong, Alexander; Liu, Chenyi; Wang, Xiao Yu; Fieguth, Paul; Bie, Hongxia

    2015-01-01

    Positron emission tomography scanners collect measurements of a patient’s in vivo radiotracer distribution. The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide (tracer), which is introduced into the body on a biologically active molecule, and the tomograms must be reconstructed from projections. The reconstruction of tomograms from the acquired PET data is an inverse problem that requires regularization. The use of tightly packed discrete detector rings, although improves signal-to-noise ratio, are often associated with high costs of positron emission tomography systems. Thus a sparse reconstruction, which would be capable of overcoming the noise effect while allowing for a reduced number of detectors, would have a great deal to offer. In this study, we introduce and investigate the potential of a homotopic non-local regularization reconstruction framework for effectively reconstructing positron emission tomograms from such sparse measurements. Results obtained using the proposed approach are compared with traditional filtered back-projection as well as expectation maximization reconstruction with total variation regularization. A new reconstruction method was developed for the purpose of improving the quality of positron emission tomography reconstruction from sparse measurements. We illustrate that promising reconstruction performance can be achieved for the proposed approach even at low sampling fractions, which allows for the use of significantly fewer detectors and have the potential to reduce scanner costs

  3. General surface reconstruction for cone-beam multislice spiral computed tomography

    International Nuclear Information System (INIS)

    Chen Laigao; Liang Yun; Heuscher, Dominic J.

    2003-01-01

    A new fami