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Shape reconstruction of Conductivity Interface Problems

INTERNATIONAL JOURNAL OF COMPUTATIONAL METHODS 2019年第1期16卷

作者： Liu, Ji-Chuan China Univ Min & Technol Sch Math Xuzhou 221116 Jiangsu Peoples R China

In this paper, we consider a conductivity interface problem to recover the salient features of the inclusion within a body from noisy observation data on the boundary. Based on integral equations, we propose iterative algorithms to detect the location, the size and the shape of the conductivity inclusion. This problem is severely ill-posexl and nonlinear, thus we should consider regularization techniques in order to improve the corresponding approximation. We give several examples to show the viability of our proposed reconstruction algorithms.

关键词： Conductivity interface problem reconstruction algorithm ill-posed problem inverse problem

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The Computational Structure of Spike Trains

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NEURAL COMPUTATION 2010年第1期22卷 121-157页

作者： Haslinger, Robert Klinkner, Kristina Lisa Shalizi, Cosma Rohilla Massachusetts Gen Hosp Martinos Ctr Biomed Imaging Charlestown MA 02129 USA MIT Dept Brain & Cognit Sci Cambridge MA 02139 USA Carnegie Mellon Univ Dept Stat Pittsburgh PA 15213 USA Santa Fe Inst Santa Fe NM 87051 USA

Neurons perform computations, and convey the results of those computations through the statistical structure of their output spike trains. Here we present a practical method, grounded in the information-theoretic analysis of prediction, for inferring a minimal representation of that structure and for characterizing its complexity. Starting from spike trains, our approach finds their causal state models (CSMs), the minimal hidden Markov models or stochastic automata capable of generating statistically identical time series. We then use these CSMs to objectively quantify both the generalizable structure and the idiosyncratic randomness of the spike train. Specifically, we show that the expected algorithmic information content ( the information needed to describe the spike train exactly) can be split into three parts describing ( 1) the time-invariant structure ( complexity) of the minimal spike-generating process, which describes the spike train statistically;( 2) the randomness ( internal entropy rate) of the minimal spike-generating process;and ( 3) a residual pure noise term not described by the minimal spike-generating process. We use CSMs to approximate each of these quantities. The CSMs are inferred nonparametrically from the data, making only mild regularity assumptions, via the causal state splitting reconstruction algorithm. The methods presented here complement more traditional spike train analyses by describing not only spiking probability and spike train entropy, but also the complexity of a spike train's structure. We demonstrate our approach using both simulated spike trains and experimental data recorded in rat barrel cortex during vibrissa stimulation.

关键词： computations representation automata reconstruction algorithm Minimal TRAIN Automata

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A New Splint for Dorsal Foot Burns

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JOURNAL OF BURN CARE & RESEARCH 2018年第2期39卷 308-310页

作者： Ergun, Selma Sonmez Bezmialem Vakif Univ Bezmialem Med Sch Dept Plast Reconstruct & Aesthet Istanbul Turkey

The treatment of dorsal foot burns has always been posed as a challenge to reconstructive surgeons. Despite of numerous reconstruction methods and appropriate approaches to the dorsal foot burn in acute phase, burn scars and contractures cannot always be prevented. Results of 5 female patients operated for burn scar contracture release and a new splinting approach are reported here.

关键词： Contracture burn scar Burns Splints reconstruction algorithm

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A novel strategy for prefabrication of large and axially vascularized tissue engineered bone by using an arteriovenous loop

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MEDICAL HYPOTHESES 2008年第5期71卷 737-740页

作者： Ren, Li-Ling Ma, Dong-Yang Feng, Xue Mao, Tian-Qiu Liu, Yan-Pu Ding, Yin Fourth Mil Med Univ Sch Stomatol Dept Orthodont Xian 710032 Shaanxi Peoples R China Fourth Mil Med Univ Sch Stomatol Dept Oral & Maxillofacial Surg Xian 710032 Shaanxi Peoples R China

The repair of bone defects remains a major clinical challenge because none available reconstruction methods and biomaterials have been proved completely satisfactory. As a promising approach for bone regeneration, tissue engineered bone has become a technically feasible method to repair small to moderate sized bone defects in clinical practice, but it is difficult to repair large one, particularly when the recipient site is scarred by infection or radiation injury. Construction of large and vascularized tissue engineered bone may overcome the problems since vascularization is an essential prerequisite for the constructs to survive and integrate with existing host tissue. On the other hand, prefabrication large artificial bone in vivo bioreactor and axial vascularization by means of arteriovenous loop model in soft tissue have been proved to be feasible. Therefore, we hypothesize that combination of cells, solid scaffold, growth factors, and arteriovenous loop may eventually generate a large and vascularized tissue engineered bone flap in vivo bioreactor. Like vascularized autologous bone grafts, the new constructs could be transferred to the defect site by using microsurgical techniques. The strategy would facilitate clinical translation in bone tissue engineering and offer new therapeutic strategies for reconstruction of extended bone defects if the hypothesis proved to be practical. (C) 2008 Elsevier Ltd. All rights reserved.

关键词： Arteriovenous Shunt Surgical Biocompatible Materials Bioreactors Bone Diseases 动静脉转流术外科生物相容性材料生物反应器骨疾病骨再生骨代用品 Precast vascularization Flap with osseous tissue bone structure AXIAL bone defect Biocompatible Materials arteriovenous shunt Bone Diseases Bioreactors Surgery reconstruction algorithm

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Novel FBP based sparse-view CT reconstruction scheme using self-shaping spatial filter based morphological operations and scaled reprojections

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BIOMEDICAL SIGNAL PROCESSING AND CONTROL 2021年 64卷 102323-102323页

作者： Talha, Syed Muhammad Umar Mairaj, Tariq Yousuf, Waleed Bin Natl Univ Sci & Technol Pakistan Navy Engn Coll Dept Elect Engn H-12 Islamabad Pakistan

Computed tomography (CT) has been a major contributor in revolutionizing and commercializing the medical imaging industry. However, most of the commonly used CT reconstruction algorithms need sufficiently dense angular sampling views or a substantial dose of hazardous X-ray radiations. Reducing the radiation dose causes degradation in the quality of the reconstructed image, due to additional artifacts. The paper presents a novel algorithm for efficient CT reconstruction from under-sampled projections;which leads to radiation dose reduction with quality image reconstruction. The Sparse-View projection data is enhanced using a series of post-processing algorithms and computer based reprojection. The process involves enhancement through self-shaping/amoeba based morphological spatial filtering. The use of self-shaping spatial filter kernel in the area of under-sampled CT reconstruction is a novel contribution. The scheme is supported by computer simulations using fan-beam projections of clinically reconstructed and simulated head CT phantoms. The proposed scheme is compared with classical reconstruction techniques for reconstruction image quality, accuracy, speed, and robustness in the presence of noise. Promising results indicate the efficacy of proposed scheme. An efficient scheme for image enhancement of Sparse-View CT is presented. The results demonstrate that the proposed scheme is visually and statistically better than classical CT reconstruction techniques, as evaluated using various image quality matrices. The presented scheme is more robust to noise in CT projections and effective for enhancing few-views reconstruction.

关键词： Computed tomography (CT) Biomedical imaging Image processing Morphological amoebas Under-sampled CT reconstruction algorithm Biomedical image processing Sparse-view CT

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Estimating CO2 Emissions from IoT Traffic Flow Sensors and reconstruction

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SENSORS 2022年第9期22卷 3382-3382页

作者： Bilotta, Stefano Nesi, Paolo Univ Florence Dept Informat Engn DISIT Lab I-50139 Florence Italy

CO2 emissions from burning fossil fuels make a relevant contribution to atmospheric changes and climate disruptions. In cities, the contribution by traffic of CO2 is very relevant, and the general CO2 estimation can be computed (i) on the basis of the fuel transformation in energy using several factors and efficiency aspects of engines and (ii) by taking into account the weight moved, distance, time, and emissions factor of each specific vehicle. Those approaches are unsuitable for understanding the impact of vehicles on CO2 in cities since vehicles produce CO2 depending on their specific efficiency, producer, fuel, weight, driver style, road conditions, seasons, etc. Thanks to today's technologies, it is possible to collect real-time traffic data to obtain useful information that can be used to monitor changes in carbon emissions. The research presented in this paper studied the cause of CO2 emissions in the air with respect to different traffic conditions. In particular, we propose a model and approach to assess CO2 emissions on the basis of traffic flow data taking into account uncongested and congested conditions. These traffic situations contribute differently to the amount of CO2 in the atmosphere, providing a different emissions factor. The solution was validated in urban conditions of Florence city, where the amount of CO2 is measured by sensors at a few points where more than 100 traffic flow sensors are present (data accessible on the Snap4City platform). The solution allowed for the estimation of CO2 from traffic flow, estimating the changes in the emissions factor on the basis of the seasons and in terms of precision. The identified model and solution allowed the city's distribution of CO2 to be computed.

关键词： smart city vehicle CO2 emissions factor traffic flow reconstruction algorithm traffic congestion regression CO2 model seasonal changing

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An improved position reconstruction method for radioactive particle tracking

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NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 2023年 1055卷

作者： Mirakhori, Ghazaleh Collard-Daigneault, Audrey Alphonius, Amishga Doucet, Jocelyn Blais, Bruno Chaouki, Jamal Polytech Montreal Dept Chem Engn Res Unit Ind Flows Proc URPEI POB 6079 Montreal PQ H3C 3A7 Canada Polytech Montreal Dept Chem Engn Proc Engn Adv Res Lab PEARL POB 6079 Montreal PQ H3C 3A7 Canada Pyrowave Inc Montreal PQ H2N 2B7 Canada

This work introduces a novel reconstruction method exploiting the inverse of Finite Element Method (FEM) to reconstruct positions from ray tracing experimental measurement such as those obtained by radioactive particle tracking. FEM based Position reconstruction (FEM-PR) relies on shape function evaluation within simplex elements (i.a tetrahedron) for position reconstruction using a mean-square problem, which has proven to be robust, accurate, and fast. Tracer positions are reconstructed under the condition that least-squares compatibility is maintained between experimental counts and interpolated values within inverse elements. This approach is implemented in a module within the open-source software, Lethe-RPT, enabling user to carry out radioactive particle tracking (RPT) experiments from calibration to tracer position reconstruction. The test benchmark and experimental setup are described. For the same test cases, the reconstruction error is investigated using an increasing number of inverse elements and Monte Carlo (MC) iterations. The accuracy and robustness of FEM-PR concerning the inevitable measurement errors due to calibration, measurement systems, and the quantized nature of ��-rays is demonstrated. This approach provides a new view for immediate and precise position reconstruction. FEM-PR reconstructs the tracer position with an accuracy of 0.08 mm. Approximately 3.37 ms is required to reconstruct one position on a desktop computer, which is less than the sampling time for experimental data collection.

关键词： Radioactive Particle Tracking (RPT) Finite Element Method (FEM) Monte Carlo methods reconstruction algorithm Non-invasive technique

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The image quality of FBP and MLEM reconstruction

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PHYSICS IN MEDICINE AND BIOLOGY 2010年第11期55卷 3161-3176页

作者： Wieczorek, Herfried Philips Res Labs Aachen Germany

We have developed an image quality theory for filtered back-projection (FBP) and maximum likelihood expectation maximization (MLEM) based on quality measures like signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), signal and noise power spectra and the detective quantum efficiency (DQE) concept. Analytic expressions are derived for unattenuated SPECT reconstruction with ideal collimation to obtain the fundamental performance parameters of different reconstruction algorithms. This theory is verified by measurements of signal and noise power on simulated phantoms. We demonstrate that the noise power of reconstructed images is proportional to the diameter of the object given as a number of voxels. This is analytically proven for FBP and clarified by assessment of the convergence properties for MLEM. The latter technique is shown to be superior to FBP in terms of a noise level at least two times lower. The free choice of MLEM reconstruction parameters and correction for physical effects in the image acquisition enables quantitative evaluation of SPECT and PET images.

关键词： Quantitative Evaluation noise power single photon emission computed tomography Image quality PET Scan Noise levels image samples reconstruction algorithm characteristic parameter

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Geometrical Event reconstruction in the COMPASS Experiment

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PHYSICS OF PARTICLES AND NUCLEI LETTERS 2007年第4期4卷 350-362页

作者： Aleksakhin, V. Yu. Bedfer, Y. Gerasimov, S. G. Korzenev, A. Yu. Joint Inst Nucl Res Dubna Russia CEA DAPHNIA SPhN Saclay France Lebedev Phys Inst Moscow Russia Tech Univ Munich Garching Germany Inst Nucl Phys Mainz Germany

The procedure of geometrical event reconstruction used at the setup COMPASS (CERN/SPS) including the algorithm of charged particle tracks reconstruction and the algorithm of the search of the vertex of beam muon-target interaction is presented. The results of the calculation of the accuracy of reconstructed objects and efficiency of the track reconstruction algorithm are given.

关键词： Ions reconstruction algorithm

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reconstruction of fluorophore absorption and fluorescence lifetime using early photon mesoscopic fluorescence molecular tomography: a phantom study

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JOURNAL OF BIOMEDICAL OPTICS 2022年第12期27卷 126001-126001页

作者： Konovalov, Alexander B. Vlasov, Vitaly V. Samarin, Sergei I. Soloviev, Ilya D. Savitsky, Alexander P. Tuchin, Valery V. Fed State Unitary Enterprise Russian Fed Nucl Ctr Zababakhin All Russia Res Inst Tech Phys Snezhinsk Russia Russian Acad Sci Bach Inst Biochem Res Ctr Biotechnol Moscow Russia Saratov NG Chernyshevskii State Univ Saratov Russia

Significance: Fluorescence molecular lifetime tomography (FMLT) plays an increasingly important role in experimental oncology. The article presents and experimentally verifies an original method of mesoscopic time domain FMLT, based on an asymptotic approximation to the fluorescence source function, which is valid for early arriving photons. Aim;The aim was to justify the efficiency of the method by experimental scanning and reconstruction of a phantom with a fluorophore. The experimental facility included the TCSPC system, the pulsed supercontinuum Fianium laser, and a three-channel fiber probe. Phantom scanning was done in mesoscopic regime for three-dimensional (3D) reflectance geometry. Approach: The sensitivity functions were simulated with a Monte Carlo method. A compressed-sensing-like reconstruction algorithm was used to solve the inverse problem for the fluorescence parameter distribution function, which included the fluorophore absorption coefficient and fluorescence lifetime distributions. The distributions were separated directly in the time domain with the QR-factorization least square method. Results: 3D tomograms of fluorescence parameters were obtained and analyzed using two strategies for the formation of measurement data arrays and sensitivity matrices. An algorithm is developed for the flexible choice of optimal strategy in view of attaining better reconstruction quality. Variants on how to improve the method are proposed, specifically, through stepped extraction and further use of a posteriori information about the object. Conclusions: Even if measurement data are limited, the proposed method is capable of giving adequate reconstructions but their quality depends on available a priori (or a posteriori) information. Further research aims to improve the method by implementing the variants proposed. (C) The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License.

关键词： fluorescence molecular tomography fluorescence lifetime early arriving photons Monte Carlo method phantom with fluorophore reconstruction algorithm

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