@article{Gray2018GenetProgramEvolvableMach, title = {Data exploration in evolutionary reconstruction of {PET} images}, journal = {Genetic Programming and Evolvable Machines}, volume = 19, number = 3, pages = {391-419}, year = 2018, month = sep, issn = {1573-7632}, doi = {10.1007/s10710-018-9330-7}, author = {Cameron C. Gray and Shatha F. {Al-Maliki} and Franck P. Vidal}, keywords = {Fly Algorithm}, keywords = {Tomography reconstruction}, keywords = {Information visualisation}, keywords = {Data exploration}, keywords = {Artificial evolution}, keywords = {Parisian evolution}, abstract = {This work is based on a cooperative co-evolution algorithm called `Fly Algorithm', which is an evolutionary algorithm (EA) where individuals are called `flies'. It is a specific case of the `Parisian Approach' where the solution of an optimisation problem is a set of individuals (e.g. the whole population) instead of a single individual (the best one) as in typical EAs. The optimisation problem considered here is tomography reconstruction in positron emission tomography (PET). It estimates the concentration of a radioactive substance (called a radiotracer) within the body. Tomography, in this context, is considered as a difficult ill-posed inverse problem. The Fly Algorithm aims at optimising the position of 3-D points that mimic the radiotracer. At the end of the optimisation process, the fly population is extracted as it corresponds to an estimate of the radioactive concentration. During the optimisation loop a lot of data is generated by the algorithm, such as image metrics, duration, and internal states. This data is recorded in a log file that can be post-processed and visualised. We propose using information visualisation and user interaction techniques to explore the algorithm's internal data. Our aim is to better understand what happens during the evolutionary loop. Using an example, we demonstrate that it is possible to interactively discover when an early termination could be triggered. It is implemented in a new stopping criterion. It is tested on two other examples on which it leads to a 60\% reduction of the number of iterations without any loss of accuracy.}, pdf = {./pdf/Gray2018GenetProgramEvolvableMach.pdf} }
@article{AliAbbood2017ArtsAndScience, title = {{Fly4Arts}: Evolutionary Digital Art with the {Fly} Algorithm}, journal = {{ISTE} Arts \& Science}, volume = {17}, number = 1, pages = {11-16}, year = 2017, month = oct, issn = {2515-8767}, doi = {10.21494/ISTE.OP.2017.0177}, author = {Zainab Ali Abbood and Franck P. Vidal}, keywords = {Digital mosaic, Evolutionary art, Fly Algorithm, Parisian evolution, Cooperative co-evolution}, abstract = {The aim of this study is to generate artistic images, such as digital mosaics, as an optimisation problem without the introduction of any a priori knowledge or constraint other than an input image. The usual practice to produce digital mosaic images heavily relies on Centroidal Voronoi diagrams. We demonstrate here that it can be modelled as an optimisation problem solved using a cooperative co-evolution strategy based on the Parisian evolution approach, the Fly algorithm. An individual is called a fly. Its aim of the algorithm is to optimise the position of infinitely small 3-D points (the flies). The Fly algorithm has been initially used in real-time stereo vision for robotics. It has also demonstrated promising results in image reconstruction for tomography. In this new application, a much more complex representation has been study. A fly is a tile. It has its own position, size, colour, and rotation angle. Our method takes advantage of graphics processing units (GPUs) to generate the images using the modern OpenGL Shading Language (GLSL) and Open Computing Language (OpenCL) to compute the difference between the input image and simulated image. Different types of tiles are implemented, some with transparency, to generate different visual effects, such as digital mosaic and spray paint. An online study with 41 participants has been conducted to compare some of our results with those generated using an open-source software for image manipulation. It demonstrates that our method leads to more visually appealing images.}, pdf = {./pdf/AliAbbood2017ArtsAndScience.pdf} }@article{Abbood2017SwarmEvolComput, author = "Zainab {Ali Abbood} and Julien Lavauzelle and \'Evelyne Lutton and Jean-Marie Rocchisani and Jean Louchet and Franck P. Vidal", title = "Voxelisation in the 3-D Fly Algorithm for PET", journal = "Swarm and Evolutionary Computation", year = 2017, volume = 36, pages = "91-105", month = oct, abstract = "The Fly Algorithm was initially developed for 3-D robot vision applications. It consists in solving the inverse problem of shape reconstruction from projections by evolving a population of 3-D points in space (the `flies'), using an evolutionary optimisation strategy. Here, in its version dedicated to tomographic reconstruction in medical imaging, the flies are mimicking radioactive photon sources. Evolution is controlled using a fitness function based on the discrepancy of the projections simulated by the flies with the actual pattern received by the sensors. The reconstructed radioactive concentration is derived from the population of flies, i.e. a collection of points in the 3-D Euclidean space, after convergence. `Good' flies were previously binned into voxels. In this paper, we study which flies to include in the final solution and how this information can be sampled to provide more accurate datasets in a reduced computation time. We investigate the use of density fields, based on Metaballs and on Gaussian functions respectively, to obtain a realistic output. The spread of each Gaussian kernel is modulated in function of the corresponding fly fitness. The resulting volumes are compared with previous work in terms of normalised-cross correlation. In our test-cases, data fidelity increases by more than 10% when density fields are used instead of binning. Our method also provides reconstructions comparable to those obtained using well-established techniques used in medicine (filtered back-projection and ordered subset expectation-maximisation).", doi = "10.1016/j.swevo.2017.04.001", issn = "2210-6502", keywords = "Fly algorithm; Evolutionary computation; tomography reconstruction; iterative algorithms; inverse problems; co-operative co-evolution", publisher = {Elsevier}, pdf = {pdf/Abbood2017SwarmEvolComput.pdf}, }@article{Vidal2016ComputMedImagingGraph, author = "Franck P. Vidal and Pierre-Fr\'ed\'eric Villard", title = "Development and validation of real-time simulation of X-ray imaging with respiratory motion", journal = "Computerized Medical Imaging and Graphics", year = 2016, volume = 49, pages = "1-15", month = apr, abstract = "We present a framework that combines evolutionary optimisation, soft tissue modelling and ray tracing on GPU to simultaneously compute the respiratory motion and X-ray imaging in real-time. Our aim is to provide validated building blocks with high fidelity to closely match both the human physiology and the physics of X-rays. A CPU-based set of algorithms is presented to model organ behaviours during respiration. Soft tissue deformation is computed with an extension of the Chain Mail method. Rigid elements move according to kinematic laws. A GPU-based surface rendering method is proposed to compute the X-ray image using the Beer–Lambert law. It is provided as an open-source library. A quantitative validation study is provided to objectively assess the accuracy of both components: (i) the respiration against anatomical data, and (ii) the X-ray against the Beer–Lambert law and the results of Monte Carlo simulations. Our implementation can be used in various applications, such as interactive medical virtual environment to train percutaneous transhepatic cholangiography in interventional radiology, 2D/3D registration, computation of digitally reconstructed radiograph, simulation of 4D sinograms to test tomography reconstruction tools.", doi = "10.1016/j.compmedimag.2015.12.002", pmid = {26773644}, issn = "0895-6111", keywords = "X-ray simulation, Deterministic simulation (ray-tracing), Digitally reconstructed radiograph, Respiration simulation, Medical virtual environment, Imaging guidance, Interventional radiology training", publisher = {Elsevier}, pdf = {pdf/Vidal2016ComputMedImagingGraph.pdf}, }@article{Villard2014IntJComputAssistRadiolSurg, author = {P. F. Villard and F. P. Vidal and L. {ap Cenydd} and R. Holbrey and S. Pisharody and S. Johnson and A. Bulpitt and N. W. John and F. Bello and D. Gould}, title = {Interventional radiology virtual simulator for liver biopsy}, journal = {International Journal of Computer Assisted Radiology and Surgery}, year = 2014, volume = 9, pages = {255-267}, number = 2, month = mar, abstract = {Purpose: Training in Interventional Radiology currently uses the apprenticeship model, where clinical and technical skills of invasive procedures are learnt during practice in patients. This apprenticeship training method is increasingly limited by regulatory restrictions on working hours, concerns over patient risk through trainees' inexperience and the variable exposure to case mix and emergencies during training. To address this, we have developed a computer-based simulation of visceral needle puncture procedures. Methods: A real-time framework has been built that includes: segmentation, physically based modelling, haptics rendering, pseudo-ultrasound generation and the concept of a physical mannequin. It is the result of a close collaboration between different universities, involving computer scientists, clinicians, clinical engineers and occupational psychologists. Results: The technical implementation of the framework is a robust and real-time simulation environment combining a physical platform and an immersive computerized virtual environment. The face, content and construct validation have been previously assessed, showing the reliability and effectiveness of this framework, as well as its potential for teaching visceral needle puncture. Conclusion: A simulator for ultrasound-guided liver biopsy has been developed. It includes functionalities and metrics extracted from cognitive task analysis. This framework can be useful during training, particularly given the known difficulties in gaining significant practice of core skills in patients.}, doi = {10.1109/s11548-013-0929-0}, pmid = {23881251}, keywords = {Biomedical computing, Image segmentation, Simulation, Virtual reality}, publisher = {Springer Berlin Heidelberg}, pdf = {pdf/Villard2014IntJComputAssistRadiolSurg.pdf}, }@article{Villard2014IntJComputAssistRadiolSurg, author = {P. F. Villard and F. P. Vidal and L. {ap Cenydd} and R. Holbrey and S. Pisharody and S. Johnson and A. Bulpitt and N. W. John and F. Bello and D. Gould}, title = {Interventional radiology virtual simulator for liver biopsy}, journal = {International Journal of Computer Assisted Radiology and Surgery}, year = 2014, volume = 9, pages = {255-267}, number = 2, month = mar, abstract = {Purpose: Training in Interventional Radiology currently uses the apprenticeship model, where clinical and technical skills of invasive procedures are learnt during practice in patients. This apprenticeship training method is increasingly limited by regulatory restrictions on working hours, concerns over patient risk through trainees' inexperience and the variable exposure to case mix and emergencies during training. To address this, we have developed a computer-based simulation of visceral needle puncture procedures. Methods: A real-time framework has been built that includes: segmentation, physically based modelling, haptics rendering, pseudo-ultrasound generation and the concept of a physical mannequin. It is the result of a close collaboration between different universities, involving computer scientists, clinicians, clinical engineers and occupational psychologists. Results: The technical implementation of the framework is a robust and real-time simulation environment combining a physical platform and an immersive computerized virtual environment. The face, content and construct validation have been previously assessed, showing the reliability and effectiveness of this framework, as well as its potential for teaching visceral needle puncture. Conclusion: A simulator for ultrasound-guided liver biopsy has been developed. It includes functionalities and metrics extracted from cognitive task analysis. This framework can be useful during training, particularly given the known difficulties in gaining significant practice of core skills in patients.}, doi = {10.1109/s11548-013-0929-0}, pmid = {23881251}, keywords = {Biomedical computing, Image segmentation, Simulation, Virtual reality}, publisher = {Springer Berlin Heidelberg}, pdf = {pdf/Villard2014IntJComputAssistRadiolSurg.pdf}, }@article{Vidal2012IEEETransBiomedEng, author = {F. P. Vidal and {P.-F.} Villard and \'E. Lutton}, title = {Tuning of Patient Specific Deformable Models using an Adaptive Evolutionary Optimization Strategy}, journal = {IEEE Transactions on Biomedical Engineering}, year = 2012, volume = 59, pages = {2942-2949}, number = 10, month = oct, abstract = {We present and analyze the behavior of an evolutionary algorithm designed to estimate the parameters of a complex organ behavior model. The model is adaptable to account for patients specificities. The aim is to finely tune the model to be accurately adapted to various real patient datasets. It can then be embedded, for example, in high fidelity simulations of the human physiology. We present here an application focused on respiration modeling. The algorithm is automatic and adaptive. A compound fitness function has been designed to take into account for various quantities that have to be minimized. The algorithm efficiency is experimentally analyzed on several real test-cases: i) three patient datasets have been acquired with the breath hold protocol, and ii) two datasets corresponds to 4D CT scans. Its performance is compared with two traditional methods (downhill simplex and conjugate gradient descent), a random search and a basic realvalued genetic algorithm. The results show that our evolutionary scheme provides more significantly stable and accurate results.}, doi = {10.1109/TBME.2012.2213251}, pmid = {22907958}, keywords = {Evolutionary computation, inverse problems, medical simulation, adaptive algorithm}, publisher = {IEEE}, pdf = {pdf/Vidal2012IEEETransBiomedEng.pdf} }@article{Villard2009IntJComputAssistRadiolSurg, author = {{P.-F.} Villard and F. P. Vidal and C. Hunt and F. Bello and N. W. John and S. Johnson and D. A. Gould}, title = {A prototype percutaneous transhepatic cholangiography training simulator with real-time breathing motion}, journal = {International Journal of Computer Assisted Radiology and Surgery}, year = 2009, volume = 4, pages = {571-578}, number = 6, month = nov, abstract = {Purpose: We present here a simulator for interventional radiology focusing on percutaneous transhepatic cholangiography (PTC). This procedure consists of inserting a needle into the biliary tree using fluoroscopy for guidance. Methods: The requirements of the simulator have been driven by a task analysis. The three main components have been identified: the respiration, the real-time X-ray display (fluoroscopy) and the haptic rendering (sense of touch). The framework for modelling the respiratory motion is based on kinematics laws and on the Chainmail algorithm. The fluoroscopic simulation is performed on the graphic card and makes use of the Beer-Lambert law to compute the X-ray attenuation. Finally, the haptic rendering is integrated to the virtual environment and takes into account the soft-tissue reaction force feedback and maintenance of the initial direction of the needle during the insertion. Results: Five training scenarios have been created using patient-specific data. Each of these provides the user with variable breathing behaviour, fluoroscopic display tuneable to any device parameters and needle force feedback. Conclusions A detailed task analysis has been used to design and build the PTC simulator described in this paper. The simulator includes real-time respiratory motion with two independent parameters (rib kinematics and diaphragm action), on-line fluoroscopy implemented on the Graphics Processing Unit and haptic feedback to feel the soft-tissue behaviour of the organs during the needle insertion.}, doi = {10.1007/s11548-009-0367-1}, pmid = {20033333}, keywords = {Interventional radiology; Virtual environments; Respiration simulation; X-ray simulation; Needle puncture; Haptics; Task analysis}, publisher = {Springer}, pdf = {pdf/Villard2009IntJComputAssistRadiolSurg.pdf} }@article{Vidal2008ComputAnimatVirtW, author = {F. P. Vidal and N. W. John and D. A. Gould and A. E. Healey}, title = {Simulation of Ultrasound Guided Needle Puncture using Patient Specific Data with {3D} Textures and Volume Haptics}, journal = {Computer Animation and Virtual Worlds}, year = 2008, volume = 19, pages = {111-127}, number = 2, month = may, abstract = {We present an integrated system for training ultrasound (US) guided needle puncture. Our aim is to provide a validated training tool for interventional radiology (IR) that uses actual patient data. IR procedures are highly reliant on the sense of touch and so haptic hardware is an important part of our solution. A hybrid surface/volume haptic rendering of an US transducer is proposed to constrain the device to remain outside the bony structures when scanning the patient's skin. A volume haptic model is proposed that implements an effective model of needle puncture. Force measurements have been made on real tissue and the resulting data is incorporated into the model. The other input data required is a computed tomography (CT) scan of the patient that is used to create the patient specific models. It is also the data source for a novel simulation of a virtual US scanner, which is used to guide the needle to the correct location.}, doi = {10.1002/cav.217}, keywords = {medical virtual environment; imaging guidance; interventional radiology training; needle puncture; volume haptics; vertex and pixel shaders}, publisher = {John Wiley \& Sons}, pdf = {pdf/Vidal2008ComputAnimatVirtW.pdf} }@article{Vidal2006ComputGraphForum, author = {F. P. Vidal and F. Bello and K. W. Brodlie and D. A. Gould and N. W. John and R. Phillips and N. J. Avis}, title = {Principles and Applications of Computer Graphics in Medicine}, journal = {Computer Graphics Forum}, year = 2006, volume = 25, pages = {113-137}, number = 1, month = mar, abstract = {The medical domain provides excellent opportunities for the application of computer graphics, visualization and virtual environments, with the potential to help improve healthcare and bring benefits to patients. This survey paper provides a comprehensive overview of the state-of-the-art in this exciting field. It has been written from the perspective of both computer scientists and practising clinicians and documents past and current successes together with the challenges that lie ahead. The article begins with a description of the software algorithms and techniques that allow visualization of and interaction with medical data. Example applications from research projects and commercially available products are listed, including educational tools; diagnostic aids; virtual endoscopy; planning aids; guidance aids; skills training; computer augmented reality and use of high performance computing. The final section of the paper summarizes the current issues and looks ahead to future developments.}, doi = {10.1111/j.1467-8659.2006.00822.x}, keywords = {visualization; augmented and virtual realities; computer graphics; health; physically-based modeling; medical sciences; simulation}, publisher = {Blackwell}, pdf = {pdf/Vidal2006ComputGraphForum.pdf} }@article{Vidal2005NuclInstrumMethB, author = {F. P. Vidal and J. M. L\'etang and G. Peix and P. Cl{\oe}tens}, title = {Investigation of artefact sources in synchrotron microtomography via virtual X-ray imaging}, journal = {Nuclear Instruments and Methods in Physics Research B}, year = 2005, volume = 234, pages = {333-348}, number = 3, month = jun, abstract = {Qualitative and quantitative use of volumes reconstructed by computed tomography (CT) can be compromised due to artefacts which corrupt the data. This article illustrates a method based on virtual X-ray imaging to investigate sources of artefacts which occur in microtomography using synchrotron radiation. In this phenomenological study, different computer simulation methods based on physical X-ray properties, eventually coupled with experimental data, are used in order to compare artefacts obtained theoretically to those present in a volume acquired experimentally, or to predict them for a particular experimental setup. The article begins with the presentation of a synchrotron microtomographic slice of a reinforced fibre composite acquired at the European Synchrotron Radiation Facility (ESRF) containing streak artefacts. This experimental context is used as the motive throughout the paper to illustrate the investigation of some artefact sources. First, the contribution of direct radiation is compared to the contribution of secondary radiations. Then, the effect of some methodological aspects are detailed, including under-sampling, sample and camera misalignment, sample extending outside of the field of view and photonic noise. The effect of harmonic components present in the experimental spectrum are also simulated. Afterwards, detector properties, such as its impulse response or defective pixels, are taken into account. Finally, the importance of phase contrast effects is evaluated. In the last section, this investigation is discussed by putting emphasis on the experimental context which is used throughout this paper.}, doi = {10.1016/j.nimb.2005.02.003}, keywords = {X-ray microtomography; Artefact; Deterministic simulation (ray-tracing); Monte Carlo method; Phase contrast; Modulation transfer function}, publisher = {Elsevier}, pdf = {pdf/Vidal2005NuclInstrumMethB.pdf} }This file was generated by bibtex2html 1.97.