Franck Patrick Vidal

• MSc, MRes, PhD
• Computing scientist in imaging at Science and Technology Facilities Council

Scan planning for X-ray CT systems can be difficult due to the large number of elements affecting scan quality. The use of X-ray simulation can answer feasibility questions, however existing methods are focused on experts who are familiar with XCT and programming knowledge. WebCT is a user-centric application for performing virtual XCT scans with t...

Particle Swarm Optimisation (PSO) and Evolutionary Algorithms (EAs) differ in various ways, in particular with respect to information sharing and diversity management, making their scopes of applications very diverse. Combining the advantages of both approaches is very attractive and has been successfully achieved through hybridisation. Another pos...

gVirtualXray (gVXR) is an open-source framework that relies on the Beer–Lambert law to simulate X-ray images in realtime on a graphics processor unit (GPU) using triangular meshes. We produced four Jupyter Notebooks to compare images simulated with gVXR and ground truth image of an anthropomorphic phantom: (i) an X-ray projection generated using a...

Background and objectives: This study provides a quantitative comparison of images created using gVirtualXray (gVXR) to both Monte Carlo (MC) and real images of clinically realistic phantoms. gVirtualXray is an open-source framework that relies on the Beer-Lambert law to simulate X-ray images in realtime on a graphics processor unit (GPU) using tr...

We report on an ongoing collaboration between epidemiological modellers and visualization researchers by documenting and reflecting upon knowledge constructs—a series of ideas, approaches and methods taken from existing visualization research and practice—deployed and developed to support modelling of the COVID-19 pandemic. Structured independent c...

Quantitative imaging in synchrotron microtomographic (μCT) may be compromised due to the presence of strong artefacts. This study combines experimental data with X-ray simulations on GPU to correct linear attenuation coefficients in highly corrupted μCT volumes. We selected the scan of silicon carbide (SiC) fibres with tungsten (W) cores in a titan...

WebCT is a browser-based tool to run interactive X-ray simulations and tomographic reconstructions with a focus on rapid and accurate results. Leveraging existing open-source technologies such as gVirtualXRay for GPU-based X-ray simulations, alongside spekpy and xpecgen for spectra generation with CCPi's CIL library for tomographic reconstruction,...

We report on an ongoing collaboration between epidemiological modellers and visualization researchers by documenting and reflecting upon knowledge constructs -- a series of ideas, approaches and methods taken from existing visualization research and practice -- deployed and developed to support modelling of the COVID-19 pandemic. Structured indepen...

The effort for combating the COVID-19 pandemic around the world has resulted in a huge amount of data, e.g., from testing, contact tracing, modelling, treatment, vaccine trials, and more. In addition to numerous challenges in epidemiology, healthcare, biosciences, and social sciences, there has been an urgent need to develop and provide visualisati...

Purpose: Traditional undergraduate radiographer training mixes academic lectures and clinical practice. Our goal is to bridge the current disconnection between theory and practice in a safe environment, avoiding the risk of radiation for both practitioners and patients. To this end, this research proposes a new software to teach diagnostic radiogr...

The presence of strong imaging artefacts in microtomographic X-ray data makes the CAD modelling process difficult to carry out. As an alternative to traditional image segmentation techniques, we propose to register the CAD models by deploying a realistic X-ray simulation on GPU in an optimisation framework. A user study was also conducted to compar...

Radiographs of the hand are useful in diagnosing and staging diseases such as rheumatoid arthritis (RA) and other musculoskeletal diseases. Radiographs are projections of the 3D anatomy, with the useful information such as pose and pathology becoming lost in the process. We propose a 3D hand pose recovery method for radiographs of hands using a nov...

The effort for combating the COVID-19 pandemic around the world has resulted in a huge amount of data, e.g., from testing, contact tracing, modelling, treatment, vaccine trials, and more. In addition to numerous challenges in epidemiology, healthcare, biosciences, and social sciences, there has been an urgent need to develop and provide visualisati...

An image can encode date, time, location and camera information as metadata and implicitly encodes species information and data on human activity, for example the size distribution of fish removals. Accurate length estimates can be made from images using a fiducial marker; however, their manual extraction is time‐consuming and estimates are inaccur...

Videogrammetry and photogrammetry are increasingly being used in marine science for unsupervised data collection. The camera systems employed are complex, in contrast to "consumer" digital cameras and smartphones carried by potential citizen scientists. However, using consumer cameras in photogrammetry will introduce unknown length estimation error...

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 o...

We present an Open-source library called gVirtualXRay to simulate realistic X-ray images in realtime. It implements the attenuation law (also called Beer-Lambert) on GPU. It takes into account the polychromatism of the beam spectra as well as the finite size of X-ray tubes. The library is written in C++ using modern OpenGL. It is fully portable and...

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,...

This study is about Evolutionary art such as digital mosaics. The most common techniques to generate a digital mosaic effect heavily rely on Centroidal Voronoi diagrams. Our method generates artistic images as an optimisation problem without the introduction of any a priori knowledge or constraint other than the input image. We adapt a cooperative...

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 algo...

We use the Fly algorithm, an artificial evolution strategy, to reconstruct positron emission tomography (PET) images. The algorithm iteratively optimises the position of 3D points. It eventually produces a point cloud, which needs to be voxelised to produce volume data that can be used with conventional medical image software. However, resulting vo...

We propose a simulation framework to simulate the computed tomography acquisition process. It includes five components: anatomic data, respiration modelling, automatic parametrisation, X-ray simulation, and tomography reconstruction. It is used to generate motion artefacts in reconstructed CT volumes. Our framework can be used to evaluate CT recons...

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 va...

Visual computing represents one of the most challenging and inspiring arenas in computer science. Today, fifty percent of content on the internet is in the form of visual data and information, and more than fifty percent of the neurons in the human brain are used in visual perception and reasoning. RIVIC is the collaborative amalgamation of researc...

This paper shows new resutls of our artificial evolution algorithm for Positron Emission Tomography (PET) reconstruction. This imaging technique produces datasets corresponding to the concentration of positron emitters within the patient. Fully three-dimensional (3D) tomographic reconstruction requires high computing power and leads to many challen...

This paper is an overview of a method recently published in a biomedical journal (IEEE Transactions on Biomedical Engineering, http://tbme.embs.org). The method is based on an optimisation technique called "evolutionary strategy" and it has been designed to estimate the parameters of a complex 15-D respiration model. This model is adaptable to acco...

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 patient's 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 s...

Purpose: During the treatment, a patient is continuously monitored by video cameras. The therapists are supposedly to watch the monitors and interrupt the treatment if any significant patient motion is spotted. Unfortunately, patient motion can easily be overlooked with this manual approach, especially when there are many other monitors in the cont...

We propose a method to automatically tune a patient-based virtual environment training simulator for abdominal needle insertion. The key attributes to be customized in our framework are the elasticity of soft-tissues and the respiratory model parameters. The estimation is based on two 3D Computed Tomography (CT) scans of the same patient at two dif...

Purpose: We propose a fast software library implemented on graphics processing unit (GPU) to compute digitally reconstructed radiographs (DRRs). It takes into account first order Compton scattering. Methods: The simulation is based on the evaluation of the Beer-Lambert law and of the Klein-Nishina equation. The algorithm is fully determinist and ha...

We present and analyse the behaviour of specialised operators designed for cooperative coevolution strategy in the framework of 3D tomographic PET reconstruction. The basis is a simple cooperative co-evolution scheme (the “fly algorithm”), which embeds the searched solution in the whole population, letting each individual be only a part of the solu...

Purpose: We previously proposed to compute the X-ray attenuation from polygons directly on the GPU, using OpenGL, to significantly increase performance without loss of accuracy. The method has been deployed into a training simulator for percutaneous transhepatic cholangiography. The simulations were however restricted to monochromatic X-rays using...

Purpose: We propose an evolutionary approach for image reconstruction in nuclear medicine. Our method is based on a cooperative coevolution strategy (also called Parisian evolution): the “fly algorithm”. Method and Materials: Each individual, or fly, corresponds to a 3D point that mimics a radioactive emitter, i.e. a stochastic simulation of annihi...

Purpose: We previously proposed to compute the X-ray attenuation from polygons directly on the GPU, using OpenGL, to significantly increase performance without loss of accuracy. The method has been deployed into a training simulator for percutaneous transhepatic cholangiography. The simulations were however restricted to monochromatic X-rays using...

In this paper, we propose a deterministic simulation of X-ray transmission imaging on graphics hardware. Only the directly transmitted photons are simulated, using the Beer-Lambert law. Our previous attempt to simulate Xray attenuation from polygon meshes utilising the GPU showed significant increase of performance, with respect to a validated soft...

This paper presents an evolutionary approach for image reconstruction in positron emission tomography (PET). Our reconstruction method is based on a cooperative coevolution strategy (also called Parisian evolution): the “fly algorithm”. Each fly is a 3D point that mimics a positron emitter. The flies’ position is progressively optimised using evolu...

Haptics technologies are frequently used in virtual environments to allow participants to touch virtual objects. Medical applications are no exception and a wide variety of commercial and bespoke haptics hardware solutions have been employed to aid in the simulation of medical procedures. Intuitively the use of haptics will improve the training of...

This paper presents preliminary results of a novel method that takes advantage of artificial evolution for positron emission tomography (PET) reconstruction. Fully 3D tomographic reconstruction in PET requires high computing power and leads to many challenges. To date, the use of such methods is still restricted due to the heavy computing power nee...

An overview to medical simulation has been provided. In the context of procedural interventional radiology training, we start with the definition and history of simulation, address its increasing importance in medicine reflect on its theoretical basis and current evidence and finally review its advantages/ limitations and prospects for the future.

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 identifie...

This paper presents a method to take advantage of artificial evolution in positron emission tomography reconstruction. This imaging technique produces datasets that correspond to the concentration of positron emitters through the patient. Fully 3D tomographic reconstruction requires high computing power and leads to many challenges. Our aim is to r...

AIM: To determine face and content validity of a physics based virtual reality interventional radiology simulator, Imagine-S (Imaging guided interventional needle puncture simulation).

KEY LEARNING OBJECTIVES: To determine face and content validity of a physics-based virtual reality (VR) training simulation of visceral interventional radiology needle puncture procedures. DESCRIPTION: Imaging-guided needle puncture procedures use hand-eye coordination to direct needles, wires and catheters to perform nephrostomy. The visuo-spatial...

Medical visualization in a hospital can be used to aid training, diagnosis, and pre- and intra-operative planning. In such an application, a virtual representation of a patient is needed that is interactive, can be viewed in three dimensions (3D), and simulates physiological processes that change over time. This paper highlights some of the computa...

We present an integrated system for training visceral needle puncture procedures. Our aim is to provide a cost effective and validated training tool that uses actual patient data to enable interventional radiology trainees to learn how to carry out image-guided needle puncture. The input data required is a computed tomography scan of the patient th...

We present an integrated system for training visceral needle puncture procedures. Our aim is to provide a cost effective and validated training tool that uses actual patient data to enable interventional radiology trainees to learn how to carry out image-guided needle puncture. The input data required is a computed tomography scan of the patient th...

This paper reports on a low cost system for training ultrasound imaging techniques. The need for such training is particularly acute in developing countries where typically ultrasound scanners remain idle due to the lack of experienced sonographers. The system described below is aimed at a PC platform but uses interface components from the Nintendo...

We present an integrated system for training ultrasound guided needle puncture. Our aim is to provide a cost effective and validated training tool that uses actual patient data to enable interventional radiology trainees to learn how to carry out image-guided needle puncture. The input data required is a computed tomography scan of the patient that...

In this paper, we propose to take advantage of computer graphics hardware to achieve an accelerated simulation of X-ray transmission imaging, and we compare results with a fast and robust software-only implementation. The running times of the GPU and CPU implementations are compared in different test cases. The results show that the GPU implementat...

Throughout the practice of procedural medicine, there is an unrelenting shift to management by less invasive techniques such as interventional radiology (IR). This subspecialty within radiology uses imaging to guide needles, wires and catheters using tiny access incisions. Like other minimally invasive techniques, risk, pain and recovery times are...

Introduction and Motivations We present a method for modelling the force penetration of needles into anatomic structures that are encountered during visceral punctures. Our aim is to provide a validated haptic model that can be used for the insertion of needles within our developing medical simulations of visceral interventional needle puncture pro...

PURPOSE-MATERIALS: To use patient imaging as the basis for developing virtual environments (VE). BACKGROUND Interventional radiology basic skills are still taught in an apprenticeship in patients, though these could be learnt in high fidelity simulations using VE. Ideally, imaging data sets for simulation of image-guided procedures would alter dyna...

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 rende...

Recent years have seen a significant increase in the use of Interventional Radiology (IR) as an alternative to open surgery. A large number of IR procedures commences with needle puncture of a vessel to insert guidewires and catheters: these clinical skills are acquired by all radiologists during training on patients, associated with some discomfor...

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 rende...

The potential for the use of computer graphics in medicine has been well established. An important emerging area is the provision of training tools for interventional radiology (IR) procedures. These are minimally invasive, targeted treatments performed using imaging for guidance. Training of the skills required in IR is an apprenticeship which sti...

Interventional Radiology (IR) procedures are minimally invasive, targeted treatments performed using imaging for guidance. Needle puncture using ultrasound, x-ray, or computed tomography (CT) images is a core task in the radiology curriculum, and we are currently developing a training simulator for this. One requirement is to include support for ph...

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 perspecti...

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 c...

We present a simulator for guided needle puncture procedures. Our aim is to provide an effective training tool for students in interventional radiology (IR) using actual patient data and force feedback within an immersive virtual environment (VE). Training of the visual and motor skills required in IR is an apprenticeship which still consists of cl...

The medical domain offers many excellent opportunities for the application of computer graphics, visualization, and virtual environments, offering the potential to help improve healthcare and bring benefits to patients. This report provides a comprehensive overview of the state-of-the-art in this exciting field. It has been written from the perspec...

This work presents a method for modelling the response of X-ray detectors applied to remove artefacts in tomography. On some reconstructed volumes by tomography using synchrotron radiations at ESRF, dark line artefacts (under-estimation of linear attenuation coefficients) appear when high density material are aligned. The causes of these artefacts...

This project presents the GUI for a radiographer's training tool. It is one of the two parts of a project idea proposed by Senior Lecturer, Philip Cosson, from the School of Health and Social Care at the University of Teesside. His wish was to develop a program, which would allow students to train themselves to take X-Ray images without exposing pa...