The integration of on-line monitoring and reconfiguration functions using IEEE1149.4 into a safety critical automotive electronic control unit.

This paper presents an innovative application of IEEE 1149.4 and the integrated diagnostic reconfiguration (IDR) as tools for the implementation of an embedded test solution for an automotive electronic control unit, implemented as a fully integrated mixed signal system. The paper describes how the test architecture can be used for fault avoidance with results from a hardware prototype presented. The paper concludes that fault avoidance can be integrated into mixed signal electronic systems to handle key failure modes

Analytical Modelling and Simulation of Single and Double Cone Pinholes for Real-Time In-Body Tracking of an HDR Brachytherapy Source

© 2016 IEEE. The choice of pinhole geometry is a critical factor in the performance of pinhole-collimator-based source tracking systems for brachytherapy QA. In this work, an analytical model describing the penetrative sensitivity of a single-cone pinhole collimator to photons emitted from a point source is derived. Using existing models for single-cone resolution and double-cone sensitivity and resolution, the theoretical sensitivity and resolution of the single-cone collimator are quantitatively compared with those of a double-cone collimator with an equivalent field of view. Monte Carlo simulations of the single and double-cone pinhole collimators using an accurate 3D model of a commercial high dose rate brachytherapy source are performed to evaluate the relative performance of each geometry for a novel real-time HDR brachytherapy QA system, HDR BrachyView. The theoretical penetrative sensitivity of the single-cone pinhole is shown to be higher than the double-cone pinhole, which is in agreement with the results from the Monte Carlo simulations. The wider pinhole response function of the single-cone collimator results in a larger total error between the projected center of the source and the estimated center of mass of the source projection for the single-cone collimator, with the greatest error (at the maximum FoV angle) being 0.54 mm for the double-cone pinhole and 1.37 mm for the single-cone at θ = 60°. The double-cone pinhole geometry is determined to be the most appropriate choice for the pinhole collimator in the HDR BrachyView probe

BrachyView, a novel in-body imaging system for HDR prostate brachytherapy: Experimental evaluation

© 2015 American Association of Physicists in Medicine. Purpose: This paper presents initial experimental results from a prototype of high dose rate (HDR) BrachyView, a novel in-body source tracking system for HDR brachytherapy based on a multipinhole tungsten collimator and a high resolution pixellated silicon detector array. The probe and its associated position estimation algorithms are validated and a comprehensive evaluation of the accuracy of its position estimation capabilities is presented. Methods: The HDR brachytherapy source is moved through a sequence of positions in a prostate phantom, for various displacements in x, y, and z. For each position, multiple image acquisitions are performed, and source positions are reconstructed. Error estimates in each dimension are calculated at each source position and combined to calculate overall positioning errors. Gafchromic film is used to validate the accuracy of source placement within the phantom. Results: More than 90% of evaluated source positions were estimated with an error of less than one millimeter, with the worst-case error being 1.3 mm. Experimental results were in close agreement with previously published Monte Carlo simulation results. Conclusions: The prototype of HDR BrachyView demonstrates a satisfactory level of accuracy in its source position estimation, and additional improvements are achievable with further refinement of HDR BrachyView's image processing algorithms

Radiation dose enhancement at tissue-tungsten interfaces in HDR brachytherapy

© 2014 Institute of Physics and Engineering in Medicine. HDR BrachyView is a novel in-body dosimetric imaging system for real-time monitoring and verification of the source position in high dose rate (HDR) prostate brachytherapy treatment. It is based on a high-resolution pixelated detector array with a semi-cylindrical multi-pinhole tungsten collimator and is designed to fit inside a compact rectal probe, and is able to resolve the 3D position of the source with a maximum error of 1.5 mm. This paper presents an evaluation of the additional dose that will be delivered to the patient as a result of backscatter radiation from the collimator. Monte Carlo simulations of planar and cylindrical collimators embedded in a tissue-equivalent phantom were performed using Geant4, with an 192Ir source placed at two different source-collimator distances. The planar configuration was replicated experimentally to validate the simulations, with a MOSkin dosimetry probe used to measure dose at three distances from the collimator. For the cylindrical collimator simulation, backscatter dose enhancement was calculated as a function of axial and azimuthal displacement, and dose distribution maps were generated at three distances from the collimator surface. Although significant backscatter dose enhancement was observed for both geometries immediately adjacent to the collimator, simulations and experiments indicate that backscatter dose is negligible at distances beyond 1 mm from the collimator. Since HDR BrachyView is enclosed within a 1 mm thick tissue-equivalent plastic shell, all backscatter radiation resulting from its use will therefore be absorbed before reaching the rectal wall or other tissues. dosimetry, brachytherapy, HD

BrachyView, A novel inbody imaging system for HDR prostate brachytherapy: Design and Monte Carlo feasibility study

Purpose: High dose rate (HDR) brachytherapy is a form of radiation therapy for treating prostate cancer whereby a high activity radiation source is moved between predefined positions inside applicators inserted within the treatment volume. Accurate positioning of the source is essential in delivering the desired dose to the target area while avoiding radiation injury to the surrounding tissue. In this paper, HDR BrachyView, a novel inbody dosimetric imaging system for real time monitoring and verification of the radioactive seed position in HDR prostate brachytherapy treatment is introduced. The current prototype consists of a 15 × 60 mm2 silicon pixel detector with a multipinhole tungsten collimator placed 6.5 mm above the detector. Seven identical pinholes allow full imaging coverage of the entire treatment volume. The combined pinhole and pixel sensor arrangement is geometrically designed to be able to resolve the three-dimensional location of the source. The probe may be rotated to keep the whole prostate within the transverse plane. The purpose of this paper is to demonstrate the efficacy of the design through computer simulation, and to estimate the accuracy in resolving the source position (in detector plane and in 3D space) as part of the feasibility study for the BrachyView project. Methods: Monte Carlo simulations were performed using the GEANT4 radiation transport model, with a 192Ir source placed in different locations within a prostate phantom. A geometrically accurate model of the detector and collimator were constructed. Simulations were conducted with a single pinhole to evaluate the pinhole design and the signal to background ratio obtained. Second, a pair of adjacent pinholes were simulated to evaluate the error in calculated source location. Results: Simulation results show that accurate determination of the true source position is easily obtainable within the typical one second source dwell time. The maximum error in the estimated projection position was found to be 0.95 mm in the imaging (detector) plane, resulting in a maximum source positioning estimation error of 1.48 mm. Conclusions: HDR BrachyView is a feasible design for real-time source tracking in HDR prostate brachytherapy. It is capable of resolving the source position within a subsecond dwell time. In combination with anatomical information obtained from transrectal ultrasound imaging, HDR BrachyView adds a significant quality assurance capability to HDR brachytherapy treatment systems. © 2013 American Association of Physicists in Medicine

Tliet Grazzji

Ġabra ta’ poeżiji u proża li tinkludi: Id-disinn t’Alla fin-nawfraġju ta’ San Pawl f’Malta ta’ Dun Karm – Il-Lupu u l-Mogħża ta’ R. M. B. – Mawra sal-Buskett ta’ L. Cutajar – Dun Mikiel Xerri ta’ Dun Karm – It-Tliet Grazzji ta’ Ivo Muscat-Azzopardi.N/

Repeatability of renal arterial spin labelling MRI in healthy subjects

Arterial spin labelling (ASL) can be used to measure renal perfusion non-invasively. The aim of this study was to determine the repeatability of this technique in healthy kidneys to vindicate its use in clinic