Using emerging technologies to reduce occupational radiation exposure in the ATLAS ID Decommissioning, and other high-radiation environments

Continuing to push back the frontiers of high energy physics requires colliders and detectors of increasing scale, operating at higher energies and intensities than ever before. The unavoidable byproduct of these experiments is an increase of radiation in the surrounding area. However, reliance on human interventions for such tasks is unsustainable and other methods must be investigated. This thesis will outline the use of emerging technologies to reduce occupational radiation exposure in the ATLAS ID Decommissioning, and other high-radiation environments. This work anticipated the addition of digital twins in the Virtual Reality Intervention Planning Platform; a benchmark radiation tolerance would provide users with a lifetime estimation useful for maintenance planning

Glass Ceramics Composites Fabricated from Coal Fly Ash and Waste Glass

Great quantities of coal ash are produced in thermal power plants which present a double problem to the society: economical and environmental. This waste is a result of burning of coal at temperatures between 1100-14500C. Fly ash available as fine powder presents a source of important oxides SiO2, Al2O3, Fe2O3, MgO, Na2O, but also consist of small amount of ecologically hazardous oxides such as Cr2O3, NiO, MnO. The combination of the fly ash with waste glass under controlled sintering procedure gave bulk glass-ceramics composite material. The principle of this procedure is presented as a multi barrier concept (1). Many researches have been conducted the investigations for utilization of fly ash as starting material for various glass–ceramics production (2-4). Using waste glass ecologically hazardous components are fixed at the molecular level in the silicate phase and the fabricated new glass-ceramic composites possess significantly higher mechanical properties. The aim of this investigation was to fabricate dense glass ceramic composites using fly ash and waste glass with the potential for its utilization as building material

The Development of Microdosimetric Instrumentation for Quality Assurance in Heavy Ion Therapy, Boron Neutron Capture Therapy and Fast Neutron Therapy

This thesis presents research for the development of new microdosimetric instrumentation for use with solid-state microdosimeters in order to improve their portability for radioprotection purposes and for QA in various hadron therapy modalities. Monte Carlo simulation applications are developed and benchmarked, pertaining to the context of the relevant therapies considered. The simulation and experimental findings provide optimisation recommendations relating to microdosimeter performance and possible radioprotection risks by activated materials. The first part of this thesis is continuing research into the development of novel Silicon-on-Insulator (SOI) microdosimeters in the application of hadron therapy QA. This relates specifically to the optimisation of current microdosimeters, development of Monte Carlo applications for experimental validation, assessment of radioprotection risks during experiments and advanced Monte Carlo modelling of various accelerator beamlines. Geant4 and MCNP6 Monte Carlo codes are used extensively in this thesis, with rigorous benchmarking completed in the context of experimental verification, and evaluation of the similarities and differences when simulating relevant hadron therapy facilities. The second part of this thesis focuses on the development of a novel wireless microdosimetry system - the Radiodosimeter, to improve the operation efficiency and minimise any radioprotection risks. The successful implementation of the wireless Radiodosimeter is considered as an important milestone in the development of a microdosimetry system that can be operated by an end-user with no prior knowledge

Conception and performance of IViST : a novel platform for real-time In Vivo Source Tracking in brachytherapy

La curiethérapie à haut débit de dose (HDR pour High Dose Rate) est une modalité de traitement du cancer qui délivre au volume cible la dose prescrite avec un débit de dose élevé. Malgré les distributions de doses hautement conformes obtenues avec cette modalité de traitement, le traitement lui-même n’est pas exempt d’erreurs. En raison des forts gradients de dose, typique de la curiethérapie, de petites erreurs dans le positionnement de la source peuvent entraîner des conséquences néfastes pour les patients. L’utilisation systématique de systèmes de vérification en temps réel est le seul moyen de savoir quelles doses ont été réellement données à la tumeur et aux organes à risque. Cette thèse présente les démarches effectuées pour créer et valider un système de dosimétrie à scintillateurs plastiques multipoints (mPSD pour Multipoint Plastic Scintillation Detector) capable d’effectuer avec précision des mesures in vivo en curiethérapie HDR. Un prototype a été optimisé, caractérisé et testé dans des conditions typiques de la curiethérapie HDR. Une analyse exhaustive a été réalisée pour obtenir un modèle optimisé du détecteur, capable de maximiser la collection de lumière de scintillation produite par l’interaction des photons ionisants. Il a été constaté que le scintillateur de longueur d’onde plus courte devrait toujours être placé plus près du photodétecteur, alors que le scintillateur émettant dans la longueur d’onde la plus élevée doit être en position distale. Si la configuration, comme mentionnée précédemment, n’est pas utilisée, des effets d’excitation et d’auto-absorption entre les scintillateurs peuvent se produire, et en conséquence, la transmission de la lumière à travers la fibre collectrice n’est pas optimale. Le détecteur a été rendu étanche à la lumière. Son noyau de 1 mm de diamètre permet son utilisation dans la majorité des applicateurs utilisés pour le parcours de la source en curiethérapie HDR avec l’192Ir. Pour la meilleure configuration du détecteur multipoints (3 mm de BCF10, 6 mm de BCF12, 7 mm BCF60), une optimisation numérique a été effectuée pour sélectionner les composants optiques (miroir dichroïque, filtre et tube photomultiplicateur (PMT pour Photomultiplier Tube)) qui correspondent le mieux au profil d’émission recherché. Ceci permet la déconvolution du signal en utilisant une approche multispectrale, en extrayant la dose de chaque élément tout en tenant compte de l’effet de tige Cerenkov. Le système de luminescence optimisé a été installé dans une boîte protectrice pour assurer la stabilité des composantes optiques lors de la manipulation. Les performances dosimétriques du système IViST (In Vivo Source Tracking) ont été évaluées en curiethérapie HDR, sur une plage clinique réaliste allant jusqu’à 10 cm de distance entre la source et les capteurs du mPSD. IViST peut simultanément mesurer la dose, trianguler la position et mesurer le temps d’arrêt de la source. En effectuant 100 000 mesures/s, IViST échantillonne suffisamment de données pour effectuer rapidement des tâches QA / QC clés, telles que l’identification d’un mauvais temps d’arrêt individuel ou des tubes de transfert interchangés. En utilisant 3 capteurs colinéaires et des informations planifiées pour une géométrie d’implant provenant des fichiers DICOM RT, la plateforme peut également trianguler la position de la source en temps réel avec une précision de positionnement de 1 mm jusqu’à 6 cm de la source. Le détecteur ne présentait aucune dépendance angulaire. Un essai clinique est actuellement en cours avec ce système.High Dose Rate (HDR) brachytherapy is a cancer treatment modality that delivers to the target volume high doses in short amount of time in a few fractions. Despite the highly conformal dose distributions achieved with this treatment modality, the treatment itself is not free from errors. Because of the high dose gradient characteristics of the brachytherapy techniques, small errors in the source positioning can result in harmful consequences for patients. The routine use of a real-time verification system is the only way to know what dose was actually delivered to the tumor and organs at risk. This thesis presents the investigation done to obtain a Multi-point Plastic Scintillation Detector (mPSD) system capable of accurately performing in vivo dosimetry measurements in HDR brachytherapy. A first system’s prototype was optimized, characterized, and tested under typical HDR brachytherapy conditions. An exhaustive analysis was carried out to obtain an optimized mPSD design that maximizes the scintillation light collection produced by the interaction of ionizing photons. We found that the shorter wavelength scintillator should always be placed closer to the photodetector and the longer wavelength scintillator in the distal position for the best overall light-yield collection. If the latter configuration is not used, inter-scintillator excitation and self-absorption effects can occur, and as a consequence, the light transmission through the collecting fiber is not optimal. The detector was made light-tight to avoid environmental light, and its 1 mm diameter core allows their usage in most applicator channel used in 192Ir HDR brachytherapy. For the best mPSD design (3 mm of BCF10, 6 mm of BCF12, 7 mm BCF60), a numerical optimization was done to select the optical components (dichroic mirror, filter and Photomultiplier Tube (PMT)) that best match the light emission profile. It allows for signal deconvolution using a multispectral approach, extracting the dose to each element while taking into account the Cerenkov stem effect. The optimized luminescence system was enclosed into a custom-made box to preserve the optical chain stability and easy manipulation. The In Vivo Source Tracking (IViST) system’s dosimetric performance has been evaluated in HDR brachytherapy, covering a range of 10 cm of source movement around the mPSD’s sensors. IViST can simultaneously measure dose, triangulate source position, and measure dwell time. By making 100 000 measurements/s, IViST samples enough data to quickly perform key QA/QC tasks such as identifying wrong individual dwell time or interchanged transfer tubes. By using 3 co-linear sensors and planned information for an implant geometry (from DICOM RT), the platform can also triangulate source position in real-time with 1 mm positional accuracy up to 6 cm from the source. The detector further exhibited no angular dependence. A clinical trial is presently on-going using the IViST system

Dosimetry studies for radiation therapy with photons and radiobiology using low-energy protons.

Tesis llevada a cabo para conseguir el grado de Doctor por la Universidad de Sevilla--2017-09-15This thesis work is based on the knowledge about the interaction of radiation with matter to develop new methods with the aim of applying them to the radiation therapy and radiobiology, specifically to dose measurements in radiation therapy, dose measurements with low energy proton beams and DNA damages caused by these protons on cancer cells. Thus, it presents two main parts: one regarding the presentation of a novel prototype based on silicon detector technology for treatment verification in radiotherapy, and the other, the instrumentation and the methodology for low energy proton beam characterization, dosimetry, with a special focus on the response of radiochromic films to protons, and finally the application on biological samples to study the DNA damage produced by protons. The first part of this work presents a novel system with improved performances with respect to a previous system which was filed for a patent in September 13th 2011 at the OEMP - “Oficina Espa˜nola de Patentes y Marcas”- Ministry of Industry, Tourism and Commerce, under reference number P201101009. This work was also published in specialized reviews and thesis works. The characterization of the response in terms of absorbed dose of this novel detector was presented Here, this study was repeated because of some modifications introduced in the electronics and in one of the detector’s cables, which was modified due to a breakdown. The application of this system for complex treatment verification providing a 2D dose map reconstruction in the axial plane is presented for the first time in this thesis work. The second part of the work presents the installation of instrumentation for dosimetry and radiobiology studies using proton beams produced by the 3 MV Tandem accelerator at Centro Nacional de Acceleradores, Sevilla. The original work within this part can be divided into three main points: i) the elaboration of a protocol which allows to obtain a beam profile with low current and an homogeneous profile over the whole sample surface; ii) dosimetry with low energy protons using ionization chambers and radiochromic films; iii) study of the dosimetry at the Bragg peak. Last, the application of these studies to the irradiation of cell cultures is presented and preliminary results of the DNA damage produced by protons are shown.Peer reviewe

Assessment of Environmental Radioactivity and Radiation for Human Health Risk

Ten years have passed since the nuclear accident occurred in Fukushima, Japan, following the Great East Japan earthquake. Thereafter, many people around the world have been concerned about the risks posed by radiation. They still believe that even a small amount of radiation exposure will affect human health. In reality, however, there are many natural radionuclides in the environment, which emit a variety of types of radiation. Although it is well known that there is a positively linear relationship between acute radiation exposure and cancer risk in atomic bomb survivors, the risk of chronic radiation exposure due to natural radionuclides cannot be well explained to people who have lived in high-background radiation areas for many generations. Therefore, more studies in this research field are required to obtain new scientific findings. In order to promote further scientific activities, it will be the best for us to understand the current status of this field by summarizing what we have apprehended so far. This Special Issue will highlight measurement data, methodologies, radiation biology, and risk assessment related to radiation