Verification of electron beam parameters in an intraoperative linear accelerator using dosimetric and radiobiological response methods

Background: The availability of linear accelerators (linac) for research purposes is often limited and therefore alternative radiation sources are needed to conduct radiobiological research. The National Centre for Radiation Research in Poland recently developed an intraoperative mobile linac that enables electron irradiation at energies ranging from 4 to 12 MeV and dose rates of 5 or 10 Gy/min. The present study was conducted to evaluate the electron beam parameters of this intraoperative linac and to verify the set-up to evaluate out-of-field doses in a water phantom, which were determined through dosimetric and biological response measurements. Materials and methods: The distribution of radiation doses along and across the radiation beam were measured in a water phantom using a semiconductor detector and absolute doses using an ionisation chamber. Two luminal breast cancer cell lines (T-47D and HER2 positive SK-BR-3) were placed in the phantom to study radiation response at doses ranging from 2 to 10 Gy.  Cell response was measured by clonogenic assays. Results and Conclusion: The electron beam properties, including depth doses and profiles, were within expected range for the stated energies. These results confirm the viability of this device and set-up as a source of megavoltage electrons to evaluate the radiobiological response of tumour cells

Quality Control of PET Bottles Caps with Dedicated Image Calibration and Deep Neural Networks

Product quality control is currently the leading trend in industrial production. It is heading towards the exact analysis of each product before reaching the end customer. Every stage of production control is of particular importance in the food and pharmaceutical industries, where, apart from visual issues, additional safety regulations are demanded. Many production processes can be controlled completely contactless through the use of machine vision cameras and advanced image processing techniques. The most dynamically growing sector of image analysis methods are solutions based on deep neural networks. Their major advantages are fast performance, robustness, and the fact that they can be exploited even in complicated classification problems. However, the use of machine learning methods on high-performance production lines may be limited by inference time or, in the case of multiformated production lines, training time. The article presents a novel data preprocessing (or calibration) method. It uses prior knowledge about the optical system, which enables the use of the lightweight Convolutional Neural Network (CNN) model for product quality control of polyethylene terephthalate (PET) bottle caps. The combination of preprocessing with the lightweight CNN model resulted in at least a five-fold reduction in prediction and training time compared to the lighter standard models tested on ImageNet, without loss of accuracy

Quality Control of PET Bottles Caps with Dedicated Image Calibration and Deep Neural Networks

Product quality control is currently the leading trend in industrial production. It is heading towards the exact analysis of each product before reaching the end customer. Every stage of production control is of particular importance in the food and pharmaceutical industries, where, apart from visual issues, additional safety regulations are demanded. Many production processes can be controlled completely contactless through the use of machine vision cameras and advanced image processing techniques. The most dynamically growing sector of image analysis methods are solutions based on deep neural networks. Their major advantages are fast performance, robustness, and the fact that they can be exploited even in complicated classification problems. However, the use of machine learning methods on high-performance production lines may be limited by inference time or, in the case of multiformated production lines, training time. The article presents a novel data preprocessing (or calibration) method. It uses prior knowledge about the optical system, which enables the use of the lightweight Convolutional Neural Network (CNN) model for product quality control of polyethylene terephthalate (PET) bottle caps. The combination of preprocessing with the lightweight CNN model resulted in at least a five-fold reduction in prediction and training time compared to the lighter standard models tested on ImageNet, without loss of accuracy

Numerical Analysis and Experimental Test for the Development of a Small Shaped Charge

Currently, shaped charges are widely used in many fields of science and industry. Due to the high efficiency of piercing materials with high strength and hardness, shaped charges are commonly used in mining, military and for structural damage. The main application area of shaped charges is the military industry, where they are used in missiles with warheads (torpedoes, rocket launchers) and for piercing vehicle armor or bunker walls. When analyzing the existing solutions of shaped charges, one can find many typical solutions designed for specific applications. However, there are no universal constructions which, after appropriate regulation, will fulfil their role in a wide range of applications. The subject of this article is a new solution for a shaped charge that is characterized by compact dimensions and a short preparation time. This article presents the results of experimental research and the numerical analyses of such a charge

Development and validation of an inverse method for identification of thermal characteristics of a short laser pulse

The paper presents development and validation of an inverse method for the identification of thermal characteristics of a short single laser pulse which stroke in a metal sample. The inverse method was applied to find unknown power of the laser pulse, the dimensionless shape parameter of the super-Gaussian function which describes the beam spatial profile as well as beginning and end times of the exposition of the metal sample to the laser pulse. The proposed inverse algorithm was based on the Levenberg-Marquardt technique as well as on temporal and spatial distributions of temperature on the rear surface of the sample, i.e., the opposite to the irradiated one, measured using the experimental stand. The performed investigations showed that the problem was ill-posed but good accuracy was obtained. The low sensitivity of registered temperature to changes in both power and duration of the pulse affected the retrieving accuracy most significantly. Moreover, the dependence of solution of the inverse problem on the initial guess was observed. The accuracy was also affected by low temporal resolution (500 Hz, with the exposure time from 0.2 to 1 ms) of the IR camera. This resolution affected the temporal sampling of measured temperatures. Despite these problems, the method was able to retrieve unknown pulse parameters with 20-25% accuracy

Numerical Analyses of Fracture Mechanism of the Pelvic Ring during Side-Impact Load

The aim of this study is the analysis of the multiple pelvis fracture mechanism in side-impact dynamic load cases. The elaborated numerical model of a pelvis complex includes pelvic and sacral bones as well as soft tissues such as ligaments and cartilages. The bone has been modelled as a viscoelasticity material based on the Johnson–Cook model. The model parameters have been chosen based on the experimental data. The uniqueness of a presented approach refers to the selection of crack criteria for the bone. Thus, it was allowed to analyse the process of multiple fractures inside the pelvic bones. The analysis was evaluated for the model in which the deformation rate influences the bone material properties. As a result, the stress distributions inside particular bones were changed. It has been estimated that the results can vary by 50% or even more depending on the type of boundary conditions adopted. The second step of work was a numerical analysis of military vehicle subjected to an IED. An analysis of the impactor’s impact on the pelvis of the Hybrid ES-2RE mannequin was conducted. It was shown that the force in the pelvis exceeds the critical value by a factor of 10. The results of the numerical analysis were then used to validate the model of a military vehicle with a soldier. It was shown that for the adopted loading conditions, the critical value of the force in the pelvis was not exceeded

Development and validation of an inverse method for identification of thermal characteristics of a short laser pulse

The paper presents development and validation of an inverse method for the identification of thermal characteristics of a short single laser pulse which stroke in a metal sample. The inverse method was applied to find unknown power of the laser pulse, the dimensionless shape parameter of the super-Gaussian function which describes the beam spatial profile as well as beginning and end times of the exposition of the metal sample to the laser pulse. The proposed inverse algorithm was based on the Levenberg-Marquardt technique as well as on temporal and spatial distributions of temperature on the rear surface of the sample, i.e., the opposite to the irradiated one, measured using the experimental stand. The performed investigations showed that the problem was ill-posed but good accuracy was obtained. The low sensitivity of registered temperature to changes in both power and duration of the pulse affected the retrieving accuracy most significantly. Moreover, the dependence of solution of the inverse problem on the initial guess was observed. The accuracy was also affected by low temporal resolution (500 Hz, with the exposure time from 0.2 to 1 ms) of the IR camera. This resolution affected the temporal sampling of measured temperatures. Despite these problems, the method was able to retrieve unknown pulse parameters with 20-25% accuracy

Severe Accident Simulations Dedicated to the SAMG DecisionMaking Tool Demonstration

The paper presents preliminary severe accident (SA) simulations performed to generate a database of plant states dedicated to be used with Severe Accident Management Guidelines Decision Making Tool (SAMG DM). The novel software is being developed in the framework of the NARSIS Horizon-2020 research project. It is intended to be a supporting tool for the SAMGs implementation, Emergency Preparedness and selection of Severe Accident Management (SAM) strategies. Simulations were performed with MELCOR 2.2 integral computer code for generic Nuclear Power Plant (NPP) with Gen-II Pressurized Water Reactor (PWR). The database covers results for parameters important for both in-vessel and ex-vessel phases of different accident scenarios. Two general types of scenarios are considered in the database: low-pressure and high-pressure sequences. In this paper, a comparison was prepared for two base case low-pressure scenarios, that is hot leg and cold leg LB-LOCAs without safety injection. Sensitivity simulations were performed with and without Containment Filtered Venting (CFV) as it substantially influences the containment performance. Both accidents are characterized by rapid progression with core meltdown within 2 hours and containment failure within 40 hours and eventual venting with CFV after 13-15 hours. It was observed that for the cold-leg break, the Reactor Pressure Vessel failure occurs earlier only by ~5 minutes. On the contrary, the containment failure is predicted to occur three hours earlier for the hot-leg LOCA

Pre-Conceptual Design of the Research High-Temperature Gas-Cooled Reactor TeResa for Non-Electrical Applications

In line with Polish national activities and research programs investigating non-electrical-reactor use, the national GOSPOSTRATEG-HTR project was launched, aiming at the development of a novel pre-conceptual design of a High-Temperature Gas-cooled Reactor (HTGR). The 40 MWth research reactor would serve as a technology demonstrator for future industrial purposes. In the paper, the proposal of an established thermal-hydraulic and neutronic core design is presented as a result of the National Centre for Nuclear Research team studies, in the scope of the project, including the areas of fluid mechanics, heat exchange and reactor neutronic core design support analyses. The undertaken analyses were confirmed by the series of code investigations involving integral thermal-hydraulic (MELCOR (Sandia National Laboratories, USA), CATHARE (CEA, France)), neutronic (Serpent (VTT, Finland), MCB (AGH University’s Department of Nuclear Energy, Poland)), Computational Fluid Dynamics (ANSYS Fluent (ANSYS, USA)) and others. The calculations performed within the preliminary safety analysis on the pre-concept showed its compliance with international safety standards for the normal operation and Design Basis Accident sequences

Media 1: Application of 3D digital image correlation to track displacements and strains of canvas paintings exposed to relative humidity changes

Originally published in Applied Optics on 20 March 2014 (ao-53-9-1739