In pre-treatment dose verification, low resolution detector systems are unable to identify shifts of individual leafs of high resolution multi leaf collimator (MLC) systems from detected changes in the dose deposition. The goal of this study was to introduce an alternative approach (the shutter technique) combined with a previous described iterative reconstruction method to accurately reconstruct high resolution MLC leaf positions based on low resolution measurements. For the shutter technique, two additional radiotherapy treatment plans (RT-plans) were generated in addition to the original RT-plan; one with even MLC leafs closed for reconstructing uneven leaf positions and one with uneven MLC leafs closed for reconstructing even leaf positions. Reconstructed leaf positions were then implemented in the original RT-plan for 3D dose reconstruction. The shutter technique was evaluated for a 6 MV Elekta SLi linac with 5 mm MLC leafs (Agility(™)) in combination with the MatriXX Evolution detector with detector spacing of 7.62 mm. Dose reconstruction was performed with the COMPASS system (v2.0). The measurement setup allowed one row of ionization chambers to be affected by two adjacent leaf pairs. Measurements were obtained for various field sizes with MLC leaf position errors ranging from 1.0 mm to 10.0 mm. Furthermore, one clinical head and neck IMRT treatment beam with MLC introduced leaf position errors of 5.0 mm was evaluated to illustrate the impact of the shutter technique on 3D dose reconstruction. Without the shutter technique, MLC leaf position reconstruction showed reconstruction errors up to 6.0 mm. Introduction of the shutter technique allowed MLC leaf position reconstruction for the majority of leafs with sub-millimeter accuracy resulting in a reduction of dose reconstruction errors. The shutter technique in combination with the iterative reconstruction method allows high resolution MLC leaf position reconstruction using low resolution measurements with sub-millimeter accuracy.
The main question in this PhD thesis is: How can Business Rules Management be configured and valued in organizations? A BRM problem space framework is proposed, existing of service systems, as a solution to the BRM problems. In total 94 vendor documents and approximately 32 hours of semi-structured interviews were analyzed. This analysis revealed nine individual service systems, in casu elicitation, design, verification, validation, deployment, execution, monitor, audit, and version. In the second part of this dissertation, BRM is positioned in relation to BPM (Business Process Management) by means of a literature study. An extension study was conducted: a qualitative study on a list of business rules formulated by a consulting organization based on the Committee of Sponsoring Organizations of the Treadway Commission risk framework. (from the summary of the Thesis p. 165)
Urban planning will benefit from tools that can assess the vulnerabilityto thermal stress in urban dense cities. Detailed quick-scan heat stressmaps, as made in this study for Johannesburg, have proven valuable inthe decision-making process on this topic. It raised awareness on theurgent need to implement measures to tackle the effects of climatechange and urbanization. Awareness on heat stress has led to theimplementation of measures to mitigate the effects of climate change.As in other countries, nature-based solutions (e.g. green roofs and walls,swales, rain gardens, planting trees etc) are considered in urban areasin South Africa for various reasons. The awareness of the effect ofnature based solutions on heat stress is still low, which can be improvedby the use of heat stress maps. Some of these measures are alreadymapped on the open source web tool, Climate-scan(www.climatescan.nl) for international knowledge exchange aroundthe globe.
The research proposal aims to improve the design and verification process for coastal protection works. With global sea levels rising, the Netherlands, in particular, faces the challenge of protecting its coastline from potential flooding. Four strategies for coastal protection are recognized: protection-closed (dikes, dams, dunes), protection-open (storm surge barriers), advancing the coastline (beach suppletion, reclamation), and accommodation through "living with water" concepts. The construction process of coastal protection works involves collaboration between the client and contractors. Different roles, such as project management, project control, stakeholder management, technical management, and contract management, work together to ensure the project's success. The design and verification process is crucial in coastal protection projects. The contract may include functional requirements or detailed design specifications. Design drawings with tolerances are created before construction begins. During construction and final verification, the design is measured using survey data. The accuracy of the measurement techniques used can impact the construction process and may lead to contractual issues if not properly planned. The problem addressed in the research proposal is the lack of a comprehensive and consistent process for defining and verifying design specifications in coastal protection projects. Existing documents focus on specific aspects of the process but do not provide a holistic approach. The research aims to improve the definition and verification of design specifications through a systematic review of contractual parameters and survey methods. It seeks to reduce potential claims, improve safety, enhance the competitiveness of maritime construction companies, and decrease time spent on contractual discussions. The research will have several outcomes, including a body of knowledge describing existing and best practices, a set of best practices and recommendations for verifying specific design parameters, and supporting documents such as algorithms for verification.
The goal of UPIN is to develop and evaluate a scalable distributed system that enables users to cryptographically verify and easily control the paths through which their data travels through an inter-domain network like the Internet, both in terms of router-to-router hops as well as in terms of router attributes (e.g., their location, operator, security level, and manufacturer). UPIN will thus provide the solution to a very relevant and current problem, namely that it is becoming increasingly opaque for users on the Internet who processes their data (e.g., in terms of service providers their data passes through as well as what jurisdictions apply) and that they have no control over how it is being routed. This is a risk for people’s privacy (e.g., a malicious network compromising a user’s data) as well as for their safety (e.g., an untrusted network disrupting a remote surgery). Motivating examples in which (sensitive) user data typically travels across the Internet without user awareness or control are: - Internet of Things for consumers: sensors such as sleep trackers and light switches that collect information about a user’s physical environment and send it across the Internet to remote services for analysis. - Medical records: health care providers requiring medical information (e.g., health records of patients or remote surgery telemetry) to travel between medical institutions according to specified agreements. - Intelligent transport systems: communication plays a crucial role in future autonomous transportation systems, for instance to avoid freight drones colliding or to ensure smooth passing of trucks through busy urban areas. The UPIN project is novel in three ways: 1. UPIN gives users the ability to control and verify the path that their data takes through the network all the way to the destination endpoint, both in terms of hops and attributes of routers traversed. UPIN accomplishes this by adding and improving remote attestation techniques for on-path routers to existing path verification mechanisms, and by adopting and further developing in-packet path selection directives for control. 2. We develop and simulate data and control plane protocols and router extensions to include the UPIN system in inter-domain networking systems such as IP (e.g., using BGP and segment routing) and emerging systems such as SCION and RINA. 3. We evaluate the scalability and performance of the UPIN system using a multi-site testbed of open programmable P4 routers, which is necessary because UPIN requires novel packet processing functions in the data plane. We validate the system using the earlier motivating examples as use cases. The impact we target is: - Increased trust from users (individuals and organizations) in network services because they are able to verify how their data travels through the network to the destination endpoint and because the UPIN APIs enable novel applications that use these network functions. - More empowered users because they are able to control how their data travels through inter-domain networks, which increases self-determination, both at the level of individual users as well as at the societal level.