Computed tomography image analysis for the detection of obstructive lung diseases

Damage to the small airways resulting from direct lung injury or associated with many systemic disorders is not easy to identify. Non-invasive techniques such as chest radiography or conventional tests of lung function often cannot reveal the pathology. On Computed Tomography (CT) images, the signs suggesting the presence of obstructive airways disease are subtle, and inter- and intra-observer variability can be considerable. The goal of this research was to implement a system for the automated analysis of CT data of the lungs. Its function is to help clinicians establish a confident assessment of specific obstructive airways diseases and increase the precision of investigation of structure/function relationships. To help resolve the ambiguities of the CT scans, the main objectives of our system were to provide a functional description of the raster images, extract semi-quantitative measurements of the extent of obstructive airways disease and propose a clinical diagnosis aid using a priori knowledge of CT image features of the diseased lungs. The diagnostic process presented in this thesis involves the extraction and analysis of multiple findings. Several novel low-level computer vision feature extractors and image processing algorithms were developed for extracting the extent of the hypo-attenuated areas, textural characterisation of the lung parenchyma, and morphological description of the bronchi. The fusion of the results of these extractors was achieved with a probabilistic network combining a priori knowledge of lung pathology. Creating a CT lung phantom allowed for the initial validation of the proposed methods. Performance of the techniques was then assessed with clinical trials involving other diagnostic tests and expert chest radiologists. The results of the proposed system for diagnostic decision-support demonstrated the feasibility and importance of information fusion in medical image interpretation.Open acces

Evaluation of workbenches which support the CommonKADS methodology

SIGLEAvailable from British Library Document Supply Centre-DSC:8723.2688(EI-AIAI-TR--201) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Beyond rules: development and evaluation of knowledge acquisition systems for educational knowledge-based modelling

The technology of knowledge-based systems undoubtedly offers potential for educational modelling, yet its practical impact on today's school classrooms is very limited. To an extent this is because the tools presently used in schools are EMYCIN -type expert system shells. The main argument of this thesis is that these shells make knowledge-based modelling unnecessarily difficult and that tools which exploit knowledge acquisition technologies empower learners to build better models. We describe how such tools can be designed. To evaluate their usability a model-building course was conducted in five secondary schools. During the course pupils built hundreds of models in a common range of domains. Some of the models were built with an EMYCIN -type shell whilst others were built with a variety of knowledge acquisition systems. The knowledge acquisition systems emerged as superior in important respects. We offer some explanations for these results and argue that although problems remain, such as in teacher education, design of classroom practice, and assessment of learning outcomes, it is clear that knowledge acquisition systems offer considerable potential to develop improved forms of educational knowledge-based modelling

A knowledge-level model for concurrent design.

The concurrent approach to engineering design, concurrent design, implies that expert knowledge regarding a number of different downstream life-cycle perspectives (such as assembly, manufacture, maintainability etc) should all be considered at the design stage of a product's life-cycle. Extensive and valuable work has been done in developing computer aids to both the design and concurrent design processes. However, a criticism of such tools is that their development has been driven by computational considerations and that the tools are not based on a generally accepted model of the design process. Different models of design have been developed that fall into a number of paradigms, including cognitive and knowledge-level models. However, while there is no generally accepted cognitive model describing the way designers and design teams think, the concept of the knowledge-level has enabled a more pragmatic approach to be taken to the development of models of problem-solving activity.Different researchers have developed knowledge-level models for the design process, particularly as part of the CommonKADS methodology (one of the principal knowledge-based system development methodologies currently in use). These design models have significantly extended design thinking in this area. However, the models do not explicitly support the concurrent design process. I have developed top-down knowledge-level models of the concurrent design process by analysis of published research and discussions with academics. However some researchers have criticised models for design that are not based on analysis of 'real-life' design. Hence I wished to validate my top-down models by analysing how concurrent design actually occurs in a real-life industrial setting.Analysing concurrent design activity is a complex process and there are no definitive methodological guidelines as to the 'right way' to do it. Therefore I have developed and utilised a novel method of knowledge elicitation and analysis to develop 'bottom-up' models for concurrent design. This is based on a number of different approaches and was done in collaboration with a number of different design teams and organisations who are engaged in the concurrent design of mechanically based products.My resulting knowledge-level models are an original contribution to knowledge. They suggest that the concurrent design process consists of a number of discrete sub-tasks of propose, critique and negotiate. These models have been instantiated as generic model templates, using the modelling formalisms specified by CommonYADS. These models have been implemented on a software tool, the CommonKADS workbench, in order to provide support for developers of computer-based systems for concurrent design