Browsing by Author "Lampasona, Constanza"

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Open Access
3D digital analysis of mammographic composition
(2009) Lampasona, Constanza; Roller, Dieter (Prof. Dr.)
Breast cancer represents the most frequent cancer within women. Besides clinical examination and self-examination, breast imaging plays a very important role in detecting breast cancer before tumors turn clinically visible. The mammography, a radiograph of the breast, is the most widespread test for the early detection of breast cancer. The images obtained through mammography are known as mammograms and they visualize the breast structure. The woman breast consists of fibroglandular and fatty tissue. Increased mammographic breast density, an increase of fibroglandular tissue, is a factor that influences the risk of becoming affected with breast cancer. Computer-based image analysis could help to find such abnormal changes in the breast tissues from digital mammograms. Full-field digital mammograms are acquired using an electronic detector and they are stored using the DICOM standard file format. In this thesis we first describe the image acquisition process, the DICOM file format as well as the conventional and digital mammography, together with its advantages for computer-based image processing. Former image processing methods and their application into mammograms were also studied. These methods include the measurement of area and volumetric mammographic breast density, the segmentation and the registration of mammograms and methods that could be applied to visualize the breast density. Based on the knowledge on the acquisition process, the DICOM file format and the former methods, computer-based image analysis methods were developed during this research project. All the methods were implemented in a software prototype to test them. The software architecture of the prototype is also shown in this thesis. The main contribution of this work is a new method for the measurement of volumetric breast density. This measurement of volumetric breast density consists in the interpretation of pixels gray levels from full-field digital mammograms to determine which combinations of tissues they represent. In order to be able to compare many images, after performing the measurements, the images are standardized and registered. From the breast composition and its changes, a conclusion could be reached in relation to a suspected cancer or an elevated breast cancer risk. Additionally, some image processing methods were developed to prepare the images for the analysis. These methods segment the mammogram into background, pectoral muscle and breast tissue. The information obtained from the analysis of the mammograms could also be used for the detection of microcalcifications and the skin line or breast border. The mammograms are then graphically shown using different two and three-dimensional views. The last chapters show the results of the computer-based image analysis of the full-filed digital mammograms using the software prototype, conclusions and future work.
Open Access
Operationalised product quality models and assessment: the Quamoco approach
(2015) Wagner, Stefan; Goeb, Andreas; Heinemann, Lars; Kläs, Michael; Lampasona, Constanza; Lochmann, Klaus; Mayr, Alois; Plösch, Reinhold; Seidl, Andreas; Streit, Jonathan; Trendowicz, Adam
Context: Software quality models provide either abstract quality characteristics or concrete quality measurements; there is no seamless integration of these two aspects. Quality assessment approaches are, hence, also very specific or remain abstract. Reasons for this include the complexity of quality and the various quality profiles in different domains which make it difficult to build operationalised quality models. Objective: In the project Quamoco, we developed a comprehensive approach aimed at closing this gap. Method: The project combined constructive research, which involved a broad range of quality experts from academia and industry in workshops, sprint work and reviews, with empirical studies. All deliverables within the project were peer-reviewed by two project members from a different area. Most deliverables were developed in two or three iterations and underwent an evaluation. Results: We contribute a comprehensive quality modelling and assessment approach: (1) A meta quality model defines the structure of operationalised quality models. It includes the concept of a product factor, which bridges the gap between concrete measurements and abstract quality aspects, and allows modularisation to create modules for specific domains. (2) A largely technology-independent base quality model reduces the effort and complexity of building quality models for specific domains. For Java and C# systems, we refined it with about 300 concrete product factors and 500 measures. (3) A concrete and comprehensive quality assessment approach makes use of the concepts in the meta-model. (4) An empirical evaluation of the above results using real-world software systems showed: (a) The assessment results using the base model largely match the expectations of experts for the corresponding systems. (b) The approach and models are well understood by practitioners and considered to be both consistent and well suited for getting an overall view on the quality of a software product. The validity of the base quality model could not be shown conclusively, however. (5) The extensive, open-source tool support is in a mature state. (6) The model for embedded software systems is a proof-of-concept for domain-specific quality models. Conclusion: We provide a broad basis for the development and application of quality models in indus- trial practice as well as a basis for further extension, validation and comparison with other approaches in research.