A rapid development in computer game technology and accompanying programminglanguages have recently provided researchers with small personal supercomputers,comprised in a single graphics processing unit (GPU). This immense rise incomputational capabilities and improved programmability are currently changinghow ultrasound imaging systems are designed. When researchers are exploring newalgorithms for ultrasound imaging, it is therefore important to keep the architectureof parallel accelerators like the GPU in mind. If a new complex algorithm is supposedto run in real time, it needs to fit the programmable and parallel pipeline of modernultrasound scanners.The aim of this study has been to investigate the possibility of utilizing GPUsfor advanced processing in an ultrasound imaging system. Among the investigatedproblems are both adaptive beamforming, adaptive visualization of ultrasoundvolumes, and ultrasound simulations. The presented problems have in common thatthey require parallel programming in order to reach real-time processing.In the first part of the thesis, the Capon adaptive beamformer is investigatedand implemented on a GPU for the application of real-time sonar (Paper I) andmedical ultrasound imaging (Paper II). Real-time frame rates are achieved for bothmodalities. Paper II also presents, for the first time, videos where the Caponbeamformer has been applied on loops of simulated and in vivo medical ultrasoundimages. In Paper III, we show that Capon beamforming does not provide shiftinvariantimaging in a real-time imaging setting. A method is then proposed thatimproves the shift-invariant property. Shift-invariant imaging is essential if the methodis ever to be used in practice.In paper Paper IV we propose an adaptive method for visualization of volumetriccardiac ultrasound images. The method is capable of removing noise that byconventional methods would have occluded cardiac tissue. This work also showsthat with modern GPUs it is possible to add advanced visualization methods to anultrasound imaging system and still have real-time performance.Finally, we investigate how GPUs can be utilized to accelerate ultrasoundsimulations (PaperV). The result of this work was a simulation program whereultrasound array geometries can be interactively drawn and where the resultingpressure field is simulated and visualized in real time.
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