tailieunhanh - Synthetic aperture method in ultrasound imaging

Medical ultrasound imaging is a technique that has become much more prevalent than other medical imaging techniques since it is more accessible, less expensive, safe, simpler to use and produces images in the real time. However, images produced by an ultrasound imaging system, must be of sufficient quality to provide accurate clinical interpretation. | 3 Synthetic Aperture Method in Ultrasound Imaging Ihor Trots Andrzej Nowicki Marcin Lewandowski and Yuriy Tasinkevych Institute of Fundamental Technological Research Poland 1. Introduction Medical ultrasound imaging is a technique that has become much more prevalent than other medical imaging techniques since it is more accessible less expensive safe simpler to use and produces images in the real time. However images produced by an ultrasound imaging system must be of sufficient quality to provide accurate clinical interpretation. The most commonly used image quality measures are spatial resolution and image contrast which can be determined in terms of beam characteristics of an imaging system beam width and sidelobe level. In the design of an imaging system the optimal set of system parameters is usually found as a trade-off between the lowest side-lobe peak and the narrowest beam of an imaging system. In conventional ultrasound imaging system when one transducer in mechanical wobble or linear array are used the quality of images directly depends on the transducer acoustic field. Also in conventional ultrasound imaging the image is acquired sequentially one image line at a time that puts a strict limit on the frame rate that is important in real-time imaging system. Low frame rate means that moving structures . heart valves are not easily imaged and diagnosis may be impaired. This limitation can be reduced by employing synthetic aperture SA imaging. The basic idea of the SA method is to combine information from emissions close to each other. The synthetic aperture method has previously not been used in medical imaging. This method is a contrast to the conventional beamforming where only imaging along one line in receiving is used. This means that every image line is visualized as many times as the number of elements used. This will create an equal amount of low resolution images which are summed up to create one high resolution image. Problems with medical .