Plane Wave Formulation - 2024.1 English

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2024.1 English

In the previous paragraph, you received the basic formulation of an SA. It is very important to underline that PW is a different imaging technique but with the same expected outcome from the process of Beamformation. PW imaging, in contrast with respect to SA imaging, excites all the transducers in the same moment to emit a plane wave, whose echos are registered by the whole number of transducers in our probe. In PW, emission is called a single process of excitement of the whole transducers in the probe. As it happens in SA, every emission produces a LRI by the process of beamformation. An HRI could be obtained by compounding a set of LRIs, as it happens in SA. To have multiple emissions, a parameter called span is used, which represents an “aperture” angle and the directions in which you want to emit the plane waves. The span represent the total aperture of the investigation, and to determine the number of emission and the directions, an increment parameter is used, which represent how many areas with respect to the total angle you want to explore. Suppose you want to perform eight emissions with a spanning angle of 30 degrees. The investigations would be then be eight, starting from emitting a plane wave with direction of 0 degrees (or -15, depending on the system coordinates) and creating a LRI from the Beamformer. The second investigation would be an emission at 3.75 degrees direction (or -11.25, depending on the system coordinates), which is 0+3.75, where 3.75 represents the increment with respect to the emission made. You then obtain a second LRI from the Beamformer. This process is repeated until the eighth emission, and then the eight LRIs obtained compounded in a single HRI, as it happens in SA. PW is, in terms of frame rate, the best choice for the process of beamformation. Opposite to SA, which needs a high number of emissions, PW could be performed by a single emission (at the cost of having an enormous load in terms data processing), because of the fact that it excites all (or nearly all) the transducers at the same moment. Following an image of summary of PW Imaging.