Fast Square-Wave Transform for High Frame Rate Imaging with Limited Diffraction Beams

High frame rate(HFR) medical imaging system was developed by Lu Jian-yu in 1997. One of the important steps of this system is weighting with exact limited-diffraction array beams. Recently, Lu Jian-yu developed a new imaging method with square-wave aperture weightings instead of sine and cosine aperture weightings. Experimental results show that almost the same quality of images can be obtained with the square-wave aperture weighting method and with the exact limited-diffraction array beam weightings. But the method with square-wave aperture weighting is more simple, and this method costs less time than the method with exact limited-diffraction array beam weightings. In this paper, a fast square-wave transform is introduced to the HFR imaging method. This fast square-wave transform can be used to deal with the data when the number of data samples is prime. This method can reduce about half of the computation by rearranging the data sequence. And the characters of this method make it have a potential to be actualized easily with digital circuits.