Beam coding with orthogonal complementary Golay codes for signal-to-noise ratio improvement in ultrasound mammography

Abstract

In this paper, the experimental results of using Golay coded signals at 7.5 MHz to detect breast microcalcifications of 50 μm size is presented. For improving the success on detecting the microcalcifications, orthogonal Golay complementary sequences up to 40 chips having cross correlation for minimum interference are used as coded signals and they are compared to tone burst pulse of equal energy in terms of resolution under weak signal conditions. The measurements are conducted using an experimental ultrasound research scanner, DiPhAS having 256 channels, a phased array transducer with 7.5 MHz center frequency, and the results obtained through experiments are validated by Field-II simulation software. In addition, to investigate the superiority of coded signals in terms of resolution, multipurpose tissue equivalent phantom (Model 84-317) containing series of monofilament nylon targets, 240 μm in diameter, and cyst-like objects with attenuation of 0.5 dB/(MHz*cm) is used in the experiments. We obtained ultrasound images of monofilament nylon targets and cyst-like objects for the evaluation of resolution. Experimental results show that it is possible to differentiate closely positioned small targets with increased success by using coded excitation in very weak signal conditions.In this paper, the experimental results of using Golay coded signals at 7.5 MHz to detect breast microcalcifications of 50 μm size is presented. For improving the success on detecting the microcalcifications, orthogonal Golay complementary sequences up to 40 chips having cross correlation for minimum interference are used as coded signals and they are compared to tone burst pulse of equal energy in terms of resolution under weak signal conditions. The measurements are conducted using an experimental ultrasound research scanner, DiPhAS having 256 channels, a phased array transducer with 7.5 MHz center frequency, and the results obtained through experiments are validated by Field-II simulation software. In addition, to investigate the superiority of coded signals in terms of resolution, multipurpose tissue equivalent phantom (Model 84-317) containing series of monofilament nylon targets, 240 μm in diameter, and cyst-like objects with attenuation of 0.5 dB/(MHz*cm) is used in the experiments. We obtained ult...