Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8129845 | Ultrasonics | 2018 | 10 Pages |
Abstract
When using high-frequency (HF) ultrasound in sonography, attenuation due to the viscosity of the medium limits the available imaging depth, and strong reflection and scattering from hard tissue, such as bone, render biological diagnosis very difficult. In order to resolve these problems, the feasibility of low-frequency (LF) parametric ultrasound imaging with high directivity was explored in the present study. A pulse compression technique was applied to chirp-modulated parametric ultrasound waves in the frequency band of 100-500â¯kHz generated from modulated primary ultrasound waves with a center frequency of 2.8â¯MHz in order to improve the signal-to-noise ratio (SNR). Low-frequency ultrasound images of brass rods obtained using pulse compressed parametric ultrasound exhibit accurate target distances, a 3-mm range resolution, which agrees well with the theoretical value, and an 8-dB improvement in SNR. Parametric ultrasound imaging with pulse compression makes easy to separate overlapping targets in comparison with HF ultrasound imaging, and indicates the image with brightness independent of distance in comparison with directly radiated LF ultrasound imaging. These results reveal that pulse compressed LF parametric ultrasound is not only a useful method for improving the SNR and providing accurate distance measurements, but also enables imaging of overlapping targets.
Keywords
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Acoustics and Ultrasonics
Authors
Hideyuki Nomura, Hideo Adachi, Tomoo Kamakura,