Yujia Tang

The synthetic focusing of coherent plane-wave compounding (CPWC) has gradually developed from ultrasound linear array to convex array. The field of view (FOV) has been expanded compared to that of the linear array. However, the existing technology does not make the most of the convex structural advantages and FOV is greatly limited by the element number of a convex array. In this paper, based on the convex array of diverging wave (DW) imaging theory and the special structure design principles, the elements of the convex array probe are unequally spaced for better imaging quality and wider FOV. Firstly, the sound field pattern was simulated for sidelobe comparison. Then, DW imaging of the new convex array was simulated and the experiment was carried out on the tissue-mimicking ultrasound phantom using the commercial probe. Comparisons of lateral and axial variations illustrated that the convex array with variable spacings (CAVS) does improve the imaging quality when compared to the given convex array with uniform spacings. Finally, we conclude that CAVS can further extend the FOV of DW imaging by taking advantage of the structure of convex array and variable element spacings.

Ultrasound plane wave imaging technology has been applied to more clinical situations than ever before because of its rapid imaging speed and stable imaging quality. Most transducers used in plane wave imaging are linear arrays, but their structures limit the application of plane wave imaging technology in some special clinical situations, especially in the endoscopic environment. In the endoscopic environment, the size of the linear array transducer is strictly miniaturized, and the imaging range is also limited to the near field. Meanwhile, the near field of a micro linear array has serious mutual interferences between elements, which is against the imaging quality of near field. Therefore, we propose a new structure of a micro ultrasound linear array for plane wave imaging. In this paper, a theoretical comparison is given through sound field and imaging simulations. On the basis of primary work and laboratory technology, micro uniform and non-uniform linear arrays were made and experimented with the phantom setting. We selected appropriate evaluation parameters to verify the imaging results. Finally, we concluded that the micro non-uniform linear array eliminated the artifacts better than the micro uniform linear array without the additional use of signal processing methods, especially for target points in the near-field. We believe this study provides a possible solution for plane wave imaging in cramped environments like endoscopy.

For ultrasound plane wave imaging, the conventional ultrasonic transducer is a uniform linear array. However, the fan-shaped artifacts which usually appear around the target point in the ultrasound image affect the observation and analysis of the image. It is one of the import issues that many researchers are trying to solve using improved plane-wave algorithms. In fact, similar issue had been studied in the field of radio antenna about linear arrays with variable inter-element spacing. In order to apply this structural design in ultrasound transducer with an expectation to improve the image quality of coherent compounding plane-wave imaging, simulation about several nonuniformities have been finished. The simulation results demonstrated that the special structural design can generate flatter wave fronts of transmitted waveforms at near field, which contributes to improving the image quality of plane wave imaging.