Zhu Q, Steinberg B D
Valley Forge Research Center, Moore School of Electrical Engineering, University of Pennsylvania, Philadelphia 19104.
Ultrason Imaging. 1992 Jul;14(3):276-99. doi: 10.1177/016173469201400304.
Ultrasonic waves propagating through soft tissue experience wavefront distortion. Refraction occurs at boundaries between tissue beds having different sound speeds; scattering occurs within a tissue bed, caused by local impedance variations. This paper describes measurements of wavefront distortion in the human female breast that indicate that refraction is the dominant distortion mechanism when the ultrasonic phased array is very large. The determination that refraction dominates the wavefront distortion is based upon studies of multiple image artifacts that result from a single source radiated through in vivo breasts and breast phantoms. The receiving apertures used were 4.65 and 9.6 cm. Such image artifacts are repeatedly observed in the 10 young subjects reported in this paper, and also in older subjects. An understanding of the in vivo observations is obtained by phantom studies.
在软组织中传播的超声波会经历波前畸变。折射发生在具有不同声速的组织层之间的边界处；散射发生在组织层内，由局部阻抗变化引起。本文描述了对女性乳房中波前畸变的测量，结果表明，当超声相控阵非常大时，折射是主要的畸变机制。折射主导波前畸变这一结论是基于对通过活体乳房和乳房模型辐射的单个源所产生的多个图像伪像的研究得出的。所使用的接收孔径分别为4.65厘米和9.6厘米。在本文报道的10名年轻受试者以及老年受试者中都反复观察到了此类图像伪像。通过模型研究获得了对活体观察结果的理解。
