Center for Fast UltrasoundImaging, DTU-Elektro, Technical University of Denmark, Lyngby, Denmark.
IEEE Trans Ultrason Ferroelectr Freq Control. 2010 May;57(5):1051-63. doi: 10.1109/TUFFC.2010.1517.
Volumetric imaging can be performed using 1-D arrays in combination with mechanical motion. Outside the elevation focus of the array, the resolution and contrast quickly degrade compared with the lateral plane, because of the fixed transducer focus. This paper shows the feasibility of using synthetic aperture focusing for enhancing the elevation focus for a convex rocking array. The method uses a virtual source (VS) for defocused multi-element transmit, and another VS in the elevation focus point. This allows a direct time-of-flight to be calculated for a given 3-D point. To avoid artifacts and increase SNR at the elevation VS, a plane-wave VS approach has been implemented. Simulations and measurements using an experimental scanner with a convex rocking array show an average improvement in resolution of 26% and 33%, respectively. This improvement is also seen in in vivo measurements. An evaluation of how a change in transducer design will affect the resolution improvement shows a potential for using a modified transducer for 3-D imaging with improved elevation focusing and contrast.
体积成像可以使用一维阵列与机械运动相结合来实现。在阵列的垂直焦点之外，由于固定的换能器焦点，分辨率和对比度与横向平面相比迅速下降。本文展示了使用合成孔径聚焦技术来增强凸面摆动阵列的垂直焦点的可行性。该方法使用虚拟源 (VS) 进行离焦多元素发射，并在垂直焦点处使用另一个 VS。这允许为给定的 3-D 点直接计算飞行时间。为了避免在垂直 VS 处出现伪影并提高 SNR，实现了平面波 VS 方法。使用具有凸面摆动阵列的实验扫描仪进行的模拟和测量分别显示分辨率提高了 26%和 33%。在体内测量中也可以看到这种改进。评估换能器设计的变化将如何影响分辨率提高，显示出使用改进的换能器进行 3-D 成像的潜力，可实现更好的垂直聚焦和对比度。
