成像体模
镜头(地质)
光学
折射
失真(音乐)
传感器
图像分辨率
图像质量
相位畸变
光线追踪(物理)
相(物质)
材料科学
计算机科学
物理
声学
人工智能
图像(数学)
光电子学
量子力学
CMOS芯片
放大器
作者
Tony Matéo,Alexandre Chang,Yassine Mofid,Pierre‐Jean Pisella,L. Machet
出处
期刊:IEEE Transactions on Medical Imaging
[Institute of Electrical and Electronics Engineers]
日期:2014-11-01
卷期号:33 (11): 2149-2166
被引量:9
标识
DOI:10.1109/tmi.2014.2332519
摘要
In ophthalmic ultrasonography the crystalline lens is known to be the main source of phase aberration, causing a significant decrease in resolution and distortion effects on axial B-scans. This paper proposes a computationally efficient method to correct the phase aberration arising from the crystalline lens, including refraction effects using a bending ray tracing approach based on Fermat's principle. This method is used as a basis to perform eye-adapted beamforming (BF), with appropriate focusing delays for a 128-element 20-MHz linear array in both emission and reception. Implementation was achieved on an in-house developed experimental ultrasound scanning device, the ECODERM. The proposed BF was tested in vitro by imaging a wire phantom through an eye phantom consisting of a synthetic gelatin lens anatomically set up in an appropriate liquid (turpentine) to approach the in vivo velocity ratio. Both extremes of accommodation shapes of the human crystalline lens were investigated. The performance of the developed BF was evaluated in relation to that in homogeneous medium and compared to a conventional delay-and-sum (DAS) BF and a second adapted BF which was simplified to ignore the lens refraction. Global expectations provided by our method with the transducer array are reviewed by an analysis quantifying both image quality and spatial fidelity, as well as the detrimental effects of a crystalline lens in conventional reconstruction. Compared to conventional array imaging, the results indicated a two-fold improvement in the lateral resolution, greater sensitivity and a considerable reduction of spatial distortions that were sufficient to envisage reliable biometry directly in B-mode, especially phakometry.
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