arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2003.06934physics.med-ph
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三维全波非线性声学人体超声成像。第1部分:模拟方法

Ultrasound imaging of the human body with three dimensional full-wave nonlinear acoustics. Part 1: simulations methods

Gianmarco Pinton

摘要:

三维超声在非均匀介质中传播的模拟是计算密集型的,这是由于域的大尺寸(其为数百个波长的量级)和散射体的小尺寸(其远小于波长)引起的约束。因此,三维超声成像模拟目前基于简化传播物理的模型。在这里,全三维波物理模拟与有限差分生成人体的超声图像直接基于传播和后向散射的第一原理。可视人体项目,一个三维数据集的人体产生的0.33毫米冷冻切片的照片,转换成三维声学地图。使用全波非线性声学模拟工具,利用具有$6\times10^8$点的$93 \times 39 \times 22$ mm域中的2D肋间超声阵列将超声传播到肝脏中。成像指标,基于波束图,均方根相位像差,空间相干长度,和对比度噪声比被用来表征图像质量。结果表明,谐波图像质量优于基本图像质量,部分原因是由于较窄的光束轮廓。通过模拟体壁传播后的均方根估计的像差被证明是低的(23.4纳秒),与以前的报告一致,在人体壁实验测量的像差。在换能器表面处测量的空间相干性指示将需要$<0.81 λ$的换能器阵列元件尺寸来完全采样声场。这些直接基于传播物理学的模拟三维超声图像提供了一个平台来研究三维图像退化的来源(包括在第二部分中)。

英文摘要:

Simulations of three dimensional ultrasound propagation in heterogeneous media are computationally intensive due to the constraints arising from the large size of the domain, which is on the order of hundreds of wavelengths, and the small size of scatterers, which are much smaller than a wavelength. Consequently, three dimensional ultrasound imaging simulations are currently based on models that simplify the propagation physics. Here the full three dimensional wave physics is simulated with finite differences to generate ultrasound images of the human body based directly on the first principles of propagation and backscattering. The Visible Human project, a 3D data set of the human body that was generated with photographs of 0.33 mm cryosections, is converted into 3D acoustical maps. A full-wave nonlinear acoustic simulation tool is used to propagate ultrasound into the liver with a 2D intercostal ultrasound array in a $93 \times 39 \times 22$ mm domain with $6\times10^8$ points. Imaging metrics, based on the beamplots, root-mean-square phase aberration, spatial coherence lengths, and contrast-to-noise ratio are used to characterize the image quality. It is shown that the harmonic image quality is better than the fundamental image quality due, in part, to a narrower beam profile. The root-mean-square estimate of aberration after propagation through the simulated body wall is shown to be low (23.4 ns), consistently with previous reports of aberration measured experimentally in a human body wall. The spatial coherence measured at the transducer surface indicates that a transducer array element size of $<0.81 λ$ would be required to fully sample the acoustic field. These simulated three dimensional ultrasound images based directly on propagation physics provide a platform to investigate the sources of image degradation in three dimensions (included in Part II).

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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