Optimized transducer configuration for ultrasound waveform tomography in breast cancer detection
Optimized transducer configuration for ultrasound waveform tomography in breast cancer detection
复制标题
乳腺癌检测中超声波断层扫描的优化换能器配置
DOI：
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
A. Fichtner
中科院分区：
文献类型：
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作者：
N. Vinard;Naiara Korta Martiartu;C. Böhm;I. Balic;A. Fichtner
波形反演是一种很有前途的方法，超声计算机断层扫描能够产生高分辨率的图像的人类乳腺组织。然而，波形反演的计算复杂性仍然是一个相当大的挑战，并且每次迭代的成本与发射换能器的数量成正比。我们提出了一个双重的战略，以加快时间的解决方案，通过确定最佳的数量和位置的发射器使用序贯最优实验设计（SOED）。SOED是一个强大的工具，可分别迭代添加最具信息量的传感器或删除冗余测量。这种方法同时提供了优化的传感器配置和成本效益曲线，量化的信息增益与计算成本。首先，我们提出了一种方法来确定的发射器，提供重建与最小的预期不确定性。使用贝叶斯方法，模型的不确定性和分辨率可以用后验协方差的迹线来量化。通过线性化波动方程，我们可以使用Hessian的Gauss-Newton近似的逆来计算后验协方差。此外，该后验独立于乳房模型和实验数据，因此能够实现预采集实验优化。然后，对于采集后反演，我们提出了一种方法来选择一个子样本的源，准确地近似在每次迭代的全梯度方向。我们通过随机添加新的发射器到子样本中来控制连续梯度方向之间的角度差的收敛。我们提出了在2D和3D的合成研究，考虑一个环形和半椭圆形的扫描设备，分别。数值结果表明，所提供的方法有可能从相应的成本效益曲线识别冗余。此外，梯度方向迅速收敛到全梯度的方向，这似乎是独立的模型和发射器的位置。
Waveform inversion is a promising method for ultrasound computed tomography able to produce high-resolution images of human breast tissue. However, the computational complexity of waveform inversion remains a considerable challenge, and the costs per iteration are proportional to the number of emitting transducers. We propose a twofold strategy to accelerate the time-to-solution by identifying the optimal number and location of emitters using sequential optimal experimental design (SOED). SOED is a powerful tool to iteratively add the most informative transducer or remove redundant measurements, respectively. This approach simultaneously provides optimized transducer configurations and a cost-benefit curve that quantifies the information gain versus the computational cost. First, we propose a method to identify the emitters that provide reconstructions with minimal expected uncertainties. Using a Bayesian approach, model uncertainties and resolution can be quantified with the trace of the posterior covariance. By linearizing the wave equation, we can compute the posterior covariance using the inverse of the Gauss-Newton approximation of the Hessian. Furthermore, this posterior is independent of the breast model and the experimental data, thus enabling pre-acquisition experimental optimization. Then, for the post-acquisition inversion, we present an approach to select a subsample of sources that accurately approximates the full gradient direction in each iteration. We control the convergence of the angular differences between consecutive gradient directions by randomly adding new emitters into the subsample. We present synthetic studies in 2D and 3D that consider a ring-shaped and a semi-ellipsoidal scanning device, respectively. Numerical results suggest that the provided methods have the potential to identify redundancies from the corresponding cost-benefit curves. Furthermore, the gradient direction rapidly converges to the direction of the full gradient, which appears to be independent of the model and the emitter locations.
非线性反问题的 A 最优编码权重，及其在亥姆霍兹反问题中的应用
影响因子：
2.1
作者：
Crestel, Benjamin;Alexanderian, Alen;Stadler, Georg;Ghattas, Omar
通讯作者：
Ghattas, Omar