Diffuse optical tomography (DOT) is a new emerging modality in the diagnosis of soft tissue abnormalities. DOT image quality substantially depends on the reconstruction stage. In the literature, there are many reconstruction algorithms used in DOT systems. However, some algorithms were improved for solving specific cases but still need to be improved. The bi-conjugate gradient (BiCG) enhanced is one of the conjugate gradient (CG)-based reconstruction techniques for non-Hermitian systems. The BiCG provides a solution to a non-Hermitian system. However, it has erratic convergence in some cases. Therefore, DOT images reconstructed by BiCG can be at the wrong location and is inaccurate in some cases. In this study, we used continuous-wave diffuse optical tomography (CW-DOT) to acquire measurements from breast tissue phantoms with single or double inclusion at different depths and center-to-center separations and we have used the transpose free quasi minimal residual (TFQMR) reconstruction algorithm, improved as an alternative to BiCG for the first time in the CW-DOT system. Moreover, we have experimentally proved that TFQMR is superior to BiCG in some specific cases for the first time in CW-DOT. Therefore, we concluded that TFQMR has the potential to be able to be used in the reconstruction stage in CW-DOT.

中文翻译：

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使用双共轭梯度和无转置准最小残差算法的漫反射光学断层扫描图像重建及其比较

漫射光学断层扫描 (DOT) 是一种新兴的软组织异常诊断方式。DOT 图像质量在很大程度上取决于重建阶段。在文献中，有许多用于 DOT 系统的重建算法。但是，一些算法针对特定情况进行了改进，但仍需改进。增强的双共轭梯度 (BiCG) 是用于非厄米系统的基于共轭梯度 (CG) 的重建技术之一。BiCG 为非厄米系统提供了解决方案。然而，它在某些情况下会出现不稳定的收敛。因此，BiCG 重建的 DOT 图像可能位于错误的位置并且在某些情况下不准确。在这项研究中，我们使用连续波漫射光学断层扫描 (CW-DOT) 从具有不同深度和中心到中心间距的单个或两个包含物的乳房组织模型中获取测量值，并且我们使用了无转置准最小残差 (TFQMR) 重建算法，首次在 CW-DOT 系统中改进为 BiCG 的替代品。此外，我们首次在 CW-DOT 中通过实验证明了 TFQMR 在某些特定情况下优于 BiCG。因此，我们得出结论，TFQMR 有可能用于 CW-DOT 的重建阶段。我们在 CW-DOT 中首次通过实验证明了 TFQMR 在某些特定情况下优于 BiCG。因此，我们得出结论，TFQMR 有可能用于 CW-DOT 的重建阶段。我们在 CW-DOT 中首次通过实验证明了 TFQMR 在某些特定情况下优于 BiCG。因此，我们得出结论，TFQMR 有可能用于 CW-DOT 的重建阶段。