Jiang H, Paulsen K D, Osterberg U L
Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA.
Phys Med Biol. 1996 Aug;41(8):1483-98. doi: 10.1088/0031-9155/41/8/015.
In this paper, we explore optical image formation using a diffusion approximation of light propagation in tissue which is modelled with a finite-element method for optically heterogeneous media. We demonstrate successful image reconstruction based on absolute experimental DC data obtained with a continuous wave 633 nm He-Ne laser system and a 751 nm diode laser system in laboratory phantoms having two optically distinct regions. The experimental systems used exploit a tomographic type of data collection scheme that provides information from which a spatially variable optical property map is deduced. Reconstruction of scattering coefficient only and simultaneous reconstruction of both scattering and absorption profiles in tissue-like phantoms are obtained from measured and simulated data. Images with different contrast levels between the heterogeneity and the background are also reported and the results show that although it is possible to obtain qualitative visual information on the location and size of a heterogeneity, it may not be possible to quantitatively resolve contrast levels or optical properties using reconstructions from DC data only. Sensitivity of image reconstruction to noise in the measurement data is investigated through simulations. The application of boundary constraints has also been addressed.
在本文中，我们利用光在组织中传播的扩散近似来探索光学图像形成，该近似通过有限元方法对光学非均匀介质进行建模。我们展示了基于使用连续波633 nm氦氖激光系统和751 nm二极管激光系统在具有两个光学不同区域的实验室模型中获得的绝对实验直流数据的成功图像重建。所使用的实验系统采用了断层扫描类型的数据收集方案，该方案提供了从中推导出空间可变光学特性图的信息。从测量和模拟数据中获得了仅散射系数的重建以及组织样模型中散射和吸收分布的同时重建。还报告了异质性与背景之间具有不同对比度水平的图像，结果表明，尽管有可能获得关于异质性位置和大小的定性视觉信息，但仅使用直流数据的重建可能无法定量解析对比度水平或光学特性。通过模拟研究了图像重建对测量数据中噪声的敏感性。还讨论了边界约束的应用。
