Pogue B W, Patterson M S, Jiang H, Paulsen K D
Hamilton Regional Cancer Centre, ON, Canada.
Phys Med Biol. 1995 Oct;40(10):1709-29. doi: 10.1088/0031-9155/40/10/011.
Diffuse optical tomography is an imaging technique whereby spatial maps of absorption and scattering coefficients are derived from the characteristics of multiply scattered light transmitted through the object. The system described here used four intensity-modulated light sources and measurements of the intensity and phase (relative to each source) at 16 or 20 detectors on the surface of a 10 cm diameter cylinder. An iterative Newton-Raphson algorithm was used to estimate the absorption and scattering coefficients at each pixel in a 17 x 17 array minimizing the difference between measured and calculated values of the intensity and phase at the measurement sites. Forward calculations of the intensity and phase were based on a multigrid finite-difference solution of the frequency domain diffusion equation. Numerical simulations were used to examine the resolution, contrast, and accuracy of the reconstructions as well as the effects of measurement noise, systematic uncertainties in source-detector location, and accuracy of the initial estimates for the optical properties. Experimental tests also confirmed that the system could identify and locate both scattering and absorbing inhomogeneities in a tissue-simulating phantom.
扩散光学层析成像技术是一种成像技术，通过该技术，可根据透过物体的多次散射光的特性得出吸收系数和散射系数的空间分布图。此处描述的系统使用了四个强度调制光源，并在直径为10厘米的圆柱体表面的16个或20个探测器上测量了强度和相位（相对于每个光源）。采用迭代牛顿-拉夫逊算法来估计17×17阵列中每个像素的吸收系数和散射系数，以使测量点处强度和相位的测量值与计算值之间的差异最小化。强度和相位的正向计算基于频域扩散方程的多重网格有限差分法。数值模拟用于检验重建的分辨率、对比度和准确性，以及测量噪声、源探测器位置的系统不确定性和光学特性初始估计值的准确性的影响。实验测试也证实，该系统能够识别并定位组织模拟体模中的散射和吸收不均匀性。
