Pogue B, McBride T, Osterberg U, Paulsen K
Opt Express. 1999 Apr 12;4(8):270-86. doi: 10.1364/oe.4.000270.
Images produced in six different geometries with diffuse optical tomography simulations of tissue have been compared using a finite element-based algorithm with iterative refinement provided by the Newton-Raphson approach. The source-detector arrangements studied include (i) fan-beam tomography, (ii) full reflectance and transmittance tomography, as well as (iii) sub-surface imaging, where each of these three were examined in a circular and a flat slab geometry. The algorithm can provide quantitatively accurate results for all of the tomographic geometries investigated under certain circumstances. For example, quantitatively accurate results occur with sub-surface imaging only when the object to be imaged is fully contained within the diffuse projections. In general the diffuse projections must sample all regions around the target to be characterized in order for the algorithm to recover quantitatively accurate results. Not only is it important to sample the whole space, but maximal angular sampling is required for optimal image reconstruction. Geometries which do not maximize the possible sampling angles cause more noise artifact in the reconstructed images. Preliminary simulations using a mesh of the human brain confirm that optimal images are produced from circularly symmetric source-detector distributions, but that quantitatively accurate images can be reconstructed even with a sub-surface imaging, although spatial resolution is modest.
使用基于有限元的算法和牛顿 - 拉夫逊方法提供的迭代细化，对六种不同几何结构下组织的漫射光学层析成像模拟所产生的图像进行了比较。所研究的源 - 探测器布置包括：（i）扇形束层析成像，（ii）全反射和透射层析成像，以及（iii）表面下成像，其中这三种成像方式中的每一种都在圆形和平板几何结构中进行了研究。在某些情况下，该算法能够为所有研究的层析几何结构提供定量准确的结果。例如，仅当待成像物体完全包含在漫射投影内时，表面下成像才能得到定量准确的结果。一般来说，漫射投影必须对目标周围的所有区域进行采样，以便算法能够恢复定量准确的结果。不仅对整个空间进行采样很重要，而且为了实现最佳图像重建，还需要最大角度采样。未最大化可能采样角度的几何结构会在重建图像中导致更多的噪声伪影。使用人脑网格进行的初步模拟证实，圆形对称的源 - 探测器分布能产生最佳图像，但即使是表面下成像也能重建出定量准确的图像，尽管空间分辨率适中。
