Detectability of inhomogeneities within highly diffusing media
Detectability of inhomogeneities within highly diffusing media
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高扩散介质内不均匀性的可检测性
DOI：
10.1117/12.210033
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
A. Sassaroli
中科院分区：
文献类型：
--
作者：
G. Zaccanti;D. Contini;M. Gurioli;A. Ismaelli;Heather Liszka;A. Sassaroli
本文用数值模拟和物理测量的方法研究了高散射介质中的非均匀性对反射率和透射率的影响。研究了一种光学性质类似于压缩乳房的漫射介质板。用基本的Monto Carlo程序计算了从薄准直光源不同距离处出射的光子的时间点扩展函数。对于某些探测器位置，存储每个接收到的光子的所有散射点的坐标。首先对均匀介质进行了数值模拟，需要几天的计算时间。使用存储的轨迹，它是可能的，在很短的时间内获得，相应的时间点扩散函数时，吸收不均匀性被认为是在板内。这是可能的，以获得许多不同的位置，大小和形状的扩散介质内的不均匀性的时间点扩散函数。数值计算结果的准确性进行了检查，从具有已知的光学性能的校准球悬浮液上的测量获得的实验结果进行比较。用皮秒系统和连续波系统进行测量。
The effect of inhomogeneities within a highly scattering medium on the reflectance and on the transmittance was studied both with numerical simulations and with measurements on phantoms. A slab of diffusing medium with optical properties similar to those of a compressed breast was condidered. With an elementary Monto Carlo code the temporal point spread functions corresponding to photons emerging at different distances from the thin collimated light source were evaluated. For some detector positions, the coordinates of all the scattering points for each received photon were stored. Numerical simulations were carried out first for a homogeneous medium, requiring a few days for calculations. Using the stored trajectories it was possible to obtain in a short time, the corresponding temporal point spread functions when an absorbing inhomogeneity was considered within the slab. It was possible to obtain the temporal point spread function for many different positions, sizes, and shapes of the inhomogeneity inside the diffusing medium. The accuracy of the numerical results was checked by a comparison to experimental results obtained from measurements on suspensions of calibrated spheres having known optical properties. Measurements were carried out both with a picosecond system and with a continuous wave system.