Burcin Unlu Mehmet, Birgul Ozlem, Shafiiha Roshanak, Gulsen Gultekin, Nalcioglu Orhan
University of California, Tu and Yuen Center for Functional Onco-Imaging, Irvine, California 92697, USA.
J Biomed Opt. 2006 Sep-Oct;11(5):054008. doi: 10.1117/1.2363370.
We investigated the use of multifrequency diffuse optical tomography (MF-DOT) data for the reconstruction of the optical parameters. The experiments were performed in a 63 mm diameter cylindrical phantom containing a 15 mm diameter cylindrical object. Modulation frequencies ranging from 110 MHz to 280 MHz were used in the phantom experiments changing the contrast in absorption of the object with respect to the phantom while keeping the scattering value the same. The diffusion equation was solved using the finite element method. The sensitivity information from each frequency was combined to form a single Jacobian. The inverse problem was solved iteratively by minimizing the difference between the measurements and forward problem using single and multiple modulation frequency data. A multiparameter Tikhonov scheme was used for regularization. The phantom results show that the peak absorption coefficient in a region of interest was obtained with an error less then 5% using two-frequency reconstruction for absorption contrast values up to 2.2 times higher than background and 10% for the absorption contrast values larger than 2.2. The use of two-frequency data is sufficient to improve the quantitative accuracy compared with the single frequency reconstruction with appropriate selection of these frequencies.
我们研究了利用多频扩散光学层析成像（MF-DOT）数据来重建光学参数。实验在一个直径63毫米的圆柱形体模中进行，该体模包含一个直径15毫米的圆柱形物体。在体模实验中使用了范围从110兆赫兹到280兆赫兹的调制频率，在保持散射值不变的同时改变物体相对于体模的吸收对比度。使用有限元法求解扩散方程。将每个频率的灵敏度信息组合起来形成一个单一的雅可比矩阵。通过使用单调制频率数据和多调制频率数据最小化测量值与正向问题之间的差异，迭代求解反问题。采用多参数蒂霍诺夫方案进行正则化。体模实验结果表明，对于高达背景值2.2倍的吸收对比度值，使用双频重建在感兴趣区域获得的峰值吸收系数误差小于5%，而对于大于2.2的吸收对比度值，误差为10%。与单频重建相比，通过适当选择这些频率，使用双频数据足以提高定量精度。
