Grabtchak Serge, Montgomery Logan G, Whelan William M
Department of Physics, University of Prince Edward Island, Charlottetown, PEI C1A4P3, Canada. Departments of Electrical and Computer Engineering, and Physics, Dalhousie University, Halifax, NS B3H3J5, Canada.
Phys Med Biol. 2014 May 21;59(10):2431-44. doi: 10.1088/0031-9155/59/10/2431. Epub 2014 Apr 17.
We demonstrated the application of relative radiance-based continuous wave (cw) measurements for recovering absorption and scattering properties (the effective attenuation coefficient, the diffusion coefficient, the absorption coefficient and the reduced scattering coefficient) of bulk porcine muscle phantoms in the 650-900 nm spectral range. Both the side-firing fiber (the detector) and the fiber with a spherical diffuser at the end (the source) were inserted interstitially at predetermined locations in the phantom. The porcine phantoms were prostate-shaped with ∼4 cm in diameter and ∼3 cm thickness and made from porcine loin or tenderloin muscles. The described method was previously validated using the diffusion approximation on simulated and experimental radiance data obtained for homogenous Intralipid-1% liquid phantom. The approach required performing measurements in two locations in the tissue with different distances to the source. Measurements were performed on 21 porcine phantoms. Spectral dependences of the effective attenuation and absorption coefficients for the loin phantom deviated from corresponding dependences for the tenderloin phantom for wavelengths <750 nm. The diffusion constant and the reduced scattering coefficient were very close for both phantom types. To quantify chromophore presence, the plot for the absorption coefficient was matched with a synthetic absorption spectrum constructed from deoxyhemoglobin, oxyhemoglobin and water. The closest match for the porcine loin spectrum was obtained with the following concentrations: 15.5 µM (±30% s.d.) Hb, 21 µM (±30% s.d.) HbO2 and 0.3 (±30% s.d.) fractional volume of water. The tenderloin absorption spectrum was best described by 30 µM Hb (±30% s.d), 19 µM (±30% s.d.) HbO2 and 0.3 (±30% s.d.) fractional volume of water. The higher concentration of Hb in tenderloin was consistent with a dark-red appearance of the tenderloin phantom. The method can be applied to a number of biological tissues and organs for interstitial optical interrogation.
我们展示了基于相对辐射度的连续波（cw）测量在恢复650 - 900纳米光谱范围内猪肌肉大块体模的吸收和散射特性（有效衰减系数、扩散系数、吸收系数和约化散射系数）方面的应用。侧面发射光纤（探测器）和末端带有球形漫射器的光纤（光源）都被插入到体模中预先确定的位置。猪体模呈前列腺形状，直径约4厘米，厚度约3厘米，由猪里脊肉或腰大肌制成。先前使用扩散近似法对均匀的1% Intralipid液体体模获得的模拟和实验辐射度数据验证了所描述的方法。该方法需要在组织中距离光源不同的两个位置进行测量。对21个猪体模进行了测量。对于波长<750纳米，腰大体模的有效衰减系数和吸收系数的光谱依赖性与里脊肉 体模的相应依赖性有所偏差。两种体模类型的扩散常数和约化散射系数非常接近。为了量化发色团的存在，将吸收系数的曲线与由脱氧血红蛋白、氧合血红蛋白和水构建的合成吸收光谱进行匹配。猪腰大肌光谱的最佳匹配浓度如下：15.5微摩尔（±30%标准差）血红蛋白、21微摩尔（±30%标准差）氧合血红蛋白和0.3（±30%标准差）水的分数体积。里脊肉吸收光谱的最佳描述是30微摩尔血红蛋白（±30%标准差）、19微摩尔（±30%标准差）氧合血红蛋白和0.3（±30%标准差）水的分数体积。里脊肉中较高浓度的血红蛋白与里脊肉 体模的暗红色外观一致。该方法可应用于多种生物组织和器官进行组织间光学检测。
