线光束照射下局部病变组织背散射场角分布研究

Angular Distribution of Backscattered Light from Locally Pathological Tissues Irradiated by Pencil Light

将内含异质层的半无限生物组织作为研究线光束照射下局部病变组织背散射场的近似模型 ,在此基础上 ,引入倍加算法对线光束照射下局部病变组织背散射场角分布进行数值计算。根据数值计算结果 ,分析了不同组织层几何参量和光学参量对背散射场角分布的影响 ,结果表明 :“病变组织层对背散射场中小角度光的影响明显大于对大角度光的影响 ;背散射场的角分布对病变组织的几何参量 (埋藏深度和光学厚度 )较为敏感 ,而对病变组织光学参量亦即病变组织性质的差异敏感度较低。”同时还对含肿瘤的乳房组织的背散射场角分布进行了计算和分析 ,为将背散射场角分布应用于组织内隐藏异物的无创伤诊断提供了理论参考。

Semi-infinite normal tissues embedded a heterogeneous layered tissue is chosen as the simplified tissue model of local-pathological-changed tissues. Based on the model, double-adding method is introduced to calculate the angular distribution of backscattered light from local-pathological-changed tissues. According to the numerical calculations, the effects of geometrical and optical parameters of tissue models on the angular distribution of backscattered light are analyzed comprehensively. It is concluded that the variation of light intensity originated from local-pathological-changes tissues highly depends on the exit angle of backscattered light——the variation of backscattered light with small exit angle is much more obviously than that of backscattered light with large exit angle. The results also show that the angular distribution of backscattered light is much more sensitive to the geometrical parameters than the optical parameters of pathological-changes tissues. Finally,the angular distributions of backscattered light from breast tissue embedded with a tumour are also calculated and analyzed, which provide a theoretical basis for angular distribution of backscattered light applied in diagnosing the abnormal object hided in normal tissues.