Changes in spectral shape of tissue optical properties in conjunction with laser-induced thermotherapy
Changes in spectral shape of tissue optical properties in conjunction with laser-induced thermotherapy
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DOI：
10.1364/ao.37.001256
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发表时间：
1998-03-01
期刊：
影响因子：
1.9
通讯作者：
Andersson-Engels, S
中科院分区：
文献类型：
--
作者：
Nilsson, AMK;Sturesson, C;Andersson-Engels, S
我们用Nd：YAG激光对大鼠肝组织进行了激光热疗，测量了热疗前后肝组织的光学特性。这使得不仅可以监测凝结对散射特性的影响，而且可以监测血管损伤和血液热诱导损伤对吸收特性的影响。改进了实验积分球布置，以允许使用光谱仪和CCD照相机来确定g因子以及吸收和散射系数与600-1050-nm光谱区域中的波长的关系。结果显示，在热疗之后，在整个光谱范围内，g因子平均相对降低21 +/-7%，散射和吸收系数的相应相对增加分别为23 +/-8%和200 +/-100%。因此，对于降低的散射系数，发现平均增加200 +/-80%。这些变化的原因在米氏等效平均半径的组织散射体以及组织吸收体的分布和生物化学方面进行了分析，利用所产生的信息的gr因子和减少的散射和吸收系数的光谱形状。这些结果与组织学评价中发现的超微结构改变相关。组织散射中心的平均半径（通过使用基于Mie理论计算的g因子或基于Mie理论计算的约化散射系数的光谱形状确定）估计在处理的肝脏样品中比在未处理的肝脏样品中低21-32%。由这两种方法推导出的未处理的肝组织中的散射中心的米氏等效平均半径对应良好，并被发现分别为0.31和0.29 μ m，产生的颗粒大小在相同的范围内作为一个粒子的大小。(C)1998年美国光学学会。
We measured the optical properties on samples of rat liver tissue before and after laser-induced thermotherapy performed in vivo with Nd:YAG laser irradiation. This made it possible to monitor not only the influence of coagulation on the scattering properties but also the influence of damages to vessels and heat-induced damage to blood on the absorption properties. An experimental integrating-sphere arrangement was modified to allow the determination of the g factor and the absorption and scattering coefficients versus the wavelength in the 600-1050-nm spectral region, with the use of a spectrometer and a CCD camera, The results show a relative decrease in the g factor of on average 21 +/- 7% over the entire spectral range following thermotherapy, and a corresponding relative increase in the scattering and absorption coefficients of 23 +/- 8% and 200 +/- 100%, respectively. An increase of on average 200 +/- 80% was consequently found for the reduced scattering coefficient. The cause of these changes in terms of the Mie-equivalent average radius of tissue scatterers as well as of the distribution and biochemistry of tissue absorbers was analyzed, utilizing the information yielded by the gr factor and the spectral shapes of the reduced scattering and absorption coefficients. These results were correlated with the alterations in the ultrastructure found in the histological evaluation. The average radius of tissue scattering centers, determined by using either the g factors calculated on the basis of Mie theory or the spectral shape of reduced scattering coefficients calculated on the Mie theory, was estimated to be 21-32% lower in treated than in untreated liver samples. The Mie-equivalent average radii of scattering centers in untreated liver tissue deduced by the two methods corresponded well and were found to be 0.31 and 0.29 pm, respectively, yielding particle sizes in the same range as the size of a mitochondrion. (C) 1998 Optical Society of America.