Department of Mechanical Engineering and Materials Science, Rice University, 6100 Main Street, Houston, TX 77005-1892, USA.
Lasers Med Sci. 2013 Jul;28(4):1159-68. doi: 10.1007/s10103-012-1195-z. Epub 2012 Oct 6.
Using the finite volume method, the present work numerically explored the feasibility of extending nanoparticle-assisted photothermal therapy (PPTT) from treating subcutaneous tumors to treating organ tumors, particularly tumors growing in the clearance organ liver. To serve this purpose, a superficially embedded liver tumor and its immediate surrounding medium were selected as the study object. A 633-nm laser beam of 1- W/cm(2) intensity externally irradiated the tumor. The matching gold-silica nanoshell with a 16-nm silica core and a 5-nm-thick gold shell was used as the photothermal agent. The nanoshell retention ratio was varied to simulate different levels of nanoshell tumor discriminations. Laser light distributions, conversions from photon energy to heat, and tissues' thermal responses to the generated heat within the study object were analyzed. It was found that although nanoshells have enhanced the thermal transportation, they also restricted the optical transportation of PPTT. This indicates that laser delivery is more demanding for PPTT than for the conventional laser therapy. For the investigated case, when the nanoshell retention ratio was in the range of 2/1-4/1, the therapeutic effects were optimal: a confined medium temperature hyperthermia (47-55 °C) was achieved in the liver tumor while impacts on the surrounding health liver tissues were only marginal. When then nanoshell retention ratio was 8/1 or higher, about half of the liver tumor was ablated. However, some of the surrounding healthy liver tissues were sacrificed as well. The therapeutic effects of PPTT depend nonlinearly on the nanoshell tumor discriminations. Better tumor discriminations do not necessarily result in better PPTT therapeutic effects.
利用有限体积法，本工作通过数值模拟研究了将纳米粒子辅助光热疗法（PPTT）从治疗皮下肿瘤扩展到治疗器官肿瘤，特别是治疗位于清除器官肝脏中的肿瘤的可行性。为此，选择浅层嵌入的肝脏肿瘤及其周围的介质作为研究对象。用 1-W/cm(2)强度的 633nm 激光束从外部照射肿瘤。使用匹配的金-硅纳米壳作为光热剂，其硅核为 16nm，金壳厚 5nm。改变纳米壳保留率以模拟不同水平的纳米壳肿瘤识别度。分析了激光光分布、光子能量转化为热量以及组织对研究对象内产生的热量的热响应。结果发现，尽管纳米壳增强了热传输，但它们也限制了 PPTT 的光传输。这表明激光输送对 PPTT 的要求比传统激光治疗更高。对于所研究的情况，当纳米壳保留率在 2/1-4/1 范围内时，治疗效果最佳：在肝脏肿瘤中实现了受限介质的高温热疗（47-55°C），而对周围健康肝组织的影响仅略有增加。当纳米壳保留率为 8/1 或更高时，大约一半的肝脏肿瘤被消融。然而，周围的一些健康肝组织也受到了影响。PPTT 的治疗效果与纳米壳肿瘤识别度呈非线性相关。更好的肿瘤识别度不一定会带来更好的 PPTT 治疗效果。
