Izmir Biomedicine and Genome Center, Izmir, Turkey.
Izmir International Biomedicine and Genome Institute, Dokuz Eylul University, Izmir, Turkey.
Lasers Surg Med. 2022 Oct;54(8):1116-1129. doi: 10.1002/lsm.23595. Epub 2022 Sep 1.
The transfer and widespread acceptance of laser-induced thermal therapy into gastroenterology remain a topic of interest. However, a practical approach to the quantitative effect of photothermal injury in the esophagus needs further investigation. Here, we aim to perform computer simulations that simulate laser scanning and calculate the laser-induced thermal damage area. The simulation engine offers the results in a guide map for laser coagulation with a well-confined therapeutic area according to laser irradiance and surface scanning speed. The study also presents validation experiments that include histology analyses in an ex vivo sheep esophagus model.
The simulation engine was developed based on the Monte-Carlo method and the Arrhenius damage integral. The computational model mimicked laser scanning by shifting the position of the calculated heat source in the grating system along the axis to be scanned. The performance of the simulations was tested in an ex vivo sheep esophagus model at a laser wavelength of 1505 nm. Histological analysis, hematoxylin-eosin staining, light microscope imaging, and block-face scanning electron microscopy were used to assess thermal damage to the tissue model.
The developed simulation engine estimated the photothermal coagulation area for a surface scanning speed range of 0.5-8 mm/second and laser power of up to 0.5 W at a 0.9-nm laser diameter in a tissue model with a volume of 4 × 4 × 4 mm . For example, the optimum laser irradiation for effective photothermal coagulation in the mucosa and superficial submucosa depths was estimated to be between 16.4 and 31.8 W/cm , 23.2 and 38.1 W/cm at 0.5 and 1 mm/second, respectively. The computational results, summarized as a guide map, were directly compared with the results of ex vivo tissue experiments. In addition, it was pointed out that the comparative theoretical and experimental data overlap significantly in terms of energy density.
Our results suggest that the developed simulation approach could be a seed algorithm for further preclinical and clinical trials and a complementary tool to the laser-induced photothermal coagulation technique for superficial treatments in the gastrointestinal tract. In future preclinical studies, it is thought that the simulation engine can be enriched by combining it with an in vivo model for different laser wavelengths.
将激光诱导热疗技术转移并广泛应用于胃肠病学仍然是一个研究热点。然而，需要进一步研究食管光热损伤的定量效应的实用方法。在这里，我们旨在进行计算机模拟，模拟激光扫描并计算激光诱导的热损伤面积。模拟引擎根据激光辐照度和表面扫描速度为激光凝固提供了一个限制在治疗区域内的引导图。该研究还介绍了包括在离体绵羊食管模型中进行组织学分析的验证实验。
模拟引擎是基于蒙特卡罗方法和阿仑尼乌斯损伤积分开发的。计算模型通过沿要扫描的轴移动光栅系统中计算出的热源的位置来模拟激光扫描。在离体绵羊食管模型中，在 1505nm 激光波长下对模拟的性能进行了测试。使用组织学分析、苏木精-伊红染色、光学显微镜成像和块面扫描电子显微镜来评估组织模型的热损伤。
所开发的模拟引擎估计了表面扫描速度范围为 0.5-8mm/秒和激光功率高达 0.5W 时，在体积为 4×4×4mm3的组织模型中，激光直径为 0.9nm 的光热凝固区域。例如，在 0.5 和 1mm/秒时，有效光热凝固的最佳激光照射分别估计为黏膜和浅层黏膜下深度的 16.4 至 31.8W/cm 和 23.2 至 38.1W/cm。将计算结果总结为一张指导图，并与离体组织实验的结果进行了直接比较。此外，还指出，在能量密度方面，比较理论和实验数据具有显著的重叠。
我们的结果表明，所开发的模拟方法可以作为进一步的临床前和临床试验的起始算法，并且可以作为胃肠道浅表治疗的激光诱导光热凝固技术的补充工具。在未来的临床前研究中，人们认为可以通过将模拟引擎与不同激光波长的体内模型相结合来丰富该模拟引擎。
