Saccomandi P, Di Matteo F M, Schena E, Quero G, Massaroni C, Giurazza F, Costamagna G, Silvestri S
Annu Int Conf IEEE Eng Med Biol Soc. 2017 Jul;2017:4529-4532. doi: 10.1109/EMBC.2017.8037863.
Laser Ablation (LA) is a minimally invasive technique for tumor removal. The laser light is guided into the target tissue by a fiber optic applicator; thus the physical features of the applicator tip strongly influence size and shape of the tissue lesion. This study aims to verify the geometry of the lesion achieved by a tapered-tip applicator, and to investigate the percentage of thermally damaged cells induced by the tapered-tip fiber optic applicator. A theoretical model was implemented to simulate: i) the distribution of laser light fluence rate in the tissue through Monte Carlo method, ii) the induced temperature distribution, by means of the Bio Heat Equation, iii) the tissue injury, by Arrhenius integral. The results obtained by the implementation of the theoretical model were experimentally assessed. Ex vivo porcine liver underwent LA with tapered-tip applicator, at different laser settings (laser power of 1 W and 1.7 W, deposited energy equal to 330 J and 500 J, respectively). Almost spherical volume lesions were produced. The thermal damage was assessed by measuring the diameter of the circular-shaped lesion. The comparison between experimental results and theoretical prediction shows that the thermal damage discriminated by visual inspection always corresponds to a percentage of damaged cells of 96%. A tapered-tip applicator allows obtaining localized and reproducible damage close to spherical shape, whose diameter is related to the laser settings, and the simple theoretical model described is suitable to predict the effects, in terms of thermal damage, on ex vivo liver. Further trials should be addressed to adapt the model also on in vivo tissue, aiming to develop a tool useful to support the physician in clinical application of LA.
激光消融（LA）是一种用于肿瘤切除的微创技术。激光通过光纤探头导入目标组织；因此，探头尖端的物理特性对组织损伤的大小和形状有很大影响。本研究旨在验证锥形探头实现的损伤几何形状，并研究锥形光纤探头诱导的热损伤细胞百分比。实施了一个理论模型来模拟：i）通过蒙特卡罗方法模拟组织中激光能量通量率的分布，ii）借助生物热方程模拟诱导的温度分布，iii）通过阿伦尼乌斯积分模拟组织损伤。对实施理论模型获得的结果进行了实验评估。对离体猪肝使用锥形探头进行激光消融，设置不同的激光参数（激光功率分别为1W和1.7W，沉积能量分别为330J和500J）。产生了近似球形的体积性损伤。通过测量圆形损伤的直径来评估热损伤。实验结果与理论预测的比较表明，通过目视检查区分的热损伤总是对应96%的损伤细胞百分比。锥形探头能够获得接近球形的局部且可重复的损伤，其直径与激光参数有关，并且所描述的简单理论模型适用于预测对离体肝脏的热损伤效应。应进行进一步试验以使该模型也适用于体内组织，旨在开发一种有助于支持医生在激光消融临床应用中的工具。
