A Computational Study Evaluating the Effects of Diffuser Length and Pullback Distance on the Ablation Zone During Laser Ablation Treatment of Liver Cancer

Although laser ablation is not commonly used for liver cancer treatment, there are several benefits that make it an appealing alternative. Nevertheless, investigations on the efficacy of laser ablation for liver cancer has been limited to few clinical trials. Therefore, not much is known regarding the efficacy of the technique especially when operating under different protocols and device parameters. In this study, we performed a numerical study to investigate the effects of diffuser length, power density and the pullback technique on the coagulation zone formation during laser ablation of a spherical liver cancer. The objective is to demarcate the influence of diffuser length from power density, and to compare their performance to that when pullback is implemented. Four diffuser lengths (10, 15, 20 and 25 mm), and three pullback distances (5, 10 and 15 mm), were considered. Results showed that laser power density is a factor that limits the coagulation zone size when the diffuser length increases. A longer diffuser must be accompanied by an increase in laser power to achieve the desired treatment outcome. The pullback technique increases the effective diffuser length, but the coagulation volume obtained was smaller than that of a longer diffuser at the same power density. This suggests that increasing both the diffuser length and laser power is better at increasing the coagulation zone than the pullback technique. To obtain coagulation zone that is sufficiently large to cover the entire tumour, careful selection of the diffuser length, power density, and pullback distance is critical.