Quantitative investigations on light emission profiles for interstitial laser treatment

Interstitial laser treatment (ILT) using a diffusing applicator (DA) has been employed to treat tumors. However, the treatment efficacy and safety of the emission profiles from DAs have been poorly explored. This study investigated the effect of the emission profiles from DAs on prostate tumor treatment. Dual-peak and proximal-/distal-end peak profiles using 980 nm laser at 5 W for 60 s were tested to compare the extent of thermal coagulation in soft tissue numerically and experimentally. The numerical simulation predicted the temperature development in the tissue. Ex vivo porcine liver and in vivo rat models were used to compare the performance of the profiles. The dual-peak profile yielded a coagulation extent that was almost equivalent to that of the flat-top profile (in simulation) and 1.3 times larger than those of the other profiles in both ex vivo and in vivo. The dual-peak profile predictably entailed uniform coagulation within the irradiated region. Further in vivo studies using different tumor sizes will be evaluated to warrant the efficacy and safety of the dual-peak profile for the ILT of prostate tumors.