Picosecond laser-induced photothermal skin damage evaluation by computational clinical trial

Background and Objectives: Computational clinical trial (CCT) in the field of laser medicine promotes clinical application of novel laser devices, because this trial carried out based on numerical modeling of laser-tissue interactions and simulation of a series of treatment process. To confirm the feasibility of the computational clinical trial of skin treatment with a novel picosecond laser, this paper presents an evaluation method of the safety. Study Design/Materials and Methods: In this method, the light propagation and thermal diffusion process after ultrashort light pulse irradiation to a numerical skin model is calculated and the safety based on the photothermal damage is evaluated by computational modeling and simulation. As an example, the safety of a novel picosecond laser device was examined by comparing with several laser devices approved for clinical use. Results: The ratio of the maximum thermal damage induced by picosecond laser irradiation was 1.2 × 10^-2% at the epidermis, while that caused by approved laser irradiation was 99% at the capillary vessels. The numerical simulation demonstrated that less thermal damage was observed compared with the approved devices. The results show the safety simulated by photothermal damage calculation was consistent with the reported clinical trials. Conclusions: This computational clinical trial shows the feasibility of applying computational clinical trials for the safety evaluation of novel medical laser devices. In contrast to preclinical and clinical tests, the proposed computational method offers regulatory science for appropriately and quickly predicting and evaluating the safety of a novel laser device.