Model Predictive Thermal Dose Control of a Robotic Laser System to Automate Skin Photorejuvenation

In this article, we present a new method to control the thermal stimulation of skin during a photorejuvenation procedure. The proposed method can precisely administer the thermal dose while controlling the tissue's temperature under a safe limit. For that, a model-based treatment controller is developed and evaluated on a 3-D biophysics-based numerical model of skin. A hardware implementation is experimentally tested on a gelatin-based phantom tissue subjected to pulsed laser irradiation. A key component of our method is the use of a new thermal dose metric that enables quantifying and controlling the skin photorejuvenation process. This metric represents a suitable alternative to the lack of consensus on the metrics used by the photodermatology community. The reported experiments demonstrate that the developed controller endowed with the proposed dose unit can automatically deliver a prescribed laser irradiation and thermal dose over the tissue surface. The significance of our result is that it provides a control-theoretic framework to automate skin photorejuvenation treatments with thermal-guided robots. This approach has the potential to introduce standards in the automation of these types of phototreatments.