Laser treatment of nevus flammus (port-wine stain) with spectroscopic feedback: the smart scalpel

Abstract

While feedback control is widespread throughout many engineering fields, surgical instruments with embedded feedback control systems are uncommon. To improve the effectiveness of microsurgical techniques, we are presently developing a semi-autonomous robotic surgical tool as an alternative approach to treatment of skin hemangiomas like nevus flammus. Current PWS phototherapy relies on selective absorption of optical radiation by the ectatic blood vessels in a PWS resulting in thermally-mediated vessel necrosis. Although shown to be effective,heating of the surrounding tissue by photon absorption results in unacceptable collateral damage. The 'Smart Scalpel' approach employs optical reflectance spectroscopy to selectively target blood vessels in a PWS for heating with a focused laser beam. Collateral damage to adjacent tissue is substantially minimized and continuous imaging throughout the procedure allows modification of the delivered therapy to optimize therapeutic outcomes. Our work reported here involves optical system design and construction, initial quantification of imaging system resolution and contrast, and preliminary verification of the imaging and targeting strategies.