Laser treatment of hemangiomas using 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 (called the "Smart Scalpel") as an alternative approach to treatment of skin hemangiomas like nevus flammus (port wine stain or PWS). Current PWS phototherapy relies on selective absorption of optical radiation by the ectactic 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.