Controlled temperature phototheramal issue welding

Photothermal tissue welding has been investigated as an alternative surgica l tool to improve bonding of a variety of severed tissues. Yet, after almos t two decades of research, inconsistencies in interpretation of experimenta l reports and, consequently, mechanism of this photothermal process as well as control of dosimetry remain an enigma. Widespread clinical use map grea tly depend on full automation of light dosimetry to perform durable and rep roducible welds with minimal thermal damage to surrounding and/or underlyin g tissues. Recognizing photothermal damage as a rate process, radiometrical ly measured tissue surface temperature has been studied as an indirect mark er of tissue status during laser irradiation. Dosimetry control systems and surgical devices were developed to perform controlled temperature tissue w elding using surface temperature feedback from the site of laser impact. Ne vertheless, end points that mark the completion of a durable and stable wel d have not been precisely identified, and subsequently, not incorporated in to dosimetry control algorithms. This manuscript reviews thermal dosimetry control systems of the 1990s in an attempt to systematically indicate the d ifficulties encountered so far and to elaborate on major issues for phototh ermal tissue welding to become a clinical reality in the new millennium. (C ) 1999 Society of Photo-Optical Instrumentation Engineers. [S1083-3668(99)0 0203-8].