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].