Computerized thermal characterization tool (CT)2 for complete thermodynamic coefficients mapping at the wavelength of 10.6 microm: a PMMA case report.
OBJECTIVE
This paper details a proposed clinical identification tool, the Computerized Thermal Characterization Tool or (CT)(2), designed to precisely quantify and forecast the ablation capabilities of a CO(2) laser beam and to optimize its usage when human tissue is exposed to 10.6 microm wavelength radiation.


BACKGROUND
As seen in other studies by the same author, the correct identification of the optical absorption of polymethylmethacrylate (PMMA) allows isolating other key time-dependent coefficients, all described qualitatively rather than quantitatively in the literature, with better accuracy. Tests on other biological media were performed and reported as potential contribution for minimally invasive surgical procedures.


METHODS
The laser in use was configured in different combinations amongst the following parameters: transverse electromagnetic modes (TEM(22)), output power, exposure times, and focal lengths. Several PMMA blocks (1 cm x 4 cm x 4 cm) were exposed to the continuous wave radiation of three commercially available CO(2) medical laser devices with a TEM(11) beam profile.


RESULTS
The data were used in a computerized simulation to test a priori the thermal behavior of biological media exposed to a CO(2) laser beam. Interestingly, this behavior could be reproduced on a variety of biological and nonbiological media. Threshold injury conditions were reached for the myocardium at 786 W/cm(2) per pulse, for the aorta at 519 W/cm(2) per pulse, and for the PMMA samples at 393 W/cm(2) per pulse.


CONCLUSIONS
These values can be used as reference for both minimally invasive surgery and for transmyocardial laser revascularization protocols, combined with the proposed (CT)(2). Further investigations are needed to completely validate the potential clinical utilization.
Canestri
Franco
F
Agilent Technologies GmbH, Böblingen, Germany. franco_canestri@agilent.com
D000465:Algorithms; D001696:Biomechanical Phenomena; D001843:Bone Cements / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D053685:Laser Therapy; D054020:Lasers, Gas; D008962:Models, Theoretical; D019904:Polymethyl Methacrylate / Q000528:radiation effects*; D012016:Reference Values; D012815:Signal Processing, Computer-Assisted; D025321:Surgery, Computer-Assisted; D013816:Thermodynamics
D001843:Bone Cements; D019904:Polymethyl Methacrylate