A proposed clinical application of a model of CO₂laser radiation induced damage craters

Abstract

A method for a controlled generation of primary damage craters in methacrylate ester samples (Vedril C, Montedison) induced by continuous and long-term exposure to CO2 laser radiation is proposed. The results are compared with the experimental values obtained 'in vitro' with 10 W continuous output power of a CO2 laser beam and fg = 7.5 in focal length of the laser's focusing head, and this shows that the proposed model can explain the phenomenon related to the generation of the limiting crater in typical biological tissue. It may have applications in clinical procedures where long-term exposure of the tissue to a laser beam must be considered. Also, the method may possibly be used to create and update a computer library automatically collecting data regarding different thermodynamic characteristics and values of various biological media.

Optical Absorption Coefficient, Time of Thermal Relaxation, Time of Surface Threshold, and Time of Heat Incubation for PMMA Samples at the CO2Laser-Beam Wavelength of 10.6 µm

“…Therefore, for PMMA at 10.6 mm, imposing Io = Fth/t1b in the following limit equation: (7) we can write: (8) where Fth (at 10.6 µm ) = 6.7 J/cm 2 , t1b = 3.5 · 10 Ϫ4 sec, and k = 1.06 · 10 Ϫ3 cm 2 /sec, 6,7,12 so that we can finally obtain: (9) This value is lower than the absorption coefficients available in the literature for other biological media, which have higher water content than PMMA even in in vitro samples without formalin and therefore showing higher absorption of the 10.6-µm wavelength. This value coincides with the threshold sug- Scholz et al 12 in studies on PMMA utilization in orthopedic applications, in which the utilization of colorants might generate bone damage.…”

“…7 The most critical uncertainty to be determined is the one associated with ␣ from Eq. (8). Assuming that all the parameters, including the coefficients 9000 and 4 of Eqs.…”

“…Several mathematical aspects of this analysis have published previously, by isolating the LCA model 6,7 and numerically solving the Canestri-Langerholc equation. 8 Another interesting application is the quantification of crater and cut generation processes, which brings new insight into both thermodynamic and mechanical phenomena occurring during biopolymeric media treatments and classical surgical operations. All this research will result in high-quality product outcomes to ensure good safety margins for patients.…”

“…UNCERTAINTY VALUESUncertainties ⌬% on the parameters of Equations(8) and(15)assuming that they Maximum average are all comparable in % uncertainty D␣ on ␣ in cm Ϫ1…”