Advantage of the Mark-III FEL for biophysical research and biomedical applications.
Although 6.45 micro m is not the strongest absorption band of biological tissues in the mid-infrared, a Mark-III free-electron laser (FEL) tuned to this wavelength can efficiently ablate tissue while minimizing collateral damage. A model has previously been presented that explains this wavelength dependence as a competition between two dynamic processes--explosive vaporization of saline and denaturation of structural proteins. Here it is shown that this model predicts a 'sweet-spot' for each wavelength, i.e. a region of parameter space (incident intensity and pulse width) in which explosive vaporization is preceded by substantial protein denaturation. This sweet-spot is much larger for wavelengths where protein is the dominant chromophore. At other wavelengths, collateral damage may be minimized within the sweet-spot, but the maximum intensities and pulse widths in these regions are insufficient to remove tissue at surgically relevant rates.
Edwards
Glenn S
GS
Duke University Free Electron Laser Laboratory, Durham, NC 27708, USA. edwards@fel.duke.edu
Hutson
M Shane
MS
D000818:Animals; D003198:Computer Simulation; D003319:Corneal Stroma / Q000737:chemistry / Q000528:radiation effects* / Q000601:surgery*; D004867:Equipment Design / Q000379:methods; D053685:Laser Therapy / Q000295:instrumentation* / Q000379:methods*; D008954:Models, Biological; D011506:Proteins / Q000737:chemistry* / Q000528:radiation effects*; D012965:Sodium Chloride / Q000737:chemistry / Q000528:radiation effects; D013552:Swine
D011506:Proteins; D012965:Sodium Chloride