• M.A. Mackanos, E.D. Jansen
  VUFEL, Nashville, Tennessee
• A. Schwettman, D. Simanovski
  Stanford University, Stanford, Califormia

Funding: Medical Free Electron Laser Program of the Department of Defense under grant number F49620-01-1-0429

A Mark-III FEL, tuned to 6.45 μm has demonstrated minimal collateral damage and high ablation yield in soft tissue. Further clinical advances are limited due to the overhead associated with an FEL; alternative mid-IR sources are needed. The FEL parameters needed to carry out efficient ablation with minimal damage must be determined. Studies by this author have shown that the unique pulse structure of the FEL does not play a role in this process [1]. We focused on comparing the macropulse duration of the FEL with a ZGP-OPO. No difference in pulse structure between the two laser sources with respect to the ablation threshold of water and mouse dermis was seen. There is a difference between the sources with respect to the crater depths in gelatin and mouse dermis. At 6.1 μm, the OPO craters are 8 times the depth of the FEL ones. Brightfield imaging shows the classic ablation mechanism. The timescale of the crater formation, ejection, and collapse occurs on a faster scale for the OPO. Histology shows that the OPO provides for similar or less thermal damage than the FEL at all wavelengths tested. This research shows that a ZGP-OPO laser could be an alternative to the FEL for clinical applications.

[1] Mackanos, M.A., J.A. Kozub, and E.D. Jansen, The effect of free electron laser pulse structure on mid-infrard soft-tissue ablation: ablation metrics. Physics in Medicine and Biology, 2005. 50(8): p. 1871-1883.