Mechanisms for soft-tissue ablation and the development of alternative medical lasers based on investigations with mid-infrared free-electron lasers

Experimental evidence indicating the potential biomedical advantages of using a Mark-III Free-Electron Laser (FEL) for the ablation of soft tissue were first reported in 1994. Research progress since that time is reviewed, including: 1) successful human surgery using the Mark-III FEL; 2) advances in understanding the physical mechanism for infrared tissue ablation and how these mechanistic features correlate with the preferential ablative properties; 3) the pursuit of table-top, nanosecond-pulsed laser technology that mimies the preferential ablation properties of the Mark-III FEL with the aim of improving clinical acceptance of mid-infrared laser ablation of soft tissue and 4) Current research challenges. Ablation cavity in rat brain cortex due to irradiation with it Mark-III FEL tuned to a wavelength of 6.45 microns. One hundred macropulses (20 mJ each) at a macropulse repetition rate of 4 Hz were focused to a spot with a diameter of similar to 100 microns oil the tissue Surface. The section was stained with H&E. A) Full view of ablation cavity, where the original magnification was x 100. Total incision depth was 3.060 mm. B) [GRAPHICS] Ablation cavity with an additional magnification of x 17. Coagulation heat necrosis was not measurable (