The use of 100 micron fiber is clinically important, since it is sufficiently flexible to be inserted into small cerebral arteries for blood clot ablation in ischemic stroke. This study measured the clot ablation efficiencies at energies 2, 4, 6, and 8 times the ablation threshold of 22 mJ/mm2.
A pulsed dye laser was used to ablate gelatin clot phantoms (µa=150cm-1). The clot models were confined in 3mm diameter silicone tubes to simulate the geometry of an artery. The fiber tip was 0.5mm from the gelatin surface, resulting in a laser spot size of 275µm. The ablated material from 10 pulses was collected for each sample and ten samples were conducted at each energy. Mass removed was measured using a spectrophotometric technique.
Ablation efficiencies (mass/energy) were constant for all four radiant exposures.
We conclude that radiant exposures just above threshold might be used in clinical situations to minimize arterial stresses, since bubble size increases with energy.
J. Viator, U. Sathyam, A. Shearin, and S. Prahl. Ablation Efficiency Measurements of Soft Materials with a Small Optical Fiber. Lasers in Surgery and Medicine, April 3-6, Phoenix, AZ, 1997.