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Noncontact tissue ablation by Holmium: YSGG laser pulses in blood
Author(s) -
van Leeuwen Ton G.,
van der Veen Maurits J.,
Verdaasdonk Rudolf M.,
Borst Cornelius
Publication year - 1991
Publication title -
lasers in surgery and medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 112
eISSN - 1096-9101
pISSN - 0196-8092
DOI - 10.1002/lsm.1900110108
Subject(s) - holmium , ablation , materials science , laser , penetration (warfare) , penetration depth , biomedical engineering , microsecond , laser ablation , saline , optics , medicine , physics , operations research , engineering , endocrinology
To assess the feasibility of intra‐arterial tissue ablation by Holmium:YSGG laser pulses (2.1 μm) in a noncontact mode, the transmission of the laser pulses through saline and blood was measured. The temporal interaction between the 500 μs laser pulse and saline at the fiber tip was investigated with time‐resolved flash photography. The penetration depth in blood and saline depended on the fiber output energy. In blood at 37°C, the penetration depth varied from 1.2 to 2.1 mm for intensities of 3.1 to 12.4 J/mm 2 per pulse, respectively, whereas its theoretical value for water is 0.33 mm, which is based on the measured absorption coefficient of 3.0 ± 0.1/mm. The large penetration depth was due to the development of a transparent vapour cavity around the fiber tip. In saline, its maximum length was 4.7 mm. Its maximum width was 2.8 mm. The lifetime of the cavity was 450 μs. In blood, ablation of porcine aorta was feasible at a distance of 3 mm. Large fissures observed in adjacent tissue are likely to be caused by the expansion of the vapour cavity. We conclude that, due to a “Moses effect in the microsecond region,” Holmium: YSGG tissue ablation is possible through at least 2.7 mm of blood.