Quantitative evaluation of high power effect on 532 nm laser vaporization of bovine prostate in vitro.
OBJECTIVE
We investigated the effect of 120 to 200 W high power levels on in vitro vaporization of bovine prostate using a custom-made 532 nm lithium triborate laser system.


METHODS
Light (532 nm) delivered through a newly designed 750 microm core diameter side firing prototype fiber vaporized 114 bovine prostate tissue specimens in saline at 20C using a 2-dimensional scanning system. Various conditions were tested, including 120 to 200 W power, 1 to 5 mm working distance and 2 to 8 mm per second treatment speed.


RESULTS
Regardless of treatment speed 180 W was the optimal power to maximize tissue vaporization efficiency by removing 80% more tissue than at 120 W. At 120 and 180 W laser light vaporized tissue more efficiently at a 4 mm per second treatment speed and vaporized equally efficiently at up to 3 mm working distance. At the slowest treatment speed the mean thickness of the coagulation zone at 180 W was 20% thicker than at 120 W (1.31 vs 1.09 mm) but still thin, comparable to previous findings of 1 to 2 mm.


CONCLUSIONS
In vitro the 532 nm lithium triborate laser showed that 180 W is the optimal power to maximize tissue vaporization efficiency with enhanced coagulation characteristics. These desirable outcomes must be validated in vivo.
Kang
Hyun Wook
HW
American Medical Systems, Inc., San Jose, California 95134, USA. wook.kang@ammd.com
Peng
Yihlih Steven
YS
Stinson
Douglas
D
D000818:Animals; D002417:Cattle; D066298:In Vitro Techniques; D053685:Laser Therapy; D008297:Male; D011467:Prostate / Q000528:radiation effects*; D020728:Transurethral Resection of Prostate / Q000379:methods*