Neodymium: yttrium-aluminum-garnet laser dosimetry for the prolase II side-firing delivery system in the human prostate.

OBJECTIVES

The objective of this study was to define optimal treatment parameters and quantitative dosimetry for neodymium:yttrium-aluminum-garnet (Nd:YAG) laser coagulation prostatectomy utilizing the ProLase II side-firing laser delivery system.

METHODS

Transurethral Nd:YAG laser application was performed with the ProLase II side-firing laser fiber in adult human prostates prior to planned radical prostatectomy. Depth and volume of prostatic tissue coagulation for single, continuous laser applications were measured at variable power settings from 40 to 80 W, while holding total energy delivery constant. Holding the power setting constant, the extent of tissue coagulation was similarly measured for variable treatment times from 45 to 90 seconds.

RESULTS

Peak tissue coagulation for the ProLase II was observed at 60 W--up to a maximum of 13 mm tissue penetration and 3.92 cc volume coagulation following a single spot laser application. The mean depth of tissue coagulation at 60 W power setting was 12.7 mm, with a mean volume of tissue coagulation of 3.07 cc. Holding the power setting constant at 60 W, and increasing treatment time from 45 to 60 seconds, the extent to tissue coagulation increased significantly. However, beyond 60 seconds continuous laser application at 60 W, a plateau in tissue effects was observed, with minimal increase in tissue coagulation between 60 and 90 seconds.

CONCLUSIONS

Using the ProLase II side-firing laser fiber, 60-second Nd:YAG spot laser applications at 60 W power setting represent optimal treatment parameters. The quantitative dosimetry curves produced for the ProLase II fiber are compared with prior dosimetry studies with the Urolase delivery system.