How to perform the dusting technique for calcium oxalate stone phantoms during Ho:YAG laser lithotripsy

Abstract

Background To determine the most efficacious setting of Holmium:yttrium-aluminum-garnet (Ho:YAG) laser with a maximum power output of 120W with in vitro phantom-stone dusting technique.

Methods A laser was used to treat two 4 × 3 × 3mm3 sized phantom stones in 5mL syringes with 1mm-sized holes at the bottom. According to the pulse width (short 500, middle 750, long pulse 1000μsec), maximal pulse repetition rates from 50 to 80Hz were tested with pulse energy of 0.2, 0.4, 0.5, and 0.8J. Six times of the mean dusting times were measured at each setting. Dusting was performed at continuous firing of the laser until the stones become dusts < 1mm.

Results The mean Hounsfield unit of phantom stones was 1309.0 ± 60.8. The laser with long pulse generally showed shorter dusting times than short or middle pulse width. With increasing the pulse energy to 0.5J, the dusting time decreased. However, the pulse energy of 0.8J showed longer dusting times than those of 0.5J. On the post-hoc analysis, the pulse energy of 0.5J, long pulse width, and the repetition rates of 70Hz demonstrated significantly shorter dusting times than other settings.

Conclusions The results suggest that long pulse width with 0.5J and 70Hz would be the most efficacious setting for dusting techniques of plaster stone phantoms simulating calcium oxalate stones using the 120W Ho:YAG laser.