Introduction: When evoking stones with a laser (Dusting) it is common to use the "popcorn" technique to complete the dusting. Today there are advanced and much more powerful laser machines, which allows the use of a variety of intensities, rates, and modulations. The purpose of the study is to check what are the most effective holmium laser settings while performing the popcorn technique. Methods: Stones were brewed from gypsum mixtures in three density levels. Their density was measured by CT imaging. 5 stones of size 2.8-3.3 mm were filtered and put into test tubes, and their weight was measured. Under continuous washing, "popcorn" stone dusting was performed with a holmium laser using a 272 micron fiber, using the popcorn technique for 2 minutes at intensities 0.3J/80Hz, 0.5J/40Hz, 1J/20Hz, 1J/ 30Hz, 1.5J/20Hz. With/without Moses modulation (distance). 3 repetitions were performed for each intensity. The mass of the remaining stone was weighed, and the stones larger than 1 and 2 mm were counted. The efficacy and evaporation rates of the stones were compared. Results: The density of the hard, medium and soft stones was 2095,995,548 HU respectively. The average rate of evaporation in soft, medium and hard stones was 68%, 50%, 47%. In soft stones it was found that the rate of vaporisation was the largest in the laser settings of 1J/30Hz without Moses (93%). There were no stones >2 mm left, and the number of crumbs between 1-2 mm was 3. In medium density stones, the rate of vaporisation was the greatest in the settings 1.5J/20Hz with Moses (71%). No stones >2 mm remained, and the number of stones between 1-2 mm was 3. In hard stones, it was found that the rate of vaporisation was the greatest in the laser settings of 1J/30Hz with Moses (76%). There were no stones >2 mm left, and the number of stones between 1-2 mm was 7. Moses modulation did not change the total vaporisation rate (p=0.256). Conclusions: When using the "popcorn" technique for laser dusting of kidney stones, we found different efficiency rates between the different laser settings. The most effective laser settings were in soft stones 1J/30Hz without Moses, in medium 1.5J/20Hz with Moses, and in hard stones 1J/30Hz with Moses. SOURCE OF Funding: Sheba Medical Center
