Presentation Authors: Paul Chiron*, Saint Mandé, France, Laurent Berthe, Mattieu Haddad, Steeve Doizi, Olivier Traxer, Paris, France
Introduction: As its wavelength of 1940nm more closely matches the water absorption peak of electromagnetic radiations, the SuperPulsed Thulium Fiber Laser should be more efficient than the Holmium:YAG Laser, which is the current gold-standard. Therefore, this technology should allow working with higher efficiency for stone treatment.We aimed to compare in vitro the efficiency of SuperPulsed Thulium Fiber Laser (TFL) and Holmium:YAG Laser.
Methods: First, a TFL of 50W (IPG PhotonicsÂ®) and an MH1 Holmium:YAG laser of 30W (RocamedÂ®), were modified at our convenience in order to deliver only one single pulse on hard kidney stones phantoms made of Begostone, with a 272Âµm fiber placed perpendicularly to the target, at different distances established with a micrometric screw. Experiments were repeated ten times. The resulting craters were studied and measured by optical microscopy (ZeissÂ® AxioCam Imager 2). Secondly, we treated hard and soft kidney stones phantoms for two minutes in an in vitro model, using a 200 Âµm fiber and a LithovueÂ® ureterorenoscope (BostonScientificÂ®): kidney stones were dried and weighed before and after treatment, with a Mettler AT261 analytic balance (MettlerÂ®) allowing to calculate the speed of destruction for each parameter.
Results: For a single pulse, the volume ablated was about 3 times higher with the thulium laser. This was due to a bigger surface of the crater with TFL, and there was no significant difference between the depth of the impacts obtained with the two lasers. During lithotripsy, the average destruction speed was 0,57, 1,32 et 1,99 mg/sec for TFL parameters of &[Prime]fine dusting&[Prime], &[Prime]dusting&[Prime] and &[Prime]fragmentation&[Prime], while it was 0,25 and 0,98 mg/sec respectively for Ho:YAG parameters of &[Prime]dusting&[Prime] and &[Prime]fragmentation&[Prime].
Conclusions: Compared to the Ho:YAG laser, the volume ablated by a single pulse with TFL is three times higher, and its speed of ablation is 2 (fragmentation) to 5 (dusting) times higher. Technologic superiority of TFL added to very high frequencies seems to lead to significant time saving. Further studies are necessary to confirm these observations in vivo.