Category: New Technology: Stones

MP5-20 - SuperPulsed Thulium Fiber Laser for endocorporeal lithotripsy: superior from the very first pulse?

Fri, Sep 21
10:00 AM - 12:00 PM

Introduction & Objective :

The Thulium fiber laser (TFL) is being explored as an alternative to Ho:YAG Laser, the current gold standard laser source. We can even expect a greater efficiency of this technology, as its wavelength of 1940 nm more closely matches the water absorption peak, providing an absorption coefficient about five times higher than Ho:YAG.
The aim of this study was to compare in vitro the effect of a single impact of TFL and Ho:YAG Laser on kidney stones phantoms.


Methods :

We performed an in vitro observational study, using a 50W SuperPulsed surgical laser prototype of TFL (IPG Photonics, Oxford, MA). The distance from the laser fiber tip and the fURS camera was established thanks to a micrometric screw. Each of them has been modified in the laboratory at our convenience, and their activation have been modified in order to deliver only one single pulse. For each laser sources, we used a new 272 µm fiber. Same energy of 2J was used for both laser, with the shorter pulse allowed by the source (0,15 ms for Ho:YAG and 4 ms for TFL). Identical hard kidney stones phantoms made of Begostone® were used: fiber tip was placed perpendicularly to the stone at different distances with a micrometric screw. Experiments were repeated ten times. The craters were studied and measured by optical microscopy (Zeiss® AxioCam Imager 2).


Results : We observed that the depth of the impact decreased linearly as the distance between the tip of the fiber and the kidney stone phantom increased. there was no significant difference between the depth of the impacts obtained with the two generators (Figure 1). On the contrary, the surface of the crater increased linearly with the distance between fiber and stone. The destroyed area was about 4 times higher with the thulium laser (Figure 2).


Conclusions :

With a single impact, for an equivalent delivered energy, the area destroyed by the thulium laser is four times higher than the effect of Ho:YAG laser. This difference could be related to the difference in the pulse duration between the two lasers at this energy. Further studies are necessary to confirm that this phenomenon leads to a lithotripsy superiority.

Paul H.L. Chiron

MD, FEBU
Sorbonne Université, GRC n°20, Groupe de Recherche Clinique sur la Lithiase Urinaire, AP-HP, Hôpital Tenon, F-75020 Paris, France
Saint Mandé, Ile-de-France, France

Laurent L. Berthe

Paris, Ile-de-France, France

Vincent De Coninck

Urologist
AZ Klina
Brasschaat, Antwerpen, Belgium

Vincent De Coninck graduated as a medical doctor from the Free University of Brussels, Belgium (VUB) in 2011. He became a certified urologist in 2017 after a training at the University Hospital of Brussels (Prof. Dr. Dirk Michielsen) and OLV Aalst (Prof. Dr. Alex Mottrie), where he developed a special interest in the minimal invasive treatment of benign and malignant pathologies. In the same year, he became Fellow of the European Board of Urology.
In 2018, he completed a one-year fellowship program of the Endourological Society in Paris, France under the supervision of Prof. Dr. Olivier Traxer. During that fellowship, he also obtained a diploma in urolithiasis, organized by Dr. Michel Daudon at the Sorbonne University in Paris, France. Afterwards, he was trained in HoLEP by Dr. Karin Lehrich in Berlin, Germany.
Currently, he is completing a three-month fellowship under the supervision of Dr. Guido Giusti in Milan, Italy. In December 2018, he will start working as an endourologist in AZ Klina, Brasschaat, Belgium. He will focus on the medical and surgical treatment of kidney stones and benign prostatic obstruction (HoLEP) and he will continue publishing articles relating to the management of patients with renal stone disease.

Etienne X. Keller

Fellow of the ES
Sorbonne Université, GRC n°20, Groupe de Recherche Clinique sur la Lithiase Urinaire, AP-HP, Hôpital Tenon, F-75020 Paris, France
Paris, Ile-de-France, France

Steeve S. Doizi

Urologist
Sorbonne Université, GRC n°20, Groupe de Recherche Clinique sur la Lithiase Urinaire, AP-HP, Hôpital Tenon, F-75020 Paris, France
Paris, Ile-de-France, France

Olivier O. Traxer

Professor
Sorbonne Universite, GRC n020 Lithiase Renale, AP-HP, Hospital Tenon, F-75020 Paris, France
Paris, Ile-de-France, France