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Comparaison des lasers holmium : yag et thulium fibre sur des applications tissulaires

Abstract : The Holmium: YAG (Ho: YAG) laser is currently the benchmark laser in urology due to its efficiency and versatility: lithotripsy, incision of strictures (endopyelotomy, ureter and urethra), coagulation of tumors of the upper urinary excretory tract, and enucleation of the prostate for benign hyperplasia. However, this laser has several limitations:- Its wavelength of 2140 nm differs from the maximum absorption peak of water in tissue which is 1940 nm,- The laser pulse duration of around 250 microseconds is not optimal for applications requiring cutting or coagulation,- The laser beam produced (of the order of 300 µm) must be focused in optical fibers of small diameter (<365 µm) in order to be able to be used in flexible endoscopes. The scattering of laser radiation in these fibers can cause a loss of transmission as well as damage to the latter, which can lead to its rupture.- Finally, a high electrical intensity is necessary in order to make it work (laser + water cooling circuit), with a low efficiency (<0.1%)For these reasons, other options have been explored to improve these limits. A promising solution is the arrival of the Thulium fiber laser which offers several theoretical advantages:- Its wavelength ranges from 1750 nm to 2220 nm and therefore includes the maximum absorption spectrum of water (1940 nm)- The laser beam is 18 µm, which allows the use of optical fibers of smaller diameter, thus providing more flexibility when using with flexible endoscopes- it is a fiber laser pumped by means of diode lamps instead of a flash lamp and offering a better efficiency (> 5%) which allows a greater compactness of the laser and a cooling system to air.Thulium fiber laser is not currently marketed in Europe and does not have any evaluations on its effects on tissue or on lithotripsy compared to them of the current reference laser (Ho: YAG laser). Preliminary work has been carried out at the tissue level with a Thulium fiber laser different from that proposed [1]. Likewise, studies evaluating the Ho: YAG laser are rare [2].The objectives of this science thesis will be to compare the pulsed Thulium fibered and Ho: YAG lasers on an ex vivo tissue application:- Material: Thulium fiber laser (IPG, 50W) and Lumenis 120 W- Comparison of the efficiencies on different tissues (urothelial (bladder and ureter) and prostate) by varying the following parameters: laser parameters (pulse duration, energy, frequency), the laser mode used (Ho: YAG standard mode and Thulium fiber in standard mode), diameter of the laser fibers, the distance between the end of the laser fiber and the fabric. The experiments will be repeated 5 times. The effect will be appreciated by a blind histological study of the laser used to study the depth of the laser incision, the area of ​​coagulation produced.- Study the volume of prostate tissue ablation by laser vaporization by varying the following parameters: laser parameters (pulse duration, energy, frequency), the laser mode used (Ho: YAG standard mode, MOSES Technology mode for Ho : YAG and Thilium fiber in standard mode), diameter of the laser fibersClinical applications:- It will be a question of determining the laser parameters that can be recommended according to the type of surgical intervention (coagulation of tumor of the upper urinary excretory tract, prostatic enucleation, stenosis incision) and the desired effect
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  • HAL Id : tel-03378240, version 1

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Steeve Doizi. Comparaison des lasers holmium : yag et thulium fibre sur des applications tissulaires. Génie mécanique [physics.class-ph]. HESAM Université, 2020. Français. ⟨NNT : 2020HESAE068⟩. ⟨tel-03378240⟩

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