Thulium Fiber Laser - meet the game changer in laser technology.
Thulium fiber laser technology explained
Thulium fiber laser (TFL) uses long, thin and thulium-doped silica fiber as the active laser medium. Multiple diode lasers are pumping energy through the fiber and excite the thulium ions. Photons are emitted at 1940 nm wavelength and directed at the operational field via an outgoing laser fiber.
There are two operating modes to choose from - the continuous and pulsed mode. Furthermore, TFL can operate within different energy, frequency and pulse shape settings. A highly efficient pumping mechanism allows obtaining high powers while generating small amounts of heat. Consequently, there is a significantly smaller cooling apparatus in the machine compared to other laser systems, reducing the overall weight of a TFL system. Thanks to the thin gain medium and more uniform spatial profile, smaller surgical fibers can be employed.

Key clinical applications of TFL technology
Stone management
One of the main applications of laser technology (including Ho:YAG and TFL) is flexible ureteroscopy, used for ureteric and kidney stone management. This both diagnostic and therapeutic procedure allows for minimally invasive stone management without breaking the skin barrier.
Soft Tissue Treatment
The cutting-edge thulium fiber laser technology allows for conducting procedures diagnosing and treating soft tissue conditions, including the management of benign prostate hyperplasia (BPH).

BPH treatment
Laser treatment options for BPH include vaporization, endoscopic enucleation (EEP), resection and ablation. In a majority of cases, EEP is the favoured method. Even though various lasers have been tested for treating EEP, the significant efficacy of the holmium lasers prompted holmium laser enucleation (HoLEP) to be the preferred choice. It allows removing a large amount of tissue in prostates of all sizes.
However, the recent addition of the thulium fiber laser to the urological arsenal might shift the paradigm. Given that TFL has identical average and peak powers of 100W, the laser does not burst tissues, providing clean and precise cutting.
What are the differences between Ho:YAG and Tm-Fiber technologies?
“Finer and faster”
Holmium:YAG laser has been used in urology for more than two decades (learn more about Ho:YAG laser here). Various key advantages over other existing lithotripsy techniques have established this method as a principal laser lithotripter [1, 2]. However, recent technological advances have resulted in the advent of new promising technology - the thulium fiber laser. According to previous studies, thulium fiber laser has the following advantages over Ho:YAG laser regarding laser lithotripsy [1,2]:

Highly effective fragmentation and dusting
Although the holmium:YAG (Ho:YAG) laser lithotripter can operate at high pulse energies, the efficient operation during lithotripsy is limited to low pulse rates (∼10 Hz). Conversely, the thulium fiber laser is limited to low pulse energies but operates efficiently at high pulse rates (up to 1000 Hz). The higher pulse rate significantly improves dusting - a higher quantity of dust and a smaller volume of particles [1,2].

Increased safety profile
La longueur d'onde du TFL (λ = 1908 nm) correspond à un pic d'absorption d'eau à haute température dans les tissus, dans une plus large mesure que la longueur d'onde du Ho:YAG (λ = 2120). Par conséquent, l'ablation du calcul peut être améliorée [2]. De plus, une profondeur de pénétration des tissus et de l'eau plus faible est bénéfique pour la sécurité du TFL [1].

Improved handling due to smaller fibers and better operability
Le faisceau laser sortant du connecteur de la fibre chirurgicale est environ 16 fois plus petit, permettant ainsi de réduire le diamètre de la fibre de 200 µm à 50 µm. Il est donc possible d'augmenter l'énergie du laser et de fournir une lumière laser plus focalisée : 70 µm dans le TFL contre 300 µm dans le Ho:YAG. La flexibilité des fibres plus petites facilite considérablement l'utilisation d'un urétéroscope minuscule dans des endroits anatomiques difficiles [1,2]. En outre, les fibres laser TFL sont plus résistantes à la rupture et causent moins de brûlures, ce qui améliore la durée de vie des fibres et réduit les coûts d'exploitation.
Un système TFL se présente sous la forme d'un appareil plus petit et plus léger, il est globalement plus silencieux et utilise une prise de courant standard. En outre, il ne nécessite pas de refroidissement par eau et il n'est pas nécessaire d'aligner la lampe et le miroir laser avant une procédure. Cette commodité dans la salle d'opération permet d'économiser un espace précieux et des coûts d'installation et permet également d'utiliser le dispositif spontanément dès que la décision de pratiquer une chirurgie au laser est prise.

Better visibility with less retropulsion
There is a notable reduction in retropulsion when compared with the Ho:YAG laser. In addition, the smaller fiber enables increased irrigation through the minute working channel within the instrument. This leads to improved visibility that can provide greater safety of the procedure.
Last but not least: super pulse creation
La fibre de thulium de ce laser permet d'augmenter la durée d'impulsion jusqu'à 12 ms. Les impulsions sont régulières, de sorte que leur puissance de crête est constante : des superimpulsions sont créées. Cet effet est stable dans le temps, ce qui rend fiable la puissance de sortie. En revanche, les impulsions générées par le laser Ho:YAG ne sont pas identiques entre elles.
Reference
- Traxer O, Keller EX. Thulium fiber laser: the new player for kidney stone treatment? A comparison with Holmium:YAG laser. World J Urol. 2020 Aug;38(8):1883-1894. doi: 10.1007/s00345-019-02654-5. Epub 2019 Feb 6. PMID: 30729311; PMCID: PMC7363731
- Blackmon RL, Irby PB, Fried NM. Comparison of holmium:YAG and thulium fiber laser lithotripsy: ablation thresholds, ablation rates, and retropulsion effects. J Biomed Opt. 2011 Jul;16(7):071403. doi: 10.1117/1.3564884. PMID: 21806249
- Kronenberg P, Traxer O. The laser of the future: reality and expectations about the new thulium fiber laser-a systematic review. Transl Androl Urol. 2019 Sep;8(Suppl 4):S398-S417. doi: 10.21037/tau.2019.08.01. PMID: 31656746; PMCID: PMC6790412.
- Panthier, Frédéric et al. “Comparison of the ablation rates, fissures and fragments produced with 150 µm and 272 µm laser fibers with superpulsed thulium fiber laser: an in vitro study.” World journal of urology vol. 39,6 (2021): 1683-1691. doi:10.1007/s00345-020-03186-z
- Keller, Etienne Xavier et al. “Thulium fiber laser: ready to dust all urinary stone composition types?.” World journal of urologyvol. 39,6 (2021): 1693-1698. doi:10.1007/s00345-020-03217-9
- Andreeva, Viktoria et al. “Preclinical comparison of superpulse thulium fiber laser and a holmium:YAG laser for lithotripsy.” World journal of urology vol. 38,2 (2020): 497-503. doi:10.1007/s00345-019-02785-9
- Kronenberg, Peter et al. “Outcomes of thulium fibre laser for treatment of urinary tract stones: results of a systematic review.” Current opinion in urology vol. 31,2 (2021): 80-86. doi:10.1097/MOU.0000000000000853
- Khusid JA, Khargi R, Seiden B, Sadiq AS, Atallah WM, Gupta M. Thulium fiber laser utilization in urological surgery: A narrative review. Investig Clin Urol. 2021;62(2):136-147. doi:10.4111/icu.20200467