Cw high-power IR laser at 2 μm for minimally invasive surgery

Abstract

The potential of a new continuous wave Thulium YAG laser is investigated for tissue ablation and cutting focusing on applications in minimally invasive surgery. The laser emits at a wavelength of 2.01µm, which is well suited for tissue ablation due to its high absorption by water. The laser power can be tuned up to 60 W output through a 365 µm core diameter quartz fibre. For the ablation studies, the quartz fibre was placed in contact under various pressures (20 to 90mN) to porcine liver under saline solution in vitro at angles varying between 30° to 60°. The influence of different powers (10 to 60W) and cutting velocities (2 to 10mm/s) on the incision depth and coagulation zones of the tissue were investigated. A maximum incision depth of 3.3 mm was found with a power of 60W, a cutting velocity of 2mm/s and a fibre-tissue angle of 45°. The incisions were surrounded by coagulated tissue between 0.4 and 0.8mm in thickness, sometimes with an inner zone of carbonization of 0.2mm on average. In conclusion, the first experiments show that a cw Thulium laser is very well suited for tissue dissection as required in minimally invasive surgery.

Tm:KY(WO_4)_2 waveguide laser

“…Tm 3+ -activated materials are extensively studied as laser media for the 2 µm spectral range [1][2][3][4][5][6]. Lasers in this eye-safe wavelength region are in particular interesting for atmosphere monitoring, remote sensing and medical applications due to the low atmospheric absorption and the strong water and human tissue absorption [7,8]. The attraction of Tm lasers based on the 3 F 4 → 3 H 6 transition is related to the possibility for diode pumping near 800 nm, while maintaining high efficiency and low thermal load.…”

Potential of a new cw 2μm laser scalpel for laparoscopic surgery

“…Due to the high water absorption coefficient of a ¼ 6.19 mm À1 at the emitted wavelength (2.01 mm) [7] near the mid-IR absorption peak (1.94 mm), the tissue could be dissected very efficiently. In earlier in vitro studies performed on extracted porcine liver, the thermally damaged zone around the incisions ranged from 0.4 to 0.8 mm [5]. In this study the handling and safety were evaluated in an animal model, showing a reduction in dissection time of 19% compared to bipolar scissors.…”

“…Since 1999, in vitro investigations for different tissues are performed with continuous-wave (cw) solid-state thulium laser systems to investigate the potential of the cw mode in combination with an emitted wavelength at 2 mm for medical laser therapy [4,5]. Thulium fibre laser systems emitting at a wavelength at 1.9 mm are currently investigated in vivo as dissection devices in urology with successful results [6].…”

Effect of Tm2O3 doping on microstructure and optical properties of Tm:YAG ceramics

“…Laser radiation at the wavelength of about 2 mm is used in various technological fields, in particular including military engineering [24], meteorology [25], altimetry as well as medicine (surgery, ophthalmology, gynaecology, orthopaedics, arthroscopy and angioplasty) [26]. For instance, strong radiation of absorption through the water and human tissues ranging between 1.92 and 1.94 mm is particularly interesting for laser surgery, while low atmospheric absorption and "eye-safe" properties make such lasers suitable for the processing of materials, remote sensing and other applications [27,28].…”