Dr. Hans-Helge Seifert Profile

Dr. Hans-Helge Seifert

at Univ Hospital Zürich

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Publications (4)

Proceedings Article | 9 February 2012 Paper

Tissue ablation after 120W greenlight laser vaporization and bipolar plasma vaporization of the prostate: a comparison using transrectal three-dimensional ultrasound volumetry

Benedikt Kranzbühler, Oliver Gross, Christian Fankhauser, Lukas Hefermehl, Cédric Poyet, Remo Largo, Michael Müntener, Hans-Helge Seifert, Matthias Zimmermann, Tullio Sulser, Alexander Müller, Thomas Hermanns

Proceedings Volume 8207, 820713 (2012) https://doi.org/10.1117/12.909294

KEYWORDS: Prostate, Tissues, Surgery, Laser ablation, Ultrasonography, Laser tissue interaction, Plasma, Electrodes, Fiber lasers, Bladder

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Proceedings Article | 18 February 2011 Paper

Ablative efficiency of lithium triborate laser vaporization and conventional transurethral resection of the prostate: a comparison using transrectal three-dimensional ultrasound volumetry

Oliver Gross, Tullio Sulser, Lukas J. Hefermehl, Daniel D. Strebel, Remo Largo, Ashkan Mortezavi, Cédric Poyet, Daniel Eberli, Matthias Zimmermann, Alexander Müller, Maurice S. Michel, Michael Müntener, Hans-Helge Seifert, Thomas Hermanns

Proceedings Volume 7883, 78831I (2011) https://doi.org/10.1117/12.874024

KEYWORDS: Prostate, Tissues, Surgery, Laser ablation, Ultrasonography, Laser tissue interaction, Lithium, Ferroelectric materials, Laser energy, Laser systems engineering

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Proceedings Article | 23 February 2009 Paper

Loss of power output and laser fibre degradation during 120 watt lithium-triborate HPS laser vaporisation of the prostate

Thomas Hermanns, Tullio Sulser, Lukas Hefermehl, Daniel Strebel, Maurice-Stephan Michel, Michael Müntener, Alexander Meier, Hans-Helge Seifert

Proceedings Volume 7161, 71611I (2009) https://doi.org/10.1117/12.809751

KEYWORDS: Fiber lasers, Prostate, Tissues, Ferroelectric materials, Laser therapeutics, Surgery, Laser systems engineering, Laser scattering, Structured optical fibers, In vitro testing

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It has recently been shown that laser fibre deterioration leads to a significant decrease of power output during 80 W potassium titanyl phosphate (KTP) laser vaporisation (LV) of the prostate. This decrease results in inefficient vaporisation especially towards the end of the procedure. For the new 120 W lithium-triborate (LBO) High Performance System (HPS) laser not only higher power but also changes in beam characteristics and improved fibre quality have been advertised. However, high laser power has been identified as a risk factor for laser fibre degradation. Between July and September 2008 25 laser fibres were investigated during routine 120 W LBO-LV in 20 consecutive patients. Laser beam power was measured at baseline and after the application of every 25 kJ during the LV procedure. Postoperatively, the surgeon subjectively rated the performance of the respective fibre on a scale from 1 to 4 (1 indicating perfect and 4 insufficient performance). Additionally, microscopic examination of the fibre tip was performed. Median energy applied was 212 kJ. Changes of power output were similar for all fibres. Typically, a steep decrease of power output within the first 50 kJ was followed by a continuous mild decrease until the end of the procedure. After the application of 50 kJ the median power output was 63% (58-73% interquartile range) of the baseline value. The median power output at the end of the 275 kJ-lifespan of the fibres was 42% (40-47%). The median surgeons' rating of the overall performance of the laser fibres was 2 and the median estimated final decrease of power output 60%. Some degree of degradation at the emission window was microscopically detectable in all cases after the procedure. However, even after the application of 275 kJ, these structural changes were only moderate. Minor degradation of the laser fibre was associated with a significant decrease of power output during 120 W LBO-LV. However, following an early, steep decrease, power output remained relatively constant on a medium level for the rest of the fibre's lifespan. The subjective rating by the surgeons is in accordance with these findings. Improved properties of the LBO laser and enhanced fibre quality resulted in an only moderate decrease of power output which allowed for a consistently effective performance.

Proceedings Article | 8 February 2008 Paper

Intra-operative power measurement of laser fibers during photoselective vaporization of the prostate using the 80W-KTP-Greenlight laser

Thomas Hermanns, Tullio Sulser, Martin Baumgartner, Markus Fatzer, Julien Rey, Markus Sigrist, Hans-Helge Seifert

Proceedings Volume 6842, 684211 (2008) https://doi.org/10.1117/12.763745

KEYWORDS: Fiber lasers, Prostate, Tissues, Laser systems engineering, Laser marking, Laser applications, Laser ablation, Sensors, Control systems, Nd:YAG lasers

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