Tfl the game changer 28-04

Thulium Fiber Laser : The game changer!!
Ranchi Urology Centre
Dr. Prem Kumar
Consultant Urologist
Ranchi Urology Centre, Ranchi

Laser pulse-induced calculus damage
• Spallation – Stress wave on the calculus surface and thermal effects
• Micro-explosion
• Melting
• Breaking- mechanical or chemical bonding
• Motion – debris ejection & reteropulsion

 Rare earth element
 Neighbours of Holmium in periodic table

Thulium Fibre Laser
Holmium : YAG Laser

Technical Specifications
Detailed Parameters High power Ho:Yag Thulium Fibre Laser (TFL)
Energy (light) source Flash Lamp Laser diodes (electronically
controlled)
Gain medium Several mm thick laser
crystal rod (containing
holmium ions)
10-20 μ thick laser fibre core
(containing thulium ions) 10-30 m
long Silica fibre
Laser radiation generation

Machine Specifications
Detailed Parameters High power Yo:Yag Thulim Fibre Laser (TFL)
Size 47 cm × 116 cm × 105 cm 55 cm × 46 cm × 29 cm
Weight 245–300 kg (depending on model) 36 kg
Power supply Dedicated high amperage power
outlet
Standard/household power outlet
Energy efficiency 1% 12%
Energy consumption 9,000 W 1,000 W
Cooling system Water cooling system Air cooling system
Form factor and energy considerations

Comparison of machine-related parameters

Absorption: depth of tissue interaction
TFL
TFL Operates at a wavelength that has a higher absorption peak in water compared to Ho:YAG
which operates at 2120nm.
So, it has been hypothesized that increased water absorption leads to better fragmentation
TFL

Wavelength 2100 μm (2,090 to 2,120) 1,940 μm (1,908 μm for
older models)
Water absorption
coefficient
31.8 cm -1 (at 2,090 nm) 129.2 cm -1
Optical penetration depth
in water
0.314 mm 0.077 mm
Pulse profile Irregular energy pulses with
several spikes
Symmetrical, constant and
square wave energy pulses
Laser radiation properties

Fig: Relationship between optical coefficient α, optical penetration depth (OPD) and energy inside
water at 20 0 C.
Showing how laser energy at Ho:YAG (2,090 nm) and TFL (1,940 nm) wavelength decreases as it
travels through waves.
Wavelengths, water absorption coefficient, and ablation
thresholds

Laser coupling into patient
laser fibre
System of calibrated focussing
lenses
Almost direct fibre-fibre
coupling
Patient laser fibre core
diameter
200 μm or higher 50 μm or higher (technically
feasible for some prototypes)
Laser Fibre Features

Machine Specifications
Pulse energy 0.2- 6.0 J 0.025-6.0 J (0.005 J for some
specifications)
Pulse frequency 5-80 Hz (upto 100 Hz in newer
models)
5 - 2,200 Hz
Pulse duration 50-1,300 μs 200- 12,000 μs
Maximum average laser
power
120 W (140 W in newer
models)
50-55 W
Laser parameters
Low energies (0.025 J ) are important for dusting.
Smallest possible dust particle
Minimal Reteropulsion

Fig: Comparison of laser setting specifications

Optimal Settings for Lithotripsy using TFL
Pulse Energy Laser Power
Renal Stone Dusting 0.1-0.2 J 15- 30 W
Ureteric Stone (Dusting & Fragmentation) 0.2- 0.5 J 10-15 W
Large Bladder Stone 2-5 J 30-50 W
PCNL
Fragmentation 1-1.5 J (15-30 Hz)
Dusting 0.1-0.3 J (50-100 Hz)
Very preliminary recommendations
ideal TFL Lithotripsy settings yet to established

 4 x more ablative for dusting
 2 X more ablative for fragmentation
 5-10 x more efficient for uric acid & Ca OM stones
Dusting & Fragmentation
TFL (50 W)

 Larger quantity (3-4 x more)
 Better quality of dust (0.1-0.5 mm)
TFL (50 W)
High frequency dusting
 Pop-corning
 Pop-dusting
 Corn- Dusting
 Micro dusting
Dust Size

 Uniform pulse energy profile
 4 x smaller bubble dimension  Moses capabilities occur naturally
 10 x lower pressure generation
TFL (50 W)
 Better endoscopic view- reduced snow storm effect
 Can be operated by less experienced.
 Reduced learning curve
Retropulsion

 Currently 150 μm being used.
 Lab studies using 50 & 100 μm fibres with >1000 Hz frequency
 Less degradation of laser fibre ***
 Less degradation at connector end
 Less fibre burn back improved fibre life  lower cost
 Can sustain extreme bending
TFL (50 W)
Fibre Size

TFL:
Shorter “laser on” time and reduced reteropulsion
Decreasing fatigue and increasing comfort level of Surgeon

Installation Options
Laser Cost Energy frequency
Thulium Fiber Laser ( 35 W ) 30 L 0.025 J- 4.5 J 1-1400 Hz
Thulium Fiber Laser ( 60 W) 50 L 0.025 J-6.0 J 1-2200 Hz
Thulium Fibre Laser ( 120) 70 L 0.025 J- 8.0 J 1-2000 Hz
** IPG Photonics

Maintenance Costs
• Minimal maintenance cost
• Standard power outlet ( 5 Amps at 220 V ), higher efficiency
• Simple air cooling mechanism
• Long lifetime of laser diodes
• No lenses/mirrors/flash lamp/ chillers & di-ionized water
• Reusable non locking fiber and less degradation.

Small diameter fibres, low energy and long pulse reduced
laser fiber fracture.

Safety profile
• Patient & instrument safety:
– Greater safety margin from accidental perforation of tissues or damage to
instruments i.e, nitinol basket
• Radiation & electrical hazards:
– TFL is more retina safe
– Does not use high power supply
• Noise levels:
– Quieter
– Calm & less noisy working environment.

Limitations of TFL
• Peak power is low
– Not good for fragmentation lithotripsy ( Experience based )
• Sparks on stone
– It will reduce visibility
– reduced life of flexible uretero-renoscopy
• Low visibility over 60 Hz frequency
• Risk of thermal injury to ureter due to high temperature of water

• Temperature rise during lithotripsy:, specially frequency > 60 Hz
• Use of irrigation fluid cooled to at least 20 0 C is suggested.

Limitations of TFL
• Still an experimental laser, clinical studies lacking
• No CE certification
• FDA approval recently (Olympus)
• Clinical studies supporting fragmentation of large renal stones is not
available.
• Limited use in stone mainly, not proven for prostate & other urological
diseases.

Take home message
TFL is likely to stay and out perform
other lasers as far as RIRS is concerned

Tfl the game changer 28-04

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