7. Nd:YAG Laser
Solid state Laser
• Wavelength 1064 nm
• Pulse duration CW - Pulsed - Q switched
Long pulsed
• Spot size variable
• Chromophore Non specific
8. Dye Lasers
Lasers containing fluorescent dyes
dissolved in a common solvent e.g.
alcohol or water,that absorbs light at
one wavelength and emits light at
another wavelength.
9. Dye lasers work based on the theory of
SelectivePhotoThermolysis(SPTL)
which means :
- Site specific
-Thermally mediated injury of
-Microscopic tissue targets
-By selectively absorbed pulses of radiation.
Dye Lasers
11. Why 585 nm?
Oxyhaemoglobin has 3 peaks for light
absorption:
* 418nm (The strongest)
* 542nm
* 577nm (The deepest & least
absorbed by melanin)
585nm was found to be deeper than 577nm&
less absorbed by melanin.
13. Thermal RelaxationThermal Relaxation
TimeTime
The time necessary for the targetThe time necessary for the target
chromophore to cool down 50%,chromophore to cool down 50%,
through the transfer of its heat tothrough the transfer of its heat to
surrounding tissue via thermalsurrounding tissue via thermal
diffusion.diffusion.
14. In order to get
OPTIMUM results:
* The wavelength must be well absorbed by
oxyhaemoglobin, less by melanin & of deep
penetration.
* The pulse duration must be shorter than or
equal to the TRT of the target.
This makes the majority of the absorbed
energy to be retained by the target structure
& minimizes non-specific thermal damage.
15. Delivery System
Flexible fiberoptic with different size
changeable hand pieces (2, 3, 5, 7,10,
&2x7 or 3x5 mm ).
17. Safety
measures(precautions)
Protect eyes ……….. eye glasses &
shields.
Laser off or standby when not in use.
Plume or steam ……….smoke evacuator.
Avoid reflecting objects.
* Labeling the theatre.
22. spots with overlap of 10%
are required to cover
effectively
DIRECTION OF TREATMENT
laser
23. Post treatment measures
*Sun screen for at least 6 months after
the end of last session.
*Topical antibiotic ointment once/day
until disappearance of purpura.
24. Complications Of Laser treatment
*Generally it is very safe with very low incidence
of side effects, and can be used at any age.
-Scarring(<1%).
-Hyperpigmentation ( 10 - 15% , transient,
resolves in 2-3 months).
-Hypopigmentation (5%, transient,resolves
within 2 months).
25. Pediatric Port Wine StainPediatric Port Wine Stain
Before Treatment
Following Treatment
Photo Courtesy of
Milton Waner, MD
26. Adult Port Wine StainAdult Port Wine Stain
Before Treatment Following Treatment
Photo Courtesy of
Milton Waner, MD
30. Leg VeinsLeg Veins
Pre TreatmentPre Treatment 33weeks post treatmentweeks post treatment
Courtesy: Emil Tanghetti. MD
Notes de l'éditeur
&lt;number&gt;
The thermal relaxation time is defined as the time necessary for the target chromophore to loose 50% of the acquired heat energy, through the transfer of its heat to surrounding areas via thermal diffusion. To destroy a target the thermal relaxation time of the target must be considered.
This graph is an idealized representation of this principle. In this case the chromophore would have a relaxation time of approximately ten milliseconds as this is where the graph returns to 50% of the maximum energy.
&lt;number&gt;
Laser terms used in laser therapy: