Layer by Layer vs. In Toto
In 1900’s the two rivals but both were twice noble prize warded , Max Planck and Albert Einstein initiated the quantum theory and stimulated emission . Their theories took another 50 years to realize the first laser machine (Maser) .
In 1963, Leon Goldman, also known as the “father of lasers in medicine”, was the first to use the laser in dermatology. In his first studies, Goldman reported the effects of Maiman’s laser (ruby laser ) in the selective destruction of cutaneous pigmented structures, like black hairs
In 1966, Mester, having discovered the positive effects of low-energy red laser on hair growth in rats, and the its healing on ulcers.
Only a year later, Dougherty experimented with the use of laser in activating photosensitive substances which were able to bind and destroy cancer cells selectively. This was the origin of photodynamic therapy.
1980 Rox Anderson and John Parrish initiated the ” Selective Phototherapy ” laser treatment theory. His theory is based on the experiment with Port Wine Stain (PWS) , the capillary size 120-150 micron.
The eighties are also characterized by the first use of a photo-acoustic laser in the treatment of penis plastic calcifications .
SPT could not explain many episodes in laser surgery . 2001 GB Altshuler and RR Anderson made the ” Extended Theory of Selective Photothermolysis to explain laser hair removal.
Both the above theories have the sample principle in ” removing target tissue in toto” , irradiating the whole target at once.
What are problems of this concept ?
- This conventional concept consider enough irradiation energy to remove the whole target without injuring adjacent tissue. But this is only a theory . In real world practice , we cannot apply accurately the exact laser dose to irradiate the target tissue through its whole depth ( because we are not certain how deep it is .) So, most of the time for novices in cosmetic laser surgery run into either ineffective treatment or complications.
- The concept does not give value to biological response of living tissue to irradiation . Living tissue absorbs laser energy and converts it into heat energy. Heat causes biochemical changes as well as physical changes in the tissue. The temperature of the histological water in the tissue is raised up from 37 C to 100 C . During temperature rise, there is a cascade of change in the tissue in various temperature , like we fry raw park in a hot oil . The color of the tissue changes. Degeneration occurs. The conventional concept does not define any of these changes . Practitioners only use laser equipment by protocols they have been advised by suppliers or their peers.
- Skin tissue is not a homogeneous one. It is heterogeneous. Physical properties varies from person to person and place to place of the same person. There is different absorption, scattering . Using the same protocol for every person or the same parameters and techniques everywhere on a client’s face is not a good algorithm.
- The conventional method describes vague “End Point” & ” Complications”. We have seen many episodes of “person’s end-point is another person’s complication “.
Layer by Layer Concept(SLT)
The principle of Soft Lasing Technique (SLT )
We have seen a lot of lase complication in aesthetic procedures done by novices in laser.
The main problem is that they found it hard to grasp the Conventional Concept of ” Removing Target Tissue In Toto”. They do not know how to design parameter for each laser machine appropriately with the skin lesion confronting them. They just open “the protocol ” sheet and doing laser blindly. The other big problem is that they do not know how to sweep laser beam across the client’s face ( using sweep beam delivery effectively).
1 SLT first concept : Depth of Target : ” Removing Target Tissue Layer by Layer ” like in surgical operation ” removing tissue layer by layer “. They need not know the depth of the target.
2 Define each target by its Physical Property : solid / liquid / fractional volume of chromophore, in order to choose laser photothermal, photo-biochemical or photoacoustic effect.
3 Define Clinical Effective Signs & Early Complication Signs :
For each target there are signs of clinical effectiveness which may not an “all-or-one” logic, there are spectrum of effectiveness which time and experience will teach attentive surgeons. Also for early complication signs for each type of targets , there are spectrum of variation. These signs are warning or stop signs, beyond these there are impending dangers.
4 Parameter setting .
SLT tells all its novices to assign parameters ( fluence, pulse duration ,spot size and frequency) according to clinical effective signs and early complication sings. Then test effect sweep beam speed and effective distance ( distance between handpiece and the skin surface) against clinical effective signs with himself/herself and then with the client .
Experienced SLT specialists know scenarios of skin changes immediately after , one or more days after. They can foresee their client’s prognosis.