Laser Hair Removal: Key Facts
Dermatologists and plastic surgeons always give a great deal of attention to the time required to perform laser treatments. The time factor eventually determines the cost of the treatment.
There are only two methods to increase the coverage rate of a laser hair removal treatment: increase the pulse repetition frequency OR increase the spot size.
As shown in Table 1, time taken for a treatment area is a multiple of the spot size and repetition rate.
Table 1
|
Spot Size |
Repetition Rate |
Coverage Rate |
|
Æ15 mm |
1 Hz |
1.8 cm2/sec |
|
Æ12 mm |
2 Hz |
2.3 cm2/sec |
|
Æ10 mm |
3 Hz |
2.4 cm2/sec |
|
9 x 9 mm sq. |
2 Hz |
1.6 cm2/sec |
|
Æ9 mm |
3 Hz |
1.9 cm2/sec |
|
Æ7 mm |
5 Hz |
1.9 cm2/sec |
It is always seen that an increase of the pulse repetition frequency leads to lower output energy levels. The capability of the laser to deliver high average power is a very important factor for consideration. It becomes hard to maintain cost-effective operation if the laser is not fast enough.
The data can be used to guess treatment time needed for different body areas, as given in Table 3.
Table 2
|
Site |
Approximate Size |
|
Upper lip |
15 cm2 |
|
Face |
80 cm2 |
|
Bikini area |
125 cm2 |
|
Underarms (2) |
190 cm2 |
|
Man’s back |
2750 cm2 |
|
Legs (2) |
8100 cm2 |
Table 3
| Area Treated |
Treatment Time |
# of Laser Treatments |
| Upper Lip |
4 Minutes |
3 - 8 |
| Chin |
5-10 Minutes |
3 - 8 |
| Bikini Line |
10-15 Minutes |
3 - 8 |
| Underarms |
4 Minutes |
3 - 8 |
| Man’s Back |
1 Hour |
3 - 8 |
|
Legs |
1-2 Hours |
3 - 8 |
That real treatment time depends on the following factors:
 |
Technical characteristics of the laser system |
|
Body area under treatment |
|
Patient’s skin and hair characteristics |
|
Surgeon’s talent and experience |
The most desired wavelength needed to achieve best results by laser is in the range of 670 to 890 nm (nanometer). It allows for the farthest penetration of the tissue without any loss of light intensity.
The amount of power required for this optimum range varies with the depth of the follicle opening. There are usually 3 types of hair growth.
Table 4
|
Type of Hair |
Depth (into the dermis) |
Power Required |
|
Terminal Hairs |
7-8 mm |
10 Joules per cm2 |
|
Secondary Hairs |
5-6 mm |
5 Joules per cm2 |
|
Vellus Hairs |
- |
2 Joules per cm2 |
|
