Biomedical Engineering Reference
In-Depth Information
Figure 8.11
Tile cascade for stamping nonablative fractional laser showing
50% overlap pulse to pulse.
Figure 8.9
XD optic showing optical prongs to press water out of tissue.
Fractional 1540-nm Laser
The 1540-nm original microlenses from the Palomar Starlux™
and Artisan™ Fractional laser platforms are available in two
sizes. A fl at circular 10-mm tip has a microbeam density of
100 mb/cm
2
and a fl at circular 15-mm tip has a microbeam
density of 320 mb/cm
2
. The pulse durations are adjustable to
10 or 15 ms. The 10-mm tip can deliver energies between 14
and 70 mJ/mb. The 10-mm tip delivers a smaller number of
higher energy beams of laser light that can penetrate deeper
with a wider coagulation column diameter in one pulse when
compared with the 15-mm tip. The 15-mm tip can deliver
energies between 3 and 15 mJ/mb. The standard 10-mm tip
averages a 725 µm depth of penetration while the 15-mm tip
averages a 600 µm depth of penetration (Table 8.4).
The Palomar Icon™ Aesthetic System can use a standard
10-mm or 15-mm handpiece, but additionally has the
12
12-mm XD Microlens (25 mb/cm
2
) and the 15-mm XF
Microlens (115 mb/cm
2
). The XD Microlens delivers laser
energies from 20 to 70 mJ/mb. The XF Microlens emits ener-
gies from 6 to 60 mJ/mb. The XF Microlens provides a higher
coverage per pulse compared with the original optics allowing
fast treatment coverage comparable to the 1440 with the added
benefi t of increased depth. Average depth of penetration of the
microbeam is approximately 750 µm for the XF and 1060 µm
for the XD Microlens. Pulse stacking has been studied with the
XD Microlens. For example, three stacked pulses with the LUX
1540 XD tip have reached a depth of 1900 µm into the dermis.
Settings for the XD microlens are typically from 40 to 70 mJ/mb
and three to seven passes with overlap ranging from 10% to
50% depending on the desired total coverage and clinical con-
dition treated (Table 8.5).
×
Figure 8.10
Prong pattern of 1540 XD after 30 seconds of compression on
the skin.
passes performed with the stamping technique of the micro-
lens. More overlapping and passes increase the aggressiveness
of treatment (total surface coverage). Additionally, use of
manual compression with the standard and XD Microlens is
suspected to increase penetration of laser energy into the skin.
Regardless of the tip or wavelength used, the laser procedure
is delivered in a stamped method. Multiple stamps are deliv-
ered into the skin with varying amounts of overlap. The
amount of overlap between the stamps usually varies from
20% to 50%. Rows of stamps are performed in a single cos-
metic unit at a time. The rows may be overlapped from 0% to
50% depending on the wavelength, the microlens used, and
the desired total coverage and rate at which the coverage is
administered. One pass is completed when the entire cosmetic
unit is covered by the stamps. Passes are then alternated
between perpendicular and horizontal directions. This is also
known as the tile cascade method (Fig. 8.11). One to fi ve passes
are typically performed, depending on the total desired cover-
age. It is important to keep the treatment tip in full continuous
contact with the skin during each laser pulse. As with the roller
technique for delivering fractionated laser pulses, when there
are overlapping stamped pulses, they also produce laser impact
sites, which are not evenly distributed on the skin surface.
Palomar Fractional Laser for Home Use
PaloVia® Skin Renewing Laser was cleared by the FDA in 2009.
It is the fi rst FDA-cleared at-home laser treatment delivering
nonablative fractional treatment. The wavelength is specifi ed
as 1410 (
20) nm. It delivers a pulse duration of 10 ms with a
maximum of 15 mJ of energy. The PaloVia® Skin Renewing
Laser has been FDA cleared to reduce fi ne lines and wrinkles in
the periorbital area. In a study of 124 subjects who used the
device daily for 4 weeks, blinded evaluations revealed improve-
ment in the Fitzpatrick Wrinkle Score by one or more grades in
90% of the subjects. Post-treatment erythema was graded as
trace in the majority of test subjects.
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