An estimated 10% of the US population has at least one
tattoo, with up to one fourth in those younger than 30
years of age. Yet more than half of all people with tattoos
eventually regret having them and many want them removed.1
Tattoos are made up of small particles of pigment located in the
dermis. The discovery of selective photothermolysis has facilitated
the targeted destruction of tattoo pigment with only minimal
damage to surrounding skin.2
There are three conditions that must be met for successful tattoo
removal. First, the ink molecules must absorb the beam to
convert a sufficient amount of light energy to heat. Transient skin
whitening serves as an indicator of proper light absorption by
the tattoo pigments. Second, the radiant exposure of the applied
laser pulses must be high enough to generate a sufficiently high
temperature increase in the ink particle. Third, the pulse duration
must be very short (in the range of nanoseconds or picoseconds)
due to the small size of the ink particles.3
Q-Switched Lasers
A special technique, known as “Q-switching†provides high
intensity, ultra short pulse durations. Use of a quality-switched
(QS) laser for tattoo removal (694 nm ruby) was first reported
in 1965 by Leon Goldman.4 But it was not until the theory of
selective phototherymalysis was introduced in 1983 that QS
lasers became the gold standard for modern day tattoo removal.
5 A Q-switched laser is necessary to achieve selective
photothermalysis, as the exposure time in the nanosecond
(10-9) domain is less than half the thermal relaxation time of
the target pigment.
A QS laser ensures that the thermal damage is confined to the
target chromophore, resulting in photoacoustic destruction
and minimizing damage to the surrounding skin from thermal
diffusion. The four QS laser wavelengths are in the visible and infared spectrum, and include the 694 nm ruby, the 755 nm
alexandrite, the 1064 nm Nd:YAG and the 532 nm KTP. If a tattoo
is comprised of different colors, several wavelengths must
be used to target the tattoo pigments, which have different
absorption characteristics (see chart).6 The lighter one’s skin
the more successful the procedure will be because the melanin
in darker skin competes with the laser’s beam of light, thus
making the light less likely to reach the deeper level of pigment.
The QS Nd: YAG is usually recommended when treating
tattoos on Fitzpatrick type IV to VI patients, as the 1064 nm
wavelength penetrates deeper and is minimally absorbed by
epidermal melanin.
Immediately upon treatment, there is a photoacoustic effect,
which creates a very superficial wound. It is not unusual for some
of the tattoo pigment to come off with dressing changes. But the
main fading of the tattoo color occurs as a delayed phenomenon
weeks after treatment. It is the result of cellular mechanisms ie,
phagocytosis by macrophages, which transport and dispose of
the ink particles via the lymphatic system. Laser treatments are
usually spaced 1 to 2 months apart. However, it may take up to
three months for the full effect of a single treatment to be realized.
The difficulty with tattoo removal is that it can take up to
10 to 15 treatment sessions to remove the unwanted pigment. A
recent retrospective review of 238 patients who underwent an average
of 3.57 treatments (ranging between 1 to 18 sessions) found
that only 1.26% achieved total clearance of the tattoo defined as
complete absence of pigment.7 Many patients get discouraged
and discontinue treatment due to the expense and/or prolonged
treatment regimen. Even after a series of numerous treatments, in
some cases, complete removal is still not possible.
The “R20†Protocol and “RO†Protocol
Laser tattoo removal is typically frustrating for patient and doctor
alike since it can take numerous treatments at 1-2 month
intervals. The limiting factor when treating a tattoo has been that
