Lasers and energy devices for the skin

390 Pages·2013·81.457 MB·English

by  Goldman, Mitchel P

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Lasers and
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s Energy Devices
Edited by

a
Mitchel P. Goldman, MD, Volunteer Clinical Professor of Dermatology / Medicine, University of
n
California at San Diego, and Cosmetic Laser Dermatology, San Diego, California
d
Richard E. Fitzpatrick, MD, Volunteer Associate Clinical Professor of Dermatology, University of

California at San Diego, and Cosmetic Laser Dermatology, San Diego, California
E
for the Skin
E. Victor Ross, MD, Scripps Clinic Laser and Cosmetic Dermatology Center, San Diego, California n
e
Suzanne L. Kilmer, MD, Laser & Skin Surgery Center of Northern California, Sacramento, California
r
Robert A. Weiss, MD, FAAD, FACPH, Associate Professor, Johns Hopkins University School of
g
Medicine, and Director, Maryland Laser, Skin, and Vein Institute, Baltimore, Maryland
y

D S e c o n d ed i t i o n
e
Rapid technical developments with lasers and other energy devices have continued over recent
v
years, both in the different types of device available and in what can be offered for cosmetic and
i
other treatments, such as scar and tattoo removal, hair removal, cellulite, and lipolysis. The second c
edition of this acclaimed text has been revised to ensure the reader has a clear guide to the latest e
refinements, but can also easily locate the practical treatment parameters for a device. The top s
practitioners in the field have pooled their expertise to offer a broad and balanced perspective.
f
o
CONTENTS
r
Laser-tissue interactions • Laser treatment of vascular lesions • Laser treatment of benign pigmented

lesions • Tattoo removal • Hair removal • Skin resurfacing with ablative lasers • Fractional ablative t
lasers • Non-ablative fractional lasers • Treatment of scars • Photodynamic therapy • Treatment of h
leg telangiectasias with laser and high-intensity pulsed light • Body contouring: Noninvasive fat e
removal • Use of lasers on Asian skin • Laser lipolysis • Laser, light and energy devices for cellulite
S
and lipodystrophy • Anesthesia for cutaneous laser surgery • Laser safety: risk assessment and
quality management k
i e d i t e d b y
n
Mitchel P Goldman
H100302
ISBN: 978-1-8418-4933-1
90000 Richard E Fitzpatrick • E Victor Ross
9 781841 849331 Suzanne L Kilmer • Robert A Weiss
H100302_Cover_mech.indd All Pages 1/30/13 9:51 AM
Lasers and Energy Devices
for the Skin

Lasers and Energy Devices
for the Skin
Second Edition
Edited by
Mitchel P. Goldman,
MD
Volunteer Clinical Professor of Dermatology/Medicine, University of California, San Diego, California, USA
Goldman, Butterwick, Fitzpatrick, Groff, and Fabi Cosmetic Laser Dermatology, San Diego, California, USA
Richard E. Fitzpatrick,
MD
Volunteer Associate Clinical Professor of Dermatology/Medicine, University of California, San Diego, California, USA
Goldman, Butterwick, Fitzpatrick, Groff, and Fabi Cosmetic Laser Dermatology, San Diego, California, USA
E. Victor Ross,
MD
Scripps Clinic Laser and Cosmetic Dermatology Center, San Diego, California, USA
Suzanne L. Kilmer,
MD
Laser & Skin Surgery Center of Northern California, Sacramento, California, USA
Robert A. Weiss, , ,
MD FAAD FACPH
Associate Professor, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
Director, Maryland Laser, Skin, and Vein Institute, Baltimore, Maryland, USA
Boca Raton London New York
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Contents
List of Contributors vi 11. Treatment of leg telangiectasias with laser and
high-intensity pulsed light 272
1. Laser–tissue interactions 1 Mitchel P. Goldman
E. Victor Ross and R. Rox Anderson 12. Body contouring: Noninvasive fat reduction 283
2. Laser treatment of vascular lesions 31 Lilit Garibyan, H. Ray Jalian, Mathew M. Avram,
E. Victor Ross and Andrew C. Krakowski and Robert A. Weiss
3. Laser treatment of benign pigmented lesions 58 13. Use of lasers on Asian skin 293
Omar A. Ibrahimi and Suzanne L. Kilmer Woraphong Manuskiatti
4. Tattoo removal 74 14. Laser lipolysis 325
William T. Kirby Melanie D. Palm, Ane B.M. Niwa Massaki,
Sabrina G. Fabi, and Mitchel P. Goldman
5. Hair removal 94
Omar A. Ibrahimi and Suzanne L. Kilmer 15. Laser, light, and energy devices for cellulite and
lipodystrophy 339
6. Skin resurfacing with ablative lasers 110 Mitchel P. Goldman, Jennifer D. Peterson, and
Omar A. Ibrahimi, Richard E. Fitzpatrick, Sabrina G. Fabi
Mitchel P. Goldman, and Suzanne L. Kilmer
16. Anesthesia for cutaneous laser surgery 349
7. Ablative fractional lasers 162 Mitchel P. Goldman, Sabrina G. Fabi, and
Douglas A. Winstanley and E. Victor Ross Jennifer G. Wojtczak
8. Nonablative fractional lasers 178 17. Laser safety: Risk assessment and
Karen L. Beasley and Robert A. Weiss quality management 364
9. Treatment of scars 192 Penny J. Smalley
Richard E. Fitzpatrick
Index 383
10. Photodynamic therapy 222
Mitchel P. Goldman and Ane B.M. Niwa Massaki
v
List of Contributors
R. Rox Anderson Suzanne L. Kilmer
Department of Dermatology Laser & Skin Surgery Center of Northern California,
Wellman Center for Photomedicine Sacramento, California, USA
Massachusetts General Hospital
Boston, Massachusetts, USA William T. Kirby
Laser Tattoo Removal and Laser Hair Removal, Beverly Hills,
Mathew M. Avram California, USA
Department of Dermatology
Massachusetts General Hospital Andrew C. Krakowski
Harvard Medical School Pediatric Dermatology, University of California and
Boston, Massachusetts, USA Rady Children’s Hospital, San Diego, California, USA
Karen L. Beasley Woraphong Manuskiatti
Department of Dermatology Department of Dermatology, Faculty of Medicine Siriraj
The University of Maryland School of Medicine and Hospital, Mahidol University, Bangkok, Thailand
The Maryland Laser, Skin, and Vein Institute
Hunt Valley, Maryland, USA Ane B.M. Niwa Massaki
Former fellow at Goldman, Butterwick, Fitzpatrick, Groff and
Sabrina G. Fabi Fabi Cosmetic Laser Dermatology,
Goldman, Butterwick, Fitzpatrick, Groff, and San Diego, California, USA
Fabi Cosmetic Laser Dermatology
San Diego, California, USA Melanie D. Palm
Art of Skin MD, Solana Beach, and Laser Skin Care Center,
Richard E. Fitzpatrick Long Beach, California, USA
University of California and Goldman, Butterwick,
Fitzpatrick, Groff, and Fabi Cosmetic Laser Dermatology Jennifer D. Peterson
San Diego, California, USA Dermatology and Laser Surgery Center, Houston, Texas, USA
Lilit Garibyan E. Victor Ross
Laser, Cosmetic Center and Laser and Cosmetic Dermatology Center, Scripps Clinic,
Wellman Center for Photomedicine Massachusetts San Diego, California, USA
General Hospital and Department of Dermatology
Harvard Medical School Boston, Penny J. Smalley
Massachusetts, USA Technology Concepts International, Chicago, Illinois, USA
Mitchel P. Goldman Robert A. Weiss
University of California and Goldman, Butterwick, Fitzpatrick, Johns Hopkins University School of Medicine and The Maryland
Groff, and Fabi Cosmetic Laser Dermatology Laser, Skin, and Vein Institute, Baltimore, Maryland, USA
San Diego, California, USA
Douglas A. Winstanley
Omar A. Ibrahimi Laser and Cosmetic Dermatology Center, Scripps Clinic,
Connecticut Skin Institute, Stamford, Connecticut, USA San Diego, California, USA
Wellman Center for Photomedicine, Massachusetts General
Hospital and Harvard Medical School, Jennifer G. Wojtczak
Boston, Massachussets, USA Weiss Memorial Hospital, Chicago, Illinois, USA
H. Ray Jalian
Laser and Cosmetic Center and Wellman Center for
Photomedicine, Massachusetts General Hospital and
Department of Dermatology, Harvard Medical School
Boston, Massachusetts, USA
vi
1
Laser–tissue interactions*
E. Victor Ross and R. Rox Anderson
introduction
skin (4). Depending on the angle between the light beam and
When using a light source, many physicians dial in “suggested” the skin, this value varies considerably. More light is refl ected
settings and proceed, using identifi able endpoints to deter- as the angle of incidence between the beam and the surface
mine if the parameters are appropriate. For example, when approaches zero. It follows that, in most laser applications, we
treating a port-wine stain (PWS) with the pulsed dye laser want to maintain a perpendicular angle to minimize refl ective
(PDL), the physician looks for immediate purpura and is vigi- losses (5,6). This regular refl ectance is about 4–7% for light
lant to ensure that no surface whitening occurs. Although this incident at right angles to the skin (Fig. 1.2). One can reduce
is a good way, perhaps the best, to ensure that a favorable out- interface losses by applying an alcohol solution (n = 1.4)
come is secured, it is instructive for the operator to know from or even water (n = 1.33). This allows for optical coupling
fi rst principles how the clinical endpoint was achieved. This (vide infra). On the other hand, because of multiple index of
will allow the physician to expand his laser repertoire and refraction mismatches (keratin–air–keratin–air, etc.), dry
optimize the use of this very expensive equipment. For exam- skin refl ects a great deal of light (hence the white appearance
ple, armed with an education in laser–tissue interactions of a psoriasis plaque). Light not refl ected at the skin surface
(LTIs), one can cajole the PDL to treat pigmented lesions penetrates into the epidermis. At this point, further light
without purpura by compressing the lesions with a clear plas- propagation in skin is determined by wavelength-dependent
tic piece (Fig. 1.1). This removes blood as a chromophore and localized absorption and scattering (vide infra) (4). Overall,
increases the ratio of melanin to vascular heating (1). There because of scattering, much incident light is remitted (remit-
are many other creative ways to use light-based technologies, tance refers to the total light returned to the environment due
but without a basic understanding of LTIs, one is reduced to to multiple scattering in the epidermis and dermis, as well as
treating skin ailments like one microwaves popcorn (accord- the regular refl ection from the surface; Fig. 1.2). The amount
ing only to the instructions with no license to do it better). of light “wasted” because of remittance varies from 15% to as
In short, an understanding of light–tissue and electrical–tissue much as 70% depending on wavelength and skin type. For
interactions optimizes clinical outcomes in cutaneous laser example, for 1064 nm, 60% of an incident laser beam may be
surgery. remitted. One can easily verify this by holding a fi nger just
adjacent to the beam near the skin surface. Considerable
macroscopic basis of lti
warmth will be felt with higher fl uences, all of which is
Light demonstrates both wave and particle properties. Nor- due to a remitted portion of the beam. For our purposes, light
mally, wave behavior accurately describes light’s behavior in can be divided into the ultraviolet (UV; 200–400 nm), visible
space and at large interfaces (i.e., skin and air) (2). However, (VIS; 400–760 nm), near-infrared (NIR; 760–1400 nm), mid-
the particle properties (and quantum physics) are more use- infrared (MIR; 1.4–3 μm), and far-infrared (FIR; 3 μm and
ful in characterizing electromagnetic radiation (EMR)–tissue beyond). These are the wavelength ranges that are important
interactions on a molecular level (vide infra) (3). On a mac- in laser dermatology (2).
roscopic level, light behavior conforms to various laws and
types of lasers and properties of lasers
e quations that are consistent with our “eyeball” observations
in nature. For example, we are familiar with refraction and Lasers as light sources are useful because they can, depending
refl ection (4). Normally, the percentage of incident light on parameters, allow for exquisite control of where and how
refl ected from the skin surface is determined by the index of much one heats. However, most reactions with biological sys-
refraction mismatch between the skin surface (stratum cor- tems are nonspecifi c to radiation from laser sources and
neum, n = 1.55) and air (n = 1) (2). The Fresnel equations can at least in principle could be induced by thermal sources as
be used to describe how much light will be refl ected from the well (3). What are the advantages of laser? For the most part,
properties of laser light (i.e., coherence) are irrelevant insofar
as the way light interacts with skin in therapeutic applications.
* The reader should note that although the title of this chapter is
This contention is supported by the increasing use of fi ltered
“Laser–tissue interactions”, the introduction of many new and diverse
fl ashlamps in dermatology. There are four properties that are
technologies makes the term somewhat obsolete. We will continue to
common to all laser types: (i) beam directionality, (ii) narrow
use the term, but a more appropriate is “electromagnetic radiation
beam divergence, (iii) spatial and temporal coherence of the
(EMR)–tissue interactions.” Both terms are used interchangeably in
beam, and (iv) high intensity of the beam (7).
the remainder of the text.
1
2
LASERS AND ENERGY DEVICES FOR THE SKIN
Figure 1.1 Example of compression technique. The plastic piece is used to Figure 1.3 Ruby rod attached to high-power voltage. Flashlamp assembly is
“remove” blood so that lentigo can be treated with 1.5-ms pulsed dye laser adjacent to rod. Normally the lamp is attached atop the rod assembly. Mirror
without purpura. allows the rod to be excited circumferentially.
Incident Regular
laser light reflectance
Epidermal Dermal
remittance remittance
Stratum
corneum
θ
(~10 μm) i
Internal
Absorption
Epidermis reflection
(~100 μm)
Scattering
Basal layer
Dermis
(~4 mm)
Transmission
Figure 1.4 Diode laser where the diode light is coupled into fi ber that is
Figure 1.2 The behavior of light at skin surface. attached to the handpiece.
The greatest advantages of laser light are the intensity and pumped by a fl ashlamp (Fig. 1.3). Miniaturized diode lasers
the monochromaticity—this allows a degree of precision that have become more powerful and popular. Some diode lasers
is hard to reproduce with nonlaser sources. The beam of the are housed separate from the handpiece (Fig. 1.4). Others are
laser is easy to manipulate. The beam can, for example, be confi gured with the laser diodes in the handpiece (Fig. 1.5).
expanded, or focused, quite easily. On the other hand, with Modern diode lasers are capable of much higher powers than
nonlaser sources, such as fl ashlamps, one cannot exceed the in the past years, but their peak powers are still limited com-
brightness of the source lamp. It follows that the intensity of pared with most pulsed solid-state lasers (10).
the beam can only be attenuated once emitted from the lamp IPL devices are becoming increasingly popular (11–17).
surface. Lasers can create very high intensity light because of Because the absorption spectra of skin chromophores are not
the property of stimulated emission. With laser, a lamp similar monochromatic, a broadband light source is a logical approach
to the intense pulsed light (IPL) fl ashlamp pumps the laser for cosmetic applications. Rather than using a lamp to pump a
cavity. The amplifi cation of the light within the cavity sets laser, these devices use the lamp directly. Appropriate fi ltration
laser light apart from other sources. Laser is really a fancy way creates the optimal output spectrum for a particular applica-
to convert lamplight to a more powerful monochromatic form tion. Much like a slide projector with a specifi c color slide,
(8). The high power of the light (especially peak power with these bright lamps produce spectra that can mirror the absorp-
pulsed lasers) is not attainable outside of laser sources. The tion spectrum of melanin, hemoglobin, and even water. The
ability to focus the laser beam is an important contributor to advantages of these devices are their fl exibility, but one disad-
the peak power density of the laser. Very small beam angles can vantage is that one must hold the lamp, cooling, and the high-
be obtained that are not possible with intrinsically divergent voltage source in the hand. This creates a larger “umbilical
nonlaser light sources (i.e., IPL) (9). cord” compared with the fi bers and articulated arms used by
With respect to lasing media, there are diode lasers, solid- most laser devices. Also, the beam diverges quickly, and non-
state lasers, and gas lasers. An example of a solid-state laser is laser beams are not optically as easily manipulated as true laser
the neodymium (Nd) laser. These lasers have a rod that is beams. Very short pulses (e.g., Q-switched nanosecond (ns)
3
LASER–TISSUE INTERACTIONS
Figure 1.5 Another diode laser; in this case, the diodes are in the handpiece.
This confi guration allows for more direct application of laser light. However,
placement of diodes in the handpiece requires that “high voltage” and laser
cooling be attached to the handpiece by larger “umbilical” cord.
pulses) are not possible with these sources alone; they can,
however, be used to pump a Q-switched laser, and newer IPLs
have featured a Q-switched attachment (Fig. 1.6).
Basic parameters for any EMR procedure are power, time,
and spot size for continuous wave (CW) lasers, and for pulsed
lasers, the energy per pulse, pulse duration, spot size, fl uence,
repetition rate, and the total number of pulses (18). Energy is
measured in joules (J). The amount of energy delivered per
unit area is the fl uence, sometimes called the dose or radiant
exposure, is given in J/cm2. The rate of energy delivery is called
power, measured in watts (W). One watt is 1 joule per second
(W = J/s). The power delivered per unit area is called the irra-
diance or power density, usually given in W/cm2. Laser expo-
sure duration [called pulse width (pw) for pulsed lasers] is the Figure 1.6 Q-switched laser pumped by fl ashlamp in IPL device (from ALMA
time over which energy is delivered. Dermatology uses EMR Laser website). The laser rod is in the handpiece.
exposures ranging from many seconds to nanoseconds. The
fl uence is equal to the irradiance times the exposure duration
(19). Power density is one of the most important parameters,
for it often determines the action mechanism in cutaneous 1015 Photodisruption
applications (Fig. 1.7). For example, a very low irradiance (typ-
ical range of 2–10 mW/cm2) does not markedly increase tissue 2) 1012 Photoablation
tpedexehmtnorspetiometcireehas,te uamar sevisc eoaraclyn i adpsth reoiodscr etwas snsisetsohs c,p ipuaanthlsedoed t ocbwaminoites hgcti hemdnaniuearilgcaanatteiloo shnitni.ig cjuOh ra nypp eptaalhnikced a p tooieotwvhneeesnrr, nsity (W/cm 110096 Pianbldaluasctmieoadn- 1 J/c1000 J/cm2
de m2
plasma formation (20). Other important factors are the laser r 103
e
exposure spot size (which greatly affects intensity inside the w Thermal interaction
o
skin), whether the incident light is convergent, divergent, or P 100
diffuse, and the uniformity of irradiance over the exposure Photochemical interaction
area (spatial beam profi le). The pulse profi le, that is, the char- 10–3
acter of the pulse shape in time (instantaneous power vs. time)
10–15 10–12 10–9 10–6 10–3 100 103
is another feature that can impact the tissue response (18).
Exposure time (s)
When we train residents, one of the greatest challenges is
understanding all of these above terms within the context of a Figure 1.7 The relative mechanisms of action as a function of power density
ranges. Source: Modifi ed from Ref. 157.
specifi c EMR device. When a novice confronts a laser instru-
ment panel, there is often a grimace born of confusion. The
staggering array of options on some user interfaces can be laser surgeon usually wants the fl exibility in tweaking param-
overwhelming (Fig. 1.8). Many physicians would prefer to eters. Many manufacturers have accommodated both types of
have fewer options and a simpler display, especially early on in users, providing preset parameter sets (and “go-bys”) while
their use of a particular laser. However, like the driver who still allowing for experienced physicians to choose parameter
feels confi ned by an automatic transmission, the experienced confi gurations of their liking.