Table Of ContentPractical Introduction
to Laser Dermatology
Vishal Madan
Editor
123
Practical Introduction
to Laser Dermatology
Vishal Madan
Editor
Practical Introduction
to Laser Dermatology
Editor
Vishal Madan
Consultant Dermatologist, Laser and Mohs Surgeon
Salford Royal NHS Foundation Trust, Stott Lane
Salford
UK
ISBN 978-3-030-46450-9 ISBN 978-3-030-46451-6 (eBook)
https://doi.org/10.1007/978-3-030-46451-6
© Springer Nature Switzerland AG 2020
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Contents
1 Fundamentals of Lasers and Light Devices
in Dermatology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Elizabeth Raymond Brown
2 Lasers for Vascular Indications . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Giulia Rinaldi, Samira Batul Syed, and Vishal Madan
3 Pigment Specific Lasers and Light Devices . . . . . . . . . . . . . . . . . 91
Sanjeev Aurangabadkar
4 Epilation Lasers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Samantha Hills and Daron Seukeran
5 Ablative Lasers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Vishal Madan
6 Fractional Laser Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
Sarah Felton and Vishal Madan
7 Radiofrequency Devices Including Fractional
Radiofrequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
Ileana Afroditi Kleidona, Ali M. Ghanem,
and Nicholas J. Lowe
8 Light Emitting Diodes and Low Level Laser
Light Therapy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
Caiwei Zheng, Ali Rajabi-Estarabadi, Melanie M. Hirsch,
and Keyvan Nouri
9 Intense Pulsed Light in Dermatology . . . . . . . . . . . . . . . . . . . . . . 219
Sam Hills and Miguel Montero
10 Cosmeceuticals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
Rhonda Meys
11 Self-Assessment Questionnaire . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
Vishal Madan
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
v
1
Fundamentals of Lasers and Light
Devices in Dermatology
Elizabeth Raymond Brown
Historical Development of the Laser Table 1.1 summarises the historical landmarks
in the development of laser devices.
The theory describing the properties of light emit- The 1980s onwards saw a rapid development
ted by the process of stimulated emission was pro- in lasers capable of delivering new wavelength
posed by Albert Einstein in 1917 [1] but Einstein wavelengths, stable beam and output characteris-
did not use the term laser in his publication. tics and devices that were more compact and effi-
According to Hecht [2] the development of the cient. The growth in laser types mirrored the
laser was ‘neither simple nor easy’ yet we take search for new applications and tailoring to spe-
lasers and laser applications very much for cific interventions, e.g. wavelengths for improv-
granted because they are so widely used in the ing absorption by a given target or depth of
field of medicine, dentistry, veterinary, entertain- penetration.
ment, commerce, industry and research.
The first practical laser was demonstrated in
1960 by Theodore H. Maiman at the Hughes Properties of Light
Research Laboratory in America [3], using a cyl-
inder of synthetic ruby just 1 cm in diameter and Light is described as a wave-particle duality,
2 cm long in an arrangement that Maiman meaning it displays characteristics of waves and
referred to as an optical maser. The foundation particles (Fig. 1.1). Beams of light being
for this incredible achievement was made possi- reflected, diffracted or experiencing interference
ble by the fundamental physics studies of Max are evidence of light travelling as a wave. Light
Planck who in 1900 described light as a form of acting as a particle is evidenced by the photoelec-
energy and presented the concept of quanta, for tric effect that causes a precise and specific
which he received the Nobel Prize in physics in removal of materials such as ablation of corneal
1918 [4]. Planck’s work inspired Albert Einstein tissue by excimer lasers. Either concept may be
to investigate the interaction of light with matter used depending upon the sense of scale, e.g.
and in 1905 he too concluded that light delivers wavelength versus photon energy and both
energy in discrete quantum particles which are descriptions are relevant to laser and light inter-
now referred to as photons [5]. ventions and laser safety. For example, light as a
wave is used to describe spectral output, i.e., the
wavelength of the output beam, while light as a
E. Raymond Brown (*) particle explains specific interactions with matter
Laser Education Limited, Gainsborough, UK
and tissues, i.e. tissue ablation.
e-mail: [email protected]
© Springer Nature Switzerland AG 2020 1
V. Madan (ed.), Practical Introduction to Laser Dermatology,
https://doi.org/10.1007/978-3-030-46451-6_1
2 E. R. Brown
Table 1.1 Historical landmarks in laser development
Year Contributor Contribution
1917 Albert Einstein Proposed the conditions required for ‘stimulated emission’ of light.
[5]
1957 Gordon Gould Proposed the conditions required for stimulated emission at visible wavelengths.
[6] Acknowledged to be the first person to use the term ‘LASER’. Gould did not
immediately patent his concepts and the ideas of Schawlow and Townes were patented
first.
1958 Arthur Demonstrated a maser (microwave amplification by stimulated emission of radiation)
Schawlow and using ammonia gas and microwave radiation. Their papers published in 1954 and
Charles Townes 1958, led to patents on the theoretical requirements for designing ‘optical masers’.
[7] While technically they invented the first laser it was referred to as an ‘optical maser’.
1960 Theodore Demonstrated the visible first laser using a rod of synthetic ruby with reflective
Maiman [3] coatings on each end surrounded by a helical flashlamp. The publication Physical
Review rejected Maiman’s original article (June 1960), but the scientific community
later recognised it as a discovery that changed the world.
1960 Ali Javan [8] In 1959 Javan proposed the first gas laser and in 1960 demonstrated a helium-neon
(HeNe) gas laser operating continuously rather than in pulses. The HeNe laser initially
emitted in the near IR with the 632.8 nm (red) output discovered in 1962, making it
one of the most popular early lasers in research and medicine.
1963 Zhores Alferov In 1963 Alferov and Kromer independently proposed the principles for semiconductor
[9] heterostructures to be used to emit light. It took until the 1970s to produce stable, room
Herbert temperature operated devices and semiconductor lasers are now the commonly used
Kroemer [10] laser types.
1964 William Bridges Bridges was the first to report ten different laser transitions, including blue and green
[11] light, from an argon gas laser.
1964 Kumar Patel Patel demonstrated the first carbon dioxide (CO) laser showing it to be capable of
2
[12] very high continuous-wave and pulsed power output at very high conversion
efficiencies.
1964 James Geusic Demonstrated the first neodymium yttrium aluminium garnet (Nd:YAG) laser. Initially
et al. [13] developed in 1961 neodymium-based lasers required the inclusion of yttrium
aluminium garnet (YAG) to emit stable and reliable outputs.
1968 Peter Sorokin Demonstrated the first laser using an organic dye as the active medium.
et al. [14]
1970 Nikolai Basov Basov is generally credited with the initial development of a gas laser using a xenon
et al. [15] dimer. However, research groups including IBM developed the technology using noble
gases for a family of devices known as excimer lasers. Initially designed for
photoetching materials, applications extended to human tissue in particular corrective
eye surgery.
1983 Rox Anderson Published a paper describing thermal confinement of heat to target tissue thus allowing
and James precise and selective destruction through a process termed selective Photothermolysis.
Parish [16] Their publication significantly advanced the understanding of laser and light-tissue
interactions.
Light as an Electromagnetic Wave Electromagnetic radiation (EMR) is the con-
tinuous range of energies that extends from
For safe and effective practice, it is essential X-radiation to radio waves. Although these forms
that clinicians understand the different types of of energy are different from one another, they all
lasers, the differences between laser and travel through space as waves thus exhibiting
intense light sources (ILS), also known as wavelike properties. A key feature of EM waves
intense pulsed light (IPL (TM)) devices and is that they propagate and move without a propa-
the properties of laser and light beams. The gation medium and hence can travel the vast
starting point is to understand electromagnetic distances of outer space. The electromagnetic
radiation (EMR) and the electromagnetic (EM) spectrum is the term used to describe the range of
spectrum. EMR (Fig. 1.2).
1 Fundamentals of Lasers and Light Devices in Dermatology 3
LIGHT PHOTONS
Evidenced by Wave Particle Evidenced by
interference effects photoelectric effects
Size Energy
Wavelength
λ
Ephoton= hf
Fig. 1.1 Illustration of the concept of the wave-particle duality of light
High Frequency Low Frequency
1018 Hz 1015 Hz 1012 Hz 109 Hz 106 Hz
1pm 1nm 1µm 1mm 1m 1km
Shorter Wavelength Longer Wavelength
10-12 10-11 10-10 10-9 10-8 10-7 10-6 10-5 10-4 10-3 10-2 10-1 0 101 102 103 104
E
L
B
X-RAYS ULTRAVIOLET VISI INFRARED MICRO WAVES RADIO WAVES
OPTICAL SPECTRUM
180 nm 1 mm
UV-C UV-B UV-A VISIBLE SPECTRUM IR-A IR-B IR-C
Fig. 1.2 Illustration of the concept of the electromagnetic (EM) spectrum
4 E. R. Brown
Fig. 1.3 Illustration of
the concept of light as
an electromagnetic (EM) Wavelength
wave l
Electric field
variation
Magnetic field
variation
Many of the properties that electromag- Table 1.2 Divisions of the Optical Region of the EM
netic radiation demonstrates including reflec- spectrum [17]
tion, refraction and diffraction are explained Region of optical Wavelength
by considering a propagating wave compro- spectrum Division (nm/mm)
mised of electric and magnetic fields which Ultraviolet (UV) UV—C 180–
radiation— 280 nm
are at right angles, both to each other and to
‘beyond’ violet UV—B 280–
the direction of propagation as illustrated
315 nm
(Fig. 1.3). UV—A 315–
In layman’s terms, EMR can be described in 400 nm
several ways. For example: Visible radiation A sensation of 400–
(VIS)—‘light’ violet coloured 780 nm∗
light through to red
• by name e.g., microwave energy
coloured light
• by wavelength e.g., 755 nanometres (nm) Infrared (IR) IR—A (near IR) 780–
quoted in fractions of a metre (m) radiation— 1400 nm
• by frequency e.g., radio waves quoted in Hertz ‘Below red’ IR—B (mid IR) 1400–
3000 nm
(Hz)
IR—C (far IR) 3000 nm
• by photon energy, e.g. amount of energy car-
−1 mm
ried by individual photons (E ).
photon *The spectral regions defined by CIE are shorthand nota-
tions useful in describing biological effects and may not
The EM spectrum includes a specific wave- agree with spectral breakpoints for laser safety calcula-
length range referred to as the optical spectrum tions. The visible range (light) is quoted as 400–700 nm
for laser safety purposes
that includes ultraviolet (UV), visible (light) and
infrared (IR) radiation. The wave nature of EMR
allows this range to be categorised into distinc- the visual response in human eyes and therefore is
tive bands Table 1.2. described as invisible but lasers emitting UV or IR
Laser and light practitioners should note that radiation still pose a potential hazard to eyes and
ultraviolet and infrared radiation does not invoke skin. Equally the sensitivity of the human eye is not
1 Fundamentals of Lasers and Light Devices in Dermatology 5
uniform over the visible spectrum, being a smooth concept of stimulated emission to the known
function of wavelength and differing between indi- effects of spontaneous emission and spontaneous
viduals. For example, the human eye detects absorption [1]. The phenomenon of transferring
approximately 1% of light at 690 nm (red) but only discrete amounts of photon energy to skin and
0.01% at 750 nm (near infrared), effectively mak- tissues subsequently led to the medical laser and
ing wavelengths longer than 750 nm ‘invisible’ light interventions available today.
unless the light source is extremely bright [18].
Characteristics of Electromagnetic
Light as a Particle Radiation
Light has been described as an electromagnetic Wavelength
wave propagating through space yet the develop- The simplest way to think of optical radiation is as a
ment of the laser would not have been possible beam that travels as a wave. Hence the term wave-
without the realisation of the particle properties length, which for laser and light therapies is usually
postulated by Planck as cited by Nauenberg [19]. quoted in micrometers (μm) or nanometers (nm).
Planck observed that matter could only absorb or Wavelength is an important concept to under-
emit energy in discrete amounts or quanta that stand because it:
cannot be further sub-divided.
The energy of an individual photon is related • identifies a particular region of the EM spec-
to the frequency of the corresponding light wave trum, e.g., 635 nm (visible radiation)
by the relationship: • determines the ‘colour’ of the beam, e.g.,
532 nm = green light
E=hf orE=hc/l (1.1) • determines the light-tissue interactions, e.g.,
transmission or absorption by tissues
where • dictates the lens colour or lens material used
E energy of the photon in Joules (J) in protective eyewear
h the Planck’s constant (6.626 × 10−34) in Joule • relates to the amount of energy carried by the
second waves.
f photon frequency (Hz)
λ wavelength Figure 1.4 illustrates wavelength defined as
c speed of light (3.00 × 108 ms−1) the horizontal distance of two consecutive
This relationship shows that photon energy troughs or crests on the wave, written as λ
increases with increasing frequency which is (lambda) and expressed in metres (m).
vital in the context of light-tissue interactions.
For example, comparing photothermal effects Frequency
induced by longer wavelength, lower frequency Electromagnetic radiation is described as an
radiation, e.g. infrared, with photochemical inter- oscillating wave travelling through space.
actions induced by shorter wavelength, higher Therefore an alternative way to describe light is
frequency radiation, e.g. ultraviolet/blue light. by the frequency (f or ν) of oscillation of the
Planck’s observations that electromagnetic electromagnetic field. The frequency of a wave
radiation is quantised proved that light has both refers to the number of wave peaks (full wave-
wave-like and particle-like properties and subse- lengths) that pass a given point in space every
quently paved the way for the discovery of the second, expressed in cycles per second (s−1) or
photon by Albert Einstein. His understanding hertz (Hz).
that atoms and molecules gain energy by absorp- Wavelength and frequency are inversely pro-
tion and lose energy by emitting photons led to portional, that is the shorter the wavelength the
his 1917 publication in which Einstein added the higher the frequency as more wave peaks can
