Chapter 1: Introduction To Photothermolysis Flashcards
What does Laser stand for?
Light Amplification Stimulated Emission Radiation
What is laser light? (The electromagnetic spectrum of radiation)
Laser light is really a sophisticated method of converting light into energy for use as in devices with many applications in nearly every major industry
What is sunlight?
Sunlight is a beam or a ray of light that is made up of a variety of invisible and visible forms of electromagnetic energy
—commonly called EM energy
What is a wavelength?
It is measured from the distance from the top of one wave (amplitude) to the top of the next.
Visible Spectrum of Light:
Light is measured by its _____________ in _____.
Wavelength in nanometers.
What is the wavelength of violet light?
400nm-420nm
What is the wavelength of Indigo?
420nm-440nm
What is the wavelength of Blue?
440-490nm
What is the wavelength of green?
490nm-570nm
What is the wavelength of yellow?
570nm-585nm
What is the wavelength of orange?
585nm-620nm
What is the wavelength of red?
620nm-780nm
What is one wavelength equal to?
One wavelength equals the distance between two successive wave crests or troughs
What is Ionizing radiation (ionizing vs non-ionizing radiation)
- occurs at short wavelengths <400nm
- strips the elctrons from transport media
- alters cellular function
- causes mutation on DNA (ex: X-rays, ultraviolet UV rays)
Http://youtu.be/rApXQmkpk-Q
What is non-ionizing radiation? (Ionizing vs. Non-ionizing radiation)
- it can NOT strip electrons from transport media
- can NOT alter cellular function
- greatest risk is Ocular (eye) damage. (Ex: medical lasers, IPL machines)
Properties of laser light:
- lasers have unique properties that are not seen in any other type of energy form
- normal white light (flashlight or light bulb) is made of a multitude of visible and invisible infrared wavelengths merged and created white light that’s can quickly disperse in space within a short distance.
What are the 4 effects laser light can have on tissue of the skin (tissue effects)
- Absorption
- Reflection
- Transmission
- Scatter
What is photothermolysis (how do we use light energy?)
- the absorption of light by chromosphere’s (hemoglobin, melanin or water)
- the transformation of absorbed light into heat (thermo)
- the breakdown of cells (lysis)
What is a chromophore?
Melanin, Collagen, Hemolglobin, and water
Particles in our body which absorb light
What are the 5 parameters of photothermolysis?
- Wavelength
- Pulse width (pulse duration)
- Exposure time
- TRT: thermal relaxation time
- Fluence
What is a wavelength?
-the distance between two successive wave crests or troughs
What is Pulse width (pulse duration)?
-the amount of time the laser is emitted on the skin measured in nanosecond and millisecond.
What is Exposure Time?
-should be less than or equal to the time necessary for cooling of the target structure
What is TRT
- thermal relaxation time of a mass is the time required for it to cool down to the normal temp of the surrounding tissue
What is fluence?
-the energy delivered per unit area
What is the process of selective photothermolysis?
- The use of light energy to target a particle that’s is in our body which absorbs light.
- These particles are called chromophores
Chromophore facts: (2)
- there are many types of chromophores
- studies have mapped the wavelength absorption of each chromophore
Selective Photothermolysis is achieved by: (3)
- Wavelength
- Pulse width/ duration
Thus causing…
- Exposure Dose/ Joules
How is photothermolysis achieved through wavelength?
-selective absorption- the longer the wavelength, the deeper the penetration
How is photothermolysis achieved through pulse width/ duration?
- heat confinement
- pulse duration is measure in nanoseconds (ns) or milliseconds (ms) it is the timing of the light energy or how long the laser is actually on the skin
How is photothermolysis achieved with exposure dose/ joules?
-fluence refers to the energy of the pulsed laser beam it is expressed in joules per square centimetre (J/CM2) and refers to energy x time
Energy absorption targeting 3 main chromophores:
- Melanin
- Hemoglobin
- Water
5 components of photothermolysis:
- Wavelength
- Joules
- Pulse width
- TRT
- Cooling
Light transmits ___________
Energy
-it is an electromagnetic wave that carries energy
What is the wavelength range of visible light? (Light characteristics)
400nm - 700nm (visible light)
Wavelength diagram (another example)
Electromagnetic Scale Diagram:
What is the “secret” or key to the creation of laser light?
-the secret to the creation of laser light lies within a machines general design, computer software, cooling system and optics
What is an optical resonator?
- Within every laser device is a tube or optical resonator
- the resonator contains a medium, usually a gas, solid or liquid, that is responsible for the creation of light
What is a resonator containing medium made of?
- a gas medium can be made up of argon, carbon dioxide, or helium-neon gas particles
- a solid medium is usually a synthetic crystal made up of yttrium aluminum garnet (YAG) particles and then doped with certain elements such as holmium, neodymium, and thulium or erbium electrons.
- Lasers are named in reference to their medium
Describe how turning on a laser machine creates laser light:
- turning on a laser machine creates a high voltage electricity that stimulates an intense light source from within that stimulates an intense light source from within the machine.
- the electrons within the laser medium becomes stimulated by this electricity, then collide with mirrors placed on opposite ends of the laser tube and spontaneously produce identical photons.
- turning on a laser machine creates a high voltage electricity that stimulates an intense light source from within that stimulates an intense light source from within the machine.
- the electrons within the laser medium becomes stimulated by this electricity, then collide with mirrors placed on opposite ends of the laser tube and spontaneously produce identical photons.
As a result…
All of the photons travel at the same frequency, parallel to each other and in phase in a collimated, coherent, monochromatic beam of light.
Properties of laser light: (3)
- Coherent light
- Monochromatic Light
- Collimated Light
Define Coherent light: (properties of laser light)
This means that all the light waves are travelling in the same direction and in unison with each other.
Define monochromatic light: (properties of laser light)
- normal light contains all of the visible colors of light and appears white.
- when light is passed through a prism or water droplet, one can actually see the full spectrum of visible light in a rainbow
- laser light referred to as monochromatic (mono means one) it is made up of one wavelength and one colour and can be wither visible or invisble
- each different colour of light acts differently when exposed to different tissue and will create a unique clinical effect
Describe a Ruby Laser device:
- 694nm
- highly melanin attraction
- best suited for skin type I and II (very light skin)
- not penetrate as deeply as other laser machines
- less effective for deep follicles and dark skin
Describe an Alexandrite laser device:
- 755nm
- 2nd highest melanin attraction
- effective in skin type I to IV
- using cooling system specially for darker skin type (IV)
- most devices have a built in cooling system
Describe the Diode Laser 810nm
- Has variety of pulse duration (pulse width)
- Effective on all skin types
- Long term hair reduction
Describe the ND-YAG 1064:
Doesn’t have high melanin attraction
- very safe for darker skin type
- long pulse ND-YAG laser can penetrate 3-5nm deep. Higher fluence and aggressive cooling is needed in order to see the best result without damaging surrounding skin
- ND-YAG causes more discomfort due to deep penetration
Describe Tattoo removal lasers:
- due to absorption curve of laser versus the different colours of tattoo ink, each colour mayu require a different laser for proper clearance.
- The result is not guaranteed and fair amount of trauma to the skin is necessary for deep tones
Describe Q-Switched ruby laser device
- 694nm
- clears green, black and blue pigment (multiple treatment required)
Describe the Q-switched Alexandrite Laser
- 755nm
- ALSO CLEARS GREEN, BLACK AND BLUE PIGMENT AND REQUIRES MULTIPLE TREATMENTS
-Describe Q-switched ND:YAQ Laser
- 1064nm
- Treats black and blue pigment and has an advantage over the Alexandrite because it can be used on darker skin types
- although the YAG is an effective device, blistering, bleeding, and bruising are often some of the side effects of the treatment
What is IPL?
- stands for INTENSE PULSE LIGHT (quite different from a laser)
- a computer generated system which emits a broad spectrum of light wavelength from 420nm-1200nm.
In IPL, what are cut off filters used for?
- cut off filters are used to block out WL’s of a light below the filter number selected and only those WL’s of light above the filter numbers to pass through
- IPL system is very versatile
Describe how IPL effects or treats chromophores:
- one wavelength is absorbed by a chromophore, heat is released
- has an advantage of treating more than one specific chromophore at the same time
Describe the IPL light source, and wavelength spectrum:
- it is high intensity light source which emits polychromatic, non coherent light
- IPL has a broad wavelength spectrum (420-1200nm)
Does IPL emit incoherent or coherent light?
-Laser emits monochromatic, coherent light
Depth of penetration diagram:
Colour coded hand pieces: Blue:
Acne (AC 420)
Colour coded hand pieces: Green:
Pigmented and Vascular Skin (DUAL VP)
Colour coded hand pieces: Yellow:
Skin Rejuvenation (SR 580)
Colour coded hand pieces: Red:
Hair reduction (HR 365)
*each light (wavelength) will penetrate skin differently. Blue is most superficial and red is deeper
What is Light Intensity defined by?
-Light intensity is defined by the energy density FLUENCE, which is measured in joules per centimetre squared (J/cm2)
What can joules be compared to?
-sun rays. It is how much energy/ heat is being delivered to the skin
How do darker skin or clothing influence energy absorption?
- The darker the skin or clothing, the more optical energy (light) is absorbed
- darker surfaces heat up faster, thus they require a lower fluence
What are joules?
-The unit of measurement used to describe the intensity (fluence) of the light energy per cm2
Joules can also be referred to as ______ or _______ _______.
Fluence or light energy
Fluence or energy density refers to:
- the amount of optical (light) energy delivered to a certain area measured in J/cm2
- It defines the intensity of the light pulse
- The technician will dictate in parameters, on your sharpLight modality, as to how many joules will be used during the treatment
- They may be increased or decreased depending on the clients skin type and comfort level
What is Pulse duration?
Pulse duration = conduction/ induction
-the pulse duration/ pulse width determines the aggressiveness of the treatment and is often measured in milliseconds (ms)
—the unit of measurement can vary depending on the technology being used
What are we heating and how are we heating it? (Short vs long pulses)
-shorter pulses are more aggressive and longer pulses are less agressive
Are longer or shorter pulses safer for darker skin?
- For dark skin and hair, longer pulses are safer
- for light skin and hair, short pulses are more effective
DPC technology allows you to:
- offer your client a personalized treatment that will cater to their needs effectively and safely
- our goal is to be specific. It is important to achieve a therapeutic temperature only in the targeted area, while leaving the surrounding tissue intact.
When was selective photothermolysis developed?
-in 1983 by Anderson and Parrish
-relates to the correct use of chromophore:
—wavelength selection for specific chromophore
—bigger impact lesion
—selectively achieve damage temperature only on lesion
What is “our mission”?
- to be specific
- to provide selective treatment where we achieve therapeutic temperature only in the targeted tissue, while leaving the surrounding tissue intact
Problem: Selective heating =/ specificity
On one hand: chromophore selective heating
On the other hand: heat conduction to healthy tissue
Solution: Thermal Relaxation Time (TRT)
What does TRT mean?
Thermal Relaxation Time
-the time it takes the heat to conduct away from the lesion
For example:
- If TRT = 1 sec
- After 1 sec of heating, we will damage healthy tissue
What should be done to specificity to protect the tissue?
-increase specificity to protect the tissue
What are the benefits of cooling?
- Higher cooling= higher specificity
- Cooling slows heat conduction to the healthy tissue
Clinical manifestation of cooling:
- decreases heating rates on healthy tissue
- the heating of the lesion is not effected
- the lesion will heat up fast where as the healthy tissue will heat up slow, therefore the different rates of heating improve specificity
Describe contact cooling hand pieces:
-contact cooling prevents superficial skin burns, adds comfort to the patients treatment and provides added confidence to the practitioner
Effect of contact cooling on the skin diagram:
