Midterm Review

Question 1

Wavelength:

Answer 1

Wavelength:

The distance between two consecutive peaks or troughs in a wave.

Question 2

Photons:

Answer 2

Photons:

It is a basic unit of all light.

Question 3

High Optical Energy:

Answer 3

High Optical Energy:

The highest amount of energy delivered to the tissue and needed to destroy the target.

Question 4

Spot Size:

Answer 4

Spot Size:

The width of a laser beam.

Question 5

Thermal Relaxation Time (TRT):

Answer 5

Thermal Relaxation Time (TRT):

The amount of time takes a chromophore, after heating, to return to its normal temperature, by diffusion.

Question 6

EMSR:

Answer 6

EMSR:

Electromagnetic Spectrum of Radiation.

Question 7

Pulse Duration:

Answer 7

Pulse Duration:

Length of the individual pulse of light, measured in milliseconds.

Question 8

Selective Photothermolysis:

Answer 8

Selective Photothermolysis:

Controlling or light to create heat to distinct but surrounding tissue remains intact.

Question 9

What happened in 1917?

Answer 9

Albert Einstein developed the modern physics theory.

Question 10

What is the name of the first laser?

Answer 10

Theodore Maiman created the 1st laser of 694 nanometer (nm) the red spectrum of light- the Ruby Crystal.

Question 11

Which light is visible?

Answer 11

Wavelength between 400-750 nm (rainbow colors).

Question 12

What is Dr. Fitzpatrick skin typing?

Answer 12

Method of skin typing that considers skin’s complexion, hair color, eye color, ethnicity and the
individual’s reaction to unprotected sun exposure.

Question 13

What is the chromophore for targeting collagen, pigment and vascular lesions?

Answer 13

Collagen: Water or collagen
Pigment/Lentigo: Melanin’s in epidermis or dermis
Vascular Lesions: Blood or oxyhemoglobin

Question 14

What does LED stand for?

Answer 14

Light Emitting Diodes

Question 15

What does LASER stand for?

Answer 15

L-Light 
A-Amplification by
S-Stimulated 
E-Emission of 
R-Radiation

Question 16

What are the components of the laser?

Answer 16

a. Optical Reasonator:
The part of the laser that contains the active medium, also called the pumping activity.
b. The Active Medium:
The part of a laser that absorbs and stores energy. Located in the optical
resonator. What is stimulated to create light. Could be gas, liquid or crystal.
c. Delivery System:
The physical hardware needed to transfer the energy from the laser head to the treatment site.
d. The Power Supply:
Electrical source (important to check electrical requirements before purchase).
e. The cooling System:
Found on the laser hand piece, cools the skin while being treated.
f. The Software:
Found inside the machine, similar to a computer.

Question 17

What are the tissue effects?

Answer 17

a. Photo-thermal tissue reaction: When lasers energy comes in contact with tissue, the light is
absorbed by its targets chromophore & transfers to heat.
Vascular lesions, Pigmented lesions, Collagen stimulation.
b. Photo-mechanical tissue response:
Pulsed lasers can be made to create shock waves in the tissue.
Used for tattoo removal
c. Photo-chemical/ Photo-dynamic tissue response:
Also known as PDT. A chemical reaction activated by light. This reaction selectively destroys
tissue. Used in Oncology-medicine that deals with cancer.
d. Photo-ablative tissue response:
The process in which chemical bonds are broken when tissue comes in contact with certain
laser wavelengths. Mainly used for in corrective eye surgery (Lasix).

Question 18

Name the 4 characteristics of laser light?

Answer 18

a. Coherent Energy:
The laser photons travel through space temporarily and spatially.
Single unit of energy, in one direction, not scattered, precise and adjustable.
b. Monochromatic Energy
Light of one wavelength = one color, can be visible or invisible.
c. Collimated Energy
Laser light remains for extended distance, harnessed to produce a focused spot.
d. High Optical Energy:
The highest amount of energy delivered to the tissue and needed to destroy the target

Question 19

What is the unit of energy used to measure energy?

Answer 19

Joules

Question 20

What are the laser properties?

Answer 20

(ARTS)
a. Absorption:
The uptake of one substance into another.
The physical process in which a part of the energy of the laser is attracted to a chromophore
And converted into either heat, acoustic response, chemical reaction or cellular stimulation.
b. Reflection:
The process in which a part of the laser light is rejected by a flat, shiny surface as a mirror,
jewelry or instrumentation. Caution! Reflected laser beam can cause burns, fire and eye
damage.
c. Transmission:
Depends on the wavelength of the light.
• Shorter (300-400nm)
• Superficial penetration < 0.1mm in epidermis
• Longer (400-1300nm)
• Penetration into epidermis/dermis through liquid/gas laser
d. Scattering:
The physical process that causes the laser beam to deflect in some new directions.

Question 21

What are the 3 different types of lesions targeted by laser?

Answer 21

Vascular lesions, Pigmented lesions, Collagen stimulation.

Question 22

What does IPL stand for?

Answer 22

Intense Pulsed Light.

Question 23

What % of overlap must be done for an effective hair removal treatment?

Answer 23

20%

Question 24

List and explain the 3 types of cooling?

Answer 24

a. Pre-Cooling:
Lower epidermal temperature prior to emission of thermal energy.
DCD cryogen spray, Ice and/or chilled gel, Aluminum roller.
b. Parallel Cooling:
Allows for epidermal cooling during the emission of the energy during a laser/light procedure.
c. Post- cooling:
Applied after the pulse to reduce epidermal injury: ice, cold air, chilled sapphire window, cool
aloe, and cryogen spray of gas.

Question 25

Explain the difference between ablative and non-ablative?

Answer 25

a. Ablative:
• Removal of surface material of the body
• Usually associated with a presence of a wound
• Long downtime
• Penetrates deeper

b. Non-ablative:
• Not removing the surface tissue
• Short downtime
• Penetrates superficially