week 6 cellular effects Flashcards
what are the 3 unique characteristics of a laser?
it is monochromatic, coherent and collimated.
What are the biological effects largely dependent on?
wavelength, power density and fluence (ED)
what is ‘wavelength’?
The distance between 2 peaks
what is ‘power density’?
The amount of power per unit area (usually expressed as watts per cm 2)
what is ‘fluence’?
Otherwise known as Energy density! The measurement of energy in an area
how do you measure PD?
PD = watts / beam area
What are 4 types of tissue interactions that can occur?
electromechanical, photoablative, photothermal & photomechanical
What is an electromechanical tissue interaction?
the rupture of tissue, high power beams, small pulses (NS), ED of 100 joules per CM 2
what is a photoablative tissue interaction?
breaking of intramolecular bonds (YAG & C02)
What is a photothermal tissue interaction?
conversion of energy into heat, controlled by the target absorption (water, melanin & blood)
what is a photomechanical tissue interaction?
The uptake of chemicals by target cells (PDT)
What effect on tissue does a temp of <43 deg have?
bio-stimulation LLLT
What effect on tissue does a temp of 45 deg have?
cell mortality (if sustained)
What effect on tissue does a temp of 50 deg have?
reduced enzyme activity
What effect on tissue does a temp of 52 have?
edema, enzyme changes
What effect on tissue does a temp of 60 have?
protein denaturation, coagulation (vein treatments)
What effect on tissue does a temp of 80 have?
cell membrane becomes permeable collagen denaturates
What effect on tissue does a temp of 100 have?
vaporization, ablation, tissue carbonation. hair
at around what temperature does protein coagulation occur?
45 deg
What temp does LLLT not go above?
43 degs
What does LLLT do to cellular function? (S&I)
stimulate or inhibit cell function
what are some physiological effects of LLLT?
bio-stimulation, increase blood circulation & vasodialation, increase ATP production, analgesic effects (chronic pain), anti inflammatory, stimulates wound healing, increase collagen, increase macrophage activity, stimulates nerve functions
How do you calculate the ED?
ED = Watts X Time / Beam area.
