- once it has entered the tissue, laser is scattered by divergence
- reflected and refraction, and it is attenuated by absorption
- once absorbed, increases kinetic energy
What are the penetration depths of LLLT?
1-2mm for red visible light
2-4mm for short infrared
How is LLLT absorbed in the tissues?
- by photosensitive molecules called chromophores in cell wall or mito
- cytochromes within the cell mitochondria
Is laser thermal of chemical?
What electrode is visible red wave lengths and what is it absorbed by?
- absorbed by melanin, Hb and myoglobin
- very pigment specific
What does the diode gallium arsenide give off?
- non visible wavelength
- 600-1200 nm
- less pigment specific
- water and mm and other organic chromophores in cell membrane
What does the permeability of tissue effet of LLLT?
- the effectiveness of absorption and stimulation
- calcium ions are transported across the cell membrane setting the cell function- healing effects
LLLT has two main functions
- potobiostimulation v photobioinhibition
- Arndt- Schultz
- low LLLT- photostimu
- High LLLT- photoinhib
What are the direct and indirect effects of LLLT?
direct- response in tissue to absorption
- indirect effect-normal metabolic process in the deeper tissue is sped up from the energy absorption in the superficial structures
Therapeutic uses of LLLT?
Tissue healing of LLLT?
- wave length- young et al 660, 820 and 870 wavelengths encourage macrophages to release factors that stimulated fibroblasts. 880nm was inhibitory
- pulse frequency - 700Hz - more organised fibroblasts
LLLT effective for what sort of pain relief
- mmskeletal disorders
- neurogenic conditions- trigeminal, post traumatic
- trigger/ acupuncture points
- nerve conduction rate
What is the effectiveness of LLLT?
- ongoing discussion about the effectiveness
What are the principle of application?
- most applied directly to skin by hand held applicator- light pressure can increase the penetration depth and squeeze blod out of the capillaries
- thers held in a rigid stand 30 cm away- covers large area
- cluster probes- emit at diff wavelengths
EYEWEAR needs to be worn
Application of LLLT
- - applicator at right angles- maximum penetration
- if contact not wanted- glad wrap or hold off
- if area is large reprosition applicator and start again
1cm2 is one application
What is visible red laser used for?
- superficial conditions such as wounds, ulcers and other skin conditions
What are infrared to treatment
- they are used for deeper mmskeletal structures
Energy density of LLLT
treatment given in J/cm2
- other names for this are energy density or radiant exposure
- mean power output in mW is usually fixed. When divided by the fixed area of the beam, it gives the power desity or irradiance in mW/cm2
- when this is x by time for it is applied it is given in j/cm2
- usual range is 1-10J/cm2
- higher dosages are usually recommended for subcutaneous tissues
- dosages described are those applied to the skin surface. The dosage depth is unknow
What is the pulse output?
- pulse duration is adj such that low pulse rates have long pulse lengths
- low frequencies and long durations are used for acute condition and higher pulse rate and shorter pulse duration for chronic conditions
Area of treatment?
- discrete lesions should be treated directly over the afected part
- if treating wounds and larger areas, the part is divided into 1cm2 by a grid
- painful areas are usually treated at the point of max pain- subcutaneous
What are the dangers and contraindications?
- beam application to the eye
-neoplastic tissue- increase acitivty
- uterus of preg woman (unclosed fontanelle)
- haemorrhaging or infected tissue
What is the warning for LLLT?
During laser treatment you should feel nothing other than the pressure of the applicator against your skin. If you feel any discomfort, you must inform me immediately and the treatment will be terminated. Side effects from laser therapy include dizziness, nausea or an initial increase in pain. They are short term only and usually only occur if the treatment dose is too high. Please do not move or touch any of the equipment during treatment. If you become uncomfortable tell me immediately.
Do you understand what I have said? Do you have any questions? Are you happy for me to proceed?
- output 10, 20, 30 or 40mW
- Ga Al as diode
- 830nm wavelength
- continuous output mode
- 60 sec time
NEED TO KNOW THIS!!!
mW- milli watts Power density= mean power/ area of beam = mW/ cm2 Power density x n# seconds = number of jules/ cm2- energy density EXAM!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Mean power = 10mW
Beam area= 0.125
Power density = 10/0.125 = 80 mW/cm2
Time 50 sec= PDx time= enery density = 80 x 50 = 4000mJ/cm2 = 4J/cm2