Therapeutic Use of Light Flashcards
What is an Angstrom?
measurement of a wavelength
What is a nanometer?
measurement of a wavelength (billionths of a meter)
What is the electromagnetic spectrum?
range of all possible frequencies of electromagnetic radiation.
What is the inverse square law?
intensity of the waves from a point source varies inversely with the square of the distance from the source. I = 1/D^2
What is the cosine law?
optimal radiation of a surface occurs when the source of the radiation is at right angles to the irradiated surface.
What are the properties of light?
- Wavelength
- frequency
- reflection
- refraction
- absorption
- Photon
- Coherence
- Divergence
- monochromaticity
What is wavelength?
distance between the beginning and end of a single wave cycle.
Each wavelength of visible light has its own specific color
What is frequency?
- inversely proportional to wavelength
- higher frequencies are absorbed more superficially
- usually measured in Hz equal to one cycle per second
What is reflection?
bouncing back of light or sound waves from a surface that they strike
What is refraction?
Change in direction of a sound or light wave when it passes from one medium of different density to another
What is absorption?
substance’s ability to take in light or radiant energy.
What is a photon?
- light as it travels in bundles.
- unit of energy of a ray of light
What is monochromaticity?
all photons have a single wavelength = one color
What is coherence?
- way the wavelength travels;
- all photons travel in the same phase and direction producing a precise parallel beam of light
What is divergence?
-relative parallelism of the beam, minimal divergence over distance = collimated (parallel) or concentrated beam.
What are the factors that influence radiation intensity?
- the strength of the energy output of the source
- the distance of the irradiated area from the source
- the angle of the rays striking the area
- the size of the irradiated area
What are the sources of UV?
- The sun (heliotherapy)- near ultraviolet
- Hot quartz lamps- mercury vapor arc lamp has 2 tungsten filaments; produces complete UV spectrum
- cold quartz lamps- produces energy in the far or short UV range; primarily used for bacterial effect b/c will produce erythema
What is the measurement of UV the sun
2900-4000 angstroms
290-400 nm
What is the measurement of cold quartz?
2540 angstroms
254 nm
What is the range of the UV irradiation?
3900-1800 angstrom
390-180 nm
*divided into near UV and far UV
What is the range of the near UV?
3900-2900 A
390-290 nm
continuous with visible light
What is the range of far UV?
2900 to 1800 A
290 to 180 nm
*less visible light
What are the physiological effects of UV irradiation?
- erythema production: radiant energy in wavelengths of 2400-3200 A, 240-320 nm, produces a local erythema of the skin, caused by histological changes.
- Pigmentation of the skin due to deposits of melanin in the basal cells of the skin; it results primarily from wavelengths of 2900-3200 A, 290-320 nm
- Thickening of the horny layers of the skin
- possible carcinogenic effects on the skin
- Metabolic effect: production of vitamin D enhanced –> promotes anabolism of calcium and retention of phosphorus
- Bacterial effects: wavelengths of 2640 A are most effective–> produced by cold quartz lamp
- Systemic physiological effects occur with full body exposure, including temporary drop in blood pressure due to peripheral vasodilation and slight increase in muscle tone.
What are the indications for UV?
- diagnostic, to detect dead or deviatalized teeth and to detect ringworm infestations of the skin.
- dermatitis, including alopecia, herpes zoster, ringworm, acne.
- Surface infections within wounds and decubitis ulcers
- Osteomyelitis
- Psoriasis
What skin conditions can UV exacerbate?
- psoriasis
- acute eczema
- lupus erythematosus
- herpes simplex
- hives (urticaria)
What is an MED?
minimal erythemal dose
-shortest duration of exposure to UV radiation at a given distance between the source and the skin which is necessary to produce erythema which appears within 8 hours and disappears within 24 hours on the average untanned skin. It is expressed in seconds of exposure at a specific distance.
How do you do determine an MED?
Sleeve test! Be sure you can write out how to do it
What are the degrees of erythema?
1st, 2nd, 3rd, and 4th
What is the 1st degree of erythema?
faint erythema is perceptible after a few hours latent period; erythema disappears w/in 24 hours, leaving NO pigmentation
What is the 2nd degree of erythema?
a mild sunburn reaction; erythema is plainly visible and is followed by a slight desquamation (sloughing); erythema subsides in about 3 days; there may be SOME pigmentation.
What is the 3rd degree of erythema?
an intense reaction of severe sunburn; slight edema; desquamation of the skin WITH PIGMENTATION; subsides in about one week
What is the 4th degree of erythema?
bactericidal or destructive dose; intense reddening after a short latent period (about 2 hours); increase in edema until exudation and blistering result; persists for several days; leaves dark pigmentation
What does LASER stand for?
Light Amplification by Stimulated Emission of Radiation
What are the properties of laser?
- incapable of causing burns
- no sensation felt when using laser
- efficient- take 5 min
- cumulative effect (need 6-8 tx)
- photon energy interacts with cells to promote healing
- doesn’t affect normal cell function
- Type of laser HeNe 632.8 nm- superficial
- New lasers use super luminous diodes 830nm penetrates 3cm
What are the indications for LILT?
- cutaneous wounds and ulcers
- Acute and chronic pain relief/management of local and systemic inflammatory conditions
- Headache
- Muscle spasms
- Rheumatoid and osteoarthritis
- trigger points
- diabetic neuropathy
What are the infrared ranges on the electromagnetic spectrum?
-Far/ Nonluminous Infrared: 1,500-15,000 nm; 2 mm penetration
-Near/ Luminous Infrared; 770-1500 nm; 5-10mm penetration
Just beyond the red portion of the visible light on electromagnetic spectrum
What does infrared radiation (lamps) cause?
- Superficial heat of the tissues
- Heat conducted through radiation
- Rays absorbed or reflected- remember 90 degrees best
- per
What are the indications of infrared heat lamps?
- Subacute and chronic traumatic or inflammatory conditions
- wounds
- preparation of skin for electrical stimulalation
What are the indications for anodyne?***
- Pain in the extremities
- Numbness in the extremities (peripheral neuropathy)
- Wounds
- Carpal tunnel syndrome
- Lymphedema
- Edema
What are the physiological effects of anodyne?
- Increase ciruclation. Attributed to 890 nm. Based in part on the small release of NO from hemoglobin as RBCs pass under diode array.
- Temporarily decreases pain
- Reduces edema
- Decreases inflammation
- Increases range of motion
- Patient may regain sensation in the extremities
What are the thermal light therapies?
Ultraviolet: cold or hot quartz lamps
Infrared heat lamps
What are the non-thermal light therapies?
- Laser: infrared non-thermal
- Monochromatic infrared photo energy (MIRE): infrared non-thermal (Anodyne)
What does MIRE stand for?
Monochromatic infrared photo energy
Also known as Anodyne
