Electromagnetic Radiation Flashcards
what is EMR?
radiation composed of electric and magnetic fields that vary over time and are oriented perpendicular to each other. transport energy through space. do not require a medium through which to travel
characterized according to its frequency and wavelength which are inversely proportional to each other
what’s low freq EMR?
nonionizing
cannot break molecular bonds or produce ions
what’s high freq EMR?
is ionizing
can break molecular bonds to form ions
what’s intensity?
- proportional to energy output of the source
- inverse square of the distance of the source from the patient
- cosine of the angle of incidence from the beam with the tissue
- greatest when energy ouput is high, source is close, beam is perpendicular*
clinical effects?
determined primarily by the radiation’s frequency and wavelength range
infrared radiation produces what? advantages are?
- produces superficial heating
+= does not require direct contact with body
shortwave and microwave can be used for what? when applied at a low-average intensity using a pulsed signal, it may?
- used to head deep tissues
- decrease pain and edema/fascilitate tissue healing
laser is used for what?
to promote tissue healing, control pain and inflammation
what are physiological thermal effects?
IR radiation and continuous short wave and microwave diathermy can increase tissue temperature
IR lamps –> superficial
continuous shortwave diathermy –> superficial and deep
what are physiological nonthermal effects?
UV radiation, low levels of pulsed diathermy, and light do not increase tissue temperature
Proposed mechanisms:
- can cause changes at the cellular level by altering membrane function and permeability
- promote binding of chemicals to the cell membrane
- can cause proteins to undergo changes that promote active transport across cell membranes and to accelerate ATP synthesis and use
UVRadiation: freq range? wavelengths? 3 bands? thermal effect? depth of penetration depends on what? physiological effect? primarily used for what? contraindications? adverse effects?
freq= 7.5x10^4 - 10^15 Hz
wavelengths 400 to below 290nm
Bands:
UVA(Long)= 320-400nm
UVB(Middle)= 290-320nm
UVC(short)= less than 290nm
UV radiation does not produce heat, therefore effects are non-thermal
Depth of penetration depends on:
- intensity reaching the skin
- wavelength and power of source
- freq
- size of area
- thickness and pigmentation of skin
- duration of treatment
Produces erythema:
sleeve test= smallest does that produces erythema that appears in 1-6 hours and fades without a trace within 24
Tans the skin –> increased production and upward migration of melanin granules and oxidation or premelanin in the skin
Epidermal hyperplasia (72 hours) [prostaglandin precursors –> increased DNA synthesis by epidermal cells –> cellular hyperplasia]
vitamin D synthesis
bactericidal (UVC)
primarily used for treatment of psoriasis and other skin disorders
contraindications= irradiation of eyes, skin cancer, pulmonary TB, cardiac/kidney/liver disease, systemic lupus erythematosus, fever
precautions= photosensitizing medications and dietary supplaments, photosensitivity, recent x-ray therapy, no does of UV Rad should be repeated until the effects of the previous dose have disappeared
adverse effects= burning, premature aging of skin, eye damage
how to apply UV Rad
warm up lamp place opaque UV googles on pt and PT remove clothing/jewelry from area wash/dry area to be treated cover all areas not needing treatment position the area to be exposed comfortably position the lamp stay close/give a call bell direct the beam, start the timer following treatment, observe the area, document
What is diathermy?
shortwave radiation frequency range of 3kHz-300MHz
wavelengths 1m-100km
because it falls within the radiofreq range, it could interfere with radiofreq signals used for communications. –> FCC allocated 3 SWD bands. ***27.12MHz is most commonly used
continuous or pulsed modes, both can generate heat
can heat deeper tissue than a superficial agent and can heat larger areas than US
inductive coils/ capacitive plates are used to apply
diathermy: inductive coils?
coil–> alternating electrical current flows–> produces magnetic field perpendicular to the coil–> induces electric eddy currents in tissue–> charged particles in tissue osscilate–> friction–> elevation in tissue temp
coils can heat both superfiscial and deep tissue
2 forms of coils: cables and drums
diathermy: capacitive plates?
current flows from one plate to the other through the patient
produce more heat in the skin and superficial tissues, whereas whereas inductive coils produce more heat in deeper structures
thermal effects: increase tissue temp. vasodilation, increase rate of nerve conduction, increase soft tissue extensibility
nonthermal effects = altered cell membrane function: alters ion binding in the cell membrane, alters Ca ion building, can accelerate cell growth and division when it is too slow/inhibit it when it is too fast
