pulsed short wave therapy Flashcards
what is short wave therapy?
form of electromagnetic therapy used for therapeutic purposes esp in physiotherapy
-application of high frequency electromagnetic energy - generates heat in body tissues
what type of radiation does SWT use & what is the most common used frequency?
non -ionizing radiation
-27.12 is the most commonly used frequency
what are examples of physiological effects of SWT ?
-tissue temperature increases
- increased blood flow - vasodilation
-increased venous and lymphatic flow
-changes in physical properties of tissues
-muscle relaxation
-analgesia
how do non-ionising radiation interact with biological tissue to cause healing?
the electro-magnetic waves interact with molecules within the tissue -charged ions & proteins, water etc
what happens to charged molecules eg ions and proteins within the tissue when they come into contact with the electromagnetic waves?
- causes the ions to be accelerated along the lines of the electric field
-electric field is oscillating, which causes the ions to oscillate or vibrate
-ions kinetic energy is converted to heat
what happens to dipolar molecules eg water & proteins when they come into contact with electromagnetic waves?
-high frequency current causes rotation of the dipolar molecules.
-since the electric field is oscillating, the molecules will rotate at the same frequency
-heating occurs due to the frictional drag between the molecules
how does electro-radiation wave therapy interact with fat? (non polar molecules?)
- paths of orbiting electrons become distorted
-very little heat is produced
what body tissues or fluids have high ions and dipolar molecule content and what does this indicate?
-blood
-muscle
-sweat
- they are responsive to short wave therapy
what are safety risks to applying short wave therapy?
if patient has metal implants or metal on clothes etc - would heat up a lot and could cause burns
what is a capacitor?
a device that stores electrical energy
what is an inductance coil?
electronic component that stores energy in the form of a magnetic field when an electric current flows through it
describe this diagram - top vs bottom circuit
top circuit
- mains power supply turns on current (50/60Hz)
-then the current is converted to high frequency (27.12 MHz) by high freq generator
-then the current is amplified ie increased
-then current is passed to induction coil
bottom circuit
- signal travels between the 2 induction coils
-current is then passed through the tissue via 2 electrodes
what is the capacitive method?
- when the patients tissue is placed between the 2 electrodes, essentially acting like a capacitor
-oscillation and rotation of the molecules in the tissue produces heat
what 3 ways can the capacitance method be applied?
contraplanar
Coplanar
longitudinal
describe the contra planer application of the capacitance method?
-electrodes are placed on either side of the limb
describe coplanar application of the capacitance method?
electrodes are parallel with the longitudinal section of the body part
what is the longitudinal application of the capacitance method?
-when electrodes / plates are placed at each end of the limb
what is the inductive method of applying SWT?
when the capacitor in the ‘patient circuit’ is connected in parallel with another inductance coil mounted in a single electrode rather than 2 electrodes like the capacitance method
what 2 currents does the capacitive technique give rise to?
conduction current
displacement current
what does the rise in tissue temp associated with the application of SWT depend on?
specific absorption rate
what is the specific absorption rate?
the rate at which energy is absorbed per unit mass of tissue (Watts/Kg)
what is the name of the current that the induction techniques produce?
an Eddy current
what factors does the specific absorption rate depend on?
-tissue
-tissue density
-electric/ magnetic field strength
what is pulsed short wave therapy?
results in a patient receiving a lower dose of SWT
what is the difference between continuous and pulsed SWT?
-continuous - SWT is switched on at the beginning of the 20 min treatment time and remains at the same intensity for the 20 mins
-pulsed mode- SWT energy is switched on at the beginning of 20 mins, but then intermittently switched on and off
what are examples of precautions for SWT?
-wooden non conducting furniture
-awareness of microshock sensitive patients
-awareness of other implanted devices eg hearing aids, cochlear implants etc
