Shortwave Diathermy

Shortwave Diathermy

1. Induction field

   • drum electrodes
   • 200 cm2
   • circumferential sleeve

2. capacitor electrodes

   • air space plates or pad electrodes

3. Induction Field diathermy

   • Magnetic field diathermy
   • pt. placed in field but not part of circuit
     • adipose doesn't provide as much resistance = greater depth of penetration
   • produces greater magnetic field
     • produces secondary eddy currents = vibrations = heat
   • produces the greatest amount of heat in muscle layer directly beneath coil
     • because muscle tissue allows for eddy currents and vibrations

4. Capacitive plate diathermy

   • two plates like electrodes
   • effects tissue under each plate
     • pt. is in the circuit
   • creates stronger electrical field
   • heating dependent on tissue's consitution
     • severely heats tissue that are poor conductors like adipose
   • produces more heating in superficial tissues and bone/muscle interface

5. Typical units

   • high frequency alternating current
     • pulsed shortwave diathermy (PSWD)
       • 27.12 MHz (wavelength = 11 meters)
   • continuous shortwave diathermy (CSWD)
     • 13.56 MHz (wavelength 22 meters)
       • rebound

6. Pulsed and continuous

   • electromagnetic energy similar to broadcast radio waves but with shorter wavelengths
   • high-frequency waves generate heat into body tissues
     • heat produces by the tissue resistance to passage of energy
     • transmission/penetration and absorption of energy by the body

7. Energy

   • electromagnetic radiation of longer wavelengths can penetrate tissue and increase temp
     • electrical and magnetic fields changed into heat through conversion
     • as radio frequency exits the drum, an oscillating magnetic field is produced in the body
       • as magnetic field passes through tissues, it causes tissue vibrations/oscillations = heat
     • magnetic field in space around electric current is directly proportional to electric current