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FUNDAMENTALS OF PHYSIOTHERAPY

ashok0509004
December 17, 2011

FUNDAMENTALS OF PHYSIOTHERAPY

6.01 - 6.03 SHORT WAVE DIATHERMY

ashok0509004

December 17, 2011
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  1. 6.01 – 6.03 SHORT WAVE DIATHERMY TEACHER : Dr. MONALI

    MYANGAR (PT) VERIFIED BY : Dr. ASHOK CHAUDHARY (PT) VALIDATED BY : Dr. POONGUNDRAN P. (PT)
  2. WHAT IS A HIGH FREQUENCY CURRENT ? • Frequency is

    more than 10000 cycles/second. • Used as Therapeutic Current. • Produce deep heat in the tissues. E.g. Short Wave Diathermy Long Wave Diathermy Ultra Sound Microwave Diathermy 2 6.01 - 6.03 Short Wave Diathermy
  3. INTRODUCTION • The word “diathermy “ is Greek word that

    means “treatment through heating” . • It is applied by using electromagnetic waves (radio-waves) that produce heat. 3 6.01 - 6.03 Short Wave Diathermy
  4. • The short-wave diathermy current has a frequency of between

    107 to 108 Hz and wave-length between 30 and 3 meters. • But commonly used for medical purpose has frequency of 27.12 MHz and wave- length of 11 meters. 4 6.01 - 6.03 Short Wave Diathermy
  5. PRINCIPLE • It is not possible to produce high frequency

    current required for SWD purpose by mechanical device which causes sufficiently rapid movement to produce High frequency current. • Therefore, this type of current is obtained by discharging condenser through an inductance of low ohmic resistance produces the high frequency current with desired frequency & wavelength. 5 6.01 - 6.03 Short Wave Diathermy
  6. • Short- wave diathermy causes induction of high-frequency current in

    the body by alternating electric and magnetic fields and thus heating the superficial and deep tissue. 6 6.01 - 6.03 Short Wave Diathermy
  7. CIRCUIT • There are two main circuits of SWD and

    both are coupled to get proper effect. • Machine/oscillator circuits: produces high frequency current and amplifies its intensity. • Patient/resonator circuit : it is coupled with the machine circuit and transfers electrical energy in form of electrostatic and electromagnetic fields to the patient. 7 6.01 - 6.03 Short Wave Diathermy
  8. OSCILLATOR CIRCUIT • Also Known as Generator or Machine Circuit.

    • High frequency current generated by circuit, which consist of a capacitance & inductance whose dimensions are arranged to allow electron oscillation at precise frequency, i.e- 27.12 MHZ. 10 6.01 - 6.03 Short Wave Diathermy
  9. • The frequency F at which circuit will oscillate depends

    only on electrical size, Which is the product of Capacitance (C) & Inductance (L) : • F=1/√2π.LC • Main function is to give an amplified AC , that has a very high frequency of 27.12 MHZ & Wave Length of 11.06 meter. 11 6.01 - 6.03 Short Wave Diathermy
  10. OSCILLATOR CIRCUIT • Main Supply : • Transformer : •

    Step Down Transformer : • Step Up Transformer : • Triode Valve : • Grid Leak resistance : • Oscillator : 12 6.01 - 6.03 Short Wave Diathermy
  11. RESONATOR/PATIENTS CIRCUIT • Resonator Coil : • Variable Condenser :

    • Electrodes : 1) Pad electrode 2) Disc electrode 3) Cable electrode • Ammeter/Neon lamp: • Tissue : 13 6.01 - 6.03 Short Wave Diathermy
  12. RESONATOR/PATIENTS CIRCUIT • The patients circuit is coupled to the

    machine circuit by inductors and high frequency current is produced by electromagnetic induction. • Maximum current will flow if both the circuits are in resonance with each other. • And for this product of the conductance and inductance must be same in both the circuits. 14 6.01 - 6.03 Short Wave Diathermy
  13. • Machine’s frequency = C1*L1 • Patients circuits frequency =

    C2*L2 • For maximum power output, C1*L1 = C2*L2 15 6.01 - 6.03 Short Wave Diathermy
  14. FACTORS AFFECTING CAPACITANCE • Material of capacitor. • Surface area

    of capacitor. • Material of dielectric medium. • Width of dielectric medium (distance). 16 6.01 - 6.03 Short Wave Diathermy
  15. INDICATIONS FOR CIRCUIT IN TUNE/ TESTING APPRATUS • Indication light

    on the equipment glow • An ammeter wired into the circuit shows maximum reading that is diminished by turning the knob • A neon tube placed within the electric field will glow at maximum intensity when both the circuits are in resonance. 17 6.01 - 6.03 Short Wave Diathermy
  16. PRODUCTION OF HEAT IN CELL • There are 3 methods:

    o TO AND FRO/IONIZATION o In our body, there are number of charged molecules. In presence of SWD field, there will be attractive and repulsive forces causing acceleration of charged molecules along the lines of electric force. The charged molecule oscillate and kinetic energy is converted into heat. 18 6.01 - 6.03 Short Wave Diathermy
  17. o DIPOLE METHOD o water and various other proteins are

    dipolar molecules in our body. Under the influence of alternating field of SWD, the positive pole of the molecule moves towards the negative pole of the electric field and vice-versa. This ultimately causes rotation of the dipoles and heat production. 19 6.01 - 6.03 Short Wave Diathermy
  18. o NON-POLAR MOLECULES – Fat and other insulators are called

    non-polar molecules. In them the electrons are firmly held to nucleus and are not displaced easily. The alternating electric field causes distortion of the electron cloud and thus production. All these procedure produces heat in accordance to Joules’ law. 20 6.01 - 6.03 Short Wave Diathermy
  19. References: 1. Clayton’s Electrotherapy: Theory and Practice - Forster &

    Palastanga (Ninth Edition) 2. Electrotherapy Explained – John Low & Ann Reed (Third Edition) 3. Electrotherapy Simplified – Basanta Kumar Nanda 4. Basics of Electrotherapy – Subhash Khatri 21 6.01 - 6.03 Short Wave Diathermy