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PULSED SHORTWAVE DIATHERMY - Coggle Diagram
PULSED SHORTWAVE DIATHERMY
Definition of Pulsed Short Wave Diathermy.
Frequency and Wavelength of pulsed short wave diathermy.
Production of pulsed short wave diathermy.
Methods of application-capacitor and induction electrode using pulsed short wave diathermy.
Parameters of pulsed short wave diathermy.
Physiological effects of pulsed short wave diathermy.
Indications and contraindications of pulsed short wave diathermy.
Therapeutic effects of pulsed short wave diathermy.
Precautions and Potential harmful effects of treatment.
Dosage of pulsed short wave diathermy
PSWT employs the same operating frequency as traditional SWD
ie. 27.12MHz
The output from the machine is pulsed such that the ‘on’ time is considerably shorter than
the ‘off’ time,
thus the mean power delivered to the patient is relatively low
even though the peak power
(i.e. during the on pulses) can be quite high (typically around 150 – 200 Watts peak power
with modern machines,
though some still go up to 1000W).
Pulsed Electormagnetic field (PEMF),
Pulsed Radiofrequency (PRF),
Pulsed Electromagnetic Energy (PEME)
MAIN MACHINE PARAMETERS
Pulse Repetition Rate (Hz or pps)
the no of pulses delivered per second
Variable output on most if not all machines
Can usually select from a range of preset options (depends on machine)
e.g. Megapulse
100 / 200 / 400 / 600 / 800 pps
e.g. Curapulse 403
26 / 35 / 46 / 62 / 82 / 110 / 150 / 200 / 300 / 400 pps
There is no current evidence that the ‘number’ of pulses per second is critical
– what is important however is that
by varying the pulse rate, the mean power delivered to the tissues can be
varied
Pulse Duration (Width) (microseconds)
the duration (time) of each ‘ON’ phase
The pulse durations are very short – measured in microseconds (millionths
of a second)
is a variable parameter on many but not all machines
It is sometimes fixed (most usually on the machines that deliver both pulsed and continuous shortwave energy, and most commonly ‘fixed’ at 400 microsec)
The term pulse duration is preferable to pulse width (commonly used)
as it is a time based measurement rather than a size.
Examples of pulse durations in some commonly encountered PSWT
machines :
Curapulse 419 - fixed at 400 microsec
Curapulse 403 - 65/82/110/150/200/300/400 microsec
Megapulse - 20 / 40 / 65 / 100 / 200 / 400 microsec
Power (Peak and Mean)
power delivered from the machine
(during pulse and averaged)
Mean Power (MP)=Pulse duration (PD) X Pulse repetition rate (PRR) X Peak pulse power (PP)
SHORTWAVE CYCLES PER PULSE
The number of cycles completed during each pulse (or ‘on’ phase) remains quite high.
Pulse Duration ---- No of cycles completed per pulse
65 microsec 1,763 cycles
100 microsec 2,712 cycles
400 microsec 10,848 cycles
check slide
MARK : SPACE RATIO (DUTY CYCLE)
Short Pulse (65 microsec )
: Low Repetition Rate (26 pps)
Machine is ‘ON’ for about 0.0017 sec per sec
(0.17% duty cycle)
Mark:Space Ratio of about 1:590
Long Pulse (400 microsec)
: High Repetition Rate (400 pps)
Machine is ‘ON’ for about 0.16 sec per sec
(16% duty cycle)
Mark:Space Ratio of about 1:6
Power
Pulse peak power = 150-200 Watts
Applied mean power = 0.1 – 30+ Watts
MACHINE OUTPUT
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