ultrasound therapy

1. ULTRASOUNDTHERAPY

2. INTRODUCTION
Ultrasound is the modality that is used for a number of purposes
• diagnosis,
• destruction of tissues
• therapy
Ultrasound refers to mechanical vibrations which are essentially the same as sound
waves but of a higher frequency. Such waves are beyond the range of human hearing
and therefore also be called ultrasonic.
Frequency- above audible range 20-20000 HZ
A generator that can be set between 1 and 3 MHz affords the therapist the treatment
flexibility.

3. Depth of penetration
• Ultrasonic energy generated at 1 MHz is
transmitted through the more superficial
tissue and absorbed primarily in the deeper
tissues at depths of 3 to 5 cm.
• Suitable for person with high fat content
• 3 MHz, the energy is absorbed in the more
superficial tissues with a depth of pene-
tration between 1 and 2 cm

4. Medical frequency of Ultrasound
• Physiotherapy Equipment -0.75 MHZ , 1 MHZ , 1 MHZ, 1.5 MHZ and 3.3 MHZ
• Dignostic – 1 MHZ-10 MHZ
• Surgical Eq1uipment- 1 MHZ-5 MHz

5. PROPERTY OF SOUND WAVE
• Sonic waves are a series of mechanical
compression and rarefactions in the
direction of travel of the wave, hence they
are called longitudinal waves

6. PROPOGATION AND SPEED OF ULTASOUND
Z ∝ 𝜌𝑉
Z = impedance ofTissue
𝜌 = 𝐷𝑒𝑛𝑠𝑖𝑡𝑦
V =Velocity Of Propagation
Velocity
Velocity of ultrasound Is the rate of successive zone of compression travel through
medium
Propagation occur as a result of oscillation of particle about their mean position
which transfer energy through medium
Density
Propagation is controlled by density of medium
Air- 344ms−1
Water – 1410ms-1
Muscles – 1540 ms-1

7. PRODUCTION OF ULTRASOUND
For 1 MHz machine a vibrating source with a frequency of one million cycles per second is needed
. This is achieved by using
• a quartz crystal
• barium titanate crystal
• lead zirconate crystal
• nickel-cobalt ferrite crystal
These crystals deform when subjected to a varying potential difference, this is called piezoelectric
effect

8. PRODUCTION OF ULTRASOUND
• Power supply on
• Energy to oscillator circuit
• Produces oscillating voltage
• Cystal inside transducer embedded between
the link electrode and metal front plate
respond to oscillating voltage which fed
through coaxial cable
• Crystal expand and contract at same frequency
at which the current changes polarity
• Metal front plate of the treatment head moves
backward and forward generating a stream of
compression waves that form sonic beam

9. PRODUCTION OF ULTRASOUND
• Intensity controller controls the amplitude of
alternating voltafge thereby controls
amplitude of sonic waves
• Intensity is expressed in watts per square
centimeter (W/cm2 )
Mark space ratio
Mark-space ratio, or mark-to-space ratio, is
another term for the same concept, to
describe the temporal relationship between
two alternating periods of a waveform
Mark space ratio=
Both PW is duration of alternating period
𝑃𝑊𝑂𝑁
𝑃𝑊 𝑂𝐹𝐹

10. TRANSMISSION OF ULTRASOUND