Ultrasound therapy uses high frequency sound waves to deliver thermal and non-thermal effects to tissues. It can be used to treat a variety of musculoskeletal conditions. The device generates frequencies between 1-3 MHz which determine treatment depth. Coupling methods like gel or immersion in water are required to transmit ultrasound to the body. Treatment parameters like duration, intensity and duty cycle are set based on the target tissue and therapeutic goals. Precautions must be taken when using ultrasound near the spine or growing bones. Proper maintenance ensures safe and effective use of these devices.

1. DESIGN &
FUNCTIONING OF AN
ULTRASOUND THERAPY
DEVICE
By акаш радж

2. ULTRASOUND THERAPY
◦ Ultrasound (US) is a form of mechanical energy (not electrical), and therefore,
strictly speaking, not really electrotherapy at all, but does fall into the Electro
Physical Agents grouping. Mechanical vibration at increasing frequencies is
known as sound energy. The normal human sound range is from 16 Hz to
something approaching 15-20,000 Hz (in children and young adults). Beyond
this upper limit, the mechanical vibration is known as ultrasound. The
frequencies used in therapy are typically between 1.0 and 3.0 MHz (1 MHz = 1
million cycles per second).

3. THERAPEUTIC ULTRASOUND TREATMENT
AREA
US heats a limited area- About the size of a catsup
packet
Treatment area should be 2 to 3 times the size of the ERA
For larger areas, divide the area into
smaller zones

4. COUPLING METHODS
Direct Coupling
Immersion Method
Pad/Bladder Method
◦ Ultrasonic energy cannot pass through the air
◦ A coupling is required
◦ Medium should be water-based
◦ Coupling method should confirm to the body area
◦ The body area should be clean & relatively hair-free

5. DIRECT COUPLING
◦ Gel or Creams
◦ Only used approved coupling agents
◦ Apply liberally to area
◦ Remove air bubbles by passing sound head over area(before power is increased)
◦ Move the head slowly – 4cm/sec
◦ Moving the head faster deceases heating
◦ If the patient describe discomfort, decreases the output intensity

6. IMMERSION TECHNIQUE
◦ Used to treat irregularly shaped areas
◦ The limb is immersed in a tub of degassed water
◦ If tap water is used, increase the output intensity by 0.5 w/cm2
◦ Transducer is held approx. 1” from the body part
◦ Avoid the formation of air bubbles

7. PAD(BLADDER) METHOD
◦ A mass of conducting gel
- commercial pads
- self-made bladder
◦ Conforms to the treatment area
◦ Commercial pads to help limit the size of the treatment area

8. OUTPUT PARAMETERS
Output frequency
Duration
Duty cycle
Output intensity
OUTPUT FREQUENCY
◦ Determines the treatment depth
◦ 1 MHz output – deep (5 to 7 cm) tissues
*Rotator cuff, vastus intermedius,gastric
3Mhz output
-superficial(upto 3cm deep)tissues
◦ Patellar tendon, MCL,branchialis
◦ Remember that adipose tissue is transparent to ultrasound.

9. TREATMENT DURATION
◦Depend on:
◦ Size of treatment area
◦ Output intensity
◦ Therapeutic goals
◦ Vigorous meeting
-1MHz output – 10 to 12 minuts
-3MHz output-3 to 4 minuts
◦OUTPUT INTENSITY - at a 100%duty cycle
◦ 1.75W/cm output
◦ Apporximately 4 min treatment required to increase tissue temperature 4*C

10. DUTY CYCLE
◦ Determines the proportion of thermal and non-thermal effects
-high duty cycle: Predominantly thermal effects
-low duty cycle: Predominantly nonthermal effects
◦ Thermal effects used in subacute and chronic conditions
◦ Nonthermal effects may be beneficial in acute stages

11. ULTRASOUND & ELECTRICAL STIMULATION
“COMBO TREATMENT”
◦ Theorectically combine the benefit of the two treatment
◦ Used to treatment :
-trigger point
-muscle spasm
◦ output parameters
-thermal ultrasound
-motor level electrical stimulation

12. PRECAUTIONS
◦ Symptoms may increase after initial treatments
◦ Use caution when applying ultrasound around the spinal cord,
espically after laminectomy
◦ The use of ultrasound over metal implants is not contradicted
- keep the sound head moving
◦ Use caution when applying ultrasound over epiphyseal plates of
growing bone.

13. MAINTENANCE
Daily maintenance:
◦ Clean ultrasound head and transducer face as recommended by the
manufacturer
Monthly maintenance
◦ Check all electrical cords for frays or kinks
◦ Check the sound head cables for frays or kinks
◦ Clean the transmitter face as recommended by the manufacturer.