ULTRASOUND (US) THERAPY

WHAT IS ULTRASOUND 

Ultrasound is defined as sound waves with higher frequency which is greater than audible sound frequency, therefore is beyond the limit of human hearing, the frequency of ultrasound is greater than 20kHz.

WHAT IS MEDICAL ULTRASOUND 

Medical ultrasound is defined as sound waves used for diagnostic and therapeutic purpose, In Physiotherapy we used medical ultrasound for therapeutic purpose for the treatment of human body tissues because ultrasound is a form of acoustic vibration which produce high energy waves that penetrate into the body tissues and produce physiological and therapeutic effects.

Medical Ultrasound has frequency range of 1MGHz to 20MGHz but in Physiotherapy we only used 1MGHz and 3MGHz ultrasound for therapeutic purpose.

WHAT IS ULTRASOUND THERAPY

Ultrasound therapy is the application of ultrasound energy by using a transducer head which consist of crystal quartz that vibrates to produce the ultrasound energy for therapeutic purpose.

COMPONENTS OF ULTRASOUND MACHINE

Components of therapeutic ultrasound machine are:

(1) MAIN SUPPLY: This is the alternating current (A.C) of 220 volt with frequency of 50Hz.
(2) TRANSFORMER: Here, a step-up transformer is used to increase the volt of the current and then the current flows to the rectifier.
(3) RECTIFIER: In rectifier, the alternating current (A.C) is converted to direct current (D.C). then the direct current (D.C) flows to the amplifier, but before passing to amplifier, it will pass through the oscillator.
(4) OSCILLATOR: The important of oscillator here is to give high frequency oscillating current to the output circuit which is amplifier.
(5) AMPLIFIER: The use of amplifier here is to increase the magnitude of the current called amplification and then the amplified current flows to the coaxial cable. 
(6) COAXIAL CABLE: Is a simple wire covered by metallic plate, which parallel to the wire, through this coaxial cable the current flows to the transducer head and the transducer head consist of crystal quartz, which vibrate to produce ultrasound energy when this high frequency currents hit the quartz, this phenomenon is called Piezoelectric effect.

PRODUCTION OF ULTRASOUND

Ultrasound waves can be produced by applying high electrical potential on certain metal compounds like Quartz or Barium titanate or Zirconate titanate crystal of a specific size, which will vibrates and produce sound which when the electric potential increased will produce the ultrasound by a phenomenon called Piezoelectric effect.

PHYSIOLOGICAL EFFECTS OF ULTRASOUND THERAPY

Therapeutic ultrasound is generally considered to be a form of deep heat. similar to any form of deep heating modality, therapeutic ultrasound has thermal effects and non-thermal effects.

• Thermal effects, include the following:

(1) Increasing the tissue temperature and local metabolism 
(2) Increasing local circulation
(3) Softening of tissues

• Non-thermal effects, include the following:

(1) Chemical effects 
(2) Biological effects 
(3) Mechanical effects
(4) Acoustic streaming: which is the undirectional movement in the tissues produced by pulsed ultrasound.

CAVITATION 

This is the phenomenon which occur when ultrasound is applied on the body after 30 seconds, a small bubbles are formed due to the ultrasound vibration inside the tissue.

There are 2 types of cavitation:

(1) Stable Cavitation: this cavitation occurs when the bubbles formed oscillate forward and backward but they are still intact with each other. this is of therapeutic use.

(2) Unstable Cavitation: this cavitation occurs when the formation of bubbles results in increasing the diameter which after few seconds cause damage to the tissue.

METHODS OF ULTRASOUND THERAPY

(1) Direct Contact method: is based on 3 different ways

Small concentric circles 

8 figure method

Parallel method

(2) Underwater bag method

(3) Water bag method.

INDICATIONS OF ULTRASOUND THERAPY

(1) Most acute and chronic musculoskeletal conditions such as:

• Sprains and strains 
• Tendinitis
• Bursitis
• Capsulitis 
• Tenosynovitis
• Fibrositis
• Myositis

(2) Muscle spasms 

(3) Joint contractures

(4) Osteoarthritis

(5) Scar tissue

(6) Neuralgia

(7) Carpal tunnel syndrome

(8) Myofascial trigger points 

(9) Calcific deposits

(10) Radiculitis.

CONTRAINDICATIONS OF ULTRASOUND THERAPY

(1) Over nerve plexuses

(2) Over eyes, heart or brain 

(3) Over reproductive organs or abdominal organs

(4) Over metal implants

(5) Near pacemaker

(6) Infection

(7) Peripheral neuropathies 

(8) Peripheral vascular disorders such as thrombosis

(9) Tuberculosis of bone

(10) For patients on blood thinning medication.

PRECAUTIONS OF ULTRASOUND THERAPY

(1) Transducer head should be continually moved in circular way throughout the treatment time to prevent accumulation of waves in one side which may cause burn, if applied for long period of time.

(2) Do not apply ultrasound on the shoulder of patient with pacemaker implanted.

(3) Use good amount of coupling medium and there should no be gap between the transducer head and skin.

(4) Avoid applying ultrasound over the anterior portion of the neck or over carotid artery.

(5) When applying more coupling medium during treatment, turn off the machine first.

(6) Transducer head should kept perpendicular to the skin.