Microwave Therapy Principle Application

Microwave Therapy Principle Application Electromagnetic radiations used for the treatment of different pathologies lying between the radio waves and the infra red waves in the electromagnetic spectrum are called microwaves. These waves have a wavelength of between 1 m and 1 cm and frequencies of 300MHz-30GHz. For gaining the therapeutic effects in medicine, three frequencies are used in most parts of the world. These frequencies include:

1. 2450 MHz having wavelength of 12.245 cm.
2. 915 MHz having wavelength of 32.79 cm.
3. 433.9 MHz having wavelength of 69.14 cm

however, 2450 MHz is the widely used frequency.

Microwave Therapy Principle Application:

microwave work on the same principle on which other electromagnetic radiations work, they reflect, refract at interface and absorb as well as penetrate in the materials depending upon the properties of the material on which they fall. These waves also show the phenomena of the divergence that can be explained by inverse square law.
when microwaves are applied on the part, then there will be ionic movement, rotation of dipoles as well as distortion of the orbits. When all these processes get combined, there is production of heat.

Production:

High frequency currents are responsible for the production of the microwaves. As these currents are of very high frequency, so in order to obtain them, magnetron is used. The magnetron is responsible for the generation of high oscillating currents from high velocity motion of the electrons.
After the production, this high frequency current is carried through coaxial cable to a small antenna mounted on a reflector from which these microwaves emit. Coaxial cable has a central wire that is surrounded by an outer sheath of metal. Both are separated by means of an insulating material. Emitters are available in a wide variety. Some emitters are placed at a certain distance from the body. They are usually circular or rectangular in shape with greatest densities in the peripheral and the central parts of the area to be treated respectively.
There are emitters that are placed in direct contact with the tissues. These emitters are smaller in size and mostly they are only effective for the treatment of the cavities. Some emitters have a concave surface that fits around the body and is most effective of all the emitters.

Physiological Effects:

According to Grotthus law, of all the waves penetrating the part, only those will be responsible for producing an effect that is absorbed. So if the waves pass perpendicular, they will not be able to produce the effects that are required(cosine law). Although the depth of penetration of microwave is more than the infrared radiations butt is less than the shortwave diathermy making it unsuitable for the treatment of the deeper structures. The penetration of microwaves that is considered as  effective is 3cm. Absorption of microwaves in the tissues depends upon the content of water in the tissues. For this reason, more heat is produced in the muscles having good blood supply than fats which have decreased blood supply.
once the heat is produced, the following effects will occur in response

1. Increase metabolism
2. increase circulation
3. Receptor stimulation

Technique Of Application:

1. Prepare the apparatus by connecting the emitter to machine and power the switch on, as it requires time for the production of the waves, so it should be switched on sometime before it is placed on patient’s body.
2. Support the patient in comfortable position. Remove clothing from the part to be treated and cover the eyes of the patient by means of a wire mesh goggles.
3. Arrange the emitter on the body in such a way that it lies parallel to the part that has to be treated. The distance of emitter from body depends upon the area of the part. If the area that has to be treated is small i.e 2-5 cm, place the emitter close and if the part treated is large then place the emitter at a considerable distance i.e 10-15 cm.
4. Warn the patient to report any excessive heat that would be felt. Patient should be explained that he might fell slight warmth but no marked reaction to heat should be felt.

 Microwave Therapy Principle Application Dosage:
Dose of about 200 W/cm2 for 10-30 min is usually indicated for the treatment.
Microwave Therapy Principle Application Indications:

• Muscle spasm
• Joint stiffness
• Pain relief
• Bacterial infections
• Rheumatic problems
• joint contractures
• Myofascial trigger points

Microwave Therapy Principle Application Contraindications:

• Decreased sensations
• Decreased flow of blood
• Malignant tumors
• TB
• X-rays exposed areas
• Acute inflammatory conditions
• Testes
• Pregnancy
• Metal implant
• Cardiac pacemaker
• Joint effusion
• Hemorrhage
• Osteomyellitis

Microwave Therapy Principle Application Dangers:

• Burn

To avoid it, adequate intensity should be used and metal objects should be removed.

• Lens opacities

To avoid it, special goggles should be provided to cover the eyes.