Along with ultrasound, shortwave diathermy are the two primary deep heating modalities used in physical therapy.



<-- Write you own html,js and css code -->


Like sound when some forms of electromagnetic energy contacts matter it may be reflected, refracted, or absorbed



Laws Governing the Behavior of Electromagnetic Energy


Law of Grotthus-Draper

There is an inverse relationship between energy absorption and energy penetration Tissues must be able to absorb a requisite amount of energy for physiologic reaction can occur.

Inverse Square Law

Doubling the distance with radiant light sources typically increases the spread of the light so that it covers a larger area (magnitude of 4). Doubling the distance will decrease intensity by 25% of the original amount.


Cosine Law

At angle of incidence close to 0 degrees, most of the light energy is transmitted across the boundary and very little of it is reflected. As the angle is increased to greater and greater angles, we would begin to observe less refraction and more reflection. This law provides rationale for administering electromagnetic energy perpendicular to the target tissue.




Capacitive Method
versus
Inductive Method



Capacitive SWD units use condenser plates to transfer oscillations of electric field between the plates. The target tissue is placed between the condenser plates and acts as a capacitor to store electrical charge, resulting in local heating of the tissue.

Inductive SWD units contain coils which creates a magnetic field. This field projects forward into the body and generates a circular, electric field within the target tissue. Typically, the coils are confined to flexible cables or within a rigid drum.




In addition to the general contraindications to heat. Given the introduction of specific electromagnetic energy, there are additional contraindications and precautions.