Infrared Radiations.ppt Electrotherapy lecture for dpt department

infrared radiation used to relieve pain and improve functions

2. INFRARED
RADIATIONS

3. Learning Objectives are

4. Heat is commonly classified into 3 major categories
Chemical action associated with cell metabolism
Electrical or magnetic currents as those found in diathermy
devices
Mechanical action as found with ultrasound
The application of heat modalities is known as thermotherapy,
and methods of heating are classified as being superficial or
deep.

5. Superficial heating agents must be capable of increasing skin
temp within a range of 104-113°F.
The transfer of heat to underlying tissues occurs via
conduction, but superficial heating agents are limited to a
depth of less than 2cm.
The use of heat is indicated in the sub acute and chronic
inflammatory stages of injury.
Because the effects of heat application are essentially
opposite to those of cold, its use in the treatment of acute
injuries should be avoided.

6. When a body is heated extensively it emits
electromagnetic waves.
The biggest source of heat is sun. the sun emits
infrared ,visible and ultraviolet rays along with other rays.

These rays travel by the movement of electrons.
The waves have different frequencies and Wavelengths
and they have different properties.

7. Infrared (IR) light is electromagnetic radiation with longer
wavelengths than those of visible light, extending from the
nominal red edge of the visible spectrum at 700
nanometres (nm)to 1 mm.
This range of wavelengths corresponds to a frequency
range of approximately 430 down to 1 Hz, and includes
most of the thermal radiation emitted by objects near room
temperature.
Infrared light is emitted or absorbed by molecules when
they change their rotational-vibrational movements.

8. Infrared light is used in industrial, scientific, and
medical applications.
Night-vision devices using infrared illumination allow
people or animals to be observed without the
observer being detected.
Infrared imaging cameras are used to detect heat
loss in insulated systems, to observe changing blood
flow in the skin, and to detect overheating of
electrical apparatus.
Uses

9. •Infrared radiation is popularly known as "heat
radiation", but light and electromagnetic waves
of any frequency will heat surfaces that absorb
them.
Infrared light from the Sun only accounts for 49%

of
the heating of the Earth, with the rest being
caused by visible light that is absorbed then re-
radiated at longer wavelengths.

10. INFRA-RED RADIATION
Definition:
Infra red rays are electromagnetic waves with wavelength of
750nm-400,000nm.
infra red rays are emitted from;
the sun
gas fires
coal fires
Hot water pipes etc.
The lamps available generally emit IR radiation with wavelengths of
between 780 and 1500 nm
peak intensity 1000 nm.

11. Classification of IRR:
IRR are also classified according to their
distance from the visible spectrum as:
Near or short IRR:
Having a wavelength from 770-1500nm
Far or Long IRR:
Having a wavelength from 1500-12,000nm
11

12. Types of infra red
There are two main groups:
Non luminous generators: they provide infra red rays
only .components
 Type 1: A coil of wire wound on a cylinder of some
insulating material, such as a fireclay or porcelain. An
electric current is passed through the wire and
produces heat, infra red rays are emitted from the hot
wire and from the fireclay former, which is heated by
conduction. When the element is hot red glow is visible,
so this type of element is not perfectly non luminous.

13. Type 2: a coil of wire is embedded in the fireclay
or placed behind a plate of fireclay .The emission
of rays is then entirely from the fireclay which is
commonly painted black, and very few visible
rays are produced .both types of elements are
connected into the circuit by a screw-cap device
and placed at the focal point of a parabolic or
gently curved spherical reflector. The reflector is
mounted on a stand and its position can be
adjusted as required.

14. Type 3: consist of steel tube containing spiral of wire
embedded in some electrical insulator which is a
good conductor of heat.
Require some time to heat up before emission of
rays reaches maximum intensity.
Produces IR rays with wavelengths from 15,000nm
down to 750nm, or less if some visible rays are
emitted. The maximum emission is in the region of
4000nm.

15. Luminous Generators:
Luminous generators (incandescent lamps) consist of a
tungsten filament in a large glass envelope, which contains
inert gas at low pressure.
The filament is heated to a high temperature (around 3000°C)
by the current passed through it and so gives off a continuous
spectrum in the infrared and visible regions.
Oxidation of the filament does not occur because there is no
oxygen present, only a trace of some inert gas.
The peak emission occurs at near 1000 nm but radiation
extends from the long infrared throughout the visible to the
ultraviolet. These later radiations are absorbed by the glass
and are not therefore transmitted by the lamp.
Wavelength between 350-4000nm

17. Depth of penetration of IR:

18. Infrared light lies between the visible and microwave portions of
the electromagnetic spectrum.
"Near infrared" light is closest in wavelength to visible light and
"far infrared" is closer to the microwave region of the
electromagnetic spectrum.
The longer, far infrared wavelengths are about the size of a pin
head and the shorter, near infrared ones are the size of cells, or
are microscopic.
Far infrared waves are thermal. In other words, we experience
this type of infrared radiation every day in the form of heat! The
heat that we feel from sunlight, a fire, a radiator or a warm
sidewalk is infrared. The temperature-sensitive nerve endings in
our skin can detect the difference between inside body
temperature and outside skin temperature.

19. Shorter, near
infrared waves
are not hot at all
- in fact you
cannot even feel
them. These
shorter
wavelengths are
the ones used by
your TV's remote
control.

20. Technique of treatment:
Choice of apparatus
Preparation of patient
Arrangement of lamp and patient
Application of IR treatment
Duration and frequency of treatment

21. Patient Preparation: 
Expose the area Check skin sensation. Warn against excessive
heat. Not to touch the lamp or move near to it. Should be
comfortable and fully supported.
Lamp Arrangement: 
Position opposite to centre of area. Rays strike the skin at right
angles. Distance of lamp from the patient is 50-75 cm. Face
should not expose to rays. Eyes must be shielded.
Application: 
Warm up of 5 to 15 minutes for non luminous Start with low
intensity. After 5-10 minutes increase the intensity PT should be
at hand throughout. Encourage sweating by giving water
during treatment. Patient should not stand up or go to the cold
immediately after treatment.

22. Absorption & Penetration
Some radiations striking the surface of the skin will be
reflected and some will penetrate, to be scattered,
refracted, and ultimately absorbed in the tissues.
Close to 95% of the radiation applied perpendicular to
the skin is absorbed.
In general, water and proteins are strong absorbers of
infrared
Therefore, any radiation entering into skin is highly
complex and depends on
Structure
Vascularity
Pigmentation of the skin
Wavelength of the radiation

23. Increased intensity and increased wavelength
produces increase in penetration

At 1200 nm, 50% Infrared penetrates beyond 0.8 mm,
through skin, into subcutaneous tissues

24. Therapeutic uses of IR:
Relief of pain: Both types of infrared rays are used to relieve pain
and reduce muscle spasm. It is thought that pain is due to the
accumulation of waste products of metabolism in the tissues so
when blood flow is increased it removes the substances and thus
relieves the pain. Pain relief is also associated with muscle
relaxation.
In acute pain usually infrared rays should not be
given in the first 24 hours after injury.
Pain due to chronic lesion requires stronger
heating so treatment should be given for 30
minutes with comfortable warmth.

25. Muscle relaxation :muscles relax more easily when the tissues
are warm. Infrared radiation thus helps in achieving muscular
relaxation.
Thus after the radiations movements are easily performed
through greater range and relief of pain also makes the
exercises more efficient.
Increased blood supply: It mostly takes place in superficial
tissues and can also be used in treatment of superficial
wounds .a good blood supply is essential for healing to take
place.
Wound healing is due to the vasodilatation effects. Infrared
also helps in drainage of wounds and sinuses.

26. Dermal ulcers IR RAYS used for treatment of dermal
ulcers.
Improves healing by improving circulation.
Retarding bacterial growth.
Dehydrating wound site.
But current research says moist environment is more
effective for wound healing

27. Prior to other Treatments
Infrared is sometimes chosen as a form of heat
prior to stretching, mobilization, traction,
massage and exercise therapy. It may also be
used prior to electrical stimulation, testing or
biofeedback to warm the skin, making it more
vascular and hence a better conductor.

28. Dangers of IR
Burns: IRR can cause superficial heat burns. It appears as a red
patch which appears during or after the treatment. Burn is caused if
the intensity is too high. The patient is unable to understand the
nature of treatment, fails to report overheating ,moves closer to the
lamp or falls asleep during the treatment.
It can also occur due to defective skin sensation of the patient.
Impaired blood flow due to pressure or some circulatory defect can
also cause over heating of the part.
Electric Shock :It can take place if some exposed part of the
circuit is touched or if a live wire comes in contact with the
apparatus casing.

29. Gangrene :Heat accelerates chemical changes thus
increasing the demand for oxygen. But if there is impaired
arterial blood supply then the demand for oxygen is not met
and gangrene is developed in that area. So heat is not
applied to the area with impaired arterial blood supply
Headache :If the weather is very hot then extensive radiations
should be discontinued .If sweating does not occur it causes
headache. So plenty of fluid should be used by the patient in
hot weather to encourage sweating. Back of the head should
be protected from the radiations.

30. Faintness : extensive radiation results in fall of blood pressure
which results in faintness due to brain hypoxia. This may occur
if the patient suddenly rises up from recumbent position.
Injury to the eyes :It is wise to protect eyes from infrared rays
as they may lead to cataracts.

31. Contra indications of IR:
Infrared rays should not be used in the following
Conditions:
Impaired or loss of sensation would result in burn. If
heat is to be applied then indirect or sub thermal dose should
be given.
Skin conditions like fungus and eczema can be made
worse if infrared rays are given .
Patients using strong analgesics or narcotic drugs have raised
pain threshold thus they are unable to determine the intensity
of heat.

32. After deep X- ray therapy infra red rays should not be given
for 3 months. Deep X-ray therapy also reduces the sensation
of the area.
In skin tumors it would accelerate the growth of the tumor.
In acute infections heat would exacerbate the infective
process.
In patients with severe cardiac problem a larger area
heating would produce a demand on heart to enhance
circulation which a problematic heart is unable to
compensate and thus it is serious threat for life.