INFRARED RADIATION

INFRARED RADIATION- ELECTROTHERAPY

1. INFRARED RADIATION
- NITHIN
NAIR
-

2. INTRODUCTION
Infrared rays are electromagnetic waves.
It lies between visible light and microwaves.
Wavelength: 750 nm to 400000 nm.
Frequency: 4×10
14
Hz and 7.5×10
11
Hz.

3. TYPES OF INFRARED
RADIATION
INFRARED RADIATIONS ARE SUBDIVIDED INTO:
Type Wavelength
IRA
IRB
IRC
760-1400 nm
1400-3000 nm
3000nm –1mm
Former classification
Near or short IRR
Far or Long IRR
760-1500 nm
1500-15000nm

4. TYPES OF IR LAMPS
Two types of infrared sources are used in
physiotherapy practice:
(a) Non-luminous generators
(b) Luminous generators

5. Non luminous generators
Also known as low temperature generators.
Produces only infra-red rays of wavelength 750
nm to 15000 nm.
These generators are heated by passage of
electric current through a bare wire or carbon,
held in a non-conducting material like
porcelain, mounted in the centre of parabolic
reflector.
For recent injury, sedative effect of non
luminous generators may prove more useful.

6. Non luminous generators

7. Luminous generators
Also known as high temperature generators.
Emits visible rays, ultraviolet rays, and infra-red
rays of wavelength 350 nm to 4000 nm.
Are in the form of incandescent bulb – consist of
a wire filament enclosed in a glass bulb which
may contain inert gas at low pressure.
Filament made of tungsten as it tolerates
repeated heating and cooling.
For lesion of more chronic type the effect of
shorter rays may prove to be of value and under
these circumstances a luminous generator is
used.

8. Luminous generator in form of incandescent bulb

9. ABSORPTION
Some radiations striking the surface of the skin
will be reflected and some will penetrate,
scattered, refracted and ultimately absorbed.
Close to 95% of the radiation applied
perpendicular to the skin is absorbed.
Water and proteins are strong absorbers of
infrared.
Any radiation entering into the skin depends
on : Structure, vascularity, pigmentation of
skin, wavelength of radiation.

10. LAwS ReguLATINg
ABSORPTION Of RAdIATION
Grothus-Drapper law
Law of inverse square
Cosine law
Beer-Lambert law
Kirchhoff’s law
Wien’s law
Arndt-Schultz principle
Stefan-Boltzman law

11. PeNeTRATION
IR rays produced by Luminous generators can
penetrate into dermis and epidermis.
IR rays produced by Non-luminous generators
can penetrate the superficial dermis only.
Penetration of energy into a medium is depended
upon :
a) Intensity of the source of infrared
b) Wavelength and frequency
c) Angle at which the radiation hits the surface
d) Coefficient of absorption of the material.

12. Depth of penetration

13. PHYSIOLOgICAL effeCTS
Increases metabolic rate
Cutaneous vasodilatation
Sweating
Stimulation of thermal heat receptors.

14. THeRAPeuTIC uSeS
Relief of pain
Muscle relaxation
Increased blood supply
Increase in joint mobility
Acceleration of healing and repair.

15. DANGERS
Burns
Electric shock
Faintness or giddiness
Headache
Gangrene
Injury to the eyes
dehydration

16. TEchNiquE of APPLicATioN
Patient position: Position the patient in a
suitable, well supported position with the
area to be treated exposed.

17. TEchNiquE of APPLicATioN
Explanation: Explain the nature and effects
of the treatment to the patient
Examination: examine the skin to be treated
and test the thermal sensation and also
check for contraindication

18. coNTRAiNDicATioNS
Defective arterial blood supply
Haemorrhage
Defective skin sensation
Over pelvic region during pregnancy
Varicose veins
Known cases of tumors
Directly over the eyes
Patient whose consciousness is lowered
After deep X-ray and cobalt therapy
Acute skin disease like dermatitis or eczema
Advanced cardiac disorders.
Patients who are in extremes of age
Over testes

19. APPARATuS
Non-luminous generators take some time to
get heated, so they should be switched on
before 5-7min of treatment.
Luminous generator needs no warm up
time and can be switched on once the
patient is ready for the treatment.

20. ARRANGEmENT of LAmP AND
PATiENT
Expose the skin to be irradiated and cover or
shield the eyes.
The lamp is positioned opposite to the
treatment area such that rays strike the skin
at right angles.
Set the lamp at an appropriate distance
which is usually 50-75 cm.

22. INSTRUCTIONS AND WARNINGS
The patient is warned that he should
experience comfortable warmth
Patient should report immediately if the
heating becomes excessive
Patient should not touch any part of the
lamp or to move nearer to it

23. APPLICATION
At the commencement of the treatment, intensity
of the radiation should be low but after 5-10
minutes(after vasodilatation) strength of radiation
can be increased
Physiotherapists should be near the patient
throughout the treatment.
Sweating is encouraged

24. TERMINATION
On completion of the treatment the skin
should be checked carefully.
On palpation it may feel mildly or moderately
warm and a moderate erythema should be
evident.
After extensive irradiation the patient should
not rise suddenly from the recumbent position
or go out in cold therapy.

25. DOSAGE
For acute cases irradiation with infra-red
rays can be given for 10 to 15 minutes daily
for 1 to 3 times as per the requirement.
For chronic cases upto 30 minutes once
(daily) or on alternate days can be given.

26. REFERENCE
Electrotherapy explained (Low and Reed)
Basics of electrotherapy (Subhash Khatri)
Clayton 9
th
edition
Textbook of electrotherapy (Jagmohan Singh)
www.scribd.com (Sagar Naik’s notes)
Google
Electrotherapy evidence-based practice 12
th

edition (Sheila Kitchen)