MICROWAVE DIATHERMY for diagnostic and therapeutic equipments - ii

Microwave diathermy

2. Microwave diathermy
Objectives
•discuss the working of the generator
•Identify indications and contraindications
•describe procedure of treatment and
techniques of application of micro wave
diathermy
•identify Advantages, disadvantages and
danger

3. Microwave diathermy
•Electromagnetic radiation which lies between the shortwave and the
infrared regions of the electromagnetic spectrum.
•Frequency of microwave is 300 – 30000 MHz
•The wavelength is 10mm – 1m.
•Frequency and wavelength used for therapeutic purposes
•2450 MHz is the frequency that is widely available for therapeutic
purposes.
•Effective penetration of it is about 30mm
•But the lower frequencies have the ability to penetrate more.
Frequency Wavelength
2450 12.2
915 32.8
434 69.1

4. 4
Microwave Diathermy Unit
•A= Power Switch
•B=Timer
•C=Output Meter (indicates relative output in watts)
•D= Power Output Level Knob
•E= Amber Light-Warming up / Red Light- Ready

5. Circuit

6. Microwave diathermy: Production
•High frequency current is fed to a device called
magnetron.
•Magnetron is a special type of thermionic valve
characterized by centrally placed cathode,
which is surrounded by a circular metal anode.
•Primary function of the magnetron is to
generate oscillating currents directly from high
velocity electron motion.

7. Microwave diathermy: Production
•These currents are passed to the
antenna that emits microwaves.
•The antenna is a piece of wire that is
mounted in front of a metal reflector
which emits the waves in one direction.
•Output of the microwave energy can be
controlled by varying the power supply
to the magnetron.
•The frequency produced depends on
the structure of the magnetron and it is
therefore fixed.

8. 8
MWD Applicators (Electrodes)
•Circular Shaped Applicators
–4” or 6”
–Maximum Temperature At Periphery
•Rectangular Shaped Applicators
–4.5 x 5” or 5 x 21”
–Maximum Temperature At Center

9. Microwave diathermy: Physiological
effects
•Heat production in the tissues is the
prominent effect.
•Water containing tissues such as muscles
absorb more rays than the tissues like fat and
bone.
•Skin is heated up to a greater extend than the
other tissues. However, 50% of rays are
reflected from the air-skin surface.

10. Microwave diathermy: Therapeutic
uses
•Pain
•Muscle spasm
•Chronic inflammation
•Delayed healing
•Chronic infection
•Fibrosis

11. Microwave diathermy: Indications
•Disorders of musculoskeletal conditions
–Sprains
–Strains
–Capsular lesions
–Degenerative joint disease
–Chronic rheumatoid arthritis
–Stiffness in superficial joints
–Haematoma

12. Microwave diathermy: Indications
•Superficial inflammatory or infective
conditions
–Tenosynovitis
–Bursitis
–Synovitis
–Infected surgical incisions
–Carbuncles
–Abscesses

13. Contraindications
•Over malignant tissues
•Over ischemic tissues
•Moderate and excessive oedema
•Over wet dressings and
adhesive tapes
•Metallic implants
•Pace makers
•Over growing bone
•Haemorrhagic areas
•Tuberculous joints
•Impaired thermal sensation
•Unreliable patients
•The eyes
•Recent radiotherapy
•Hypersensityvity to heat
•Acute infection or inflammation
•Obesity
•Analgesic therapy
•Venous thrombosis or phlebitis
•Pregnancy
•Menstruation
•Acute dermatological
conditions
•Severe cardiac conditions
•Blood pressure abnormalities

14. Dosage
–Duration: 20 minutes is the most favorable
treatment time.
–Intensity: Only safe measure is the sensation of
warmth described by the patient.
–Frequency of treatment: treatment may be given
daily or on alternative days. It is most beneficial if
given once or twice daily.

15. Techniques
•Variation in the application
depends on the size and the
heating pattern of the
emitter 9 director/
transducer/applicator/radi
ator).

16. Microwave diathermy: Application
•The patient should be positioned in well comfortable
manner with adequately exposing the part to be
treated.
•Explain the procedure to the patient.
•Check for contraindications.
•Localize the site to be treated.
•Test the skin for hot and cold sensation.
•Pair of microwave goggles should be given to the
patient.
•Select the type of director and fix it to the machine.
•Check all the connections.

17. Microwave diathermy: Application
•Emitter should be position to get a beam of radiation
which strikes the skin at right angles. Emitter- skin
distance is about 2 cm.
•Test the machine by placing the therapists hand
under the director.
•Switch on the machine after setting the timer
•Instruct the patient to not to look at the applicator
and warn him regarding the burns.

18. Advantages and disadvantages
•Simplicity of application and operation of machine
•Accurate localization of heat.
•Low frequency microwaves causes selective heating
in muscles.
•Deep structure cannot be heated.
•It can heat only one aspect of a joint.
•Skin burns may develop rapidly.

19. Thank You..