Microwave Diathermy ELECTROTHERAPY Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

OBJECTIVES OF THE LECTURE 1. Define microwave current 2. Review the physics of the current 3. Effects of application 4. Indications 5. Contra-indications 6. Procedure of application Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

Microwave Diathermy Microwaves are a form of electromagnetic radiation, lying between the shortwaves and infrared waves. Their frequencies ranges between 300 and 30 000 MHz with wavelengths of 10mm to 1 meter. Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

Microwave Diathermy Microwave diathermy is a deep heating modality, similar to short wave diathermy but differs in its physics and mechanical properties. Physics: The clinical microthermy frequency is limited to 2.450 Mc range (10-12 cm wavelength), which is shorter than short wave diathermy. Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

Magnetron The high frequencies of microthermy are obtained from a unique device called the magnetron, which is perforated with tiny holes, through which the electrons flow into the treatment heads. The special design of the treatment heads shapes and focuses the field directly at the target area. The whole device is used to direct the waves onto the tissues. Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

Transducer Magnetron Power supply Antenna Reflector Timing circuit Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

Microwave emission by: This device is sometimes termed *the emitter, *the director or *the applicator. In this kind of treatment, the patient does not form a part of the circuit, so no tuning is necessary as in short wave application. Microwave emission by: Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

Microwave Radiation The heat produced by microthermal radiation is known to be more concentrated than that produced by short wave diathermy. Although penetration is theoretically increased with higher frequencies, absorption still depends on the target density and the intervening tissues. Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

Microwave Penetration According to the differences in absorbability of tissues, the clinical effect of microwave radiation depends on the type of tissue involved. Tissues with low water content are penetrated to a greater depth. Tissues with a high water content are penetrated to a lesser depth. Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

Physiological Effects: Absorption of the waves results in production of heat in the tissues, but differs from other heat treatment methods in the distribution of heat. Electromagnetic energy is transformed into heat energy. Microwave is not suitable for deeply placed structures. Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

Penetration of the Microwaves The effective depth of microwave penetration is about 3 cm, so the depth of heating is intermediate between that of infrared radiation and short wave diathermy. As the microwaves are strongly absorbed by water, tissues with high fluid content are heated most, while less heat is produced for tissues with low fluid content as fat or bones. Moreover, there is an appreciable heating of tissues having good blood supply such as muscles. Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

Reflection The proportion of waves reaching the deeper layers of the tissues depends also on the amount of energy reflected at the air/skin surface. As much as 50% of the energy can be reflected. Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

Indications: The clinical indications for microthermy are, more or less, similar to those for short wave diathermy. Microthermy may be preferable to short wave when more concentrated or localize heating is needed. Traumatic and inflammatory lesions, in which increase of blood supply and relief of pain and muscle spasm are required. Lesions in the superficial regions and those of high fluid content. Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

INDICATIONS (2) Traumatic and rheumatic conditions affecting soft tissues and small superficial joints. Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

INDICATIONS (3) Superficial infections such as septic fingers, carbuncles and other superficial abscesses. It heals by increased circulation with increased white blood cells and antibodies Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

Indications Pain relief ( muscular origin) Healing of the skin ( by direct application on the wound or by reflex vasodilatation to a proximal level of the wound) Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

Contraindications and precautions: Burns: As water is heated rapidly by microwaves, burning of wet skin may occur. Eyes: Irradiation to the eyes may develop opacities. Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

Contraindications Circulatory defects: Such as hemorrhage, thrombosis, phlebitis and other vascular lesions. Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

Contraindications Malignancy: Microwave diathermy should not be applied to regions of malignant growth or tubercular infections (tuberculosis). Cardiac pacemakers. Genital area ( sterility). Pregnancy (miscarriage , hemorrhage) Obesity, unreliable patients, metallic implants, hypersensitivity to heat, impaired sensation Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

Treatment procedures: 1. Selection of the treatment head (Director): Generally, two designs of directors are found: Circular: In which heat is denser at the periphery more than at the center. Two sizes of circular directors are available: Small: for small areas. Large: for large areas. - Rectangular: for elongated areas. Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

Selection of the treatment head The director selection depends on the shape and the anatomical configuration of the treated area. The actual distance from the director to the skin will determine the extent of the treatment zone. It can be detected by passing an ordinary fluorescent lamp between the treatment head and the patient’s skin. Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

2. Preparation of the patient: The target area should be bare skin. Clean the skin thoroughly to avoid refraction or burn if the skin is wet. Choose the comfortable position for the patien on a wooden stool. No towel is needed. Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

3. Monitoring the treatment: The target distance will determine the power levels, as the closer the director to the skin, the lower the power levels and vice-versa. A warm-up period must be allowed to permit the magnetron to develop enough efficiency (+-4 minutes). The desired sensation of the patient is gentle warmth. Reports of hot spots should be attended immediately either by reducing the power or increasing the distance. Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

4. Duration of treatment: Treatment by microthermy requires between 10 and 20 minutes. Generally, smaller target areas need less time, while larger ones need more. Treatment may be applied daily or every other day. Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

Advantages Operation of the machine is simple Comfortable for the patient Localised heat to small surfaces No overheating if precautions are followed Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

Disadvantages Not for deep structures Heats only one aspect of the joint No accurate measurement of the energy given and the heat received by the patient Risk of burn Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux

THANK YOU Electrotherapy Prof. Khaled Mamdouh, Ms. I. Devreux