Microwave Diathermy: Advantages and Disadvantages

This article explores the benefits and drawbacks of microwave diathermy, including its basic principles.

What is Microwave Diathermy?

The term “diathermy” originates from the Greek language, meaning “through heating.” It involves applying a high-frequency electromagnetic current to generate deep heating within body tissue. This induced heat produces physiological effects beneficial for therapeutic purposes. Diathermy can help relieve pain, accelerate the healing of infections, and promote relaxation.

Microwave diathermy specifically utilizes microwave frequencies ranging from 300 to 3000 MHz, with corresponding wavelengths of 1 meter to 10 mm. Common microwave frequencies used in these devices include:

• 2450 MHz frequency with 12.33 cm wavelength
• 915 MHz frequency with 32.7 cm wavelength
• 433.9 MHz frequency with 69 cm wavelength

The image above illustrates a microwave diathermy generator and its internal components. As shown, it comprises a power supply, timing circuit, magnetron, and transducer. The device directs the waves onto the targeted tissues. The antenna, with its specialized head design, focuses the field directly at the treatment area. High-frequency waves are generated by a magnetron with tiny perforations through which electrons flow towards the treatment heads. These waves then pass through the space and are absorbed, heating the tissues at the desired depth.

The effective depth of microwave penetration is approximately 4.5 cm, placing it between infrared (~2 cm) and shortwave diathermy (>5 cm).

The treatment parameters for microwave diathermy include:

• Spacing of applicators: 2-6 cm for small treatment areas, 10-15 cm for large treatment areas
• Time of treatment: 20 to 30 minutes
• Frequency of treatment: Daily or on alternate days, depending on the patient’s response, condition, and availability.

Benefits or Advantages of Microwave Diathermy

Here are the key benefits of using microwave diathermy:

• The technique and machine operation are straightforward and user-friendly.
• It doesn’t require pads, electrodes, capacitor pads, or inductive coils, as is the case with shortwave diathermy.
• It produces a more localized and concentrated heating effect compared to shortwave diathermy.
• It offers more superficial tissue heating, depending on the specific type of tissue involved. It is strongly absorbed by tissues with a high fluid content, such as muscle or blood, leading to significant heating at a superficial depth of around 0.7 cm. Tissues with low fluid content, such as fat or bone, experience greater penetration.
• The patient doesn’t become part of the circuit in microwave diathermy, eliminating the need for tuning as required in shortwave diathermy.
• It’s a very comfortable treatment method for patients.
• Overheating is preventable when proper precautions are followed.
• Low-frequency microwaves cause selective heating in muscles.

Drawbacks or Disadvantages of Microwave Diathermy

Here are the drawbacks to consider when using microwave diathermy:

• No metal should be within 4 feet of the microwave diathermy device, as it can interfere with the signal.
• Various factors influence heat absorption, including water content, frequency, distance, and the principles of reflection, refraction, absorption, and the inverse square law.
• It’s not suitable for treating deep structures within the body.
• Only one area of the body can be treated at a time.
• There’s a risk of skin burns if treatment procedures and safety guidelines are not strictly followed.
• Patients should avoid looking directly at the applicator during treatment to prevent burns. It is recommended that patients wear microwave goggles.