Electromagnetic Radiation: Diathermy and Laser

Electromagnetic Spectrum: Types of Radiation
- Radio Waves
- Microwave
- Infrared
- Visible Light
- Ultraviolet
- X-ray
- Gamma Ray
Wavelength and Energy Relationship
- Long wavelength corresponds to low energy and low frequency.
- Short wavelength corresponds to high energy and high frequency.
- The radiation associated with radios, visible light, and nuclear blasts are all forms of electromagnetic radiation but differ in energy levels.

EM fields are used therapeutically and can be applied externally to the body.
Non-ionizing Radiation:
- This means the energy does not have the ability to change the chemical structure of tissues. It can still promote tissue healing in therapeutic ranges.
- Heating effects can occur in therapeutic applications.
Ionizing vs Non-ionizing Radiation:
- Ionizing Radiation: Example - X-rays (it's critical to exercise caution around ionizing radiation due to its ability to damage tissues).

Definition:
- Diathermy means “to heat through.” It refers to heating that occurs from within body tissues due to the absorption of EM energy.
Sensation:
- Unlike superficial heat treatments like hot packs, diathermy generates heat internally, leading to no immediate sensation in superficial structures.

Diathermy can:
- Heat deeper tissue than hot packs.
- Cover larger treatment areas compared to ultrasound.
- Avoid concentrating heat at the periosteum, mitigating the risk of burns.
- Require minimal application time and does not necessitate clinician contact with the patient.

Molecular Interaction:
- Water acts as a dipole molecule within tissues + presence of metals can increase heating during diathermy.
Thermal Effects:
- Vasodilation.
- Increased nerve conduction velocity.
- Elevation of pain threshold.
- Increased soft tissue extensibility.
- Enhanced circulation in muscular structures.
Non-thermal Effects:
- Increased microvascular perfusion, enhancing oxygenation and nutrient delivery.
- Alterations in cell membrane function.

Continuous Short Wave Diathermy (CSWD): Higher doses delivering consistent heat.
Pulsed Short Wave Diathermy (PSWD): Lower doses delivered intermittently.
Capacitive Method: Involves two conducting electrodes generating an electric field.
Inductive Method: Utilizes an inductive applicator to create oscillating magnetic fields.

When applying diathermy, a towel needs to be situated on the skin to absorb moisture, optimizing conductivity.

Dosage Levels and Applications:
- I - Lowest: Just below sensation of heat; used for acute inflammation.
- II - Low: Mild heating sensation; beneficial for subacute inflammation.
- III - Medium: Moderate heating; aimed at resolving inflammation.
- IV - Heavy: Vigorous heating, comfortable; used for chronic conditions.
Duration: Typically between 15-30 minutes; peak temperature can increase 3 cm below the skin after 15 minutes.

Do not apply diathermy near:
- Metal materials (including pacemakers, IUDs).
- Pregnant individuals.
- Areas around the eyes, testicles, or cancerous tissues.
- Individuals with hemophilia, impaired mental states, acute inflammation, or bleeding.
- Avoid contact with wet tissues or moist areas.

Definition and Characteristics:
- Laser light is made of electromagnetic waves and photons.
- Monochromatic: All photons emitted are of a single wavelength.
- Collimated: Light travels parallel with a uniform beam profile.
- Coherent: All emitted photons travel in the same direction uniformly.

Chamber Design:
- Contains an active medium (gas, liquid) with an electrical energy input.
- Enables molecular excitation, leading to photon emissions.
- Includes a resonant cavity with mirrors, emitting a small percentage of energy as laser light.

Gotthus-Draper Law: Light must be absorbed to produce an effect on matter; if not absorbed, it penetrates deeper tissues.
Low-Level Laser Therapy (LLLT): Involves using low-power light energy (visible red and near-infrared), activating cellular mechanisms and enhancing tissue repair along with pain modulation.

Helium Neon (HeNe): Emits red light within the visible spectrum.
Gallium Arsenide (GaAs): Emits wavelengths outside the visible range; both considered low-power lasers with no thermal effects.
Effectiveness: Pain modulation and reduction of inflammation.

High Power: > 500 mW causing thermal effects, useful for cutting or cauterizing; also used in therapy.
Conditions and Outcomes: Reference studies indicate beneficial results for TMD, spine pain, and shoulder dysfunction.

Enhanced Tissue Repair: Increases ATP synthesis, mRNA production related to pro-collagen.
Inflammation Management: Increases vasodilation, decreases ischemia, promotes circulation by delivering nutrients and debris clearance.
Effect of Wavelength: Visible range (650 nm) is effective in reducing inflammation and neutrophil migration.

Dermatological wounds, tendinopathies, myofascial pain, rheumatoid arthritis (RA), osteoarthritis (OA), neck and low back pain, TMJ disorders, and carpal tunnel syndrome (CTS).

Avoid using lasers over:
- Eyes or malignancies.
- Abdominal and pelvic areas of pregnant women.
- Hemorrhagic areas and thyroid glands.
- Patients with epilepsy.

Caution advised for:
- Areas of infection, bruised muscle, testicles, regions near the vagus nerve or cardiac areas in patients with heart diseases, photosensitive skin areas, and open growth plates.