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Basic Radiology - Coggle Diagram
Basic Radiology
1. Radiation Physics
Ionizing Radiation: High-energy, short-wavelength radiation capable of removing electrons to form ions, which can cause chemical and biological changes in tissues.
Classification:
Electromagnetic: No mass or charge (e.g., X-rays, gamma rays).
Particulate: Has mass (e.g., alpha and beta particles, neutrons).
Sources of Radiation:
Natural (Background): Cosmic rays (outer space), terrestrial (soil/rocks), radon gas, and internal (potassium-40 in the body).
Artificial (Man-made): Medical/dental X-rays, radiotherapy, nuclear power, and industrial radiography.
X-ray Production: Occurs in a vacuum-sealed X-ray tube where heated cathode filaments release electrons (thermionic emission) that strike a tungsten anode. This converts kinetic energy into heat (99%) and X-ray photons (1%) via Bremsstrahlung and characteristic radiation.
Key Properties: Penetrating power, differential absorption (dense tissues appear radiopaque/white; soft tissues appear radiolucent/dark), and ionizing ability.
2. Radiation Biology
Cellular Interaction: Radiation transfers energy to atoms, causing ionization that can damage DNA, change cell function, or cause cell death.
Mechanisms of Damage:
Direct Effect: Radiation hits the DNA molecule directly, causing strand breaks or base damage.
Indirect Effect: Radiation interacts with water molecules (radiolysis) to create highly reactive free radicals (e.g., hydroxyl radicals) that then attack DNA. This is the most common mechanism since the body is 70–80% water.
Tissue Sensitivity: Rapidly dividing cells, such as those in bone marrow and reproductive organs, are most sensitive to damage.
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3. Radiation Protection
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Clinical Methods: Use of aluminum filtration, rectangular collimation, fast digital receptors, lead aprons/thyroid collars, and maintaining a distance of at least 1.5m from the tubehead