Definition
Radiobiology is the study of the interactions between ionizing radiation and biological systems, from molecules to whole organisms. In radiation oncology, it provides the scientific foundation for using radiation to kill cancer cells while protecting normal tissues.

Core Concepts

  • Ionizing radiation: Radiation with enough energy to remove tightly bound electrons from atoms, creating ions. Examples: X-rays, γ-rays, protons, carbon ions.

  • Therapeutic ratio: The balance between effective tumor control and acceptable normal tissue toxicity. Radiobiology helps maximize this ratio.

  • Critical target: DNA is considered the most important target; damage here correlates best with cell death and mutation.

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