Cells exposed to radiation can die in several distinct ways:

  1. Mitotic Catastrophe

    • The most common form after conventional radiotherapy.

    • Cell tries to divide with unrepaired DNA → chromosome mis-segregation → death in mitosis.

  2. Apoptosis (Programmed Cell Death)

    • Energy-dependent, organized process: DNA fragmentation, cell shrinkage, membrane blebbing.

    • Important in lymphocytes, thymocytes, and some tumors.

  3. Senescence

    • Permanent loss of ability to divide, though cells remain metabolically active.

    • Plays a role in late normal tissue injury.

  4. Autophagy

    • “Self-digestion”: lysosomal degradation of cell contents.

    • Sometimes protective, sometimes leads to death.

  5. Necrosis (less typical for standard RT)

    • Passive, unregulated death → swelling, rupture, inflammation.

    • Seen at very high doses or in hypoxic/necrotic tumors.

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