☢️ Alpha Particle
An alpha particle (α) is a type of ionizing radiation consisting of two protons and two neutrons — the same as a helium-4 nucleus (⁴He²⁺).
🔬 Physical Characteristics
- Massive compared to other radiation (about 7,000–8,000 times heavier than an electron)
- Charge: +2
- Energy: High energy (typically 5–8 MeV)
- Range in tissue: Very short (~50–100 micrometers)
⚡ Biological Effects
- Causes dense ionization along its short path
- Induces double-strand DNA breaks
- Highly effective at killing cells with a few particles per cell
- Due to short range, must be delivered directly to or near cancer cells
🛡️ Penetration and Shielding
- Cannot penetrate skin
- Stopped by a sheet of paper, skin, or a few centimeters of air
- Dangerous only if inhaled, ingested, or injected
🧪 Medical Relevance
- Used in Targeted Alpha Therapy (TAT)
- Paired with tumor-targeting molecules for highly selective cancer treatment
- Examples of alpha-emitting isotopes: ^^213^^Bi, ^^225^^Ac, ^^211^^At
🧠 Summary
Alpha particles deliver high-energy, localized damage to cells, making them powerful tools in cancer therapy when precisely targeted. Their short path and high cytotoxicity are key advantages in modern radionuclide therapies.