Radiobiology – Comprehensive Cheat Sheet (with Formulas & Key Concepts) – Summary Document

RADIOBIOLOGY CHEAT
SHEET (WITH EQUATIONS
& FORMULAS)
[Document subtitle]

, 1. Cell Biology & Radiation Basics
1.1 Cell Structure & Sensitivity
 Nucleus is the most radiosensitive organelle.

 DNA is the critical target → damage leads to mutation, apoptosis, mitotic death.

 Chromosomes show dicentrics, rings, acentric fragments after radiation.

1.2 Radiobiological Law
Law of Bergonié & Tribondeau:
Radiosensitivity ↑ when cells are:
 Highly mitotic

 Undifferentiated

 Rapidly dividing
Example: Lymphocytes (very sensitive), neurons (resistant).

1.3 Types of Radiation Damage
 Direct action: ionization of DNA directly (important in high-LET).

 Indirect action: radiolysis of water → ROS (OH•) → DNA damage (dominant in
low-LET, e.g., X-rays).



2. DNA Damage & Cell Survival
2.1 DNA Damage Types
 Base damage

 Single-strand breaks (SSBs)

 Double-strand breaks (DSBs) → most lethal

 Crosslinks (DNA-DNA, DNA-protein)

2.2 Cell Survival Curve
For mammalian cells, the curve follows Linear-Quadratic Model:
2)
𝑆𝐹 = 𝑒 −(𝛼𝐷+𝛽𝐷
 α component = single-hit killing (linear)