Direct Ionization Caused By:
Indirect Ionization Caused By:
DNA and Radiation
Ionizing Radiation at the Cellular Level
Causes breaks in one or both DNA strands or;
Causes Free Radical formation
Is this change good or bad?
Our Bodies Are Resilient
DNA damage is most important and can lead to cell malfunction or death.
Our body has ~ 60 trillion cells
Each cell takes “a hit” about every 10 seconds, resulting in tens of millions of DNA breaks per cell each year.
BACKGROUND RADIATION causes only a very small fraction of these breaks (~ 5 DNA breaks per cell each year).
Our bodies have a highly efficient DNA repair mechanisms
Dividing Cells are the Most Radiosensitive
Rapidly dividing cells are more susceptible to radiation damage.
Examples of radiosensitive cells are;
Blood forming Cells
The intestinal lining
This is why the fetus has a exposure limit (over gestation period) of 500 mrem (or 1/10th of the annual adult limit)
At HIGH Doses, We KNOW Radiation Causes Harm
High Dose effects seen in:
Radium dial painters
Atomic bomb survivors
Populations near Chernobyl
In addition to radiation sickness, increased cancer rates were also evident from high level exposures.
Effects of ACUTE Exposures
Roentgen-Based on the quantity of electrical charges produced in air by X or Gamma photons 1R=2 billion pr
RAD-Radiation Absorbed Dose is the work energy resulting from the absorption of one ROENTGEN or 6.24 E5 Mev