1. CHAPTER 6 Molecular and Cellular Radiation biology
Ionizing Radiation and the Human body

2. Biologic damage
From x-rays, gamma, or high energy particulate radiation
ALPHA, BETA
Alpha=two protons and two neutrons attracts negatively charged electrons
Ionized atoms will not bond properly in molecules

3. Biologic Damage and relationship to
LET
RBE
OER

4. Low LET VS High LET X-ray/gamma rays
Streams of particles with no mass or charge
Penetrating
Sparsely ionizing
Interacts randomly
Damage via indirect action
Sublethal damage
Particles of mass and charge
Alpha, neutrons
What other characteristics?

5. LET RBE
Low
Risk of damage to DNA/Probability of interaction with DNA
What radiations are considered low LET?
High
Risk of damage to DNA/ DNA/Probability of interaction with DNA
Internal contamination
What radiations are considered high LET?
250 kVp of known radiation (usually x- ray) over dose of test radiation=biologic effect (Box 5-2)
Used in animals
Weighting factor of radiation used to determine biologic damage

6. OER
DOSE REQUIRED TO PRODUCE AN EFFECT IN AN OXYGEN DEPRIVED ENVIRONMENT VS A NORMAL OXYGEN ENVIRONMENT
OER IS HIGH FOR LOW LET
THE OPPOSITE FOR HIGH LET
THE DIFFERENCE IS DUE TO DIRECT AND INDIRECT EFFECT

7. DIRECT EFFECT INDIRECT EFFECT
BOTTOM LINE…..IF IONIZATION FROM EITHER EFFECTS DISTURBS THE CHEMICAL BALANCE OF THE CELL, THE CELLULAR ACTIVITY BECOMES ABNORMAL OR THE CELL CAN EVEN CEASE TO FUNCTION

8. DIRECT INDIRECT IMPACTS THE DNA OCCURS MORE OFTEN WITH HIGH LET
INTERACTS WITH WATER
OCCURS MORE OFTEN WITH LOW LET
RADIOLYSIS OF WATER/FREE RADICALS

9. SINGLE STRAND BREAK figure 6.6
DOUBLE STRAND BREAK figure 6-7/IN SAME RUNG figure 6-8
MUTATION figure 6-9
COVALENT CROSS LINKS figure 6-10
CHROMOSOME BREAKS
CHROMOSOMAL FRAGMENTS
CHROMOSOME ANOMALIES
Structural changes

10. MALIGNANT CELLS HIGHLY MITOTITIC ABNORMALLY DIVIDE LARGE NUCLEUS
Relate this to Bergonie and Tribondeau (pg 102) and direct/indirect effects

11. TARGET THEORY
THE MASTER MOLECULE
PG 125