Radiobiology 2016

Direct and Indirect action of radiation in biological systems - particles

Indirect Action

H

OH ·

O

H

Direct Action

most important for densely ionising radiations (high LET)

High Doses: OER = 3.0 15 MeV Neutrons

Low Doses: OER = 2.2  particles

1.0 1.0

1.0

1.0

OER = 1.0

OER = 1.6

0.9 0.1

0.1

Hypoxic

Hypoxic

0.1

2 nm 4 nm

Hypoxic

OER

Aerated

0.8 0.01

0.01

Hypoxic

0.01

Aerated

Aerated

Aerated

0.7 0.001

Surviving fraction 0.001

2.5

0 0.5

1.0

1.5

2.0

3.0

25

10 2

15

20

30

0

5

1.0

2.0

3.0

6

0

4

Dose (Gy)