1. Dose, Biological Effects, and Exposure Models
David Weisz – Nuclear Forensics

2. …so what exactly is dose?
1 Gy = 100 rad = 1 J/Kg
1 Sv = 100 rem (usually) = 1 Gy x weighting factor

3. Rem vs. Sv
rem = dose (rads) x Q
Sv = dose (Gy) x wR

4. Linear Energy Transfer

5. Cellular Radiation Effects
What is the most likely target for ionizing radiation?

6. DNA

7. So how does radiation effect DNA?

8. Acute Radiation Syndrome
What tissues are most sensitive to radiation damage???
Tissues with high cellular reproduction rate

9. Acute Radiation Syndrome

10. Acute Radiation Syndrome
LD50/60 = 4 Gy

11. Acute Radiation Syndrome
Before
After (3 weeks later)

12. How much radiation energy absorption needed to kill a human?
LD50/60 = 4 Gy
4 Gy x 1 J/kg x 70 kg = 280 Joules
How much heat energy absorbed from drinking a cup of hot coffee?
Excess temp = 60o – 37o = 23oC
250ml x 23o = 5,750 calories
So why don’t we just explode after drinking a cup of coffee?
The thermal radiation from a cup of coffee is non-ionizing…in order for thermal radiation to be ionizing, the temperature must be sufficiently high (plasma temperatures).
5,750 calories x 4.19 J/cal = 24,092 Joules
(96 J/ml of coffee)
4 Gy = 3 ml hot coffee

13. The Bombings of Hiroshima and Nagasaki

14. Radiation Effects Research Foundation, 2007

15. The Human Toll: What was the main cause of death/injury?
Hiroshima: 90, ,000 deaths within 2 months
Nagasaki: 60,000-80,000 deaths within 2 months
(50% of deaths occurred on the first day)
What was the main cause of death/injury?

16. Radiation and Cancer Risk:

17. How do we determine risk?
Human Epidimiological Studies
Cohort Studies
Case Control Studies
Ecological Studies
Animal Studies

18. The Cohort Study and ‘Relative Risk’

19. Dose Response Curves and Extrapolating Risk

20. What other populations would be appropriate for determining relative risk?

21. Extrapolating Risk
John Gofman – Professor Emeritus at Berkeley: Linear No-Threshold Model

22. What is Radiation Hormesis?

23. Medical Benefits of Radiation

24. Intro to Radiation Therapy
Hypoxia- what is it?
How can chemotherapy enhance radiotherapy?

25. Gamma Knife

26. Bragg Peak
How could this be useful in radiotherapy?

27. Questions?