1. Uses of radiation

2. Smoke Detectors
Many smoke detectors contain a small amount of americium-241, which decays to form neptunium- 237 and alpha particles.

3. Smoke detector sets off an alarm.
The alpha particles cannot penetrate the plastic cover and can travel only a short distance.
When alpha particles travel through the air, they ionize gas molecules in the air, which change the molecules into ions.
These ions conduct an electric current.
Smoke particles reduce this current when they mix with the ionized molecules.
Smoke detector sets off an alarm.

4. Radioisotopes in Medicine
Radioisotopes can be used for diagnostic or therapeutic
Diagnostic—help doctors understand what is happening in the body
Therapeutic—treating a disease or condition

5. Diagnostic Radioisotope-tracer studies
Radioisotopes with short half-lives put into patient
Must react the same a the chemically stable isotope
Show cellular abnormalities
Highlight damaged areas

7. PET- Positron Emission Topography
uses positrons (same as a beta particle but have a positive charge.)
positron hits electrons and makes 2 gamma rays that go in all directions
mapping the rays develops a picture
detects and displays metabolic activity like blood flow, O2 usage, sugar usage

8. MRI- Magnetic Resonance Imaging
No ionizing radiation absorbed into the body
gives images of soft tissue
uses low energy radio waves

9. Therapeutic Uses energy from the radioisotope to destroy tissue
Used to treat cancer
Targeted to cancerous cells but will also kill normal cells at the same time

11. Radiation Exposure
Energy can be transferred from nuclear reactions to other molecules and cause ionization
Ionization can cause tissue damage

12. Measuring Exposure

13. Detection Film badges-exposure of film used to estimate human exposure
Geiger-Muller counter- counts electric pulses carried by ionized gas
Beta particles, Xrays and gamma radiation
Scintillation counters

14. Effects of Exposure

15. The biological effect of exposure to nuclear radiation can be expressed in rem.
Healthcare professionals are advised to limit their exposure to 5 rem per year.
This exposure is 10 times higher than the recommended exposure level for most people, including you.
People exposed to a single large dose or a few large doses of radiation in a short period of time are said to have experienced an acute radiation exposure

16. Exposure to small doses of radiation over a long period of time can be as dangerous as a single large dose if the total radiation received is equal.
Chronic radiation exposure occurs when people get many low doses of radiation over a long period of time.
Some scientific studies have shown a correlation between chronic radiation exposure and certain types of cancer.