1. Isotope Applications Medical Tracers PET Scan

2. 131 I can be used to image the thyroid, heart, lungs, & liver and to measure iodine levels in blood. 24 Na injected into the bloodstream as a salt solution can be monitored to trace the flow of blood & detect possible constrictions or obstructions in the circulatory system. PET (positron emission tomography) scans use 15 O in H 2 15 O & 18 F bonded to glucose to measure energy metabolism in the brain.

3. Implants of 198 Au or mixtures of 90 Sr & 90 Y have been used to destroy pituitary & breast cancer tumours. Gamma rays from 60 Co are used to destroy brain tumours.

4. Stable isotopes such as 16 O and 18 O were used to indicate global temperatures in the distant past. This can be done by determining the ratio of 18 O to 16 O in ice cores extracted from Earth’s polar caps or from sediment cores exhumed from the ocean floor.

5. Nuclear weapons test put large & detectable amounts of certain radioactive isotopes into the atmosphere. Due to the Limited Test Ban Treaty in 1963, 14 C concentration in the atmosphere began decreasing. Anybody born before 1965 possesses a higher concentration of 14 C. We can tell how old many living things are based on the 14 C concentration.

6. Carbon-14 is used to determine the age of bones in archeological sites. Uranium-238 & lead-206 are used to date very ancient objects such as minerals contained within rock samples.