7 - 24 Applications of radioactivity
Uses of radioactivity
● Radiocarbon dating
○ Measures level of carbon-14 which is made in atmosphere
○ Carbon-14 isotopes react the same way as normal carbon-12, react with
oxygen forming carbon dioxide, then enters food chain
○ After living matter died, carbon-14 within it decays in half-life of [5730 ± 40]
years
○ Can be used to investigate ages of historic sites (e.g.: from the
Neolithic era [新石器時代] - started from 10000 BCE)
● Tracers in medical diagnosis
○ ***Radioactive tracer: chemical compound which emits gamma radiation
○ Tracer taken orally by patient/injected, then traced using gamma ray
camera
○ Half-life should be around a few hours (as medical treatments usually last
for a few hours to a day)
○ Medical imaging enable doctors to produce 3D computer images of parts of
patient’s body, great value in diagnosis
○ Treating cancer - kill targeted cancer cells inside body by radioactive
isotopes
○ Sterilization - gamma radiation kills bacteria and viruses, used to
sterilize surgical instruments and other medical equipment; items to be
sterilized placed in secure bags, ensuring that radiation pass through
packaging and destroy bacteria without damaging/contaminating item
before use
● Industrial uses
○ Gamma radiography - gamma radiation is very penetrating (more
penetrating than X-rays), used to scan luggages
○ Gauging (測量)
1
Uses of radioactivity
● Radiocarbon dating
○ Measures level of carbon-14 which is made in atmosphere
○ Carbon-14 isotopes react the same way as normal carbon-12, react with
oxygen forming carbon dioxide, then enters food chain
○ After living matter died, carbon-14 within it decays in half-life of [5730 ± 40]
years
○ Can be used to investigate ages of historic sites (e.g.: from the
Neolithic era [新石器時代] - started from 10000 BCE)
● Tracers in medical diagnosis
○ ***Radioactive tracer: chemical compound which emits gamma radiation
○ Tracer taken orally by patient/injected, then traced using gamma ray
camera
○ Half-life should be around a few hours (as medical treatments usually last
for a few hours to a day)
○ Medical imaging enable doctors to produce 3D computer images of parts of
patient’s body, great value in diagnosis
○ Treating cancer - kill targeted cancer cells inside body by radioactive
isotopes
○ Sterilization - gamma radiation kills bacteria and viruses, used to
sterilize surgical instruments and other medical equipment; items to be
sterilized placed in secure bags, ensuring that radiation pass through
packaging and destroy bacteria without damaging/contaminating item
before use
● Industrial uses
○ Gamma radiography - gamma radiation is very penetrating (more
penetrating than X-rays), used to scan luggages
○ Gauging (測量)
1
