What isotopes are used for radioactive dating, radioactive dating
A related method is ionium—thorium datingwhich measures the ratio of ionium thorium to thorium in ocean sediment.
Scans for the Dye that is used when the Scan is being done. Radioactive Dating Because the radioactive half-life of a given radioisotope is not affected by temperature, physical or chemical state, or any other influence of the environment outside the nucleus save direct particle interactions with the nucleus, then radioactive samples continue to decay at a predictable rate and can be used as a clock.
In nuclear medicine they are used for diagonosis, treatement et cetra. This is also radio active.
Carbon 14 is present in known concentrations in the atmosphere and in all plants and animals involved in the exchange of CO2 gas through processes of respiration. In geological research, uranium which is a naturally occurring radioactive isotope in the earth for studying continental drifts and determining the age of formation of rocks.
There are many many of them.
Carbon is a radioactive isotope of carbon, with a half-life of 5, years,   which is very short compared with the above isotopes and decays into nitrogen. Thus iodide given to a patient will bunch up and help machines "visualize" the thyroid so that a gland expert doctor can determine if there is something wrong.
Half-life is the time it takes for one-half of the the isotopes to lose their radioactivity. Geologists can determine the ages of rocks and fossils by analyzing the isotopes found in them.
Why do you use half life to measure radioactive isotopes? In nuclear medicine they are used for diagonosis, treatement et cetra. Using the common nuclear practice of calling the isotopes "parent" and "daughter", we use P and D to indicate the associated numbers of atoms.
This predictability allows the relative abundances of related nuclides to be used as a clock to measure the time from the incorporation of the original nuclides into a material to the present.