Answer asap:
what is the general idea behind the use of small amounts of radioactive tracers in medicine?
they can be used to identify an unknown sample. < i don't think its this one.
they kill cancer cells.
they allow doctors to detect problem areas.

The general idea behind the use of small amounts of radioactive tracers in medicine is to allow doctors to detect problem areas.
The medicine specialty that uses this method to diagnose and treat diseases is called nuclear medicine.
Radioactive tracers are used to investigate a patient's body without the need for surgery. Gamma rays and beta particles can pass through skin and those are used. Only a small amount of radioactive material is put into the patient's body.