When the body is exposed to radiation, tissue damage may occur, which in turn may damage DNA or chromosomes, increasing the risk of genetic mutations. When a fetus is exposed to radiation doses, it may cause abnormalities in an organ or irreparable damage and if the radiation dose is too high, it may cause the death of the fetus.

The radioactive dose used in diagnostic procedures in nuclear medicine is very low, unlike radiation treatments in which the amount of radioactive dose is high and this gives the desired effect on the tissues or organs when radiotherapy. That is why the patient must undergo a pregnancy test in the event of suspicion or if the pregnancy is uncertain before starting the therapeutic doses.