Are radioprotective substances the same as radioprotective agents?

Radioprotective agents may be useful as an adjunct to medical imaging to ... compared to those who underwent the same radiation exposure at an older age.

Chemotherapy works by stopping or slowing the growth of cancer cells, which grow and divide quickly. It can also harm healthy cells that divide quickly, such as those that line your mouth and intestines or cause your hair to grow. Damage to healthy cells may cause side effects. Chemotherapy kills cells that are in the process of splitting into 2 new cells. Because cancer cells divide much more often than most normal cells, chemotherapy is much more likely to kill them. Some drugs kill dividing cells by damaging the part of the cell's control centre that makes it divide.