biological role radioprotectant Richard T. Hoppe, Theodore Locke Phillips, Mack Roach, Leibel and Phillips Textbook of Radiation Oncology (Third Edition), W.B. Saunders, (2010), ISBN 9781416058977, https://doi.org/10.1016/B978-1-4160-5897-7.00093-7. A substance present at the time of irradiation that mitigates or prevents the biological effects of irradiation. E.G. amifostine. radioprotector