With the dawn of the nuclear age, it has become essential to develop radiomodulators, particularly radiation countermeasure agents, for the benefit of mankind. Despite years of concerted research endeavours world-over, non-toxic and effective radiomodulators remain elusive. In recent years, there has been a new focus on herbals, which are also promising sources of radiomodulatory drugs.This book discusses the potential of radiation countermeasure agents and radiosensitizers of herbal origin, and their multifaceted mode of action, particularly in nuclear operations, rescue operations, deep space missions, and application during radiotherapy. Comprising 22 chapters written by industry, clinical and academic experts, this book will appeal to readers in radiation biology, radiation oncology, military medicine, homeland defence, traditional, holistic and modern medicine, space biology, pharmacology and toxicology.