Who was responsible for stating the following? 1. Stem or im…

Who was responsible for stating the following? 1. Stem or immature cells are more radioactive than mature cells. 2. Younger tissues and organs are more radiosensitive than older tissues and organs. 3. The higher the metabolic cell activity, the more radiosensitive it is. 4. The greater the proliferation and growth rate for tissues, the greater the radiosensitivity.