Animal experiments in radiotherapy I -- small animals.

This is a brief review of the contribution that the small laboratory animal, in particular the mouse, has made to experimental radiotherapy. Despite the great differences between mouse and man (e.g. size and life span), there are similarities of tissue cell kinetics and radiation response which greatly aid in the mouse-to-man extrapolation. The crucial advantage of being able to perform experiments with spontaneous tumors transplanted into syngeneic hosts is discussed. Examples are given of work using the tumor control dose (TCD50) endpoint, the endpoint dilution assay, two different clone-counting assays, and the tumor regrowth system. The sophistication that can be achieved with an animal as small as a mouse is illustrated by two studies: one of prolonged intra-arterial catheterization, the other of blood flow measurements in an irradiated limb.