Summary
A survey of data in the literature indicates that the radiosensitivity of cells to doses less than 1 Gy varies widely within cell lineages and less so between lineages. This is due in large part to the differentiation status and division capacities of the cells, and possibly also to the grouping of cells into ‘viable units’. In addition, the mode of cell death is important, and cells susceptible to natural apoptosis are particularly radiosensitive. There are also quite marked differences in cell sensitivity between species.