Reoxygenation in the RIF-1 tumor.

The proportion of hypoxic cells in the RIF-1 tumor was examined for 13 days following a 15 Gy conditioning dose. The paired survival curve technique indicated that 100% of the surviving cells were hypoxic immediately following this treatment. However, within 1 hour, only about 50% remained hypoxic; this proportion continued to drop to about 10% but did not reach the pretreatment level of 1.1% for the duration of the study.