Recovery from X-ray Damage to the Lens. The Effects of Fractionated X-ray Doses Observed in Rabbit Lens Epithelium Irradiated in vivo

In conclusion we suggest the lens of the eye as a new system for short-term fractionation effects. Recovery has been seen between two X-ray doses, using the number of “broken” cells per half lens fixed and stained 14 days after the first X-ray dose as the biological criterion of damage. A peak-and-trough recovery pattern similar to that seen in single-cell systems was apparent, but no recovery was observed between two 500-rad X-ray doses until they were spaced more than six hours apart; the maximum first “peak” of the recovery curve was seen at eight hours' separation between doses. The D2-D1 value approximated 200 rads; a total of 1,200 rads in two fractions eight hours apart produced virtually the same number of “broken” cells as a single dose of 1,000 rads.