The response of the 59Fe uptake system in rat femoral marrow exposed to various X-ray energies

Rats were given whole-body exposures to four incident X-ray energies. The influence of dose from each of these energies upon iron uptake in the center of the femoral shaftmarrow was noted. Uptake ratios showed a change with increasing dose which may be expressed by the formula: UT = 0.87 exp [−(0.693/D50) × D] + 0.13. It was found that the D50 was essentially the same (regardless of the incident photon energy) and had a pooled value of 75 ± 9 rad. A comparison made with a previous spinal column study showed a D50 value of 71 ± 7 rad. Not only was there no difference in response with the differing photon energies studied, but it seems likely that femoral marrow may be used as a "calibration" for other marrow sites-particularly those which do not lend themselves to the usual dosimetry techniques.