Radiobiological basis of total body irradiation with different dose rate and fractionation: Repair capacity of hemopoietic cells

Similar effects on murine haemopoietic compartment of low dose rate single dose and high dose rate fractionated total body irradiation. Preliminary results after a unique dose of 750 cGy

“…were not very large and therefore it is likely that they played a very minimal role, as previously shown in some authors (Frindel et al, 1972;Glasgow et al, 1983;Tarbell et al, 1987;Travis et al, 1985;Evans et al, 1988). The similar early effects found in both groups suggest first, that fractionation did not play any role in the sparing of the CFU-S and GM-CFC clonogenic cells, and second that no significant repopulation took place during the fractionated TBI.…”

“…A considerable decline in lymphocyte numbers occurred immediately after irradiation and subnormal values were reached by the end of the observation period in both groups (Figure 3). (Evans et al, 1988;Glasgow et al, 1983;Tarbell et al, 1987) yet some other authors have suggested that CFU-S and/or GM-CFC are capable of repairing radiation damage (Peacock et al, 1986;Puro & Clark, 1972;Song et al, 1987 The results showed that the same dose of 750 cGy delivered either as a single fraction at a low dose rate (4 cGy min-1) over 3 h or in several fractions at a higher dose rate (25 cGy min-') over a longer period of time (2 days) gave similar early effects on the murine haemopoietic compartment. Furthermore, a month later there was still no significant difference between the two groups although slightly higher values were observed in the FTBI group.…”

“…Lung cells are capable of repairing radiation damage as opposed to haemopoietic stem cells thought to have no or a very limited capacity for repair (Evans et al, 1988;Frindel et al, 1972;Glasgow et al, 1983;Hendry, 1985;Krebs & Jones, 1972;Tarbell et al, 1987;Travis et al, 1985). However, some authors have shown that dose rate and/or fractionation could play an important role in the survival of haemopoietic stem cells (Hagenbeck & Martens, 1981;Peacock et al, 1986;Puro & Clark, 1972;Song et al, 1987) and suggested that these cells might be capable of repairing radiation damage. This could explain why in clinical practice a higher incidence of graft rejection and leukaemia relapses was observed in patients given T cell depleted bone marrow graft and a fractionated TBI instead of a single dose TBI (Guyotat et al, 1987;Patterson et al, 1986).…”

Total-body irradiation before bone marrow transplantation for acute leukemia in first or second complete remission

“…Although the data reported over the years generally confirm a high radiosensitivity and low repair capacity of leukemic stem cells, a number of exceptions have also been observed: decreasing the dose rate or increasing the number of fractions could affect the repair capacity of the leukemic cells [28,39,50]. The experimental data suggest that a fractionated scheme or low dose rate irradiation would probably be less effective against leukemia than STBI delivering the same dose, or high dose rate TBI [59][60][61].…”

Radiobiological characterization of two human chemotherapy-resistant intermediate grade non-Hodgkin's lymphoma cell lines

“…They observed a distinct shoulder and a split course experiment showed that these cells had a good capacity to recover from sublethal radiation damage. Also, Song et al [11] reviewed the literature and concluded that the repair capacity of some hemopoietic cell lines may be greater than previously thought.…”