Table 4.

Comparison of radiation dosing paradigns

Equivalent dose a	Physical dose and fractionation regimen a
Total dose	15 Gy (5 Gy × 3)b	15 Gy (7.5 Gy × 2)	20 Gy (5 Gy × 4)
Acute responding tissues (α/β = 10)	18.75 Gy	21.88 Gy	25 Gy
Late responding tissues (α/β = 2)	26.25 Gy	35.63 Gy	35 Gy

^aUsing an α/β ratio of 10 for acute (tumor) effects and 2 for late (normal brain) effects, the doses indicated were at conventional 2 Gy fractions.

^bDose regimen utilized in our previously published data [9].