Radiation & fractionation

tuoni

I have been reading up on radiation, but have some trouble fully understanding fractionation. Is there any simple approximation of the relation of fractionation and recovery, or some sort of adjusted effective dose?

A single continuous exposure of 1 Gy over 1 hour, compared to 20 acute doses of 50 mGy (which is still an absorbed dose of 1 Gy over 1 hour), what exactly is the difference/relation? And can it be modelled/approximated? Would the fractionation effectively be less (either expressed as an effective dose [Sv] or an arbitrary constant) than the continuous exposure?

So the continuous exposure would be (assuming photons) 1 Sv, but the fractionation actually somewhat less than 1 Sv (due to the tissue/cells being able to partially recover). Or is it not possible to express it such a manner?

EDIT:

I guess it's not a very well understood field? I've had trouble finding more practical or straight-forward material. Everything is pretty vague, "fractionation is less damaging as it spreads out the radiation," but no hard figures or formulas. No real explanation.