When considering re-irradiation of a critical organ, should EQD2 or BED be utilized?

EQD2 and BED are essentially interchangeable. I prefer EQD2 since it conceptually makes more sense to me.

BED = D x [1 + d/(α/β)]

EQD2 = D × [(d + α/β)/(2 + α/β)]
= D x [1 + d/(α/β)]/(1 + 2/α/β)
= BED/(1 + 2/α/β)

The more challenging questions (that I do not have the answer to!) are as follows:

• How do ...