EQD2 Calculator (Equivalent Dose in 2Gy)

The 2 Gy per fraction schedule is the historical standard for conventionally fractionated radiotherapy. Normalizing other schedules (hypo-fractionated or hyper-fractionated) to EQD2 allows clinicians to use familiar dose constraints developed over decades of clinical experience. It is particularly important for evaluating late-responding tissue tolerance (e.g., spinal cord, brainstem) where the dose per fraction has a non-linear impact.

EQD2 is mathematically related to BED by the formula: $$EQD2 = rac{BED}{1 + rac{2}{alpha/eta}}$$. It provides the same biological information as BED but expressed in Gy units that are more intuitive to clinicians.