BED Calculator - Biologically Effective Dose and EQD2

Your details

The dose delivered in each treatment session (fraction), in Gray. Conventional fractionation is typically 1.8-2 Gy. SBRT/SABR uses 5-20+ Gy per fraction.
Gy
The total number of treatment sessions. Multiply this by dose per fraction to get total dose.
fractions
Select the tissue or endpoint of interest. The alpha/beta ratio describes how sensitive a tissue is to changes in fractionation. Late-reacting normal tissues typically have alpha/beta around 2-3 Gy; rapidly proliferating tumors and early-reacting tissues around 10 Gy.
BEDModerate BED regimen
83.33Gy

Biologically Effective Dose - total biological effect of the schedule

EQD250Gy
Total physical dose50Gy
Alpha/beta used3Gy
BED per fraction3.333Gy
Total physical dose (Gy)50
BED (Gy)83.33
EQD2 (Gy)50

BED 83.3 Gy, EQD2 50.0 Gy for the selected tissue endpoint.

  • Your schedule delivers a physical total dose of 50.0 Gy in 25 fractions of 2.00 Gy each.
  • This is a conventionally fractionated schedule (around 1.8-2 Gy per fraction).
  • With alpha/beta = 3 Gy (late-reacting tissue), this tissue is more sensitive to fraction size than rapidly-dividing tumors. Hypofractionation increases late toxicity risk disproportionately.
  • EQD2 = 50.0 Gy: this is the dose in standard 2-Gy fractions that would produce the same biological effect, allowing direct comparison with other regimens using the same tissue endpoint (late reacting).

Next stepAlways verify these values against your institution protocol and current clinical literature. BED and EQD2 are modelling tools that guide comparison of regimens - they do not replace clinical judgement or account for repopulation, reoxygenation, or redistribution effects.

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