BED Calculator
Calculate the Biologically Effective Dose (BED) for radiation therapy to compare fractionation schemes.
Formula
BED = D × (1 + d/α/β); EQD2 = BED ÷ (1 + 2/α/β)
- D = total dose; d = dose per fraction; α/β = tissue-specific radiosensitivity ratio.
- Acute-responding tissues (tumors): α/β = 10 Gy.
- Late-responding tissues: α/β = 3 Gy.
- Hypofractionated prostate cancer: α/β = 1.5 Gy often used.
60 Gy in 30 fractions (standard lung), α/β=10
Inputs
- Total Dose: 60 Gy
- Number of Fractions: 30
- α/β Ratio: 10 Gy
d = 2 Gy. BED = 60×(1+2/10) = 72 Gy. EQD2 = 72/(1+2/10) = 60 Gy (as expected).
Frequently asked questions
What is BED?
Biologically Effective Dose — a way to compare different fractionation regimens based on their biological effect.
What is EQD2?
Equivalent Dose in 2 Gy fractions — the dose in standard fractions that would cause the same biological effect.
What is the α/β ratio?
It describes how sensitive a tissue is to fraction size. High α/β (tumors): more sensitive to small fractions. Low α/β (late effects): more sensitive to large fractions.
Is this tool for clinical use?
For educational purposes only. Clinical radiation planning requires certified medical physicists and oncologists.