Radiation Biologically Effective Dose (BED) Calculator
BED / EQD2 Calculator
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BED / EQD2:
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Calculates biologically effective dose (BED) and equivalent dose (EQD2) for cancer radiotherapy.
Why Use
Compares different fractionation regimens with hypofractionation or stereotactic body radiation therapy (SBRT) using a common numerical score.
When to Use
Patients undergoing radiation (to compare different fractionation regimens).
Formula
BED = D x (1 + [d / (α/β)]) EQD 2 = D x ([d + (α/β)] / [2 Gy + (α/β)]) Where variables are as follows: Variable Description BED Biologically effective dose, in Gy EQD 2 Equivalent dose in 2-Gy fractions, in Gy d Dose per fraction, in Gy D Total dose (number of fractions x dose per fraction), in Gy α/β ratio Property of irradiated tissue
Pearls / Pitfalls
Note that BED is the biologically effective dose, not biologically equivalent dose. EQD 2 is the equivalent dose in 2-Gy fractions. An α/β ratio of 10 is typically used for early-responding tissues and tumors. An α/β ratio of 3 is typically used for late-responding tissues, such as normal tissue. Prostate cancer has a low α/β ratio of ~1.5.
Advice
Can also be used to determine total dose received over multiple radiation courses.