Radiation Therapy Fractionation Calculator
Calculate BED and EQD2 from the Linear-Quadratic model for radiation therapy planning. Compare fractionation schedules and assess normal tissue toxicity.
Medical Disclaimer
This calculator is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about your health. Never disregard professional medical advice or delay seeking it because of results from this tool.
Inputs
Results
Total physical dose (Gy)
60
BED — Tumor (Gy)
72
How to Use This Calculator
- Enter total prescribed dose (Gy), number of fractions, and fraction size (Gy/fraction).
- Enter the alpha/beta ratio for the tissue of interest (typical: tumors 10, late-responding tissue 3).
- Read the biologically equivalent dose (BED) and equivalent dose in 2 Gy fractions (EQD2).
- Compare BED across different fractionation schemes to assess radiobiological equivalence.
- Use EQD2 to convert hypofractionated or SBRT doses to conventional fractionation equivalents.
How the result changes with Number of fractions
| Number of fractions | Total physical dose (Gy) | BED — Tumor (Gy) |
|---|---|---|
| 5.9 | 12 | 14.4 |
| 18 | 36 | 43.2 |
| 33 | 66 | 79.2 |
| 45 | 90 | 108 |
What each input means
- Number of fractions
- Total number of radiation fractions in the treatment course.
- Dose per fraction (Gy)
- Radiation dose delivered in each fraction.
- Tumor α/β ratio (Gy)
- α/β ratio for the target tissue. Typically 10 Gy for most tumors, 1.5–4 for prostate cancer, 3 for late-responding normal tissues.
- Treatments per week
- Number of treatment days per week (typically 5 for conventional, 3–5 for hypofractionation).
What each result means
- Total physical dose (Gy)
- Sum of all fraction doses: n × d.
- BED — Tumor (Gy)
- Biologically Effective Dose for tumor using the specified α/β ratio.
- EQD2 — Tumor (Gy)
- Equivalent dose in 2 Gy fractions for the tumor.
- BED — Late normal tissue (Gy₃)
- BED for late-responding normal tissue (α/β = 3 Gy). Higher values mean more toxicity risk.
- EQD2 — Late normal tissue (Gy)
- EQD2 for late-responding normal tissue.
- Treatment duration (weeks)
- Estimated treatment course length.
- Calendar days
- Total calendar days for the treatment course.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersNumber of fractions = 30, Dose per fraction (Gy) = 2, Tumor α/β ratio (Gy) = 10, Treatments per week = 5 = 4 input(s) provided
- Calculate Total physical doseTotal physical dose = numFractions * dosePerFraction60 = 60
- Calculate BED — TumorBED — Tumor = totalDose * (1 + dosePerFraction / alphaBetaRatio)72 = 72
- Calculate EQD2 — TumorEQD2 — Tumor = bed / (1 + 2 / alphaBetaRatio)60 = 60
- Calculate BED — Late normal tissueBED — Late normal tissue = totalDose * (1 + dosePerFraction / 3)100 = 100
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