Advanced EQD2 and BED Calculator

Calculation results

Calculated

Course-by-course results

Course	Physical dose	Fractions	Dose/fraction	BED	EQD2	Secondary EQD2	Recovered EQD2

Comparison result

No comparison has been calculated.

Step-by-step calculation

No report yet.

Calculation settings

Calculation mode

Dose unit

Displayed decimals

Reference fraction dose, EQDx

Use 2 Gy for standard EQD2.

Primary α/β ratio, Gy

Secondary α/β ratio, Gy

Used for parallel tumour and normal-tissue results.

Treatment courses

Advanced biological corrections

Enable treatment-time repopulation correction

Enable incomplete-repair correction

Schedule comparison

Schedule A

Total dose

Fractions

α/β

Schedule B

Total dose

Fractions

α/β

Reirradiation scenario

Previous-course EQD2

New-course EQD2

Assumed recovery, percent

Months between courses

Recovery is a user-defined scenario. The calculator does not infer a clinically safe recovery percentage.

Formula used

BED = n × d × (1 + d ÷ (α/β)) EQDx = BED ÷ (1 + x ÷ (α/β)) For EQD2, x = 2 Gy. Time-corrected BED = BED − [ln(2) ÷ (α × Tpot)] × max(0, T − Tk) The incomplete-repair option applies a simplified mono-exponential correction for closely spaced daily fractions.

How to use this calculator

Choose a calculation mode and confirm the dose unit. Enter each treatment course with its fractions and tissue ratio. Add advanced corrections only when their assumptions are clinically justified.

Review warnings before interpreting cumulative or recovered results. Compare schedules using the same biological endpoint whenever possible. Export the report for independent professional checking and documentation.

Example schedules

Example	Total dose	Fractions	Dose per fraction	Purpose
Conventional example	60 Gy	30	2 Gy	Baseline comparison
Moderate hypofractionation example	40 Gy	15	2.67 Gy	Schedule comparison
Single-fraction example	8 Gy	1	8 Gy	High fraction-size demonstration

These values are calculation examples only. They are not treatment recommendations. Qualified clinicians must review every applied schedule.

Important limitations

The linear-quadratic model simplifies complex tissue responses. Uncertainty may increase with unusual fraction sizes or treatment patterns. Time, repair, volume, and organ-specific factors can alter interpretation.

Summing EQD2 values requires compatible endpoints and assumptions. Recovery percentages are not universal biological constants. Use this calculator as an educational comparison and documentation aid.

Frequently asked questions

What is EQD2?

EQD2 expresses a schedule as an equivalent dose delivered in two-gray fractions. It supports comparison across different fraction sizes. It does not replace clinical treatment planning.

What is BED?

BED estimates biological effect using the linear-quadratic model. It depends on total dose, fraction size, and alpha-beta ratio. Different tissues can produce different BED values.

Why does the alpha-beta ratio matter?

The ratio changes sensitivity to fraction size. Lower ratios usually show stronger fraction-size effects. Select the endpoint relevant to the tissue being assessed.

Can different treatment courses be added?

Yes, each course is calculated separately before summation. Compatible alpha-beta assumptions should be used. Review spatial overlap and organ-specific constraints independently.

Can the calculator handle cGy?

Yes, select cGy from the dose-unit menu. Internal calculations convert values into Gy. Results display in the chosen unit where appropriate.

What does treatment-time correction do?

It estimates a repopulation penalty after a selected kick-off time. The result depends on several uncertain parameters. Keep this option disabled without justified inputs.

What does incomplete repair mean?

Closely spaced fractions may not allow complete tissue repair. The optional model estimates this effect using repair half-time. It remains a simplified approximation.

Can recovery be assumed for reirradiation?

The calculator accepts a user-defined recovery percentage. It does not choose a safe value automatically. Clinical evidence and organ context must guide interpretation.

Is this calculator suitable for prescriptions?

No automatic result should be used without professional review. Dose-volume information and clinical context remain essential. Confirm every calculation with qualified radiotherapy specialists.

Clinical-use notice

This calculator is an educational dose-comparison aid. It does not provide medical advice or treatment authorization. A radiation oncologist or medical physicist must verify results.