BED Calculator

Radiobiology utilizes the linear-quadratic model to predict cell survival and tissue injury following radiation exposure. The primary equation used by this calculator is: BED = TotalDose × (1 + (FractionDose / ABratio)), where TotalDose is the cumulative radiation delivered, FractionDose is the dose administered per session, and ABratio is the alpha/beta ratio representing the intrinsic radiosensitivity of specific tissues (typically 3 Gy for late-responding normal tissues and 10 Gy for acute-responding tissues and tumors). Additionally, the tool calculates equivalent dose in 2 Gy fractions (EQD) and accounts for dose rate factors when evaluating continuous or low dose rate applications.

Let us walk through a clinical scenario where a patient receives a total radiation dose of 60 Gy delivered in 30 daily fractions, targeting a tumor with an alpha/beta ratio of 10 Gy. First, determine the fraction dose: 60 Gy / 30 fractions = 2 Gy per fraction. Next, apply the BED formula: BED = 60 × (1 + (2 / 10)). Solving inside the parenthesis gives 1 + 0.2 = 1.2. Finally, multiply by the total dose: 60 × 1.2 = 72 Gy₁₀. This output indicates the biologically effective dose delivered to the target volume, providing a standardized metric for treatment comparison.

Always verify the alpha/beta ratio for the specific tissue type you are modeling, as normal structures and neoplasms have vastly different radiobiological profiles. Double-check your total dose and fractionation count to ensure input consistency before running comparisons. Use the resulting BED values strictly as a comparative index alongside clinical judgment and institutional treatment protocols.