Bed Calculator - BED and EQD2 Output

A bed calculator is a radio-oncology planning aid that turns a physical radiotherapy schedule into a biologically meaningful dose using the linear-quadratic model. It accepts a total dose in Gy, a dose per fraction in Gy, and a tissue-specific alpha-beta ratio, and returns the biologically effective dose (BED) and the equivalent total dose in 2 Gy fractions (EQD2).

• • Comparing two fractionation schedules: score a conventional plan and a hypofractionated plan on the same alpha-beta and read the BED and EQD2 side by side before changing the schedule.
• • Switching between early and late tissue endpoints: re-score the same plan with alpha-beta 3 Gy for late-reacting normal tissue and alpha-beta 10 Gy for early-reacting tissue.
• • Checking low-dose-rate or brachytherapy plans: score a brachytherapy or continuous low-dose-rate plan with the protracted BED form and a dose-rate factor g.

The form is a planning aid, not a diagnostic or treatment tool on its own. The BED and EQD2 numbers belong alongside imaging, blood work, performance status, organ-at-risk constraints, and a qualified clinical review, not in place of them.

The default 60 Gy, 2 Gy per fraction, and alpha-beta 10 reproduce the conventional curative head-and-neck reference schedule, while the alpha-beta field also exposes the late-tissue, prostate, breast, CNS, and kidney presets.

A record of absorbed dose is also useful when the radiobiology result is paired with a unit-conversion record, and the Radiation Dose Calculator supports absorbed-dose arithmetic, sievert conversion, and rem conversion in the same clinical workflow.

The form applies the published linear-quadratic formula to a total dose, dose per fraction, and tissue-specific alpha-beta ratio. The result is shown in Gy, both as the BED in Gy and as the EQD2 in Gy that is normalized to the conventional 2 Gy reference fraction used in most curative schedules.

• Total dose: Total physical dose across all fractions, in Gy.
• Dose per fraction: Dose per fraction, in Gy. The default 2 Gy is the conventional curative reference fraction.
• Alpha-beta ratio: Tissue-specific radio-sensitivity in Gy. Use 3 for late-reacting normal tissue, 10 for early-reacting tissue and many tumors, 1.5 for prostate, 4 for breast, 2 for CNS or kidney, 2.5 for melanoma, and 2 for sarcoma.
• Dose-rate factor g: Dimensionless repair factor used only for protracted low-dose-rate delivery, where values less than 1 account for intracellular repair.

When protracted irradiation is selected, the form replaces the fraction dose inside the BED formula with (g x fraction dose) but keeps the EQD2 calculation on the original fraction dose, so the result matches the published low-dose-rate form of the linear-quadratic model.

According to Fowler JF, British Journal of Radiology, 1989, the BED formula is total dose multiplied by 1 plus the fraction dose divided by the tissue-specific alpha-beta ratio, and the EQD2 formula normalizes that result to a 2 Gy reference fraction so different schedules can be compared on a common scale.

When the same prostate radiotherapy record also needs a PSA doubling-time trend, the PSA Doubling Time Calculator adds the prostate-cancer follow-up context that often sits next to a radiobiology review.

Four radiobiology ideas drive the result. Naming them keeps the form from being read as a black box.

The same total physical dose can describe very different radiobiology depending on the fraction size and the tissue. The form exposes all three inputs at once so a user can see exactly which combination produced a given BED and EQD2.

For many treatment plans the radiobiology is paired with kidney or liver blood work, and the GFR Calculator adds the kidney-function context that often sits next to a long-course radiotherapy record.

The form is read top to bottom, from the core physical schedule to the tissue-specific alpha-beta and the optional low-dose-rate correction. The order below mirrors a typical radio-oncology review.

1. 1 Enter the total dose in Gy: use the total physical dose from the plan. Curative plans often sit between 50 and 80 Gy in conventional fractionation.
2. 2 Enter the dose per fraction in Gy: use the actual dose per fraction. Conventional curative schedules use 1.8 to 2 Gy; hypofractionated schedules can use 3 to 8 Gy.
3. 3 Pick the tissue-specific alpha-beta ratio: use 3 Gy for late-reacting normal tissue, 10 Gy for early-reacting tissue and many tumors, 1.5 Gy for prostate, 4 Gy for breast, 2 Gy for CNS or kidney, 2.5 Gy for melanoma, or 2 Gy for sarcoma.
4. 4 Decide whether the delivery is protracted: switch protracted to yes for brachytherapy or continuous low-dose-rate plans, then enter the dose-rate factor g (a value less than 1).
5. 5 Read the BED and EQD2 together: the BED in Gy is the linear-quadratic effective dose, and the EQD2 in Gy is the same result normalized to the conventional 2 Gy reference fraction.

A 60 Gy in 2 Gy fractions head-and-neck plan scored at alpha-beta 10 Gy gives BED 72.00 Gy and EQD2 60.00 Gy, the conventional curative identity. Re-scoring the same plan at alpha-beta 3 Gy gives BED 100.00 Gy, showing why conventional fractionation protects late-reacting tissue.

A 60 Gy plan is often paired with a body-size and kidney-function check, and the Body Surface Area Calculator adds the body-size context that is sometimes used alongside a radio-oncology record.

Used alongside a clinical radio-oncology review, the form offers several practical advantages for clinicians, trainees, and physicists.

• • One form for BED and EQD2: the same total dose, fraction dose, and alpha-beta produce both the BED in Gy and the conventional 2 Gy EQD2 in Gy, covering the two most common radio-oncology comparisons.
• • Tissue-specific alpha-beta presets: the alpha-beta field accepts the published late-reacting, early-reacting, prostate, breast, CNS, kidney, melanoma, and sarcoma values for adult workflows.
• • Acute and protracted delivery: the protracted toggle adds the low-dose-rate form with a dose-rate factor g, covering conventional fractionation and low-dose-rate brachytherapy.
• • Visible formula and reference identity: the worked example and the schedule summary confirm that a 60 Gy in 2 Gy fractions plan scores EQD2 equal to total dose, a quick formula check.
• • Plain-text schedule summary: the summary pairs the BED and EQD2 with the alpha-beta and the implied fraction count, so the result can be quoted in a clinic note or teaching case.

The result is most useful when it is paired with a clinical review. The bed calculator exposes the radiobiology, but the decision about a fractionation change still depends on imaging, performance status, organ-at-risk constraints, and the rest of the radio-oncology record.

For a thyroid or breast cancer workup, a structured imaging workup often sits next to a radio-oncology record, and the TI-RADS Calculator applies a similar point-based approach to thyroid nodule biopsy decisions in the same clinical setting.

The BED and EQD2 depend on the three core radio-oncology inputs and the optional protracted-delivery correction. A few everyday factors can move a result without changing the underlying tumor biology.

• • The BED and EQD2 are radiobiology summaries, not direct predictors of tumor control or toxicity for one patient. Clinical decisions still depend on imaging, performance status, organ-at-risk constraints, and clinician judgment.
• • The linear-quadratic model is most reliable in the conventional 1 to 5 Gy fraction-size range. For stereotactic radiosurgery or very large hypofractionated doses, the BED should be read as a radiobiology summary, not a strict equivalence.
• • The alpha-beta list covers the most common adult tissue types. Rare histologies, pediatric tumors, and re-irradiation may need a different alpha-beta that the form accepts as a custom value.

The dose-rate factor g is dimensionless, and a value of 1 leaves the BED formula in its acute-fraction form. A value of 0.6 is a reasonable starting point for many low-dose-rate brachytherapy plans, but published g values vary with tumor type, half-life, and overall irradiation time.

According to IAEA Radiation Oncology Resources, fractionation and overall treatment time are major determinants of tumor control and normal-tissue response, and the linear-quadratic model with the BED and EQD2 formulas is one of the standard ways to compare schedules on a common scale.

According to Radiopaedia Linear-Quadratic Model, the linear-quadratic model underpins the BED and EQD2 formulas, with conventional curative fractionation delivering about 1.8 to 2 Gy per fraction and late-reacting normal tissue commonly modeled with an alpha-beta ratio of about 3 Gy.

When the same workflow also needs weight-based drug dosing alongside a radiobiology record, the Dosage Calculator provides the weight-based arithmetic and the same clinical dose-units handling.