For more about using the BED calculator follow the following links:

The linear quadratic modelComparing fractionation regimens: The IMR calculator

Equivalent courses using different fractionations: The ESC Calculator

Making up an incomplete course and/or compensating for treatment errors

Management of unscheduled treatment interruptions

Compensating for a gap in treatment

Hyperfractionation: Treating BID

Hypofractionation: using fewer fractions.

Concomitant boost: overlapping treatment schedules

Tumor repopulation

Recovery from late reactions

Normal Tissue Complication Probability (NTCP)

To calculate **Biologically Effective Dose (BED)** you must first specify the dose response curve fitting model to be used. In the biology control group select a **Model** from the menu. **Linear Quadratic** is the default. Set the adjacent model subtype menu to **LQ**. Enter an **α/β** ratio or select an entry from the Tissue library menu. The conventional LQ model is used whenever the course modality is **EBRT**.

For hypothetical high dose per fraction calculations using the LQ-L model set the model subtype menu to **LQ-L**, and enter the linear-quadratic-linear transition dose **D _{T}** or check the

In the **Reactions** group select **Acute** or **Late** as the primary focus of the calculations. Independent values for **α/β**, **D _{T}**,

While it is permissible to compare the biologically effective doses calculated for acute effects (in Gy_{(n)}) of one schedule with acute effects of other schedules (or, likewise, late vs. late effects), it is not permissible or meaningful to compare acute with late effects.

If you want to explore the effects of tumor repopulation you may optionally check the include button. Repopulation is disabled by default. Follow this link for more about repopulation.

Treatment regimens are composed using the **Integrated Multicourse Regimen (IMR)** controls group of the TDF Plan window. In the example below, course #1 will consist of 30 fractions of 200 cGy delivered 5 days per week. To create this course click the **Course 1** button.

- Enter a
**Title**for the course (the triangle button to the right of the**Title**field opens an optional popup menu of predefined titles). - Select the treatment
**Modality**from the menu (EBRT is the default). The conventional LQ model is used when the course modality is**EBRT**. The LQ-L model is used whenever the course modality is**SBRT**or**SRS**. - Check the IMR
**Include**checkbox next to the modality menu (this functionality is also duplicated in the course spreadsheet for convenience) to include this course in the BED calculation (by default, unused courses are not included. You must intentionally include them in the calculation). - From the
**Tx days/week**menu select the number of treatment days per week (5 days/week is the default). - In the
**Rx dose/fraction**field enter the prescribed dose per fraction (e.g 200) in cGy and then click adjacent**Lock**button. TDF Plan recalculates dose immediately as new values are entered. Because the parameters of dose/fraction, number of fractions, and total dose are interrelated, one of these 3 values must always be locked. For instance, in this example, since dose/fraction is locked, the total dose will automatically be updated when the number of fractions is changed, or vice versa, the number of fractions will be adjusted when the total dose is changed. - In the
**# Fractions**field, enter the number of treatment fractions (e.g 30). - The Course Calendar window may optionally be used to set the course start date (e.g August 14th). It is most efficient to use the calendar only once after all of the courses have been defined.

**Course #2** will consist of a field cone down for 4 fractions of 200 cGy beginning September 26th. **Course 3** will complete the regimen with an IMRT boost of 3 fractions beginning October 2nd. This regimen will deliver an absolute dose of 7400 cGy in 52 days and a biologically effective dose of 88.8 Gy_{(10.0)}. The (α/β) subscripts to the BED Gy are reminders that BED does not actually represent true "Gy" in the physics sense, and of the particular values of α/β used in the calculation. Again, BED_{(α/β)} values can only be summed with other BED_{(α/β)} values!

For more about using the BED calculator follow the following links:

Comparing fractionation regimens: The IMR calculatorEquivalent courses using different fractionations: The ESC Calculator

Making up an incomplete course and/or compensating for treatment errors

Compensating for a gap in treatment

Hyperfractionation: Treating BID

Hypofractionation: using fewer fractions.

Concomitant boost: overlapping treatment schedules

Tumor repopulation: