Beta Emitter Activity to Dose Rate (in air) Calculator

Formal advice

If you are after formal advice on beta dose rates in air then head over to our Radiation Protection Adviser (RPA) services , or try our online radiation protection training courses for in-depth study on beta emitter dose rates. 

Calculator use notes

Most functions and settings are self-explanatory but we will highlight some key points below. If you make a change to any parameter or input, please ensure you use the calculate button to use the most recent settings or display updated selections and results. 

• Radionuclide selection - (will be expanded over time).

• Input unit system - specify dose rate, activity and distance in SI or non Si units. The output will also mirror these settings.

• Source type : select either a point source or a planar source (e.g. Bq or Bq/cm²)

• Activity: enter activity and choose your preferred multiplier. 

• Distance (from source) - enter distance and choose your preferred multiplier.

• Dose rate unit multiplier  - apply micro, milli, base, kilo, mega etc to the output dose rate.

• Output format - choose from standard notation or scientific notation (i.e. 0.1 mGy/h or 1.000e-1 mGy/h).

• Show shielding information - the output dose rates (in air) for some radionuclides may seem high (even for a source of modest activity). If this option is selected it will provide some shielding information for typical materials (including tissue) which will put high dose rates (in air) in context.

Output

The output of the calculator will be presented as follows (using sample data results).

• Point dose rate: 0.0942976 Gy/h (at 1 cm), or

• Planar dose rate: 2.176 Gy/h (at 1 cm)

If you have selected to show shielding information then the following will also be presented (using sample data results). 

• Air: Max ≈ 630 cm
• Tissue: Max ≈ 7.45 mm
• PMMA (Acrylic): Max ≈ 6.75 mm
• Aluminium: Max ≈ 2.93 mm
• Glove (nitrile, 0.152 mm): Needs ~49 layer(s) of glove (external exposure)

As mentioned earlier, if you have calculated the dose rate and then choose to selected 'yes' to show shielding information, you need to click calculate again for the additional information to be revealed. 

The above shielding information is based on E_max (e.g. for P-32 this would be 1.7 MeV). 

Below the shielding data (or below dose rate data if shielding is not shown),  additional calculator information may be given. For example, with the planar calculations there is a minimum allowable distance from the source (it will state what this is for a given radionuclide). If you are very close to a point source it may state something like "Near-field exponential fit for (1–6 cm)" (example for P-32). In this example the data set will have initial distance data points such as at 0cm and 6cm. The dose rate at 0cm is fixed by the data used by the calculator, later data points (e.g. 12cm, 24cm, 100cm etc) are extrapolated. There is a lot going in between 0 and 6cm and a different fit is used so as not to overexaggerate in this near-field region.