Dose Rate at a Distance and Behind Lead (Inverse Square, Label Attenuation Tables)
Dose rate at another distance and behind lead, as a point-source estimate.
Open the tool → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Measured dose rate, per hour
- 100
- Distance of the measurement
- 1
- New distance
- 2
- Lead shield
- Tc-99m (Technelite label table)
- Lead thickness
- 0.09 cm
Result: Estimated dose rate at the new distance and behind the shield: 2.5 per hour, in the unit entered.
The tool opens with these values already filled in. Replace them with your own.
What you enter
- Measured dose rate, per hour (any unit)
- Distance of the measurement
- New distance (same unit)
- Lead shield: source
- Lead thickness
- Half-value layer, for another source
- Dose to stay under, in the same dose unit (optional)
How this is calculated
Citation
Inverse square law for a point source (the geometry of NRC Regulatory Guide 8.39, Equation 1). Lead attenuation tables on the Technelite (Tc-99m, Table 2) and Cardiogen-82 (Rb-82, Table 4) labels (DailyMed). Read the sources: Technelite label ↗, Cardiogen-82 label ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.