Calculator
Dose rate
Equivalent dose rate at a given distance, from the isotope gamma constant, with or without a collimator.
Equivalent dose ratemSv/h
- In microsievert
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- Dose constant K
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- Collimator
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Method
Ḣ = K / d²
K = A × 0.037 × Γ
- A — activity in Ci
- Γ — gamma constant in mSv·m²/(h·TBq)
- K — dose constant in mSv·m²/h
- d — distance in m
No shielding, no scatter. With a collimator the on-axis dose rate is divided by the isotope factor (250 for Ir-192 and Se-75, 10 for Co-60). Off axis the collimator does not protect: the calculation does not apply there. For gamma photons, 1 mSv ≈ 1 mGy.
Indicative result — check it against your authorisation and your dosimetry.