A unit converter, radiation symbols, dose-limit references, shielding data, and quick AERB tables — built for medical physicists and RSOs.
For reference and education only. Conversion factors are standard; reference values follow ICRP-103 / AERB guidance. Always verify against current official AERB Safety Codes and ICRP publications before any clinical or regulatory decision.
Convert between SI and conventional units instantly.
Standard warning symbols every radiation worker should recognise.
Ionizing Radiation
ISO 361 trefoil
Ionizing radiation trefoil
ISO 361 — the basic 'caution, ionizing radiation' symbol. Magenta or black on yellow.
ISO 21482 (supplementary)
For dangerous category 1–3 sources: trefoil + running person + skull-and-crossbones. Warns to keep away.
Radioactive transport labels
I-White, II-Yellow, III-Yellow — indicate radiation level and transport index of packages.
ICRP-103 / AERB recommended limits — occupational vs. public.
| Quantity | Occupational | Public |
|---|---|---|
| Effective dose (whole body) | 20 mSv/yr (avg over 5 yr; max 50 mSv in any single year) | 1 mSv/yr |
| Lens of the eye | 20 mSv/yr (avg over 5 yr) | 15 mSv/yr |
| Skin (localized) | 500 mSv/yr | 50 mSv/yr |
| Hands & feet (extremities) | 500 mSv/yr | — |
| Pregnancy (fetus, declared) | 1 mSv for remainder of pregnancy | — |
Representative half- and tenth-value layers for common isotopes.
| Source / Energy | Material | HVL | TVL |
|---|---|---|---|
| Co-60 (~1.25 MeV) | Lead | 12 mm | 41 mm |
| Co-60 (~1.25 MeV) | Concrete | 62 mm | 206 mm |
| Cs-137 (662 keV) | Lead | 6.5 mm | 22 mm |
| Cs-137 (662 keV) | Concrete | 48 mm | 160 mm |
| I-131 (364 keV) | Lead | 3 mm | 11 mm |
| Tc-99m (140 keV) | Lead | 0.27 mm | 0.9 mm |
Broad-beam approximations; actual values vary with geometry and buildup.
Decay and shielding estimates using exact decay and attenuation physics.
Activity remaining after a given time — A = A₀ · ½^(t / T½).
Activity remaining
50.0387
same unit as initial
Fraction remaining
50.04%
Half-lives elapsed
1.00
How much shielding to reduce a dose rate by a given factor.
79.7263 mm of lead
Reduction factor ×100 · 6.64 HVL · 2.00 TVL
Key operational values for radiation protection programmes.
Occupational annual limit
20 mSv (avg 5 yr)
Public annual limit
1 mSv
Controlled area design level
≤ 20 mSv/yr
Supervised area
> public, ≤ 3/10 of occupational
Investigation level (typical)
Defined by RSO / institution
Personnel monitoring
Mandatory for radiation workers