Radioactivity (eq. dose) Converters

Equivalent dose measures the biological harm that ionising radiation causes to human tissue, weighting the raw absorbed energy (in gray) by the type of radiation involved. Alpha particles, protons, and heavy ions cause more damage per unit of absorbed energy than gamma rays or X-rays, so a weighting factor (radiation weighting factor, w_R) is applied to produce a dose in sieverts rather than gray. This distinguishes equivalent dose from activity (becquerels), which counts decay events without regard to biological effect. The SI unit is the sievert (Sv); the older unit is the rem (1 Sv = 100 rem). Annual background radiation for most people is 2–3 millisieverts. Occupational workers are typically limited to 20 mSv/year; a single acute dose above 1 Sv causes radiation sickness, and above 6 Sv is usually fatal without medical intervention.