The equivalent dose (HT) is a measure of the
radiation dose to tissue where an attempt has been made to allow for the different relative biological effect of different types of
ionizing radiation. Equivalent dose is therefore a less fundamental quantity than radiation
absorbed dose, but is more biologically significant. Equivalent dose has units of
sieverts. Another unit,
Röntgen equivalent man (REM), is still in common use in the US, although regulatory and advisory bodies are encouraging transition to Sievert (1
REM = 1/100 Sievert.)
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