**Simple conversion from
µR to µSv. You divide µR by 100 to get
µSv.
Example: The Model 500VBR displays 123456 µR is the same
as 1234.56 µSv.
**

**The curie is the number of
particles
per second from 1 gram of Radium = 3.7 x 10 E10 counts/second
= 37 billion
cps. = 37 billion Becquerel.**

**1 Becquerel (Bq) = 1 count per
second
= 1 event per second**

** 1 microcurie = 1 uCi =
37,000
Bq = 37,000 cps.**

** 1 microcurie = 2.22 x
10E6
disintegrations / minute = 2,220,000 cpm.**

** 1 nanocurie = 1
billionth of
a curie = 2,220 disintegrations / minute.**

** 1 picocurie = 2.2
disintegrations
/ min.**

** Dosage units:**

** Gray (Gy) = 1 Joule/kg**

** Sievert (Sv) = Gray x
QF, where
QF is a "quality factor" based on the type of particle.**

** QF for electrons,
positrons,
and xrays = 1 QF = 3 to 10 for neutrons, protons dependent
upon the energy
transferred by these heavier particles.**

**QF = 20 for alpha particles
and fission
fragments.**

**The Sievert is a measure of
biological
effect.**

**Converting older units:**

**1 rad = 1 centigray = 10
milligrays
( 1 rad = 1cGy = 10 mGy )**

**1 rem = 1 centisievert = 10
millisieverts
( 1 rem = 1cSv = 10 mSv )**

**1 mrad = 10 uGy**

**Nominal background radiation
absorbed
dose of 100 mrad/year = 1 mGy/yr.**

**Nominal background radiation
dose
biological equivalent of 100mrem/year = 1mSv/yr.**

**Occupational whole body limit
is
5 rem/yr = 50 mSv/yr. ( Recently proposed that levels be
reduced to 2 rem/yr.)**

**2.5 mrem/hr or 25 uSv/hr is
maximum
average working level in industry.**

**Exposure rate from Naturally
Occurring
Radioactive Material (NORM) ; an empirically derived
conversion factor
for Ra-226 decay series: 1.82
microR/ hour = 1
picoCurie/gram.**

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