单位转换公式
UNITS OF RADIATION MEASUREMENT
The curie is the number of particles per second from 1 gram of
Radium = 3.7 ×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 = 2.22×10E6 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 onthe type
of particle. The Sievert is a measure of biological effect.
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.
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 μGy
Nominal background radiation absorbed dose of 100 mrad/year =1 mGy/yr.
Nominal background radiation dose biological equivalent of
1mrem/year = 10usv/yr.
Occupational whole body limit is 5 rem/yr = 50 μsv/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.
mR/h=10μSv/h
mR=10μSv
sievert的含义：
在物理学上，我们已经知道三种射线α、β、γ (Χ射线属于低能β射线范围)，它们不但有不同的物理特性，而且作用于人体的效果也不一样。为了让这三种射线在作用于人体时可以比较，一个数值被建立起来，这个数值基于射线作用于生物体的效果。
sievert西弗特 (符号Sv, 剂量当量单位, 1 Sv=100 rem)
rem （roentgen equivalent man）雷姆, 人体伦琴当量
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