Radiation measurement units | ||
Radioactivity | ||
Unit |
Becquerel (Bq)
(International or SI unit) |
Curie (Ci)
(Obsolete unit) |
How the unit is derived | Radioactivity represents the rate of radioactive decay. One becquerel (Bq) is equal to one radioactive decay per second. | One curie (Ci) is the approximate number of radioactive decays in one gram of radium per second – approximately 3.7 x 1010 decays per second. |
Conversions | 1 becquerel (Bq) = 2.703×10−11 curie (Ci) | 1 curie (Ci) = 3.7 x 1010 becquerel (Bq) |
Common Metric Prefixes | 1 gigabecquerel (GBq) = 1,000,000,000 Bq 1 megabecquerel (MBq) = 1,000,000 Bq 1 kilobecquerel (kBq) = 1,000 Bq |
1 millicurie (mCi) = 0.001 Ci 1 microcurie (µci) = 0.000 001 Ci 1 picocurie (pCi) = 0.000 000 000 001 Ci |
Absorbed Dose | ||
Unit |
Gray (Gy)
(International or SI unit) |
Rad (rad) (Obsolete
unit) |
How the unit is derived | Absorbed dose is energy per unit mass. 1 gray (Gy) = 1 joule(J)/kilogram(kg) | 1 rad = 0.01 joule(J)/kilogram(kg) |
Conversions | 1 gray (Gy) = 100 rad | 1 rad = 0.01 gray (Gy) |
Common Metric Prefixes | 1 centigray (cGy) = 0.01 Gy 1 milligray (mGy) = 0.001 Gy |
1 millirad (mrad) = 0.001 rad 1 kilorad (krad) = 1,000 rad |
Effective dose | ||
Unit |
Sievert (Sv) |(International or SI unit) | Rem (rem) (Obsolete
unit) |
Conversions | 1 sievert (Sv) = 100 rem | 1 rem = 0.01 sievert (Sv) |
Common Metric Prefixes | 1 millisievert (mSv) = 0.001 Sv 1 microsievert (µSv) = 0.000 001 Sv |
1 millirem (mrem) = 0.001 rem 1 microrem (µrem) = 0.000 001 rem |
ACUTE RADIATION SYNDROME | ||||
DOSE | PRODROMAL STAGE | LATENT STAGE | ACTIVE STAGE | MORTALITY |
<1Gy | Some symptoms may be experienced with doses as low as 0.3Gy | NIL | NIL | 0% |
1-2Gy | Vomiting, mild headache; onset 1-2hrs | Duration 21-35 days; lymphocyte count 800-1,500/mm3 | Fatigue, weakness | 0% |
2-4Gy | Vomiting, mild headache; onset 1-2hrs | Duration 18-35 days; lymphocyte count 500-800/mm3 | Fever, infections, bleeding, weakness, epilation | <50% |
4-6Gy | Vomiting, mild diarrhoea, moderate headache, fever; onset <1hr | Duration 8-18 days; lymphocyte count 300-500mm3 | High fever, infections, bleeding, epilation | 20-70% |
6-8Gy | Vomiting, severe, diarrhoea, severe headache, high fever, altered consciousness; <30 mins | Duration 7 days; lymphocyte count, 100-300/mm3 | High fever, diarrhoea, vomiting, dizziness, disorientation, hypotension | 50-100% |
>8Gy | Vomiting, severe diarrhoea, severe headache, high fever, unconsciousness; onset <10min | No latency; lymphocyte count 0-100/cm3 | High fever, diarrhoea, unconsciousness | 100% |
Data
adapted from International Atomic Energy Authority
publications Lymphocyte counts show the range of values that might be seen 3 - 6 days post exposure Mortality figures are for patients who do not receive medical intervention |
Radiation Halving Thickness and
Protective Factor (PF) Chart |
||||
Material |
Halving
Thickness in mm (inches) |
PF40
in mm (inches) |
PF300
in mm (inches |
PF1000
in mm (inches) |
Lead |
10.6 (0.4) |
53 (2.1) |
81 (3.2) |
106 (4.0) |
Iron |
29 (0.9) |
122 (4.8) |
183 (7.2) |
289 (9.0) |
Steel |
25 (1.0) |
135 (5.3) |
203 (8.0) |
254 (10.0) |
Stone |
56 (2.2) |
297 (11.7) |
447 (17.6) |
560 (22.0) |
Concrete |
61 (2.4) |
323 (12.7) |
488 (19.2) |
610 (24.0) |
Aluminium |
68.6 (2.7) |
363 (14.3) |
549 (21.6) |
686 (27.0) |
Brickwork |
71.1 (2.8) |
376 (14.8) |
569 (22.4) |
711 (28.0) |
Sand |
73.7 (2.9) |
391 (15.4) |
589 (23.2) |
737 (29.0) |
Packed soil |
91.4 (3.6) |
485 (19.1) |
732 (28.8) |
914 (36.0) |
Water |
183 (7.2) |
970 (38.2) |
1,463 (57.6) |
1,829 (72.0) |
Wood |
279.4 (11.0) |
1,481 (58.3) |
2,235 (88.0) |
2,794 (110) |
The
above figures have been averaged from several sources. They
are also dependent on a number of factors, including moisture
content and variability within a class of materials. |
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