Units of Radiation

Health, Safety and Environmentwww.hse.ubc.ca

Units of Radiation

Post-doc

ACTIVITYBecquerel

Activity - Becquerel• Becquerel (Bq) = 1 disintegration per second

(dps)

1 Bq = 27 picoCuries

1 kiloBq (kBq) = 27 nanoCuries

1 MegaBq (MBq) = 27 microCuries (µCi)

1 GigaBq (GBq) = 27 milliCuries (mCi)

1 TeraBq (TBq) = 27 Curies

Post-doc

ACTIVITYBecquerel

EXPOSURE INTENSITY C/kg

Exposure Intensity

• Coulomb =6.25 x1018 elementary charges• A flow of one Coulomb per sec equals one

Ampere• Coulomb/kg of air = 3876 Roentgens

• Not applicable to particle emission• Does not predict tissue effects at high

energies• Mainly used for calibration of X-ray machines

ABSORBED DOSE Gray

Post-doc

ACTIVITYBecquerel

EXPOSURE INTENSITY C/kg

Absorbed Dose

• Gray = Unit of absorbed dose= Joule/kg of tissue

• Replaced rad: radiation absorbed dose

• 1 Gy = 100 rads

ABSORBED DOSE Gray

Post-doc

ACTIVITYBecquerel

EXPOSURE INTENSITY C/kg

DOSE EQUIVALENT Seivert

Dose Equivalent

• Sievert : Replaced rem :radiation equivalent in

man Numerical product of Grays times a

quality factor Q of the emission Sv = Gray x Q

Relative Biological Effectiveness

1 SV = 100rems

Quality Factors

*Different types of radiation produce different amounts of biological damage for a given energy deposition: eg. alpha causes much more damage than an equal absorbed dose of gamma radiation.

Q=20 for alpha particles, 1 for gamma,betaQ=20 for alpha particles, 1 for gamma,beta

ABSORBED DOSE

Post-doc

ACTIVITY

EXPOSURE INTENSITY DOSE EQUIVALENT