Presentation Transcript
Slide 1:Topic 15 Radiation Units
Slide 2:Written and produced by Michael A. Thompson, Professor
Nuclear Medicine Technology Program
University of Alabama at Birmingham 1999, Board of Trustees, University of Alabama
Slide 3:Radiation Units Exist for: Activity
Exposure
Absorbed Dose
Dose Equivalent
Slide 4:Activity Indicates the amount of radioactive substance present in a sample or source
Slide 5:Commonly Used Activity Units: microcuries (Ci) or kilobecquerels (kBq) - represents low activity millicuries (mCi) or megabecquerels (mBq) - represents moderate to high activity Curies (Ci) or gigabecquerels (GBq) - represents very high activity
Slide 7:Physical Half-Life (T1/2) One recalls that the activity of a radioactive source that remains at any time is related to its physical half-life. The physical half-life being that time required for 50% of a radioactive sample to decay away.
Slide 8:Exposure A measure of the amount of radiation to which one has been exposed. Units: Roentgens (R), milliroentgens (mR)
or Coulombs/kg (C/kg)
Slide 9:Exposure Rate Measures exposure received per unit time. Units: R/hr or mR/hr
Slide 11:Absorbed Dose Takes into account that the body does not absorb all the radiation to which it is exposed. The fraction (f) of the incident energy which is absorbed depends upon the radiation energy and the absorber.
Slide 12:Units of Absorbed Dose: Rads or Grays Note: 1 rad = 100 ergs/gm of absorber 1 Gray = 1 Joule/kg of absorber 1 Gray = 100 rads
Slide 14:Dose Equivalent Accounts for the fact that certain types of radiation are more biologically damaging than others Units: Rems or Sieverts (Sv)
Slide 18:Unit Summary Activity: 1 Curie (Ci) = 3.7 x 1010 dps 1 Becquerel (Bq) = 1 dps Therefore, 1 Ci = 37 kBq
1 mCi = 37 MBq
Slide 19:Unit Summary Exposure: 1 Roentgen (R) = 2.58 x 10-4 C/kg (air) 1 C/kg 3876 Roentgen
Slide 20:Unit Summary Absorbed Dose: 1 Gray = 100 rads 1 rad = 1 centigray (cGy)
Slide 21:Unit Summary Dose Equivalent 1 Sievert = 100 rem 1 rem = 1 centisievert (cSv)