attenuation radiation

attenuation

reduction in radiation beam intensity as it traverses matter by the absorption &/or deflection of photons

intensity decreases as thickness increases

effect of intensity of transmitted beam on thickness of the barrier

linear attenuation coefficient

the probability of interaction / unit thickness (how absorbent the material is per unit of length)

linear attenuation coefficient

- increases as Z of the absorber increases

- depends on the energy of the incident photons & absorber density

- usually determined experimentally

transmission factor

fraction of original beam which successfully traverses the absorber

transmission factor

the percent remaining of the incident beam

half value layer (HVL)

thickness of a material required to attenuate 1/2 of a monoenergetic radiation beam

tenth value layer

thickness of material required to reduce the intensity of the beam to 10% of its incident value

mean free path

average distance traveled by a photon before undergoing an interaction

mean free path

analogous to mean lifetime in the decay process

mass attenuation coefficient

linear attenuation coefficient corrected for absorber density

mass attenuation coefficient

probability of an interaction in a volume

mass attenuation coefficient of a mixture

weighted sum of each element's mass attenuation coefficient

beam hardening

result of lower energy photons being filtered out of a polyenergetic beam by an absorber

broad beam geometry

norm in daily practice with radioactive emissions

broad beam effects

attributable to scatter caused by material overlying the radioactive source

buildup factor

factor which corrects the transmission factor for broad beam conditions (given in a table as a calculated value, derive the factor by cross referencing)