Visual FoxPro - Voss Associates

The buildup factor for a gamma source and shield geometry at a
point outside the shield is 20. The fraction of the dose
contributed by unscattered photons is:
A) 0.05
B) 0.1
C) 0.5
D) 0.8
E) 0.9
The correct answer is: A
Buildup factor is defined as the ratio of all photon radiation at
a point outside a shield to primary, unscattered photons at that
point. It is a correction factor which is used with the linear
attenuation coefficient when calculating for broad beam ,"poor"
geometries. If the buildup factor is 20, the ratio is 20:1, and
the fraction of unscattered photons is 1/20, or 0.05.