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IONIZING RADIATION EQUATIONS

1 - Inverse Square Law

Inverse Square Law I2, I1 = Intensity at d2, d1
d2, d1=Distance to source
2 - Activity
a) Activity Ai = Initial Activity in Becq. (dps)
Ni = Initial Number of Atoms
T1/2 = Half - Life in seconds
b) Activity A = Activity (dps) in Becq.
t = time elasped in seconds
c) Activity e = natural log
3 - Exposure & Dose
a)  Rad = 0.869 (f-factor)(Roentgens)
b)  rem = rad x Quality Factor
c)  Life Accumulation = 5 x (N-18) in rem N = Age in years
4 - Exposure Rate
Exposure Rate D = Exposure rate (R/hr)

d = distance from source in cm
A = Activity in mCi of the isotope
5 - Shielding
a) I = Intensity on other side of shield
Io = Intensity without shield (R/hr)
A = Number of Half-Value-Layers (HVL)
HVL = Shield thickness needed to reduce exposure by half.
b) shielding B = Number of Tenth-Value-Layers (TVL)
TVL = Shield thickness needed to reduce exposure by 1/10th.

c) shielding

 x = Shield thickness
d) shielding   or  shielding
6 - Effective Half - Life
Effective Half - Life T1/2eff = Effective Half - Life
T1/2rad = Half-Life of internal radioisotope or source
T1/2bio = Time for the body to eliminate half of the source.
 
 
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