Panasonic PT-DZ12000U Operating Instructions Manual page 73

Photon Fluence Rate ö from a Point Source
=
ö
A = source activity (decay per hr)
Y = photon yield (ã / decay)
r = distance from point source (cm)
Exposure Rate (X) from a Point Source
= specific gamma ray constant (R/hr @ 1 meter per Ci)
Ã
A = activity of source in curies
r = distance from source in meters
Exposure Rate (X) from a Line Source
Inside L / 2:
Outside L / 2:
d = distance from source at location 1
1
d = distance from source at location 2
2
L = length of line
Note that outside of L / 2 the equation is the same as the
inverse square law.
Exposure Rate (X) from a Disk Source
X (R/hr) =
= R/hr @ 1 meter per Ci
Ã
A = activity per unit area (curies per sq. meter)
a
R = radius of source surface in meters
D = distance from source surface in meters
Simplify the formula by canceling the R s
X (R/hr) =
2
AY / 4ðr = photon fluence rate (ã / cm -hr)
X (R/hr) =
2
ð R A Ã x ln[(R + D ) / D ]/R
a
ð A Ã x ln[(R + D ) / D ]
a
2
ÃA / r
X (d )
1 1
2
X (d ) =
1 1
2 2
2 2 2
62
= X (d )
2 2
X (d )
2 2
2 2
2
2
2