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Example for primary beam
E
0
= WUT (d
ref
/d)
2
= 69.444
n= -log(E/E
0
)= 5
Need to know the TVL (tenth value layer
or thickness required to attenuate the
beam by a factor of 10) of concrete in a
6MV beam -> TVL
≈
30cm
Required barrier thickness:
t
pri
= nTVL= ??? m
Equipment type = linac,
FAD = 1m, 6MV
W = 40000Gy/year
D = 2.5Gy
U = 0.25 (lateral approach)
d = 6m
T = 0.25 (waiting room)
E = 0.001Gy/year (limit value
in the area to be shielded
d
0
as the distance from source to
reference point (e.g. isocentre)
Waiting room adjacent to a linac bunker