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Basic Dose Calculation Principles
Simplified depth dose formalism
DD(d)
%
=D
max •
(f+d
m
/f+d)
2 •
e
-(
µ
•
d) •
K
s
f
distance from source to surface (SSD)
d
m
or depth to
D
max
d
is depth in tissue
K
s
is the scatter
Total fluence at A is same as at B:
distance
Diverging beam
Divergent beam
from point source
“Photon flux Φ is reduced
with distance from source”