Dose Course 2018_Flipping book
calculation techniques:
A particular simple case is dose at the main axis for circular fields of radius R with homogeneous energy fluence:
R
2
a r
b r
−
−
e A B + z
e
z
( )
z
z
D z
d r r
=
0 0
r
(
)
(
)
a R
b R
−
−
A
B
1 e −
1 e −
z
z
D
z
z
( ) z
=
2
+
a
b
z
z
In the same way, the dose to the central axis from a square field, with side s , can be calculated by employing the equivalent circle with R =0.561 · s .
Ahnesjö et al (1992) Med Phys 19, 263-73
Bjärngard and Siddon (1982). Med Phys 9, 258-60
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