Dose Course 2018_Flipping book
pencil kernel parameterization:
Math curiosity, goes to infinity when r->0. ( ) e e , z z a r b r z z A B p r z r r − − = +
Dose on the main axis for a circular field of fluence :
Ahnesjö et al (1992) Med Phys 19, 263-273
R
2
p
p
( )
( )
( ) ,
D z
, d r z A
d r z r r
=
=
=
0 0
circular
R
field
R
2
a r
b r
−
−
A
B
e
e
z
z
z
z
d r r
=
+
=
0 0
r
r
(
)
(
)
a R
b R
−
−
A
B
1 e −
1 e −
z
z
z
z
=
2
+
a
b
z
z
what happens when field size R goes to zero?
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