877 / 1544
DVH
NON-UNIFORM IRRADIATION
When considering non-uniform dose distributions (characterised by their DVH), the
DVH
has to be
converted
or
reduced
to an equivalent uniform dose distribution.
The DVH can be reduced to an effective homogeneous dose (EUD) to total volume
(DVH
{D=EUD,
ν
=1}). The EUD algorithm uses the power-law relationship:
n
i
n
i
i
D
EUD
⋅
=
∑
1
ν
where D
i
and
ν
i
correspond to a point of the differential DVH (the sum is performed
through the entire DVH) and
n
is a parameter that, for every organ, describes the
volumetric dependence of the dose-response relationship:
for small
n (n
0)
the EUD tends to the
maximum
dose, while for
n equal to 1
the EUD
is the
average
dose.