Imaging for early stage breast cancer

Quantification of dose homogeneity in brachytherapy

DNR: Dose non-uniformity ratio

V

1.5xref

V

V

= V

DNR =

ref

V

ref

100

1.5xref

V

ref

V

= volume receiving equal to or greater than the reference dose = volume receiving equal to or greater than 1.5 x the reference dose

ref

V

1.5xref

−

V

V

100

150

=

1

−=

DHI

DNR

Dose homogeneity index (DHI) for implant

V

100

−

V100

V150

Dose homogeneity index (DHI) for target

=

DHI

V100

DNR is specific to the implant geometry and prescription isodose The dose distribution is optimal when the DNR is minimal , DHI is maximal