CPB Ljubljana 2018 course book

Dose calculation – AAPM-TG43: The Geometry Function G(r,θ):

G(r,θ): The geometry function at radial distance r and polar angle θ. It is a dimensionless quantity.

• From a physics point of view the geometry function simply provides an effective inverse square-law correction based upon the spatial distribution of radioactivity within the source core. • It depends only on the 3D volume shape of the active core of the source and not on the radionuclide, nor on the encapsulation! • It does not consider scatter and attenuation!