Abstract: A diverging template (18) for radioactive therapy of cancer within an internal tumor volume by interstitial implants through the skin (78) comprises a proximal surface (34) for positioning adjacent the skin and a distal surface (36) opposite the proximal surface (34). An axis (32) of the template (18) is substantially perpendicular to the proximal surface (34). A plurality of holes (24'-30') are formed in the template (18) from the distal surface (36) to the proximal surface (34) for guiding respective needles (24-30) through the skin (78) and into the tumor volume. The holes comprise at least a first group (28) and a second group (26), each hole of the first group (28) spaced from the axis (32) and forming a first angle therewith that diverges from the distal surface (36) to the proximal surafce (34). Each hole (26) of the second group is spaced from the axis (32) and diverges from the distal surface (36) to the proximal surface (34) at a second angle greater than the first angle.