[A 3D brachytherapy treatment planning system].

Brachytherapy dose prescription and treatment playing lag behind the state-of-the-art for external beam therapy. We have developed a computer program on a SGI Indigo2 graphics workstation to plan the loading or stereotactic implantation of radioactive seeds. The treatment planning system, using data from the pre-treatment diagnostic CT scan or MRI scan, contours target areas on sequential images creating a 3-dimensional target volume, and is based on a dose algorithm of TG-43 formalism. The treatment isodose contour is generated at each scanningplane, reconstructed sagittal and coronal views, and overlaid on the corresponding target contour for 3-dimensional coverage visualization. Volume dose histograms are generated for the target and neighboring normal structures. We also provide two orthogonal digitally reconstructed projected images identifying virtual source positions superimposed on for fluoroscopy guided loading applicators and sources.