Interstitial high dose-rate brachytherapy: principle, practice and first clinical experiences with a new remote-controlled afterloading system using Ir-192.

In our newly developed remote-controlled afterloading system, a single Ir-192-source is moved within hollow stainless steel needles, which are arranged strictly parallel and are uniformly spaced. Dose calculation is performed by an especially designed computer program using geometrical bodies (ellipsoid, cylinder and plane parallel body) as idealized tumor shapes. Reference points for calculation are defined on the surface of the chosen geometrical body. Theoretical base, principles of dosage, handling and first clinical experiences after treatment of 28 patients are presented.