It is claimed the invention of a composition and a device to be used in medical therapy as a containment matrix in conformational intra-tissue beta brachytherapy. The composition is made so as to form a gel which can be injected intra-tissue without toxicity in the organism, holding in suspension during injection the particulate of a beta-emitting brachytherapy composition, and forming after injection a solid deposit that immobilizes the radiotherapeutic composition in the injection bolus, to prevent migration of the radioactive product into the surrounding tissues. The composition is injected with an apparatus dedicated to percutaneous intra-tissue injection comprising a 7-degree robotic apparatus, an automatic injection device under pressure, a needles system to provide the therapeutic composition application in the tissue to be treated with minimal trauma. An advanced software system is also included that allows interfacing between diagnostic imaging data, robotic arm movement scheduling, and composition dose distribution, in order to optimize the distribution of the radiotherapeutic doses of the composition into the tissue to be treated, according to a targeted individual therapeutic strategy. Additionally a method for using the invention for the application in human or animal medicine is claimed.
