Radiation delivery devices useful in brachytherapy which employ radioactive palladium-103 as the radiation source material are disclosed. Certain embodiments of the disclosed radiation delivery devices have the advantages that they can be fabricated with the desired specific activity, that the self-shielding effects of the devices are minimized, that the radioactive source material is bonded to a substrate in a manner which substantially prevents it from becoming detached, and that a variety of customizable radiation delivery devices can be made using the concepts of the invention. Also disclosed are processes for bonding radiation source material to various substrates using electroless plating, chemical vapor deposition and polymer matrices. These processes have the advantage that they can be applied to bond the radiation source material to a wide variety of substrates including different substrate materials and differently shaped substrates, thereby providing the ability to tailor the radiation delivery devices to the specific requirements of a particular brachytherapy treatment.