Method for manufacturing radioactive brachytherapy source material, brachytherapy source material and encapsulated radioactive brachytherapy source

A method of manufacturing radioactive brachytherapy source material comprising indium-114m as a radioactive isotope, said method comprising manufacturing predefinedly shaped pieces of a substantially inorganic and inactive material comprising indium oxide, the indium in said indium oxide having an abundance of indium-113 substantially equal to or greater than its natural abundance, any additional elements, present in the predefinedly shaped pieces, being selected from the group consisting of elements having a sufficiently low neutron cross-section and/or a sufficiently short half life such that they emit insignificant amounts of beta- or gamma radiation at the time of application of the source material in a radioactive brachytherapy source and subsequently subjecting the predefinedly shaped pieces of material to neutron irradiation until a specific activity of indium-114m of at least one MegaBequerel per gram indium has been reached.