Electron capture radioactive sources for intravascular brachytherapy: a feasibility study.

The feasibility of electron capture (EC) radionuclides as an alternative to the beta and high-energy gamma emitters presently in use for intravascular brachytherapy is investigated. A potential advantage of the low-energy x-ray radiation from EC isotopes may be an enhanced biological effectiveness with respect to the presently applied beta nuclides, but at the same time avoiding the shielding problems induced by the large penetrability of high-energy gamma rays. A survey considering the most important practical aspects such as dose delivery to the vessel walls in reasonable time spans, absorption properties, possible production of sources with the required specific activities and radiation safety reveals 71Ge as the most promising candidate.