Low-density magnesia-alumina-silica (MAS) microparticles for radiotherapy and/or radioimaging

Low density microspheres for radio-imaging in a mammal, comprising a biologically compatible magnesia-alumina-silica glass microspheres having a density of about 3.0 g/ml or less and a size range from about 20 to 200 um, said microspheres containing gallium -68 or fluorine-18 distributed substantially throughout the magnesia-alumina-silica glass, the microspheres having a chemical durability such that subsequent to administration of the microspheres to the mammal, the microspheres will not release a significant amount of the radioisotope into the mammal's system;

• wherein the glass microspheres comprise 8-14 wt % MgO, 32-35 wt % Al2O3, and 47-52 wt % SiO2.