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

1. 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 % Al 2 O 3 , and 47-52 wt % SiO 2 .

2. The low density microspheres of claim 1 , wherein the density of the magnesia-alumina-silica glass microspheres is about 2.8 g/ml or less.

3. A method of administering radioactive magnesia-alumina-silica glass microparticles to a patient in need thereof, comprising delivering by catheter to an artery that feeds an organ or a tumor of a patient a composition comprising the radioactive low density microspheres of claim 1 , and a physiologically acceptable carrier.

4. The method according to claim 3 , wherein the density of the magnesia-alumina-silica glass microspheres is about 2.8 g/ml or less.

5. The method of claim 3 , wherein the organ or tumor is selected from the group consisting of liver, spleen, brain, kidney, head & neck, uterine, and prostate.

6. A method of obtaining a radiologic image of an organ or tumor in a patient, comprising administering by catheter to an artery that feeds an organ or tumor of a patient a composition containing magnesia-alumina-silica glass microspheres according to claim 1 in a physiologically acceptable carrier, and obtaining the radiologic image of the patient's organ or tumor.

7. The method of claim 6 , further comprising wherein the radionuclide imaging technique is single photon emission computed tomography (SPECT).

8. The method of claim 6 , wherein the organ or tumor is selected from the group consisting of liver, spleen, brain, kidney, head & neck, uterine, and prostate.

9. The method according to claim 6 , wherein the density of the magnesia-alumina-silica glass microspheres is about 2.8 g/ml or less.

10. The microspheres of claim 1 having a diameter of 20 to 40 microns.

11. The microspheres of claim 1 having a diameter of 25 to 38 microns.

12. The microspheres of claim 1 having a surface area of 30 to 50 m 2 /g.

13. The microspheres of claim 1 having a median surface area of between about 50 and about 200 m 2 /g.

14. The microspheres of claim 1 having a median surface area of at least about 100 m 2 /g.

15. The microspheres of claim 14 having a median surface area of at least about 100 m 2 /g.

16. The microspheres of claim 10 having a median surface area of between about 50 and about 200 m 2 /g.

17. The microspheres of claim 10 having a median surface area of at least about 100 m 2 /g.

18. The microspheres of claim 16 having a median surface area of at least about 100 m 2 /g.