INERT CERAMIC MICROSPHERES containing beta emitting radioisotopes have been injected into the arterial supply of human cancers for irradiation treatment purposes.1-3 Tissue counting radioautography revealed an even distribution pattern in the lungs when the microspheres were infused into the external jugular vein of the dog. Of the microspheres, 96 to 100% were found to be filtered out and retained in the arterioles of the lungs.
We have used gamma emitting radioisotopes in these microspheres to visualize the lungs with a photoscanner.4
Ceramic microspheres 50±10 μ in diameter and containing Hg203 with a radioactivity content of 5 μc of radioactivity per mg of labelled spheres were injected into the saphenous veins of mongrel dogs weighing about 12 kg (24.2 lb), during sodium pentothal anesthesia. Doses of microspheres weighing from 10 to 60 mg and assaying from 50 to 100 μc of radioactivity were administered in from 1