PREPARATION OF GLASS FOR RADIOTHERAPY OF CANCER BY P-IMPLANTATION AT 100 KEV( ION)

A chemically durable glass containing a large amount of phosphorus is useful for in-situ irradiation of cancers. It can be activated to be a beta-emitter with 14.3 days half-life by neutron bombardment. Microsp heres of the activated glass injected into the tumors can irradiate th e tumors directly with P-rays without irradiating neighboring normal t issues, In the present study, a P+ ion was implanted at 100 keV. There was little phosphorus present in the surface region, at least to a de pth of 2.4 nm for doses of 5 x 10(16) and 1 x 10(17) cm(-2), whereas a n appreciable amount of it was distributed on to the glass surface and a part of it was oxidized for doses above 5 x 10(17) cm(-2), The glas ses implanted with doses of 5 x 10(16) and 1 x 10(17) cm(-2) released little both of the P and Si into water at 95 degrees C, even after 7 d ays, whereas the glasses implanted to doses above 5 x 10(17) cm(-2) re leased appreciable amounts of these elements. At implantation energy o f 20 and 50 keV, even doses of 5 x 10(16) and 1 x 10(17) cm(-2), respe ctively, formed oxidized phosphorus on the glass surfaces and gave app reciable releases of the P and Si into the hot water. This indicates t hat a chemically durable glass containing a larger amount of phosphoru s could be obtained if P+ ion implanted at higher energies is localize d in a deeper region.