Properties of Glass Implanted with Phosphorus for Radiotherapy

用30 keV、5 × 10 ~（-1）cm ~ 2的磷离子注入高纯石英玻璃<16>，<-2>在95 ℃的纯水中，经过7天，磷几乎全部溶解。当玻璃在H_2气氛中于400 ℃加热，然后在O_2气氛中于900 ℃加热时，玻璃中的磷变得不溶于水。这表明，在400 ℃热处理时，磷胶体生长，而在900 ℃热处理时，胶体被包裹在SiO_2-P_2O_5玻璃薄层中。当硅玻璃同时注入氮离子和磷离子，然后进行相同的热处理时，得到了具有高化学稳定性的高含磷硅玻璃。因为通过形成氮氧化硅抑制了热处理时磷的蒸发。当磷离子以50 keV、5 × 10 ~（-6）cm ~（-1）注入石英玻璃时<16><-2>，在50 nm深度处浓度最大，并没有分布到玻璃表面。结果，尽管离子注入引起表面结构损伤，但该玻璃不将磷溶解到水中。此外，在200 keV下用磷离子注入的二氧化硅玻璃即使注入大剂量的磷（1 × 10 - 4cm-3）也不溶解磷<18><-2>。预期通过本方法获得的玻璃可用于深度癌症治疗。

Highly pure silica glass implanted with phosphorus ion at 30keV by 5*10^<16>cm^<-2> dissolved almost all the phosphorus into the pure water at 95ﾟC during 7days. When this glass was heated at 400ﾟC in H_2 atmosphere and then heated at 900ﾟC in O_2 atmosphere, phosphorus in the glass became insoluble into the water. This suggests that phosphorus colloid grew by the heat treatment at 400ﾟC and that colloids were encapsulated in a thin SiO_2-P_2O_5 glass layr by the heat treatment at 900ﾟC.When the silica glass was implanted with nitrogen ion as well as phosphorus ion, and then subjected to the same heat treatment, highly phosphorus-containing silica glass with high chemical durability was obtained, since the evaporation of phosphorus on the heat treatment was suppressed by formation of silicon oxynitride. When the phosphorus ion was implanted to the silica glass at 50keV by 5*10^<16>cm^<-2>, it showed the maximum concentration at about 50nm depth and did not distribute up to the glass surface. As a result, this glass did not dissolve the phosphorus into the water in spite of the surface structural damage caused by the ion implantation. Moreover, the silica glass implanted with phosphorus ion at 200keV did not dissolve phosphorus even if a large dose of phosphorus, 1*10^<18>cm^<-2>, was implanted. It is expected that the glass obtained by the present method is useful for deep cancer treatments.