11CH4 molecule production using a NaBH4 target for 11C ion accelerationa)

Solid-state materials suitable for use as proton irradiation targets were investigated for producing high-purity 11CH4 molecules for heavy-ion cancer therapy. The radioactivity of gas produced by proton irradiation was measured for several target materials. Also, the radioactive molecular species of the produced gas were analyzed by radio gas chromatography. We found that 5 × 1012 11C molecules could be collected by proton irradiation on a NaBH4 target. We also found that the 11CH4 molecules were produced and collected directly from the irradiated target, owing to the hydrogen atoms bound in the solid-state NaBH4.