A new internal target system for production of 211At on the cyclotron U-120M

The alpha emitter 211At is a radionuclide with good potential for use in the therapy of smaller tumours and metastases. However, limited availability of this radionuclide hinders development of this application and the research of astatine chemistry in general. In this general context we have designed and tested a new internal target system. A thin bismuth layer (3-5 μm) was evaporated onto a light target backing (7.5 g) and irradiated at 0.5-1.5° angles with 29.5 MeV alpha particles beam of intensity up to 30 μA. The backing was then released from the target holder and used directly for astatine separation via dry distillation. Astatine condensed on the Teflon capillary walls was then eluted into 150-250 μl of methanol. The saturation yield was found to be ca. 400 MBq/μA, and the radionuclidic purity of 211At acceptable for medical applications (activity ratio 210At/211At<10-3 at EOB). The overall separation yield was 65-75%.