Heavy ion activation: treasure of non-conventional neutron deficient radionuclides

The non-conventional radionuclides are getting more importance in the field of nuclear medicine, mainly due to the possibility to make personalized diagnosis and therapy on case-to-case basis. For last twenty years, we are engaged in production and separation of non-conventional neutron deficient radionuclides by heavy ion (HI) activation. The varieties of projectiles like ⁷Li, ¹¹B, ¹²C, and ¹⁶O have been used for production of such radionuclides. One has liberty to go far away from the stability line by HI activation by choosing appropriate target projectile combination. Also due to larger difference in atomic number between product and target radionuclide, the separation of no-carrier-added (NCA) radionuclides become easier. This is especially true for rare earth radionuclides. We have also developed excellent separation methods of the HI induced NCA radionuclides from the target matrix. Some of the HI activation products are also excellent PET radionuclides. The disadvantage of heavy ion activation is the production cross section of HI induced reactions are much less compared to proton or α-particle activation. The lower cross section currently prohibits the use of HI activation products for their use in human application. However, there is continuous technological development in accelerator technology. In future it may be possible to produce required amount of NCA radionuclides in combination of high current ion source (e.g., ECR ion source), CW accelerators and advanced target technology. It is noteworthy to mention that though the yield of the radionuclides by HI activation is not sufficient for human application, but sufficient for pilot studies in laboratory scale such as small animal PET imaging, or bio-distribution studies