“…Therefore, the most useful nuclear reactions for carbon-11 production from a clinical standpoint are the proton and deuteron reactions on natural and enriched boron oxide [34][35][36][37] and the proton reaction on nitrogen [38][39][40][41][42]. Several reviews have appeared in the literature which describe the details and problems in the preparation of carbon-11 labelled intermediates from such targets [9,17,[44][45][46][47][48][49], Table 2 also lists the 12 C( 3 He, 4 He) n C and 12 C(y, n) 11 C reactions because they provide high yields of the radionuclide. The helium-3 reaction [50] has been used in recoil labelling [51 ].…”