Production of ultra-pure I-123 from the [sup 123]Te(p,n)[sup 123]I reaction

The problems and potentials for producing I-123 (T1/2=13.27 h) with high radionuclidic purity (RNP) in Curie quantities has been discussed in many publications for over 35 years. Depending upon the nuclear reaction selected, the isotopic enrichment of the target material used and the energy of the protons incident on the target, I-124 (T1/2=100 h), I-125 (T1/2=59.4d) and/or I-126 (T1/2=13d) may be co-produced with the I-123 and significantly reduce the RNP at the time of clinical use. For the (p,n) reaction, the important factors which influence RNP are Te-123 enrichment, Te-123:Te-124 ratio and the incident proton energy. Using targets of 99.3% Te-123 enrichment with a Te-123/Te-124 greater than 990 and 15.7 MeV incident proton energy, we have produced I-123 with a RNP of 99.9+% at EOB. Thirty hours after EOB, the average RNP is 99.8+%. Production yields are being increased gradually, from near 500 mCi to 1 Ci per run at EOB.