The objective of this program is to develop a dedicated, accelerator-based 13N-ammonia delivery system for positron emission tomography (PET). 13N- ammonia PET scans can accurately measure myocardial blood flow and can also be utilized to measure blood flow in other parts of the body. The proposed generator will utilize a very low energy Coaxial Cascade Accelerator (CCA) to produce 13N via the 12C(d,n)13N nuclear reaction in a graphite target. The self-shielded accelerator and 13N-ammonia synthesis system will be housed in a 2.2 m x 1.1 m x 1.4 m enclosure and will be fully automated. The estimated cost of the 13N-ammonia delivery system is comparable to that of a one year supply of 82Rb, another commonly used blood flow agent. In Phase I, the feasibility of extracting 13N from graphite irradiated with 1.2 MeV deuterons was established, and the conversion of target activity to 13N-ammonia in under 10 minutes with a total decay-corrected efficiency of 44% was demonstrated. In Phase II, the complete 13N-ammonia generator, including the 1.2 MeV CCA, 13N extraction and chemical synthesis system, automated controls and radiation shield will be constructed and tested. The Phase II system will be capable of delivering two 30 mCi batches per hour of radiopharmaceutical quality 13N-ammonia for clinical PET.
