A fundamental task within the framework of a project searching for new radiopharmaceuticals for systemic therapy was the evaluation of the capabilities of the Portuguese Research Reactor (RPI) for the production of several important radionuclides. The feasibility of producing 64Cu, 77As, 153Sm, 165Dy, 166Ho, 170Tm, 177Lu, 186Re, 199Au and 111Ag in useful quantities was evaluated for the present RPI operation schedule (12 h cycles) and for continuous operation. The main evaluation criteria are expressed in terms of specific activity for continuous irradiation and/or 12 h cycle and the use of natural or enriched targets if necessary. Selected samples were irradiated and a comparison between measured activities and values calculated according to the irradiation schedule and using the same software was performed.

The increasing demand for radiolabeled metaiodobenzylguanidine (mIBG) prompted the need to obtain the radiopharmaceutical by a reliable, routine and simple synthetic method for batch production. The production of mIBG labeled with either 123I or 124I has been optimized by modifying literature methods that involve solid-state exchange reaction on "cold" mIBG facilitated by ammonium sulfate. The radiochemical yield and purity of radioiodinated mIBG generally exceeded 80 and 98%, respectively, with specific activity of > 50 mCi/mg.

Excitation functions were measured for the formation of 122mCs, 122Xe, 121Xe and 121I from threshold up to 44 MeV in proton induced nuclear reactions on 99.9% enriched 124Xe. The feasibility of 122Xe→122I generator production was investigated. The optimum energy range for the production of 122Xe is Ep = 43 → 35 MeV and the thick target yield amounts to 13.5 mCi/μAh. After an appropriate cooling time a generator containing several hundred mCi of 122Xe could be produced. The daughter 122I could be milked off periodically and would be >99% pure.

Excitation functions were measured for (p, 2n) and (p, pn) reactions on 99.9% enriched 124Xe from threshold up to 44 MeV. The (p, 2n) reaction is much stronger than the (p, pn) channel; above 36 MeV, however, the two processes have almost equal cross sections. Differential yields of 123I were measured experimentally as a function of proton energy and were also calculated from the excitation functions. Our experimental and theoretical yield data are consistent within 15%, but are lower by a factor of 2 than the literature experimental values. Our studies show that the optimum energy range for the production of 123I is Ep = 29 → 23 MeV. The theoretically expected thick target yield of 123I at 6.6 h after EOB is 11.2 mCi/μAh, and is in agreement with the high-current experimental production yields.

The scintillation lifetimes of Pilot U, M and B, Naton 136, NE 111 and an experimental scintillator are compared. The new Pilot U scintillator exhibits the fastest decay time (τ1=1.3 ns) yet obtained for a plastic scintillator.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffects of deuteration and heavy atom additives on the scintillation lifetime of p-terphenyl in benzene at 22.deg.Richard M. Lambrecht, Thomas Michael Kelly, and Joseph A. MerriganCite this: J. Phys. Chem. 1970, 74, 10, 2222–2224Publication Date (Print):May 1, 1970Publication History Published online1 May 2002Published inissue 1 May 1970https://pubs.acs.org/doi/10.1021/j100909a033https://doi.org/10.1021/j100909a033research-articleACS PublicationsRequest reuse permissionsArticle Views35Altmetric-Citations6LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access options Get e-Alerts