Cyclotron products

F. Helus, W. Maierborst, U. Sahm, L.l. Wiebe, F-18 Cyclotron production methods, Radiochem. Radioanal. Lett. 38 (1979) 395-410. 

Lagunas-Solar, M., Cyclotron Production of No-Carrier-Added Medical Radionuclides, 7th Conference on the Applications of Acceleration in Research and Industry, Denton, TX, 1982. 

The third means of radionuclide production involves target irradiation by ions accelerated in a cyclotron. One example of this approach is provided by the production of Ge, which decays with a 280 day half-life to the positron emitter Ga. Proton irradiation of Ga produces Ge in a (p,2n) reaction. After dissolution of the target material a solution of the Ge product in concentrated HCl is prepared and adsorbed on an alumina column which has been pre-equilibrated with 0.005 M EDTA (ethylenediaminetetraacetate) solution. The Ga daughter may then be eluted using an EDTA solution in a system which provides the basis of a Ga generator. Cyclotron production of radionuclides is expensive compared with reactor irradiations, but higher specific activities are possible than with the neutron capture process. Also, radionuclides with particularly useful properties, and which cannot be obtained from a reactor, may be prepared by cyclotron irradiation. In one example, cyclotron produced Fe, a positron emitter, may be used for bone marrow imaging while reactor produced Fe, a /3-emitter, is unsuitable. " ... 

Lubberink M, Tolmachev V, Widstrom C, et al. (2002). In-DTPA-D-Phe -octreotide for imaging of neuoendocrine tumors using PET. J. Nucl. Med. 43 1391-1397. Tolmachev V, Bernhardt P, Forssell-Aronsson E, et al. (2000). In, a candidate for radionuclide therapy low-energy cyclotron production and labeling of DTPA-D-Phe -octreotide. Nucl. Med. Biol. 27 183-188. 

Elements.—gas-flow Te powder target for the cyclotron production of pure 2 1 has been described. The reaction involved is Te( He,3ny Xe Yields in the range 2—4 mCi h have been obtained from 1.5 g The 2 1 contamination could be held as low as 0.001 %, whereas the contamination was 0.4%. 

For medical purposes, an enormous collection of techniques is accumulated regarding production of short-Kved nuclides mainly by cyclotrons. The technique should undoubtedly be usefiil for appKcation of radioactive tracers to other fields. Such nucKdes include F, and also many nucKdes of metals, halogens, and rare gases. Reactor and cyclotron production of medical radioisotopes is described in Chaps. 38 and 39 of VoL 4, respectively. Basic data for production of short-Kved nucKdes by cyclotron were compfled with substantial references by Qaim (1982). Another review by Waters and Silvester (1982) emphasizes cyclotron-produced nuclides useful for inorganic studies with many references, too. 

Abstract Cyclotron products are gaining in significance in diagnostic investigations via PET and SPECT, as well as in some therapeutic studies. The scientific and technological background of radionuclide production using a cyclotron is briefly discussed. Production methods of the commonly used positron and photon emitters are described and developments in the production of some new positron emitters and therapeutic radionuclides outlined. Some perspectives of cyclotron production of medical radionuclides are considered. 

As mentioned above, in cyclotron production of radionuclides, the reaction cross section data play a very important role (for detailed discussion c Qaim 1982, 2001a). One needs the fiiU excitation function of the nuclear process to be able to calculate the yield with reasonable accuracy. Another important point is the number of competing reaction channels. At an incident projectile energy of 20 MeV, for example, about six reaction channels with significant cross sections may occur. It is imperative to know the cross sections of aU those processes. The demands on the data may thus be extensive. At small-sized cyclotrons, low energy reactions Kke (p,n), (p,a), (d,n), (d,a), etc., are used. At higher energies, on the other hand, (p,xn) reactions are commonly utilized. In some special cases, the (p,spall) process is applied. 

Fora detailed discussion of various experimental and theoretical aspects of nuclear reaction cross section data relevant to cyclotron production of radionuclides, the reader is referred to two recent IAEA-coordinated efforts (cf. Gul et al. 2001 Qaim et al. 2008). 

Out of all the positron emitters listed in Table 39.3, five radionuclides, namely Cu, Se, Br, and have attracted considerable interest in recent years, though as yet some of them have not been applied in investigations on humans. The radionuclide Cu emits low-energy positrons and has a suitable half-life for slow metabolic studies, ft was produced previously via the Cu(n,y) Cu reaction. Due to the rather low specific activity of the product, the Ni(p,n) Cu reaction was suggested as an alternative route (Szelecsenyi et al. 1993) that can be used at a small cyclotron. Production via this route has been successfully developed, including an efficient recovery of the highly enriched target material (cf. McCarthy et al. 1997). It is now extensively used in radioimmunotherapy. 

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