Biomedical cyclotrons

Finally, fluorine-18 can be reliably and routinely produced at the multi-Curie level [19] on widely implemented biomedical cyclotrons of relatively low-energy proton beam (e.g. 18MeV). This fact, combined with its favourable half-life. 

As an evident consequence of their short half-lives, these radioisotopes have to be produced immediately before use, normally on site by a dedicated biomedical cyclotron. Only fluorine-18 with its 110-min half-life permits off-site use. 

This prototype drug208, 217, has been 11 C-labelled209 for assessment of serotonin uptake sites in depressed patients by reaction of [nC]iodomethane with desmethylcitalopram, 218, in 18-66% radiochemical yield (equation 114). 217 has been obtained also by Dan-nals and coworkers210 by reacting freshly prepared desmethylcitalopram dissolved in DMF with [nC]methyl iodide. The radiochemical yield based on [nC]CH3l was about 20% the overall radiochemical yield was about 9% based on the initial activity of [UC]CC>2 produced by 16 MeV proton irradiation of nitrogen gas in biomedical cyclotron. 

The large, expensive, and heavily shielded biomedical cyclotron is used to produce most radioisotopes used in PET scans. 

Yoo J, Tang L, Perkins T A, et al. (2005). Preparation of high specific activity using a small biomedical cyclotron. Nucl. Med. Biol. 32 891-897. 

M. S. Livingstone, J. P. Blewett, Particle Accelerators, McGraw-Hill, New York, 1962 M. H. Blewett, The Electrostatic (Van de Graafi) Generator, in Methods of Experimental Physics (Eds. L. C. L. Yuan, C. S. Wu), Vol. 5B, Academic Press, New York, 1963 P. M. Lapostolle, L. Septier, Linear Accelerators, North-Holland, Amsterdam, 1970 A. P. Wolf, W. B. Jones, Cyclotrons for Biomedical Radioisotope Production, Radiochim. Acta 34, 1 (1983)... 

Properties of the complexes of alkali metal cations with various bases are important in understanding ion-molecule interactions, solvation effects, biomedical and physiological phenomena related to ion channels and relevant in medical treatments. Reliable experimental bond dissociation enthalpies, and thereby gas-phase alkali ion affinities, could now be obtained using various mass spectrometry techniques such as the Fourier-transform ion cyclotron resonance (FT-ICR), collision-induced dissociation and photodissociation methods. However, these methods do not provide direct information on the adduct structures. 

Because use of mass spectrometry by chemists has increased greatly, most U.S. chemists have access to mass spectrometry facilities at their own institutions to confirm synthesis and support structure elucidations. Heavily used national centers provide more expensive instrumentation and more complex experiments. Most notably, a section of the National High Magnetic Field Laboratory at Florida State University provides state-of-the-art Fourier transform ion cyclotron resonance mass spectrometry. The NSF Arizona Accelerator Mass Spectrometry Laboratory is used primarily to provide radiocarbon measurements. NIH funds a number of national mass spectrometry centers to support biomedical research, including those at Boston University and the Pacific Northwest National Laboratory. 

Fermi and colleagues at the University of Chicago put cyclotrons on a back burner in biomedical research by inventing the nuclear reartor during World War II, which made possible the production of large amounts of carbon-14, tritium, phosphorus-32, and other radionuclides. Carbon-14 became the foundation of the field of biochemistry. 

Up until our obtaining a cyclotron, we developed single photon-emitting radiotracers to image the heart, spleen, liver, kidneys, and other organs. Our NIH-proposal was entitled Short Lived Radionuclides in Biomedical Research. 

During his visit to Johns Hopkins in 1965 for the NIH site visit of our cyclotron proposal, Alfred Wolf, a chemist in charge of the cyclotron at the Brookhaven National Laboratory (BNL), saw the potential value of cyclotron-produced radionuclides in biomedical research. He and his colleagues, including Joanna Fowler, subsequently developed a large number of radioactive tracers, including fluorine-18 deoxyglucose (FDG),... 

The same year, Paul Aebersold, another graduate student of Ernest Lawrence (Fig. 7.3.), became involved in the worldwide distribution of radionuclides by the US Atomic Energy Commission. He published The Cyclotron A Nuclear Transformer (Aebersold, 1942). No one did more to make radionudides available to the biomedical community than Paul. 

TerPogossian s cydotron had been in the Physics Department. The first cyclotron in a medical facility and used exclusively for biomedical research was built at Hammersmith Hospital in London in 1955, under the auspices of the Medical Research Council. A similar cyclotron was subsequently built at Massachusetts General Hospital in Boston. Using a medically dedicated cyclotron that was built later at Washington University, Raichle and colleagues showed that vision and other mental activity resulted in an increased oxygen metabolism in the involved regions of the brain. 

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