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The radiofluorination of L-dopa with [18F]F2 was investigated with the purpose of improving the yield of 6-[18F]fluoro-L-dopa. When boron trifluoride was added to the reaction mixture in hydrogen fluoride (HF), the yield was increased threefold. Nine millicuries of 6-[18F]fluoro-L-dopa were produced from 100 mCi [18F]F2 routinely and reliably after 2 hr of preparation. If acetonitrile or water were substituted for HF, little or no 6-fluoro-L-dopa was made.

A new synthesis is described for the routine production of 3,4-dihydroxy-6-[18F]fluoro-phenyl-L-alanine (6-[18F]fluoro-L-dopa). The reaction between [18F]fluorine gas and 3,4-dihydroxyphenyl-L-alanine (L-dopa) in liquid hydrogen fluoride gave 2-, 5-, and 6-[18F]fluoro-L-dopa. 6-[18F]Fluoro-L-dopa was isolated by reverse-phase high-pressure liquid chromatography. From 100 mCi [18F]F2, the method produces 3 mCi of 6-[18F]fluoro-L-dopa at the end of synthesis.

The radiation dose to the organs of the human body after an intravenous administration of 6-[18F]fluoro-L-dopa was estimated using the recommendations of the International Committee on Radiological Protection (ICRP). The bladder wall received the highest dose, 6.95E-10 Sv/Bq (2,600 mrem/mCi), and as a consequence the dose to the genitalia was 1.6E-11 Sv/Bq (60 mrem/mCi). The major organs received a dose of 5.66E-12 to 1.87E-11 Sv/Bq (20 to 60 mrem/mCi). The effective dose equivalent was estimated at 5.39E-11 Sv/Bq (200 mrem/mCi).

The reaction between [18F]xenon difluoride, 3,4,6-tri-O-acetyl-D-glucal and boron trifluoride in ether gives exclusively [18F )3,4,6-tri-O-acetyl-2-fluoro-2-deoxy-D-glucopyranosyl fluoride, which is hydrolysed with 1 N HCl to [18F]2-fluoro-2-deoxy-D-glucose. The overall chemical yield is 75%; the radiochemical yield is 20%. The procedure takes 45 min.

The construction of a single ring positron emission tomograph with which to examine the brain is described. The ring comprises 160 bismuth germanate detectors that are not separated from each other by high Z septa. The thickness of the slice examined is 2 cm and the inherent resolution is 7 mm in the plane. The performance of the tomograph and representative clinical studies are illustrated.

A method of measuring bone blood flow has been developed using 18F sodium fluoride and positron emission tomography. The blood flow levels are in line with those obtained experimentally from microsphere embolisation. This investigative method could be applied to elucidate a number of clinical questions involving bone perfusion. [ABSTRACT FROM AUTHOR]