International Journal of Radiation Applications and Instrumentation. Part A. Applied Radiation and Isotopes最新文献

A protected 6-trimethylstannyl dopa derivative 6 has been synthesized for the first time as a precursor for the preparation of 6-[¹⁸F]fluoro-l-dopa. The tin derivative 6 readily reacted with electrophilic radiofluorinating agents such as [¹⁸F]F₂ and [¹⁸F]AcOF. The [¹⁸F]fluoro intermediate 7 was easily hydrolyzed with HBr and the product 6-[¹⁸F]fluoro-l-dopa was isolated after HPLC purification in a maximum radiochemical yield of 25%, ready for human use. The various intermediates, the stannyl precursor 6 and the final product (after ¹⁸F decay) were all fully characterized by ¹H, ¹³C, ¹⁹F and ¹¹⁹Sn NMR as well as high resolution mass spectroscopy.

The production of no-carrier-added (NCA) ¹⁸F from reactions induced by high-energy protons on Na-containing targets was studied. Single (mCi/μAh) and cumulative yields (mCi/μAh) for ¹⁸F were measured in the 67.5–20 MeV proton energy range. Total cross sections (mbarns) were then calculated from the experimental radionuclide yields. Preliminary results of a radiochemical process to separate and purify NCA ¹⁸F from Na targets are also reported and evaluated. The production of ¹⁸F from Na is compared with other existing techniques as well as with other high-energy proton-induced reactions on solid targets (Al, Mg) reported previously. Other radionuclides (i.e. ²⁴Na, ²²Na, ⁷Be and ^34mCl) were also produced with protons on NaCl and Na₂CO₃ targets. The effects of these radiocontaminants is also discussed. Finally, a comparison is made for the ²³Na(p,x) excitation function, measured experimentally and calculated using the ALICE82 nuclear reaction code.

Two established methods for measuring Ra-226 have been combined and adapted and applied in the uranium mining industry. The optimum conditions have been established. Accuracy, precision, cost efficiency and relatively short preparation time make this a useful method.

The emission of fast neutrons by recoil protons (0.02–3 MeV energies) during the electrolysis of heavy water was studied experimentally using iron, stainless steel, titanium, titanium-vanadium, platinum and palladium cathodes. Normal low-background measuring equipment was used (sensitivity up to 3 × 10⁻⁴ Bq/mL) with a proportional methane counter, volume 4 L, pressure 2 × 10⁵ N/m² which was calibrated with a californium source of 2 × 10⁷ n/s; the registration efficiency was 7%. Statistical processing of the results using the Student criterion failed to detect any neutron flux of more than 0.04 n/s from our various conditions of electrolysis with a reliability of 99.9%.

Technetium-99m radiopharmaceuticals prepared for routine clinical use, were labelled with [^99mTc]pertechnetate obtained from either a commercial chromatographic generator or from a Winnipeg Health Sciences Centre semi-automated self-shielded methyl ethyl ketone extraction system. The [^99mTc]pertechnetate source for each ^99mTc radiopharmaceutical was selected at random over a 16 month period of time. The routine quality control data (silica-gel thin layer chromatography) was reviewed retrospectively, as an in vitro assessment of the quality of the [^99mTc]radiopharmaceutical prepared from each [^99mTc]pertechnetate source. Bone scans ([^99mTc]pyrophosphate) and wall motion studies ([^99mTc]red blood cells) were evaluated as an in vivo assessment of the [^99mTc]pertechnetate used to label the pyrophosphate or red blood cells. The in vitro studies indicated no difference in the labelling efficiency and radiochemical purity of the ^99mTc radiopharmaceuticals prepared from either source of [^99mTc]pertechnetate and there was also no difference observed in the image quality of either bone scans or wall motion studies obtained with either source of [^99mTc]pertechnetate.

A series of dilute solutions of ⁹⁹Tc-HMPAO/^{99 + 99m}Tc-HMPAO diastereoisomers whose concentrations ranged from 10⁻⁸ to 10⁻⁴ M were prepared and the rates of decrease in ⁹⁹Tc-HMPAO diastereoisomers were determined. For the concentration ranges between 10⁻⁸ and 10⁻⁴ M the rates of decrease in their concentration were measured by ITLC and paper chromatography (three strips method). Ultraviolet and visible spectrophotometry was used to determine the rates of concentration changes for 10⁻⁶ ∼ 10⁻⁴ M solutions. The results were compared with previous work.

Quality control of routine radiopharmaceutical preparations of carbon monoxide, carbon dioxide and oxygen is necessary. Still, this simple task is compromised by the high demand for gas chromatograph (GC) time in a busy laboratory. Frequent production of such materials at essentially random intervals requires a dedicated radio-GC system. We report a simple, inexpensive and automatic routine quality control approach that is continuously available independently of the main laboratory instrument and provides the same accuracy.

The relative intensities of x-rays and gamma rays emitted in the decays of ¹⁵³Sm and ¹⁵³Gd have been measured precisely using a set of five HPGe and Si(Li) detectors. The intensities of L x-rays from ¹⁵³Gd and K and L x-rays from ¹⁵³Sm decays have been measured for the first time. In addition, the level scheme of ¹⁵³Eu following ¹⁵³Sm decay was also investigated using high resolution HPGe-HPGe coincidence set-up (2τ = 7 ns).

${}^{18}\text{F-labeled}\text{(}\text{E}\text{)-β-}\text{fluoromethylene}\text{-}\text{DL}\text{-m-}\text{tyrosine}$ (FMMT) was prepared by the direct reaction of FMMT with [¹⁸F]acetylhypofluorite (AcOF) resulting into three product isomers. Extensive ¹H, ¹³C and ¹⁹F-NMR spectroscopic analysis identify these products to be 2-fluoro, 6-fluoro-FMMT and 2,6-difluoro-FMMT. The HPLC isolated radiochemical EOB yields of these products were 22, 25 and 14%, respectively, based on starting [¹⁸F]AcOF. The specific activity at the end of a synthesis time of an hour was ca 200 mCi/mmol. With the possible advantage of “metabolic trapping” in dopamine nerve terminals via covalent binding to MAO and reduced metabolite formation, [¹⁸F]F-FMMT may potentially be the optimal PET tracer for CNS dopamine nerve terminals.