The International journal of applied radiation and isotopes最新文献

Measurements of the perturbation of the directional correlation of the 150 and 247 keV γ-rays of ^111mCd was applied in a study of the behaviour of Cd in equilibrium with plant cells. As the overall perturbation factor reflects the degree of binding of Cd to the plant cell-wall the technique makes it possible to distinguish between absorbed and tissue bound Cd, whereas common radiotracer methods fail in this. The results show that the measurement of perturbed directional correlations is a promising method for studying trace element behaviour in equilibrium systems and intact organisms.

Mass separated, neutron rich ${}^{143}\text{Cs (t}{}_{\mathrm{<mtext>NU>1</mtext><mtext>2</mtext>}}\text{= 1.8}\text{s}\text{)}$ and ${}^{143}\text{Ba (t}{}_{\mathrm{<mtext>NU>1</mtext><mtext>2</mtext>}}\text{= 14.5}\text{s}\text{)}$ isotopes were studied. 1565 0 Singles gamma and conversion electron spectra following the β- decay of these nuclei were investigated using Ge(Li) and Si(Li) detectors, respectively. Gamma ray and internal conversion electron relative intensities are listed, and spin and parity assignments, based on transition multipolarities, are proposed. Results are compared with earlier measurements. Some evidence for an isometric state in ¹⁴³Ba is presented.

Complexes of tetrasulfophthalocyanine with ${}^{\mathrm{99m}}\text{Tc}$, ⁶⁹Ga and ⁶⁷Ga were prepared by the condensation of sulfophthalic acid with the appropriate metal-species. The Ga-complex was also obtained by exchange of the central hydrogens of the empty tetrasulfophthalocyanine. The labeled complexes were purified by thin layer chromatography and characterized by their chromatographic properties. Their biodistribution in rabbits and tumor-bearing rats revealed that most of the radioactivity accumulated in the kidneys, liver, ovaries, adrenals and spleen. Comparison of these distribution pattern with those of [${}^{\mathrm{99m}}\text{Tc}$]pertechnetate and ⁶⁷Ga-citrate confirmed the in vivo stability of the labeled complexes. The ⁶⁷Ga-complex reached better tumor-to-blood and tumor-to-muscle ratios than ⁶⁷Ga-citrate.

Use of [¹¹C]urea as an intermediate for the preparation of “no-carrier-added” radiopharmaceuticals required optimization of synthetic parameters. A procedure has been developed to produce [¹¹C]urea from “no-carrier-added” ¹¹CN⁻ within 16 ± 1 min from end of bombardment (EOB) with a radiochemical yield of 95.0 ± 2.5%.

Measured and parametrised values of the attenuation coefficients of bone and several bone standards are presented for the photon energies 33, 75, 145, 279 and 662 keV. The values are compared, inadequacies are highlighted and possible new formulations are discussed.

Gamma absorptiometric method was used to determined uranium and thorium concentration in both aqueous and organic solutions. The complete computer-based γ-spectroscopy system includes a coaxial Ge(Li) detector used to measure the absorption of γ-rays from ²⁴¹Am through the solutions. The absolute concentration of natural uranium and thorium can be determined within 1–200 g U/L and 1–360 g Th/L concentration ranges with a precision of ± 1% for a counting time of up to 100 s with the result that the method is suitable for on-line measurement in fuel element fabrications.

The method of standard additions is a well known procedure in chemistry for the measurement of trace substances. The use of this method is described in the radiometric determination of ²¹⁰Pb activity via the γ-ray at 46.5 keV emitted in about 4% of the decays. Standard additions of ²¹⁰Pb activity are adsorbed on anion exchange resin which is then mixed with the sample. The procedure used to extract the area of the photopeak from the continuum on which it is superimposed, is described in detail. The value of the ²¹⁰Pb activity is calculated using the slope and intercept of the best straight line fitting the count-rate data plotted against added activity. Results obtained on four standard ore samples indicate that this method yields results of comparable accuracy to other methods such as β-ray spectrometry of the prompt ²¹⁰Bi daughter. This method, however, avoids the tedious chemical separations required.