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

OH radicals formed in water radiolysis may be effectively used for the oxidative decomposition of trichloroethylene and perchloroethylene contained as micropollutants in groundwater. Addition of ozone to the water before irradiation causes the reducing species of the water radiolysis to be converted into OH radicals. Moreover, this eliminates the dose rate effect observed with irradiation alone. By the ozone-electron beam treatment >95% of the organic chlorine content are mineralized, only negligible amounts of organic chlorine containing by-products are formed. AMES test has shown no mutagenic activity at all.

Methodology applicable to the synthesis of no-carrier-added [O-methyl-¹¹C]alfentanil was developed. The sequence consisted of [¹¹C]methylation and propionylation of N-aryl-4-(hydroxymethyl)-4-(N-anilino)-piperidines1a and 1c, followed by the chemoselective hydrolysis of bulk byproducts to facilitate isolation of the NCA carbon-11-labeled product by prep-HPLC. All three steps could be performed without isolation of intermediates in a single reaction vessel.

We report an investigation of the application of the Szilard-Chalmers process to improve the specific activity of reactor produced ^117mSn. The radiopharmaceutical ^117mSn⁴⁺DTPA is a promising agent for relieving bone pain in breast and prostate cancer patients. Preliminary studies in these patients have given very encouraging results. For this application high specific activity ^117mSn is required to minimize the quantity of administered DTPA. Using a tetraphenyltin target we have investigated solvent extraction and ion exchange techniques to enrich the radioactive atom concentration. Other variables studied include the effect of neutron flux, total neutron fluence and sample mass. The enrichment factor was comparable for both solvent extraction and ion exchange techniques, but solvent extraction was more convenient. For 1 h irradiations the enrichment factor averaged ∼ 70 but declined to ∼ 2 after 24 h irradiation due to accumulated radiation damage. The enrichment factor also declined with increasing neutron energy. An isotope effect on the Szilard-Chalmers process was observed as the enrichment factor for ¹¹³Sn was consistently higher than for ^117mSn.

A 4πβ-gamma coincidence system and several efficiency calibrated semiconductor spectrometers were used to determine the following ¹⁴¹Ce/¹⁴¹Pr decay data: 1. The β-transition probability to the 145 keV level of ¹⁴¹Pr, b₁. 2. The total conversion coefficient of the 145 keV transition to the ground state of ¹⁴¹Pr, α_T. 3. The gamma-ray emission probability of the 145 keV photons, P_γ. The results are b₁ = 0.697(6), α_T = 0.452(8), P_γ = 0.480(5). The value of b₁ is in agreement with most of the values reported in the literature for this quantity. The value found for α_T is higher than all experimental values determined previously but agrees well with the theoretically calculated value for an M1 transition with 0.48% E2 admixture (α_T = 0.4565). The value for P_γ agrees with the value determined by Hansen et al. (1979), P_γ = 0.482(3). In addition, emission probabilities of K and L x-rays following the decay of ¹⁴¹Ce are determined experimentally.

Technetium 99m-labeled diisopropyliminodiacetic (acid [^99mTc]DISIDA) has been used extensively in the evaluation of hepatobiliary diseases. As a result of investigation into transport mechanisms of [^99mTc]DISIDA, we undertook to determine precise concentrations of this compound in the standard clinical formulation. Calculations based on published formulas were used. These take into account column efficiency, the time since the previous elution of ^99mTc from the ⁹⁹Mo column, and the total quantity of ^99mTc eluted. Primary cultures of rat hepatocytes were used to evaluate the transport of Na^99mTcO₄ and the ^99mTc-labeled DISIDA monomer. Pertechnetate was not taken up by the hepatocytes, the amount of [^99mTc]DISIDa taken up was not dependent on the concentration of DISIDA but rather on the concentration of technetium, when the DISIDA/^99mTc ratio was varied in the culture medium. We conclude that calculation of the total technetium concentration is necessary to determine the amount of compound taken up by the liver, and to interpret kinetic studies of hepatocellular transport mechanisms.

In order to optimize the production of ¹¹⁸Te in thick targets for use in a ¹¹⁸Te/¹¹⁸Sb radionuclide generator, the excitation function for the ¹²¹Sb(p,4n)¹¹⁸Te reaction has been measured for 30–46 MeV protons. The excitation functions for the competing reactions ^natSb(p,xn)^119mTe, ^natSb(p,xn)¹¹⁹Te, ^natSb(p,xn)^121mTe, ^natSb(p,pxn)^120mSb and ¹²³Sb(p,pn)¹²²Sb have also been determined using stacked foil techniques. The ¹²¹Sb(p,4n)¹¹⁸Te reaction cross section maximum was found to be 480 mbarn at 44 MeV. In order to minimize the ^{119m + 119}Te interference a minimum proton beam energy of 40 MeV is required. The cross section results are compared with published data and with calculated excitation functions.

A new bis-hydrazide-phosphine (BHP) ligand was synthesized, characterized and complexed with ^99mTc. ^99mTc phenyl-BHP (PBHP) was shown to form a neutral-lipophilic chelate with ^99mTc, in high yields, that is stable over a wide pH range. Results with ^99mTc-PBHP indicate that the BHP chelating moiety is attractive for use in designing new ^99mTc-imaging agents.

Multielemental instrumental neutron activation analysis has been employed for the determination of >20 elements (Ag, Au, Br, Co, Cr, Cs, Eu, Fe, Hf, Hg, Ir, La, Lu, Na, P, Sb, Sc, Se, Ta, Tb, Te, Th, Zn, Zr) in water samples from different locations in Nagpur city in Central India. Several environmental standards from NIST (U.S.A.), NIES (Japan) and IAEA (Vienna) were also analyzed for accuracy determination. After preconcentration by evaporation, the samples were irradiated with thermal neutrons at ∼ 10¹³ n·cm⁻²s⁻¹ in CIRUS reactor for a day and one week and counted by high resolution γ-ray spectrometry. Elemental concentrations of most elements in the standards are in good agreement with the certified values.