A simple calibration procedure for the Inshas whole body counter for evaluating total body potassium has been adopted. More than 120 Egyptian employees in the Nuclear Research Center (N.R.C.) were studied for their total body potassium (TBK). The potassium values were found to have an average of 2.85 +/- 0.57 g K kg-1 body weight for males and 2.62 +/- 0.52 g K kg-1 for females, which are higher than the recommended value given for reference man by ICRP. The TBK varied directly with body build index and is slightly sex dependent.
A procedure for the incorporation of [125I]IdU into specific sites in DNA is described. The approach depends upon attachment of radioiododeoxyuridine to a controlled pore glass support which is then used for automated synthesis of an oligomer. The resulting oligomer, containing a terminal 3′[125I]iododeoxyuridine, is used as a primer during DNA synthesis catalyzed by the Taq polymerase employing thermal cycling. The product formed includes the radioiodonucleotide at a single internal site determined by the length of the oligomer.
The reproducible preparation of [1-11C]propenoic acid (acrylic acid) in 45–50% radiochemical yield was made possible by careful control of the temperature and time of the 11C carbonation of ethenylmagnesium bromide. It allowed the obtention of [1-11C]propenoyl chloride and N-[1-11C] substituted propenamides. These latter were highly reactive as it was shown by the obtention of a Michael adduct with secondary amines even at room temperature.
A Monte Carlo aided method of calculating the average solid angle subtended by a collimated detector from surface and volumetric sources is presented which incorporates the contribution of the collimator edge penetration effect. The validity of the method which utilizes total variance reduction is demonstrated using point reference sources. The results show that the collimator edge penetration effect could be highly significant when measuring photons with energies greater than a few hundred keV and that the method outlined is capable of quantifying the contribution to the calculated average solid angle. Case studies of the possible applications of the method to the field of quantitative photon measurement are presented and discussed.
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.
The energy transfer rate parameter K3 and the quenching rate parameter K7b are determined in a liquid scintillator system consisting of 2,5-di-[5-tertbutyl-2-benzoxazolyl)-thiophene (BBOT) as solute, toluene as solvent and bromobenzene as external solvent quencher in three different media; neat toluene (TN), dilute mixture 1:9 by volume fraction to toluene to cyclohexane (TC) and toluene to liquid paraffin (TP), in the temperature range 20°–70°C (viscosity range 0.35–39.0 cp). The results are discussed in terms of the role of diffusion, migration and long-range dipole-dipole interaction of Forster type in these three systems.
Measurements of coincidences between conversion electrons of the 88 keV transition in the 123Tem decay and subsequent 159 keV quanta have been made with a 4πβ-γ coincidence system equipped with a pressurized proportional counter (PPC) in the beta channel. With 123Tem sources prepared for activity determination, a detection probability for conversion electrons, ϵ, very close to ϵ = 1 was achieved. The following data have been derived from the slope of a polynomial fit to nβnγ/nc vs (1 − ϵ)/ϵ by varying ϵ by discrimination and taking into account the γ sensitivity of the PPC (nβ, nγ, nc are the counting rates in the β, γ and coincidence channel): the total conversion coefficient of the 159 keV transition αt = 0.1895(13), the γ-ray emission probability of the 159 keV photons p = 0.8407(9). These data agree with the theoretically calculated values, and with less accurate values determined experimentally by other authors.
A study of the background gamma radiation spectrum in Ain Shams University buildings was performed for the energy range 50 keV–3 MeV using a hyperpure Ge-detector. The absolute dose for each gamma line was calculated and an estimation of the total absorbed dose for the detected gamma lines was obtained. Comparison with other results was also performed.
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.
In response to the needs of research groups in Japan, a chemical separation procedure was developed for isolating specific radioactive isotopes from a multitracer prepared by the reaction of 235U fission induced by thermal neutrons. This efficient technique is based on solvent extraction and separates the multitracer isotopes into six groups. It is intended to be used in an automated rapid extraction system.
The intensities of K x- and γ-rays emitted following the decays of 99Mo and 111Ag have been measured with better precision using four well calibrated semiconductor detectors. These intensity results have been further used to deduce the photon emission probabilities of various γ-transitions deexciting these radionuclides. The 158.9 and 162.5 keV γ-rays have been identified and placed through coincidence evidence to be in the level scheme of 99Tc while 11 γ-rays, proposed in the earlier investigations of 99Mo decay, have been discarded. This rules out the possibility of the existence of levels at 163, 727, 762 and 1082 keV. The intensities for K x-rays emitted following the decay of 111Ag are reported for the first time.
A new radioiodination reagent, 3-iodophenylisothiocyanate (3-IPI) has been developed for coupling to monoclonal antibodies. The starting material, 3-tri-n-butylstannylphenylisothiocyanate was prepared via a reaction of hexabutylditin with 3-bromoaniline, followed by treatment with thiophosgene with an overall yield of 72%. The radioiodination of this tin precursor with Na[125I]I/iodogen in chloroform gave 3-[125I]IPI in 23–55% radiochemical yield and 81–99.6% radiochemical purity. Purification of the impure product by high pressure liquid chromatography increased the radiochemical purity of the product up to 99%. These results suggest that 3-IPI may be a useful ligand for radioiodination and coupling to a variety of monoclonal antibodies.
MDL 72222, an antagonist of 5HT3 receptors, was labeled with a specific radioactivity of 340-400 mCi/mumol by alkylation of the nor-precursor with [11C]CH3I. The yield of the synthesis, starting from [11C]methyliodide to the purified product and corrected for decay, was good approximately 70-75%. After i.v. injection, [11C]MDL 72222 diffuses readily in the central nervous system but is not detected as metabolites in brain and blood, during 1 h study carried out in rats. The time course and distribution of [11C]MDL 72222 was assessed in various organs (liver, lung, kidney, heart, whole brain) and in blood; the organ uptake was rapid and large; the highest accumulation was found in the lung. The regional brain distribution shows initial uptake and subsequent retention of tracer in favor of the cerebral cortex. The level of brain radioactivity was not reduced by pretreatment with a 1000-fold excess of unlabeled MDL 72222. These results suggest that [11]MDL 72222 is of limited interest for 5HT3 receptor binding studies in brain in vivo, presumably mainly because of large non-specific binding.
The technique of gas extraction from water and gas sample preparation for 85Kr low-level measurements was further developed to improve its applicability to isotope-hydrological "age" determinations of young groundwaters. A water sample of about 200 L is flushed with helium to extract the dissolved gases. Krypton is separated from the extracted gas mixture by repeated adsorption on charcoal, fractionated desorption and subsequent gas chromatography. The detection limit for a 10,000 min counting time in a 10 mL counter containing the krypton (15 microL) and methane as counting gas corresponds to 25 mBq 85Kr per mL (STP) krypton or 2.5% of the mean atmospheric 85Kr activity concentration in the year 1990.
A transport method is described which reduces greatly the number of calibration standards needed for hydrogen analysis by neutron induced prompt γ-rays. The counts in the photopeaks from neutron capture in hydrogen for various standard concentrations, the distribution of the source neutron rate entering the thermal group and the reaction rates in the samples are investigated theoretically using 100 energy group cross sections and experimental 252Cf spectra for a test configuration. Comparison of theoretical results with those measured from the test configuration shows good agreement.
It was demonstrated by calculation using the modified Waldmann equation that the separation between UF6 isotopes by thermal diffusion was enhanced by the addition of both an inert gas and perfluoromethylcyclohexane (C7F14). As this system is a multicomponent system consisting of four or more components, the calculation was carried out by regarding the multicomponent system as several apparent binary systems, which was a new proposition. The mutual diffusion coefficient between the two apparent components of the apparent binary system was also obtained by a new method. As a result, the system, 238UF6/C7F14/235UF6/Ne, gave 5 isotopic% enriched UF6 and 10−5 isotopic% depleted UF6 by an only 60-cm-high thermal diffusion separation column.
A simple x-ray fluorescence technique using a low power x-ray tube and a neon gas-filled proportional counter following a multichannel analyzer has been developed for the nondestructive and rapid measurement of the density of salt deposited on the surface of power insulators. To detect faint Cl K x-rays accurately interfering x-rays such as K x-rays from argon in the air and from composite elements of the insulator glazing material are eliminated by using an x-ray filter of 30 μm thick polyvinylidene chloride placed in front of the counter window. The technique was applied for crevis type suspension insulators of 250 mm dia, having surfaces which were artificially deposited with NaCl of 0.01 to 0.1 mg/cm2 surface density. The relative statistical error for a surface salt density of 0.1 mg/cm2 was 1.1% using a 100 s measurement time. The positional distribution of deposited salt and the time variation of salt accumulation on the insulator surfaces were also observed with the technique.
We suggest that radioactive food contamination, as determined solely by a quantitative gamma-ray spectroscopic measurement, may, apart from the total activity per unit mass, be for quick reference conveniently characterized by another single figure which we call the “Gamma Contamination Food Factor” (GCFF). This factor may be defined as the ratio of the total specific activity of gamma-ray-emitting radionuclides in the food sample (except that of 40K) to the specific activity of 40K either in the sample itself or in an “average man”. We discuss briefly the meaning and advantages of these definitions.
The reduction of nitrate to nitrite is studied by the transfer of energy stored in γ-irradiated NaCl crystals to aqueous ammonium nitrate solution. The G(NO2−) values are evaluated under varying conditions of energy transfer from γ-irradiated NaCl crystals. Similarly, the G(NO2−) value for direct radiolysis of 0.1 M aqueous ammonium nitrate solution is determined. The efficiency of energy transfer is the ratio of the G-values of the two pathways. The efficiency is 60% at low doses. It is explained on the basis of two processes. The first process depends upon the extent to which the energy can be stored in irradiated NaCl crystals, while the second process of energy transfer is governed by various parameters which limit the yield of nitrite.
Total photon cross-sections have been measured in 15 compounds and in 3 selected elements at 7 different photon energies in the range of 145–1120 keV on a good geometry set-up using a NaI(Tl) detector coupled to a ND 60 multichannel analyser. The results include some data points which have not been previously reported. From the measured total cross-sections per molecule of the compound, atomic cross-sections in elements have been extracted using the mixture rule. The derived atomic cross-sections have been compared with the theoretical Hubbell-Scofield values and of Storm and Israel. In addition, the experimental total photon cross-sections of the three selected elements are compared with those derived from measurements on the compounds containing the selected elements. A good agreement is observed amongst the different values, within experimental error.
