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We present a fast and effective wet-chemistry method, used to obtain the pure alpha-emitter 211At/211gPo (T1/2 = 7.214 h/516 ms), produced by 209Bi(α,2n) reaction in NCA form. It is a selective radiochemical separation of the At radionuclides from the target and the impurities, characterized by a radionuclidic purity close to 100%, based on the dissolution and the dilution of the irradiated target in acidic medium, on the extraction with DIPE, followed by the back-extraction with NaOH. As a result, we obtain a yield greater than 90–97% in a range from 0.75M to 2.00M.

Astatine-211 (T1/2 = 7.214 h) is an α-emitter at secular equilibrium by EC with its ultra-short-lived α-emitting daughter, polonium-211g (T1/2 = 0.516 s), with a high Linear Energy Transfer (LET — 130 eV·nm−1) and a half-life suitable for metabolic radiotherapy; the overall α branching of the 211At/211gPo system is 100%. The direct production of 209Bi(α,2n)211At/211gPo seems the most satisfactory method; Bi targets were irradiated at JRC-Ispra Cyclotron of European Commission, EC, using α-energy higher than 28.61 MeV in order to produce, via 209Bi(α,3n) reaction, small amounts of the γ-emitter 210At (used as internal spike).

Thanks to its favorable decay characteristics, 177gLu is finding several applications in nuclear medicine, especially for palliative metabolic radiotherapy of cancer and radioimunotherapy. 177gLu is produced in thermal nuclear reactor either by direct neutron capture 176Lu(n,γ)177(m+g)Lu on either natural or enriched 176Lu target, or by reaction on enriched 176Yb target followed by negatron decay. The latter method does produce a high radionuclidic purity and high specific activity radionuclide in no-carrier-added form, since 177Yb decays solely to the ground state 177gLu. Conversely, the first method does produce a low specific activity 177gLu in carrier-added form,1 contaminated by the long-lived radioisotopic impurity 177mLu. The accurate determination of radionuclidic purity and half-life of 177gLu carried out by HPGe and LSCS is presented in some details.

Many biological samples (urines and faeces) have been analyzed by means of chromatographic extraction columns, utilizing two different resins (AG 1-X2 resin chloride and TRU), in order to detect the possible internal contamination of 239+240Pu and 241Am for some workers of a reprocessing nuclear plant in the decommissioning phase. The results obtained show on one hand the great suitability of the first resin for the determination of plutonium, and on the other, the great selectivity of the second one for the determination of americium.

[186gRe]Re-HEDP is a radiopharmaceutical used for pain palliation in bone metastases from various primary tumors. The negatron emitter with 〈Eβ〉 = 357 keV 186gRe is suitable to irradiate cancer and inflammatory cells, but it needs labeling bis-phosphonates as vectors to reach target tissue. Paper radiochromatography was used to evaluate the radiochemical purity of [186gRe]Re-HEDP in radiopharmaceutical solution as well as in biological samples (serum and urine) from treated patients, in order to follow bone-targeting and excretion. Following the activity concentration in each sample vs. time it is effective to elaborate a bio-kinetic model of the radiopharmaceutical and to optimize administration protocols.

Kinetic fitting of substrate disappearance and of total organic carbon (TOC) mineralization of organic micropollutants, in water and air, by photocatalytic membranes immobilizing titanium dioxide, was carried out. A model was used in which mineralization of substrate to CO2 is supposed to occur, with kinetic constant k1, through one single intermediate, mediating the behaviour of all the numerous real intermediates formed in the path to CO2, kinetic constant of formation of the latter being k2. A competitive Langmuirian-type adsorption of both substrate and ‘intermediate’ was also supposed to be operative, as expressed by pseudo-thermodynamic constants K1 and K2 respectively, these constants possessing a, partly at least, kinetic significance. Nonlinear models could be fitted to data by using the least-squares method. The very satisfactory matching is shown for the laboratory-scale mineralization kinetics of methane, as model molecule of aliphatic contaminants, both in the gas phase and in aqueous solution. Furthermore, in pilot plant experiments, using phenol, as model molecule of aromatics, modelling of quantum yields was carried out, as a function of concentration and of adsorbed radiant power. Kinetics of hydroxyl radicals reacting between themselves, leading to hydrogen peroxide, other than with substrate or intermediates leading to mineralization, was considered, paralleled by a second competition kinetics due to superoxide anion radical and its conjugate acid, equally leading to mineralization. In this model the contribution of hydroxyl radicals to mineralization decreases with irradiance, while the contribution of superoxide anion radical and its conjugate acid increases. If the regression equations of these two contributions are considered together, in a linear combination, the surface model perfectly fits the experimental data. Copyright © 2008 John Wiley & Sons, Ltd.

Photomineralization of methane in air (10.0–1000 ppm (mass/volume) of C) at100%relative humidity (dioxygen as oxygen donor) was systematically studied at318±3 K in an annular laboratory-scale reactor by photocatalytic membranes immobilizing titanium dioxide as a function of substrate concentration, absorbed power per unit length of membrane, reactor geometry, and concentration of a proprietary vanadium alkoxide as photopromoter. Kinetics of both substrate disappearance, to yield intermediates, and total organic carbon (TOC) disappearance, to yield carbon dioxide, were followed. At a fixed value of irradiance (0.30 W⋅cm-1), the mineralization experiments in gaseous phase were repeated as a function of flow rate (4–400 m3⋅h−1). Moreover, at a standard flow rate of 300 m3⋅h−1, the ratio between the overall reaction volume and the length of the membrane was varied, substantially by varying the volume of reservoir, from and to which circulation of gaseous stream took place. Photomineralization of methane in aqueous solutions was also studied, in the same annular reactor and in the same conditions, but in a concentration range of 0.8–2.0 ppm of C, and by using stoichiometric hydrogen peroxide as an oxygen donor. A kinetic model was employed, from which, by a set of differential equations, four final optimised parameters,k1andK1,k2andK2, were calculated, which is able to fit the whole kinetic profile adequately. The influence of irradiance onk1andk2, as well as of flow rate onK1andK2, is rationalized. The influence of reactor geometry onkvalues is discussed in view of standardization procedures of photocatalytic experiments. Modeling of quantum yields, as a function of substrate concentration and irradiance, as well as of concentration of photopromoter, was carried out very satisfactorily. Kinetics of hydroxyl radicals reacting between themselves, leading to hydrogen peroxide, other than with substrate or intermediates leading to mineralization, were considered, and it is paralleled by a second competition kinetics involving superoxide radical anion.

An empirical equation was developed for the count rate of a cylindrical radioactive source by an HPGe detector as a function of the volume and the height of the source. The equation can be used to calculate the height of the cylinder, which will yield maximum count rate for a known volume of environmental source.

A method is described to locate a radioactive point source in a lung using a commercial array of lung detectors. The method takes advantage of the fact that modern commercial systems consist of several Ge detectors, each connected to a multi-channel analyzer, and the information from each detector can be analyzed separately. The system is calibrated with point sources placed in various locations in the lungs of a phantom. A vector method is presented for determining which of the calibration locations in the phantom is closest to the location of the unknown point source. It has been shown that the accuracy of the method increases with increasing number of the vector dimensions. A higher dimensionality can be achieved by analyzing counts of several gamma lines or by using more detectors.

(75)Se-selenite transfer was investigated in a phytoplankton-mussel-rat food chain model consisting of Scenedesmus obliquus (Turpin) Kützing, Unio mancus Lamark and Rattus norvegicus Berkenhout. (75)Se-metabolized forms were investigated in order to identify potential critical steps in the food chain, as well as its relative bioavailability looking also at intracellular, cellular and organ partitioning. Tissue and intracellular distribution of (75)Se in mussels fed with (75)Se-S. obliquus was different compared to those exposed only to inorganic (75)Se-selenite. The intracellular distribution of (75)Se in the hepatopancreas and mantle of mussels fed (75)Se-microalgae was similar to hepatic and renal distributions in rats, suggesting that their stomach dissociated larger (75)Se-containing molecules. The (75)Se partitioned from water (culture medium) to microalgae showing a bioconcentration factor of 435. The bottleneck in the trophic transfer of (75)Se occurred between S. obliquus-U. mancus. From microalgae to mussels and subsequently to rats no bioaccumulation was verified.

The limited number of radionuclides emitting alpha-particles and their limited availability is discussed. A new alpha-emitter 230U (T1/2 = 20.8 d, 100% a) is suggested and its preparation from thorium target bombarded by accelerated protons (via initial formation of 230Pa (T1/2 = 17.4 d, 8.4% decay to 230U)), or 4He is discussed. The Empire II model was used to calculate the excitation functions for the different products from bombardment of Th by protons. The calculated thick target yield for 230Pa is 0.6 mCi/mA . h, leading to about 24 mCi/mA . h of 230U or about 150 mCi/mA . h in the case of alpha-bombardment.

The short-lived (12.7h half-life) (64)Cu radioisotope is both a beta(+) and a beta(-) emitter. This property makes (64)Cu a promising candidate for novel medical applications, since it can be used simultaneously for therapeutic application of radiolabelled biomolecules and for diagnosis with PET. Following previous work on (64)Cu production by deuteron irradiation of natural zinc, we report here the production of this radioisotope by deuteron irradiation of enriched (64)Zn. In addition, yields of other radioisotopes such as (61)Cu, (67)Cu, (65)Zn, (69m)Zn, (66)Ga and (67)Ga, which were co-produced in this process, were also measured. The evaporation code ALICE-91 and the transport code SRIM 2003 were used to determine the excitation functions and the stopping power, respectively. All the nuclear reactions yielding the above-mentioned radioisotopes were taken into account in the calculations both for the natural and enriched Zn targets. The experimental and calculated yields were shown to be in reasonable agreement. The work was carried out at the Scanditronix MC-40 Cyclotron of the Institute for Health and Consumer Protection of the Joint Research Centre of the European Commission (Ispra site, Italy). The irradiations were carried out with 19.5 MeV deuterons, the maximum deuteron energy obtainable with the MC-40 cyclotron.

Radionuclide Therapy (RNT) and Radioimmunotherapy (RIT) are potentially of great interest for cancer therapy. In many therapeutic applications alpha emitters should be much more effective than already-approved beta emitters due to the short range and high linear energy transfer of alpha particles. 213Bi is an important alpha emitter already used in clinical trials but the half-life of this radioisotope is short (46 minutes) and so its use is limited for certain therapies. 211At is potentially very interesting for medical purposes because of its longer half-life of 7.2 hours, and suitable decay scheme. We have studied the cyclotron-based production of 211At via the reaction 209Bi(?, 2n), this production route probably being the most promising in the long term. The energy dependence of thick target yields and the reaction cross sections for the production of 211At and 210At were determined and found to be in good agreement with literature. The best energy to produce 211At is 28-29 MeV. The possible production of the undesired, highly radiotoxic, and long-lived alpha-emitting 210Po (138.38 days), which is produced from decay of 210At, is also discussed.

Many regulatory agencies require that all building materials and industrial waste be tested for their naturally occurring radioactive material (NORM) concentrations before they can be used or thrown away. Usually the NORM concentrations of 40K, 232Th and 238U are measured by gamma-ray spectrometry using high-purity germanium or NaI(Tl) detectors. 40K is measured through its 1460.8 keV gamma line, which is mixed with 1459.2 keV line of 228Ac from the chain of 232Th. This fact ignored till now, requires a correction in the computation of 40K concentration. Although in many cases the error is

Two widespread misconceptions regarding Tc are dealt with. First, it is shown that although primordial Tc has decayed completely, Tc is still present in nature due to natural processes, in addition to substantial man-made quantities. Thus, Tc cannot be considered as a purely artificial element. Second, it is shown that 99mTc from 99Mo/99mTc generators is certainly not carrier-free (CF) and that, “no-carrier-added” (NCA) is a more appropriate designation. As a quantitative measure of the amount of long-lived 99gTc carrier present in 99mTc preparations from generators, the Isotope Dilution Factor (IDF) is used and calculated for some practical situations.

High specific activity 64Cu is a radionuclide of increasing interest for PET imaging, as well as systemic and targeted radioimmunotherapy of tumours. The cross sections for production of 64Cu from Zn target of natural isotopic composition were measured in the proton energy range from 141 down to 31 MeV. The stacked-foil technique was used at 160 MeV intersection point of INR proton-LINAC in Troitsk, Russia. Several Ga, Zn, Cu, Ni, Co, V and Mn RNs were detected in Zn targets at the EOB. The activity of no-carrier-added 64Cu was measured through its only gamma-emission of 1346 keV (0.47% intensity). To this purpose, it was necessary to carry out a selective radiochemical separation of Ga RNs from the bulk of irradiated Zn target and other RNs. Theoretical calculations of cross sections were carried out with the CEF model and HMS-ALICE hybrid model codes and are compared with the experimental values.

An instrumentation and a method have been developed to investigate the growth of plant roots by injection of 75 Se radioactive isotope in the stem base. Since the isotope is transferred into the active root, it is possible to investigate where the growth occurs in the soil profile. The distribution of radioactivity in the root system is measured by means of an automatic detection equipment controlled by a portable PC. The design of the detection probe is discussed and its field use is surveyed. The whole instrumentation is compact and can easily be used to study the effects of irrigation and fertilization on crops growing under field conditions. The results obtained in the field tests show how the levels of nutrients and moisture influence the root development.

The nuclear properties of 186g Re make it a useful agent for radionuclide therapy and imaging. The coordination compound ( 186g Re)Re-HEDP has proved to be a successful bone seeking agent for palliation of metastatic bone pain. Chemical, radiochemical and radionuclidic purity of commercial radiopharmaceutical ( 186g Re)Re-HEDP have been checked by means by �- and �-spectrometries, INAA and paper radio- chromatography. The results indicate a good radionuclidic purity, with levels of contamination from the short-lived 188 Re well below the required specifications. After injection of the radiopharmaceutical, the radiochemical measurements conducted in vivo, on biological matrices, blood, plasma and urine, have shown that, entering the systemic circulation, 186g Re dissociates from the bis-phosphonate complex as hydrosoluble ( 186g Re)ReO4 - , and the two chemical species follow different biokinetics.

Many labeled compounds are used as radiopharmaceuticals (RP), for emission imaging and metabolic radiotherapy and contain as labeling agents γ, β-, β+, monochromatic e- and α emitting radionuclides (RN). These labeled compounds very often contain unexpected radionuclidic impurities. Some long-lived isotopic and non-isotopic impurities lead to undesirable radiation doses to the patient and his relatives, as well as to medical/paramedical personnel, other than the general population, due to rad-waste of contaminated specimen and excretion of biological fluids. Use was made of liquid scintillation counting/spectrometry (LSCS) for the detection of tiny amounts of charged particle emitting impurities in RPs labeled with 64Cu, 67Ga, 90Y, 90Sr/90Y, 123I, 153Sm, 177Lu and 201Tl.

Within the radiation protection physical surveillance program of some workers, involved in the decommissioning operations of a nuclear reprocessing plant of the Italian National Agency for New Technologies Energy and Environment, CR Saluggia (ENEA) in the north of Italy, some radiotoxicological analyses, on human urines, have been carried out, in order to determine the possible internal contamination of 241Am. After an in-depth study of a former extraction chromatographic method, based on the use of Microthene-722 supporting HDEHP, a more suitable method has been developed and adopted in our laboratory, based on the use of TRU-resin. This paper reports the results obtained with these two procedures as well as a comparison between them.

In the measurement of natural occurring radioactive material (NORM) concentrations of 40 K , 232 Th and 238 U are measured by passive gamma ray spectrometry with either HPGe or NaI(Tl) detectors. 40 K is measured through its 1460.8 keV γ line. However, till now it has been ignored that this line is mixed with the 1459.2 keV line of 228 Ac from the chain of 232 Th . A correction must be made for this contribution. All the data in literature has wrong data about the concentration of 40 K although in many cases the error is less than 1%. However, there are cases of considerably higher errors. It should be emphasized that even if the correction in 40 K concentration is large the correction of external dose index is negligible due to the higher weighing factor for 232 Th than for 40 K (by at least a factor of 10).

A novel method for production of No-Carrier-Added 64 Cu and 66,67 Ga has been developed, based on reactions induced by deuterons up to 19 MeV on Zn target. HPGe and beta (by LSC) spectrometries proved very effective to determine radionuclidic purity of 64 Cu and 66,67 Ga fractions. Experimental specific activity for 64 Cu was measured by ET-AAS and was of the order of 700 MBq · μg −1 . Radiochemical yields for 64 Cu and 66,67 Ga were >80% and >99%.

The radioisotopes of ruthenium (103Ru and 106Ru) are abundant fission products and represent a radiological risk for the population in case of nuclear accidents. Few biokinetic studies have been performed on humans up to now and consequently the current model recommended by ICRP for ruthenium is derived mainly by extrapolation from animal data. The stable isotope 101Ru and proton activation analysis have been used to study the biokinetics of Ru in blood plasma samples taken during 8 studies in three healthy volunteers. The results obtained demonstrated that complexed Ru (in the form of citrate Ru(IV) complexes) is cleared from blood plasma very rapidly (characteristic half time of 17+/-2 min), while inorganic Ru remains longer in the systemic circulation, and is transferred to other organs and/or excreted with a biological half time of 23+/-2h. Good reproducibility of the clearance curves indicated no evidence of inter- or intra-individual variability when the same Ru solution was injected in repeated experiments to different subjects.

Radionuclides of very high specific activity A S(t) have great relevance for applications in the life sciences. Updated definitions of A S are given. The real A S(t) must be measured by analytical and radioanalytical techniques. No-carrier-added (NCA) radionuclides have A S(NCA) sometimes close to the carrier-free (CF) value A S(CF). The accurate knowledge of excitation functions of nuclear reactions vs. ion beam energy is mandatory to maximize A S(NCA); the minimization of isotopic dilution factor IDF(t) has been achieved too. A range of accelerator production and radioanalytical QC methods for A S(NCA) optimization and determination is presented.

There is much interest in understanding the biokinetics of zirconium in humans due to the potential radiological risk represented by the radionuclide 95Zr and by its daughter 95Nb. Despite the significance of zirconium, few data are available on the actual biokinetics of zirconium in humans. Accordingly the biokinetic model currently recommended by ICRP for this element is based mainly on data from animal experiments. In this study, the use of the stable isotopes 90Zr and 96Zr as tracers has enabled the conduct of 6 biokinetic investigations in 3 healthy volunteers. These studies have provided new valuable information about intestinal absorption and kinetics in blood plasma of zirconium and have been used for the set-up of a more realistic compartmental model with possible applications for dosimetric purposes.

Copper-64 is a radionuclide suitable for labeling of a wide range of radiopharmaceuticals for PET imaging, as well as systemic or local radioimmunotherapy of tumors. Among the possible methods for cyclotron production of No Carrier Added (NCA) 64Cu (61Cu), we investigated the deuteron irradiation on natural Zn target, via (d,axn) and (d,2pxn) nuclear reactions. This paper reports the preliminary results about the experimental determination and theoretical calculation of thin-target excitation functions in the energy range up to 19 MeV for 61Cu, 64Cu, 66Ga, 67Ga, 65Zn and 69mZn. A fast selective radiochemical separation of NCA 64Cu from Zn target and Ga radionuclides, with quality control tests is described too.

Despite the cyclotron production method and the efficiency of the radiochemical procedures adopted, the long-lived radio-isotopic impurity 202Tl is always present in [201Tl]-labelled radio-pharmaceuticals, together with other short-lived impurities like, 200Tl. Rapid determination of the 202Tl impurity, can be achieved using HPGe gamma spectrometry and a detector shielded by a 5 mm thick envelope of lead. In this way, dead-time correction errors, Compton and X-ray background, are very efficiently avoided and suppressed. The same method could be applied routinely in nuclear medicine, to determine the radioisotopic purity of 201Tl by means of an ionisation chamber dose calibrator.

This work describes the method adopted in our laboratories, to produce 94gTc, 95gTc, 95mTc and 96gTc radionuclides via proton-cyclotron irradiation on molybdenum targets of natural isotopic composition. A new set of experimental thin-target excitation functions and "effective" cross-sections for direct natMo(p,xn)(A)Tc [with A = 94, 95, 95, 96] nuclear reactions, with incident proton energy in the range from threshold up to 44 MeV is presented. Some definitions of the equations used and nuclear data traceability are reported. Thick-target yield values were calculated and optimised, by numerical fitting and integration of the measured excitation functions. These values allow optimisation of production yield of one radionuclide, minimising at the same time the yield of the others. Radiochemical separation on NCA technetium radionuclides from both molybdenum target and niobium, zirconium and yttrium radioactive by-products is reported. Quality control tests of the radiotracers were developed for the applications envisaged in environmental metallo-biochemical toxicology.

Thin- and thick-target excitation functions of 188,189,191 Pt radionuclides were experimentally determined by cyclotron irradiation, using nuclear reactions nat Os(α,xn) in the energy range up to 38 MeV with the Scanditronix-MC40 Cyclotron of the Joint Research Centre-Ispra, VA (Italy) of the European Communities. Radionuclidic, radiochemical and chemical purities have been also measured by use of analytical and radioanalytical techniques. In this paper, the result of the experimental thick- and thin-target excitation functions of 188,189,191 Pt radiotracers, produced via nat Os(α,xn) reactions, are presented. The data are of relevant interest for optimising cyclotron production of platinum radionuclides to be used as radiotracers for metallo-biochemical, biomedical, toxicological and environmental studies. In this paper, we will present the analytical and radioanalytical methods that have been developed to determine the amount of isotopic carrier and the SA(NCA) in the case of 188 Pt, 191 Pt, to be used for ‘multiple labelling’ experiments, by: high resolution γ-spectrometry, β-spectrometry by liquid scintillation counting, neutron activation analysis, FL-AAS, and ICP-OES. Moreover, some preliminary biological applications were carried out in order to determine the cyto-toxicology of different chemical forms of platinum.

Both essential and toxic elements are present in the biosphere in different inorganic and organo–metallic forms. Some trace elements like Cr, Cu, Mn, Rb, Se, Tl, V, Zn are essential to human life and are present in human tissues, body fluids, cells and sub-cellular components, bonded to enzymes, proteins, etc. Many trace elements are introduced daily in the body in amounts ranging from ng to μg per kg. A powerful tool to set up analytical procedures, to evaluate the chemical separation yield and to follow the fate of different chemical forms of ultra-trace elements on living organisms is the use of ‘high specific activity’ radioactive tracers (RT). Amongst the more effective RTs for radio-analytical chemistry, there are the short-lived medium γ-energy emitters. A review of the last 25 years in the field of both cyclotron and nuclear reactors producing high specific activity radionuclides in radio-analytical chemistry is presented. As, Au, Cu, Ga, Mn, Np, Pd, Pt, Rb, Rh, Sb, Te, Ti, Tl, V, etc., γ- and β emitting RTs have had interesting applications in the ultra-trace metallo-toxicology field. High-resolution γ-spectrometry by HPGe detection and β spectrometry by liquid scintillation counting, have been used, hyphenated with ‘elemental analysis’ radio-analytical and analytical techniques. The ‘high specific activity’ of the No Carrier Added RTs is the ‘key factor’ of this powerful radio analytical technique.

The experimental values of thin-target excitation functions for the nuclear reactions: natOs(α,X)188,189,191 Pt,192g, 194mIr in the energy range 11-38 MeV and natMo(p,xn)94g,95g,95m,96(m+g)Tc in the energy range 5-44 MeV are presented. The experimental values were obtained by cyclotron activation followed by off-line HPGe γ-spectrometry and corrected at the End Of an Instantaneous Bombardment, EOIB. In different cases use was made of single foil and stacked foil techniques, which present significantly different advantages and disadvantages. The thintarget yield values can be easily either numerically or analytically integrated, as a function of both incoming particle energy and energy loss in target itself, in order to calculate apriori the thick-target yield of various radionuclides under any different experimental condition. Moreover, the thin-target yields are directly related to the effective cross-sections of various nuclear reaction channels involved. The data are of relevant interest for optimizing...

The increasing concentration of Pt, Pd and Rh in the environment is mainly due to the release of these elements from the catalytic converters of the motorvehicles. This situation makes it necessary to carry out metallotoxicological experiments on both cell cultures and laboratory animals, in order to assess their impact on living organisms after a Long Term and Low Level Exposure (LLE). Both nuclear reactionsnatIr(p,xn) andnatOs(α,xn) were investigated in the energy range up to 45 MeV for protons and 38 MeV for alpha-particles, in order to optimize the irradiation parameters for the production of188,189,191Pt. Several sets of thin- and thick-target excitation functions were determined experimentally by cyclotron irradiation at both Milano and Ispra cyclotrons. This paper reports the irradiation parameters studied and adopted and two radiochemical procedures for the separation of radio-Pt from an Os target, as well as from ruthenium, iridium and gold impurities. These procedures were used to obtain very high specific activity Pt radionuclides in No Carrier Added (NCA) form. Radionuclidic, radiochemical and chemical purity measurements were carred out by the use of several techniques like ψ-spectrometry, ion-exchange radio-chromatography, atomic absorption spectrometry and neutron activation analysis.

The possibility to measure the flux of thermal neutrons by activation of gold of unknown weight using the counts of both 199 Au and 198 Au gamma emission was studied. It can be used for impure gold monitors or when the activated sample has gold in it. The possible interferences are discussed.

We have measured the excitation functions of several reactions occurring in the fusion of $^{12}\mathrm{C}$ with $^{103}\mathrm{Rh}$ at incident energies up to about 230 MeV. The data can be satisfactorily reproduced by considering the preequilibrium emission of particles during the thermalization of the composite nucleus. The energy evolution of the mean-field interaction is also discussed. \textcopyright{} 1996 The American Physical Society.

First results are given from the comparison of experimental values and model calculations on accelerator-produced high specific activity radionuclides in no-carrier-added (NCA) form. The relevant radioisotopes are: 64 Cu, produced by nat Zn(d, αx n) and nat Zn(d,2p) reactions, for simultaneous positron/negatron metabolic radiotherapy and PET imaging; 66 Ga high-energy positron emitter (4.2 MeV), produced by nat Zn(d, x n) reactions, for metabolic radiotherapy and for PET; 186g Re, produced by 186 W(p,n) and 186 W(d,2n) reactions, for negatron (1.1 MeV) metabolic radiotherapy; 211 At/ 211 Po, produced by 209 Bi( α ,2n) reaction (with spike of gamma emitter 210 At produced by 209 Bi( α ,3n) reaction) and 225 Ac/ 213 Bi/ 213 Po, produced by 226 Ra(p,2n) reaction, both for high-LET radiotherapy.

Iodine-125 is a radioisotopic impurity “always” present in iodine-123, produced by nuclear reactions induced either on natural or “highly” enriched targets. Liquid scintillation counting is a very sensitive tool to determine low level impurities of both low energy electrons and photons in aqueous and organic solutions of radiopharmaceutical compounds. With this technique it was possible to determine, on commercial samples, that the content of 125I was of the order of not less than 0.1% for 123I produced via 127I(p,5n) reactions and not less than 0.01% for 123I produced via “highly” enriched 124Xe(p,X) nuclear reactions.

High Specific Activity Radio-Nuclides (HSARN) are a powerful tool to label a large range of chemical species at very low concentration levels. In order to obtain these radiotracers in a very high specific activity form, it is necessary to optimize the production methods, to separate and purify them from the irradiated target without the addition of inactive carrier, to carry out a series of analytical and radioanalytical tests to determine their “true” specific activity and to verify a series of purity parameters. A review of irradiation methods and nuclear parameters adopted in our laboratories for the preparation of some tens of radiotracers are presented.

The synthesis and scintigraphic studies in rats of99mTc-amino acid complexes containing the Tc≡N multiple bond are reported. Chromatographic analysis shows the formation of a multicomponent system affected by tertiary phosphines employed as reducing agents of pertechnetate-99m in the systhesis of the complexes with cysteine (CYS) and cysteine ethyl ester (CYS-OEt), while no influence of them is observed in99mTc-complexes having cysteamine (CSA) as ligand. Electrophoresis stresses a strong anionic character in all these compounds. It has not been possible to define their chemical identity by a comparison with the neutral technetium-99 nitrido complexes characterized by spectroscopic and X-ray crystallographic data due to the complexity of the99mTc-system. These complexes are stable at 80 °C over a period of 2 hours. Time-activity curves indicate a renal tissue retention only for the99mTc-(CSA) complexes.

The CLYC (Cs2LiYC6:Ce) crystal belongs to the elpasolite scintillator family, discovered about 15 years ago. It is a very interesting material because of its good energy resolution and its capability to identify and measure gamma rays and fast/thermal neutrons. In the present work, the fast neutron detection efficiency for two different CLYC cylindrical samples has been measured. These two crystals, both with dimension (thickness x diameter) 1"×1", were respectively enriched with more than 99% of 7Li (CLYC-7) and with ~ 95% of 6Li (CLYC-6). The presence of the 6Li isotope makes the CLYC-6 ideal to detect thermal neutrons. In order to compare the two scintillators, only the detection efficiency for fast neutrons was considered, neglecting the energy region associated to thermal neutrons in both the crystals. The measurement was performed at the L.A.S.A. Laboratory of INFN and University of Milano (Italy), using a 241Am-Be source.

High specific activity radiotracers, used in studies related to trace elements and human health, must be characterized by the following specific requirements: (i) high specific activity (activity/mass of isotopic carrier), (ii) high activity concentration (activity/volume or mass of substrate), (iii) radionuclidic, radiochemical and chemical purities, (iv) biological compatibility (physiological pH, sterility and physiological values). For this purpose, selective radiochemical separations and quality control procedures have been developed and tested at our laboratories for the production of several NCA radiotracers.

High specific activity radionuclides are a powerful tool for labeling a large range of inorganic and metallorganic species that are present in the environment at very low concentrations. In order to study the environmental impact of trace elements (TE) on the humans, it is of fundamental importance to carry out both in vitro and in vivo experiments on cell cultures and laboratory animals, with concentrations of these TE representative of the actual long-term and low-level exposures. In order to obtain these radiotracers in a very high specific activity form, it is necessary: (a) to optimize the production method by either charged particle accelerator (normally cyclotron) or nuclear reactor irradiation, (b) to separate and purify them from the irradiated target by chemical or physicochemical methods, without the addition of inactive carriers (i.e., the so-called no carrier added form), (c) to carry out a series of analytical and radioanalytical tests, in order to verify the chemical, radiochemical, and radionuclide purities of the tracer or labeled compound under investigation. Some production, separation, purification, and quality control methods developed for the two cyclotron-produced radionuclides 52gMn and 48V will be presented and discussed.

Radioactive emissions into the atmosphere from the damaged reactors of the Fukushima Dai-ichi nuclear power plant (NPP) started on March 12th, 2011. Among the various radionuclides released, iodine-131 ( 131I) and cesium isotopes ( 137Cs and 134Cs) were transported across the Pacific toward the North American continent and reached Europe despite dispersion and washout along the route of the contaminated air masses. In Europe, the first signs of the releases were detected 7 days later while the first peak of activity level was observed between March 28th and March 30th. Time variations over a 20-day period and spatial variations across more than 150 sampling locations in Europe made it possible to characterize the contaminated air masses. After the Chernobyl accident, only a few measurements of the gaseous 131I fraction were conducted compared to the number of measurements for the particulate fraction. Several studies had already pointed out the importance of the gaseous 131I and the large underestimation of the total 131I airborne activity level, and subsequent calculations of inhalation dose, if neglected. The measurements made across Europe following the releases from the Fukushima NPP reactors have provided a significant amount of new data on the ratio of the gaseous 131I fraction to total 131I, both on a spatial scale and its temporal variation. It can be pointed out that during the Fukushima event, the 134Cs to 137Cs ratio proved to be different from that observed after the Chernobyl accident. The data set provided in this paper is the most comprehensive survey of the main relevant airborne radionuclides from the Fukushima reactors, measured across Europe. A rough estimate of the total 131I inventory that has passed over Europe during this period was \textless1% of the released amount. According to the measurements, airborne activity levels remain of no concern for public health in Europe. © 2011 American Chemical Society.

The use of radiotracers with high specific activity in research on health impact of trace metals overcomes many of the analytical difficulties associated with experimentation carried out at metal levels which are typical of the polluted environment. It allows one to detect and measure ultratrace amounts of metals in biological samples and to follow them into different biochemical compartments, such as subcellular fractions and molecular components. This work shows typical examples of metallotoxicological studies carried out at the JRC-Ispra using radioisotopes with high specific radiactivity produced in the nuclear reactor and in the cyclotron. Applications refer to the use of45Ti,48V,64Cu,95Nb and106mAg in in-vivo and in-vitro studies related to environmental and occupational toxicology research on trace metals.

This chapters deals with production of radionuclides by both neutron bombardment from nuclear reactors and heavy charged accelerated atoms from accelerators. In the case of neutrons, most radionuclides have low specific activity due to the present carrier. The production of carrier-free radionuclides is described. Keywords: radionuclides; carrier-free radionuclides; nuclear reactors; accelerators