Volume 100, Issue 2 -

Studies of the superheavy elements form one of the pillars of the GSI research program. A unique combination of experimental facilities is installed at the GSI. Various topics, ranging from the synthesis of new elements, spectroscopy experiments to study the nuclear structures of the heaviest nuclei, highly accurate mass measurements beyond uranium, to chemical investigations of elements around element 114 and the synthesis of novel chemical superheavy element compound classes are being studied. This is complemented by fully relativistic quantum chemical calculations. As a recent highlight, the 244 Pu( 48 Ca,3–4 n ) 288,289 114 reaction was studied, leading to the observation of element 114 at the new gas-filled recoil separator TASCA.

Fast on-line gas chemical separations of Hs (hassium, element 108) in the form of HsO 4 were applied to investigate the reactions 26 Mg + 248 Cm and 36 S + 238 U. In an experiment at the gas-filled separator DGFRS the reaction 48 Ca + 226 Ra was studied. In all cases the product of complete nuclear fusion is 274 Hs * . For the first time, the new nuclide 270 Hs was produced in the 4 n evaporation channel and its decay properties investigated. The nuclide 270 Hs was predicted by microscopic-macroscopic calculations to be a deformed doubly magic nucleus and its decay properties are therefore of special interest to theory. Also, much more detailed information was gained on the decay of 269 Hs and its daughters, which led to a new assignment of decay properties of the daughter nuclides 265 Sg and 261 Rf. There is evidence fo r isomeric states in 265 Sg and 261 Rf, while 266 Sg is not an alpha-particle emitter as believed previously, but decays by spontaneous fission (SF) with a rather short half-life. Also, interesting features of the used reaction 26 Mg + 248 Cm led to the discovery of the nucleus 271 Hs in the same experiments. An investigation of the influence of the Q -value on the fusion reaction in relation to the location of the fusion barrier showed, that the high binding energy of 48 Ca largely compensates for the lower fusion probability compared to more asymmetric reactions, while 36 S is not as promising as a projectile.

The cyclotron produced neutron deficient technetium radionuclides ( 93 Tc, 94(m+g) Tc, 95 Tc, 96 Tc) have gained renewed interest in various fields, including nuclear imaging, provided they can be obtained in a pure form. Similarly, 211 At due to its moderate half-life and high intensity α -particle energy (both from 211 At as well as its transient decay product 211 Po) is of prime interest in targeted therapy. Another interest is to study the astatine chemistry, which is least studied compared to other halogens due to its non-occurrence in natural systems. For maximum production of these radionuclides various parameters need to be standardized. A chemical separation is required to achieve high radiochemical purity before in-vivo application. This review describes various production routes of neutron deficient astatine and technetium radionuclides that have been reported after the year 2000. The analytical chemistry developed for separation of no-carrier-added (nca) Tc and At radionuclides in the same period is also discussed in detail.

Single photon emission computed tomography (SPECT) has been the cornerstone of nuclear medicine and today it is widely used to detect molecular changes in cardiovascular, neurological and oncological diseases. While SPECT has been available since the 1980s, advances in instrumentation hardware, software and the availability of new radiotracers that are creating a revival in SPECT imaging are reviewed in this paper. The biggest change in the last decade has been the fusion of CT with SPECT, which has improved attenuation correction and image quality. Advances in collimator design, replacement of sodium iodide crystals in the detectors with cadmium zinc telluride (CZT) detectors as well as advances in software and reconstruction algorithms have all helped to retain SPECT as a much needed and used technology. Today, a wide spectrum of radiotracers is available for use in cardiovascular, neurology and oncology applications. The development of several radiotracers for neurological disorders is briefly described in this review, including [ 123 I]FP-CIT (DaTSCAN TM ) available for Parkinson's disease. In cardiology, while technetium-99m labeled tetrofosmin and technetium-99m labeled sestamibi have been well known for myocardial perfusion imaging, we describe a recently completed multicenter clinical study on the use of [ 123 I] m IBG (AdreView TM ) for imaging in chronic heart failure patients. For oncology, while bone scanning has been prevalent, newer radiotracers that target cancer mechanisms are being developed. Technetium-99m labeled RGD peptides have been reported in the literature that can be used for imaging angiogenesis, while technetium-99m labeled duramycin has been used to image apoptosis. While PET/CT is considered to be the more advanced technology particularly for oncology applications, SPECT continues to be the modality of choice and the workhorse in many hospitals and nuclear medicine centers. The cost of SPECT instruments also makes them more attractive in developing countries where the cost of a scan is still prohibitive for many patients.

The use of radionuclides as potential therapeutic radiopharmaceuticals is increasingly investigated. An important aspect is the delivery of the radionuclide to the target, i.e. the radionuclide is not lost from the chelating agent. For in vivo generators, it is not only the log  K of complexation between the metal ion and the chelator that is important, but also whether the daughter radionuclide stays inside the chelator after decay of the parent radionuclide. In our previous work, we showed that the classical recoil effect is only applicable for decays with a  Q value higher than 0.6 MeV (in the atomic mass range around 100). However, Zhernosekov et al . [1] published a result for 140 Nd/ 140 Pr ( Q  = 0.222 MeV) which indicated that >95% of the daughter ( 140 Pr) was lost by a DOTA chelator upon decay of 140 Nd. The authors ascribed this to the & ldquo;post-effect”. Their experiment was repeated with the 166 Dy/ 166 Ho generator to ascertain whether our calculations were correct. It was found that 72% of the daughter ( 166 Ho) was liberated from the DOTA chelator, indicating that the “post effect” does exist in contrast to our recoil calculations. Upon further investigation, we determined that one should not only consider recoil energy levels but also the mode of decay which was able to explain the partial recoil found for 166 Dy/ 166 Ho. It is concluded for the 166 Dy/ 166 Ho system that the low recoil energy of the daughter nucleus 166 Ho is not a sufficient reason to rule out release of the nuclide from chelators. On the other hand, we found that the ratio of the 166 Ho that gets released corresponds to the ratio of relaxation of Ho atoms via the Auger process.

177 Lu is presently considered to be a potential radionuclide for the development of agents for radionuclide therapy owing to its favorable nuclear decay characteristics [ T 1/2 = 6.65 d, E β (max) = 0.497 MeV, E γ = 113 KeV (6.4%) and 208 KeV (11%)]. While the long half-life of this promising radioisotope offers distinct logistic advantage, particularly, in countries having limited reactor facilities, the feasibility of its large-scale production with adequate specific activity and excellent radionuclidic purity in medium flux research reactors constitute yet another desirable feature. Extensive studies have been carried out to optimize the production of this isotope, with high specific activity and radionuclidic purity by the ( n , γ ) route using the highest available flux and the optimum irradiation time. The gradual evolution of clin ical grade 177 LuCl 3 as a new radiochemical, ready for commercial deployment by Radiopharmaceuticals Division, Bhabha Atomic Research Centre, to nuclear medicine centers all over India was accomplished in 2010 in a stepwise manner with the commencement of the production of high specific activity 177 Lu from enriched target in 2001. Research on 177 Lu has demonstrated its immense potential in radiotherapeutic applications, a direct outcome of which has resulted in indigenous development of two agents viz. 177 Lu-EDTMP and 177 Lu-DOTA-TATE presently being evaluated in human patients for palliative care of bone pain due to skeletal metastases and treatment of malignancies of neuroendocrine origin, respectively. Using locally produced 177 Lu, the radiolabeling of a plethora of other molecules with potential applicability in radiation synovectomy and targeted therapy of malignant tumors have been successfully demonstrated. A few of these agent such as a novel 177 Lu-labeled porphyrin has shown considerable promise in initial studies and is presently evaluated. In the present article, our research efforts toward standardization of production methodology of 177 Lu in high specific activity and its utilization in the devel opment of agents for targeted radiotherapy are being reported.

In this paper we review materials characterization techniques using radioactive isotopes at the ISOLDE/CERN facility. At ISOLDE intense beams of chemically clean radioactive isotopes are provided by selective ion-sources and high-resolution isotope separators, which are coupled on-line with particle accelerators. There, new experiments are performed by an increasing number of materials researchers, which use nuclear spectroscopic techniques such as Mössbauer, perturbed angular correlations (PAC), β -NMR and emission channeling with short-lived isotopes not available elsewhere. Additionally, diffusion studies and traditionally non-radioactive techniques as deep level transient spectroscopy, Hall effect and photoluminescence measurements are performed on radioactive doped samples, providing in this way the element signature upon correlation of the time dependence of the signal with the isotope transmutation half-life. Current developments, applications and perspectives of using radioactive ion beams and techniques in solid state and biophysics research are presented with a few examples.

Thin layer activation (TLA) technique is a powerful nuclear technique based on the production of a radioisotope in the surface of a material by a charged particle induced nuclear reaction, followed by an estimation of the loss of the activity which is a measure of the surface loss of materials in the range of nanometer to hundreds of micrometer in the fields of wear, corrosion or erosion. The technique has been found to be a very useful tool in the basic scientific research and industrial applications. The present review describes the basic principle of TLA technique, its characteristic features, methodology, scope, applications and various recent developments regarding its growing use. Some of our earlier TLA work carried out with α and heavy ion ( 16 O) in various applied areas is also included here. Heavy ions were used because no other light ions (particularly protons) were available at our cyclotron.

Various TiO 2 nanomaterials with primary particle sizes well below 10 nm and TiO 2 nanotubes with the anatase structure were studied via the nuclear quadrupole interaction (NQI) of 44 Ti(EC) 44 Sc by time differential perturbed angular correlation. In general two different NQIs were observed, the lower one attributed to the volume fraction because of the similarity to bulk values and the higher one to probes closest to the surface. Rather broad distributions of the strength of the interaction were observed which were different for nominally identical particles, contrary to the axial symmetry which is preserved to a very large extent. These distributions are interpreted as disorder arising from surface tension. These complications affect the interaction between these nanomaterials with biological systems and the environment and render toxicological assessments problematic. Dissolution studies in a synthetic body fluid mimicking blood plasma at 37 ºC for 4 weeks exhibited a very low solubility, but surprisingly slight changes in the volume fraction, probably due to surface adsorbates.