Claudio Birattari

Excitation functions and production of arsenic radioisotopes for environmental toxicology and biomedical purposes.

Many arsenic radionuclides have come to be used as tracers in biology and in the study of environmental pollution of both water and soil. In nuclear medicine, radioactive 74 As has been employed as a positron emitter for the localization of brain tumors, cerebral occlusive vascular lesions, arterious-venous malformations, etc. The aim of the work described has been to study the excitation functions for the production of the arsenic radioisotopes from targets of natural germanium via nuclear reactions ( p, xn ).

Production of 123I for medical purposes at the Milan AVF cyclotron

Abstract A method is described for the production of large quantities of 123 I by exciting a ( p , 2 n ) reaction on enriched 124 Te targets. Results are presented for the relevant excitation functions. The irradiation technique and the chemical processes used in the separation of 123 I and the recovery of the target material are described in some detail.

Efficiency evaluation of gamma-ray solid-state detectors

Abstract A method for photopeak efficiency determination for solid-state detectors is described. In the first step the shape and dimensions of the sensitive volume of the detector are experimentally determined. In the second step photopeak efficiency is evaluated by a Monte Carlo computer program utilizing the information obtained in the previous step. The program allows the calculation of the photopeak efficiency up to 10 MeV gamma-ray energy following charged and electromagnetic secondary radiations in the detectors. Results evaluated with the present method are compared with experimental data.

Neutron spectrum measurements at a 40-MeV proton cyclotron.

A set of seven activation reactions has been selected for neutron spectral analysis in the environment of a proton-cyclotron target. This choice of reactions: 59Co(n, p) 59Fe, 59Co(n, 2n) 58Co, 59Co(n, 3n) 57Co, 197Au(n, gamma) 198Au, 197Au(n, 2n) 196Au, 197Au(n, 4n) 194Au, 27Al(n, alpha) 24Na, analyzed by means of a Ge(Li) detector, reduces to a minimum of three the number of activation detectors employed, and makes possible convenient and accurate spectral measurements to at least 40 MeV. Criteria for selection of the activation materials from a list of candidates are discussed. A detailed comparison of the unfolding programs LYRA and SAND is made, and reasons are given for our choice of SAND in our application. Spectra of neutrons emitted at 0 degrees, 45 degrees and 90 degrees from thick targets of A1, Fe, Cu, Ta and stainless steel, irradiated by 40-MeV protons at the Milan AVF cyclotron, using the analysis technique described, are given and discussed.

A rapid improved method for gamma-spectrometric determination of 202Tl impurities in [201Tl]-labelled radiopharmaceuticals.

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.

High resolution γ-spectrometry by HPGe detector and β-spectrometry by liquid scintillation counting, hyphenated to elemental analysis techniques: applications of high specific activity radio-nuclides for ultra-trace metallo-toxicological and environmental studies

Abstract Thin- and thick-target excitation functions of 188,189,191Pt radionuclides were experimentally determined by cyclotron irradiation, using nuclear reactions natOs(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 188,189,191Pt radiotracers, produced via natOs(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 188Pt, 191Pt, 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.

Recent Developments in the Production of I123 at the Milan AVF Cyclotron

In this paper we report on recent results obtained at the Milan AVF Cyclotron in the production and use of I123.

Experimental Thin-Target and Thick-Target Yields for natOs(α, xn)Pt, natOs(α, X)Os, Ir and natMo(p, xn)Tc Nuclear Reactions from Threshold up to 38 and 45 MeV, by Combined Single and Stacked Foil Techniques

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 cyclotron production of platinum and technetium radionuclides to be used as radiotracers for metallo-biochemical, biomedical, toxicological and environmental studies.