1,721,205 research outputs found
Experimental excitation functions of Pd-103 production by deuteron irradiations
No full textBrachytherapy was developed to treat prostate cancer 50 years ago. It consists in the implantation of Ti or SS seeds containing suitable radionuclides: nowadays only three radionuclides are available for use in low dose rate – LDR – prostate brachytherapy: I-125 (T1/2 = 59.4 d, mean photon energy emitted: 21 keV), Pd-103 (T1/2 = 17 d, mean photon energy emitted: 27 keV), and Cs-131 (T1/2 = 9.7 d, mean photon energy emitted: 29 keV). Pd-103 is an effective alternative to I-125 for high grade, rapidly growing cancer because of its faster dose rate that also raise thanks to possible differences in external tissue complications. With the rapid development of nanoscience and nanothecnology, it starts to become feasible the possibility to substitute the implantation of the seeds of millimetric dimension with the injection in the affected tissue of radioactive NPs. While for the seeds already in use the specific activity is practically unimportant, the nanomedicine approach, involving the synthesis of nanoparticles as nano-seeds or as drug carriers, requires that high Specific Activities – As – have to be achieved.
Nowadays Pd-103 is mainly produced in nuclear reactors via 102Pd(n,) reaction with a very low AS or by accelerator in no-carrier added form – NCA – exclusively by the irradiation of rhodium metal targets with 18 MeV protons via Rh-103(p,n)Pd-103 reaction.
We have studied the possibility to produce it by deuteron beams irradiation, which is more attractive and presents some advantages in respect to proton irradiation.
A new data set of excitation functions for Rh-103(d,2n)Pd-103 nuclear reaction was measured and compared with the only other two studies reported in literature.
The experimental results are compared with the curves of theoretical nuclear model calculations EMPIRE 3.2.2 and TENDEL-2015.
The thin-target yields have been plotted as a function of their average energy into the targets and were fitted with the best mathematical functions. By integration of these functions the calculated Thick-Target Yields were obtained, in order to find the optimized couple of irradiation energy and energy loss inside the thick target to maximize the production of the radionuclide of interest.
The best incident energy for the production of 103Pd with the highest AS and the related radionuclidic purity obtainable with this method will be discussed in detail
Optimization of the production of non-conventional high specific activity radionuclides for medicine
No full textThe use of radionuclides plays a crucial role in Nuclear Medicine in the areas of diagnostics, of metabolic radiotherapy and of theranostics. To produce each non-conventional radionuclide it is necessary to point out a protocol that provides the optimization of production with high specific activity of the radionuclide of interest, typically through the use of charged-particle accelerators, the development of appropriate radiochemical separations and of a strict quality control system of the product obtained. We will present the case of Zr-89, one of the most promising radionuclide for labelling monoclonal antibodies, bio-distribution studies and immuno-PET imaging
Radionuclides Production for Theranostic Applications
No full textThe use of High Specific Activity Radionuclides HSARNs, obtained by either proton, deuteron or alpha cyclotron irradiation, followed by selective radiochemical separation from the irradiated target in No Carrier Added (NCA) form, is a powerful analytical tool for plenty applications in pure and applied sciences and technologies. The main applications of these RNs are in medical radiodiagnostics and metabolic radiotherapy in addition to toxicological, environmental and industrial studies. Nowadays the new challenge in Nuclear Medicine is the so called theranostic medicine, a relatively novel paradigm that involves specific individual ‘dual-purpose’ radionuclides or radionuclide pairs with emissions that are suitable for both imaging, therapy and monitor the response to therapy. The theranostic radionuclides would potentially bring us closer to the age-long dream of personalized medicine. A subchapter is the multifunctional nanoplatform that is an emerging highlight in nanomedicine, in which a suitable radionuclide is encapsulated in nanocarriers. Many of the “neutron-rich” radionuclides suitable for metabolic radiotherapy are produced by nuclear reactor with a very low specific activity (AS). In selected cases, they can be produced by bombardment of targets by charged particle beams in NCA with very high AS. If the irradiations are made with deuteron beams some more advantages are obtained as reported, as an example, for 186gRe production
RADIONUCLIDES FOR MEDICINE - EXCITATION FUNCTIONS FOR THE PRODUCTION OF TC-99M, ZR-89 AND PD-103
No full textThe production of radionuclides for medicine is one of the most important directions of nuclear chemistry and nuclear industry. Radionuclides are used both for medical diagnostics of various diseases as well as for internal radiotherapy: the consumption of pharmaceuticals based on radioactive isotopes is growing fast.
The main amount of commercial medical radionuclides is produced on nuclear reactors but more and more radiopharmaceuticals are produced on the base of accelerator produced isotopes. Even if the accelerator production is more expensive, it can provide a wider range of radionuclides and often provide higher specific activity.
This work is focused on the production optimization of three main radionuclides Tc-99m, Zr-89 and Pd-103 irradiating, correspondingly, targets of enriched molybdenum-100, natural yttrium-89 and natural rhodium-103 with proton or deuteron beams accelerated by cyclotrons. Formation of several by-products synthesized in the same targets is also investigated because it is important to understand the presence of all the possible impurities to be removed with the radiochemical procedures.
All these radionuclides are important and used in nuclear medicine.
Tc-99m is considered the “workhorse” of radiopharmaceutical imaging and it is usually obtained from another radioactive parent isotope Mo-99 produced mostly in the world on nuclear reactors. However, in the last years, the direct production of Tc-99m from the Mo-100-enriched targets in low-energy proton accelerators – nuclear reaction (p, 2n) – is considered as possible substitution of reactor production and has good prospects for local needs.
Zr-89 is a radionuclide extremely prospective for labelling monoclonal antibodies, bio-distribution studies, and immuno-positron emission tomography (PET) imaging.
Pd-103 is used in brachytherapy and, with the rapid development of nanoscience and nanotechnology, it becomes appealing to make injectable nano-scale brachytherapy seeds.
The production of Zr-89 and Pd-103 by protons was well studied and considered. In contrast, there are few experimental data on the excitation functions of the deuteron-induced nuclear reactions or these are rather scattered: the (d,2n) reaction appears to be very attractive and it deserves particular interest of study
Experimental excitation functions of 89Zr production by deuteron irradiations for theragnostic applications
No full textThe 89Zr is one of the most promising radionuclide in Nuclear Medicine for labelling monoclonal antibodies, bio-distribution studies and immuno-positron emission tomography – PET – imaging. Its great potentiality is related to its favorable physics characteristics: it has a half-life T1/2 = 78.41 h, suitable to study the slow metabolic processes, decays to the stable isotope 89Y by electron capture (76.6%) and beta+ (22.3%) and has an associated gamma emission at 908.96 keV (abundace = 99.87%) which is the main contribution to the absorbed dose.
This radionuclide is produced via the (p,n) nuclear reaction in small medical cyclotrons, bombarding monoisotopic yttrium targets. The experimental excitation functions in this case are measured many times and the data are relatively consistent.
On the other hand, the data related to deuteron induced reactions are few and are rather scattered.
For this reason we are studying the possibility to produce 89Zr by 89Y(d,2n) reactions starting from the experimental re-measurement of the cross sections for deuteron beam irradiation, which present indisputable advantage in respect to proton irradiation.
A new set of excitation functions for 89Y(d,2n)89Zr was measured and compared with the only other few sets presented in the literature.
The irradiations were carried out with the IBA C70 cyclotron of the ARRONAX Center, Saint-Herblain (FR), which can deliver deuterons at variable energies in 15 – 35 MeV interval.
It was used the standard staked foil technique, bombarding stacks of 89Y foils (purity 99%, 25μm nominal thickness, GoodFellow Cambridge Ltd.) interleaved with titanium and aluminum used as degraders and monitors.
The experimental data were compared with the prediction obtained from nuclear model calculation codes EMPIRE 3.2.2, ALICE-IPPE and TALYS.
The thin-target yields have been plotted as a function of their average energy into the targets and were fitted with the best mathematical functions. By integration of these functions the calculated Thick-Target Yields were obtained, in order to find the optimized couple of irradiation energy and energy loss inside the thick target to maximize the production of the radionuclide of interest.
Some consideration about the radionuclidic purity obtainable with this kind of production will be discussed
Radon measurements : a way to disseminate scientific culture amon young student in Italy
No full textTHE ITALIAN CONTRIBUTION TO EXCITATION FUNCTION MEASUREMENTS FOR TC-99m PRODUCTION BY PROTON BEAMS IRRADIATION
No full textThe radionuclide Tc-99m is the most commonly used radiotracer in nuclear medicine, for diagnostic purpose, due its suitable physics characteristics: T1/2 = 6.0 h, gamma emission at 140.5 keV suited for imaging via single photon emission computed tomography (SPECT) and causes minimal radiation dose to the patient. Since nowadays it is obtained by the Mo-99/Tc-99m generator, with the parent Mo-99 produced by nuclear reactor. The progressively closing process of the nuclear reactors around the world imposes to study alternative routes of Tc-99m production. Among them the direct production by the Mo-100(p,2n)Tc-99m reaction on highly enriched Mo-100 targets appears to be the most promising, even if this kind of production would solve only local or regional demand. In this prospective, due to some evident discrepancies among the excitation functions present in literature, some Laboratories start systematic experimental measurements of the cross sections and a careful analysis of the problems related to the direct production of Tc-99m by this route.
In this contest we have contributed with new measurements and data set to the database of the cross sections, data that now appear more consistent and accurate.
The thin-target yields have been plotted as a function of their average energy into the targets and fitted with the best mathematical function. Its integration gives the calculated thick-target yields, which allow finding the optimized couple of energy irradiation and energy loss inside the thick target to maximize the production. Some considerations about the long lived Tc-99g and the interfering radionuclides have been done
Laboratorio radon per la scuola secondaria
No full textLa scarsa informazione scientifica porta in genere ad avere paura di ciò che non si conosce attribuendo rischi esagerati, mentre si affrontano con leggerezza attività ad alto rischio, ma di cui si ha esperienza diretta, ossia, la percezione soggettiva del rischio non corrisponde al rischio oggettivo. Un tema che allarma ed è temuta in modo eccessivo è la radioattività. Mediante un laboratorio in cui i protagonisti sono gli studenti delle scuole medie superiori, i loro insegnanti e indirettamente le rispettive famiglie, viene fatta la misurazione del gas naturale radioattivo radon-222. Verranno presentati i risultati ottenuti dalle scuole della Regione Lombardia
Nasar: a project on nanosafety research by radiochemical and nuclear techniques
No full textAlthough the production and applications of engineered nanoparticles (NPs) are in a remarkable increase, many are the unresolved questions about their potential adverse health and environmental impacts arising from exposure to these innovative materials. Nanosafety is today recognized as a central scientific reference point for risk prevention and responsible nanotechnology development due to industrial and socio-economic expectations. This discipline, having to deal with very complex problems, such as the understanding of the toxicity mechanisms that underpin some peculiar NPP-induced toxic responses, is characterized by a multidisciplinary character, requiring an integrated use of different analytical techniques of a more traditional type (spectroscopic, bioanalytic, molecular biology) that is more sophisticated like highly specialized microscopy, nuclear and radiochemical techniques, that play a fundamental and crucial role in understanding the effects induced by exposure to NPs. In particular, in order to illustrate the types of information that can be obtained with the use of such techniques some examples of applications related to studies with metallic NPs and based on the use of the nuclear reactor Triga Mark II of the University of Pavia will be presented.
It will be clear from the presentation how nanotoxicology/nanosafety requires new specialists in the context of analytical chemistry, such as nuclear and radioanalytic techniques of radionochemistry. The real crucial point is the cultural and operative preparation of new operators in these fields that implies the necessity that courses like health physics, nuclear chemistry, radiochemistry and related subjects must be more present in the university curricula.
It is important to take in mind that the subjects related to these fields require a constructive collaboration between Physics, Chemistry, Biology, Medicine that are only different chapters of the only one great book of the life science
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