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Radionuclide Production
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
The most typical neutron reaction is the (n, γ) reaction in which a thermal neutron is captured by the target nucleus forming a compound nucleus. The decay energy is emitted as a prompt gamma ray. A typical example is the reaction 59Co (n, γ) 60Co that produces an important radionuclide used in external therapy. However, since the produced radionuclide is of the same element as the target the specific activity, that is, the radioactivity per mass of the sample, is low. This type of nuclear reaction has little interest when labelling radiopharmaceuticals. In light elements, other nuclear reactions resulting from thermal neutron irradiation are possible, like (n, p). Table 4.1 lists possible production reactions for some biologically important radionuclides
Medical and Biological Applications of Low Energy Accelerators
Published in Vlado Valković, Low Energy Particle Accelerator-Based Technologies and Their Applications, 2022
The “classical” positron-emitting radionuclides include 15O, 13N and 11C that possess unique properties for medical imaging. They are radionuclides of the fundamental elements of biological matter. They each possess short half-lives, which allow their use in designed radiotracers for clinical investigations with minimal risk, and they are readily able to be produced in sufficient activities by low-energy nuclear reactions. At present, several accelerator manufacturers offer production packages for these radionuclides emphasizing targetry with consideration of the cyclotron-extracted energies for nuclide production and online chemistry systems for the continuous production of specific precursors or radiotracers.
Contrast enhancement agents and radiopharmaceuticals
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
The compound 18F-fluorodeoxyglucose (18F-FDG) has the most desirable characteristics for PET imaging. 18F-FDG is produced in a cyclotron, an accelerator of subatomic particles (Fig. 2.21a); the cyclotron produces a large quantity of protons and moves them at an accelerated rate along a circular orbit inside a chamber controlled by powerful alternating electromagnetic fields. The particles gain energy and are smashed against a target at virtually the speed of light. The atoms of a chosen substance placed in this target are transformed by this bombardment into radioactive, unstable isotopes by means of a nuclear reaction.18F-FDG has the following properties: Paired gamma emission from a positron-emitting radionuclide.511 keV energy.A half-life of 110 minutes.
Investigation of radiation protective features of azadispiro derivatives and their genotoxic potential with Ames/Salmonella test system
Published in International Journal of Radiation Biology, 2023
Burak Alaylar, Bünyamin Aygün, Kadir Turhan, Mehmet Karadayı, Esra Cinan, Zuhal Turgut, Gökçe Karadayı, Mohammed Ibrahim Abu Al-Sayyed, Medine Güllüce, Abdulhalik Karabulut
The neutron cross-section is aimed to search the probability of interactions that may occur between the neutron entering a target material and the core of the target material. These interactions usually include elastic and inelastic or nuclear reactions, such as neutron capture, fission, and spallation. Barn (10−28 m2 or 10−24 cm2), which is accepted as the standard unit, is used to indicate this cross-section of interaction. These cross-sections are mostly determined with total macroscopic cross-section and the removal cross-section value is found as follows. The large total or removal cross-section of this cross-section expresses the high probability of interaction that the neutron coming to the material can make with the nucleus of the material (El-Khayatt and El-Sayed Abdo 2009). Any interaction of neutrons with the target material can be defined in different cross-sections as below.
Radiological risk assessment of the Hunters Point Naval Shipyard (HPNS)
Published in Critical Reviews in Toxicology, 2022
Dennis J. Paustenbach, Robert D. Gibbons
Pu-239 has a radioactive half-life of 24,110 years and is produced when uranium absorbs a neutron. Small amounts of plutonium occur naturally, but large quantities have been produced in nuclear reactions or released from atmospheric nuclear weapons tests. Pu-239 transitions by alpha decay. Its decay products emit alpha, beta, and gamma radiation depending upon which radionuclide is being evaluated and can pose both an internal and external radiation hazard. Pu-239 is present in most soils in the United States at various concentrations (ICRP 2008; Johnson et al. 2012). The potential for Pu-239 to be present on ships returning from nuclear weapons tests in the Pacific and Pu-239 use in calibrating radiation detection equipment were primary reasons it was identified as an ROC at HPNS (USN 2004).
A novel vertebrate system for the examination and direct comparison of the relative biological effectiveness for different radiation qualities and sources
Published in International Journal of Radiation Biology, 2018
E. R. Szabó, Z. Reisz, R. Polanek, T. Tőkés, Sz. Czifrus, Cs. Pesznyák, B. Biró, A. Fenyvesi, B. Király, J. Molnár, Sz. Brunner, B. Daroczi, Z. Varga, K. Hideghéty
Three irradiation experiments were performed at MTA Atomki. The irradiation arrangement at the p(18 MeV)+Be neutron source is shown in Figure 2. The zebrafish embryos, floating in solutions in Eppendorf tubes, were exposed to the mixed neutron-gamma field of the p(18 MeV)+Be fast neutron irradiation facility (Fenyvesi András 2004) based on the MGC-20E cyclotron. During each experiment, Ep = 18 MeV ±0.3% MeV energy protons beams were transported to the irradiation facility. The beam currents were in the Ip = (9.2–10.7) µA range and they were kept constant during irradiation. The protons passed first a stainless steel entrance window foil and then a layer of flowing helium gas that cooled the bombarded target surface. The average energy loss of the protons was <ΔEp> = 0.355 MeV before reaching the beryllium target that fully stopped the beam. The proton-induced nuclear reactions on 9Be target nuclei lead to emission of neutrons and gamma photons with continuous broad energy spectra that covered the E = 0–20 MeV energy range. Most neutrons were emitted in the En > 0.1 MeV energy range and the average neutron energy was < En> = 3.5 MeV.