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Mock examination
Published in Damian Tolan, Rachel Hyland, Christopher Taylor, Arnold Cowen, Get Through, 2020
Damian Tolan, Rachel Hyland, Christopher Taylor, Arnold Cowen
True – a neutron is converted to a proton and an electron (the beta particle). The atomic number is increased by I.True – a nucleus that emits a positron does so by converting a proton to a neutron, to conserve electric charge. The fact that it needed to reduce the number of protons indicates that there was initially an excess of protons.False – Molybdenum-99 decays to technetium-99m. Technetium cannot then decay back to molybdenum. Technetium-99m decays to technetium-99, which then decays to stable ruthenium-99.True – like electrons in their shells, the particles in a nucleus have binding energies. A gamma ray has an energy corresponding to the difference between two energy levels in a nucleus. Although a nuclide may emit several gamma rays of different energies, the spectrum is not continuous.False – although beta decay involves a fixed energy change within the nucleus, the energy is shared between the beta particle and a neutrino. This means that the beta particle can have any energy up to a fixed maximum. The maximum represents the situation where the electron takes all the available energy.
Physics of Radiation Biology
Published in Kedar N. Prasad, Handbook of RADIOBIOLOGY, 2020
In 1896, Henri Becquérel discovered the emission of energetic electrons from uranium salts. This mode of decay is usually called beta decay. Beta decay also refers to the emission of positive electrons from certain nuclei. To distinguish these decay processes, negative electron decay should be referred to as negatron decay, whereas positive electron decay is positron decay.
Organization and Management of a Radiation Safety Office
Published in Kenneth L. Miller, Handbook of Management of Radiation Protection Programs, 2020
Steven H. King, Rodger W. Granlund
Radionuclides chosen for nuclear medicine are usually gamma emitters without significant beta decay to ininimize patient dose. Proportional and GM counters are not very efficient for gamma-rays and a gamma detector such as a Nal(Tl) crystal may be required for surveys or measurements. The detector requires a high-voltage supply and a scaler with a discriminator. For identification of gamma-emitting radioisotopes a single- or multichannel analyzer is required. If a large number of gamma-emitting radionuclides are used, a germanium detector may be required to obtain sufficient resolution to identify the radionuclides present.
New frontier radioiodinated probe based on in silico resveratrol repositioning for microtubules dynamic targeting
Published in International Journal of Radiation Biology, 2023
Ashgan F. Mahmoud, Mohamed H. Aboumanei, Walaa Hamada Abd-Allah, Mohamed M. Swidan, Tamer M. Sakr
The most prominent criteria in radio-theranostics design are the prober selection of a drug with high affinity to the target organ and indeed the convenient radionuclides to be laden on it (Essa et al. 2015; Ibrahim et al. 2015; Al-Wabli et al. 2016; Swidan et al. 2019). Firstly, the molecular modeling study of the radioiodinated resveratrol had showed a good affinity toward β-tubulin binding site in the microtubules domain system with an appropriate binding energy (−34.46 kca/mol). This criterion was further enlightened through the in vivo distribution study in tumor models which showed high accumulation and retention in the tumor lesion. On the other hand, the radioactive iodine [131I] was selected for the radiolabeling process due to its convenient physical and decay characteristics. The radioactive iodine [131I], half-life ≈ 8 days, is considered as one of the most suitable radionuclides for radio-theranostics procedures due to its dual decay mode (10% gamma decay which utilized in the diagnosis while 90% beta decay which utilized in therapeutic application) (Sheikh et al. 2017; Sakr et al. 2018). So, the 131I-radioiodinated resveratrol preparation as a theranostic probe had successfully achieved the criteria mentioned above. From the molecular biology point of view, tracking of the microtubules dynamics is significantly help the physicians with soulful amelioration in the early detection of any abnormal modifications arisen during the cellular division such as tumor cell progression.
Radiological risk assessment of the Hunters Point Naval Shipyard (HPNS)
Published in Critical Reviews in Toxicology, 2022
Dennis J. Paustenbach, Robert D. Gibbons
Cs-137 has a radioactive half-life of 30 years and is a byproduct of nuclear fission. Cs-137 was released to the atmosphere from nuclear weapons testing conducted by the United States, United Kingdom, China, France, and the former USSR from 1946 to 1980 and from nuclear reactor accidents, such as those that occurred at the Chernobyl and Fukushima-Daiichi plants (Eisenbud and Gesell 1997; Balonov 2007; Marianno et al. 2018). As a result of these releases, measurable quantities of Cs-137 can be found in the environment (including soils) and in human tissues. Beta decay of Cs-137 produces a metastable excited state of barium (Ba-137m) with a radioactive half-life of 2.55 min. The decay of Ba-137m to the stable isotope of Ba-137 emits a high-energy gamma ray. Cs-137 is primarily an external radiation hazard although it can pose an internal radiation hazard if ingested or inhaled (ICRP 2008; Johnson et al. 2012). The potential for Cs-137 to be present on ships returning from nuclear weapons tests in the Pacific and Cs-137 use in calibrating radiation detection equipment were the primary reasons Cs-137 was identified as an ROC (USN 2004).
Radiobiological effects of tritiated water short-term exposure on V79 clonogenic cell survival
Published in International Journal of Radiation Biology, 2018
Mattia Siragusa, Pil M. Fredericia, Mikael Jensen, Torsten Groesser
With the important aid of COOLER, we have obtained carefully controlled sets of clonogenic cell survival curves for V79 cells internally exposed to tritium. We have found that the change in cell culture condition growth must be taken into account (single spherical cell, suspended cell clusters, and adherent cells). After comparison to S-values calculated for different cell geometries, no substantial difference was found between the use of the whole beta decay spectrum and its average decay energy. Finally, our findings underline the importance of using internal radiation and reference radiation at the same dose rate and stating the dose rate when measuring in vitro RBE-values.