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Radiopharmaceuticals for Diagnostics
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
Radiochemistry with 18F and 11C involves formation through covalent bonds requiring expertise combining radiochemistry and organic chemistry. Radiochemistry with radiometals like 68Ga, 89Zr, but also 64Cu or involves complexation, which is similar to 99mTc chemistry with chelator ligands that interact with the available metal electron orbitals. This type of radiochemistry combines radiochemistry knowledge with inorganic chemistry.
PET and SPECT in the Assessment of Cerebral Function
Published in Richard A. Jonas, Jane W. Newburger, Joseph J. Volpe, John W. Kirklin, Brain Injury and Pediatric Cardiac Surgery, 2019
Adre J. du Plessis, S. Ted Treves
Although the functional brain imaging techniques of PET and SPECT have advanced our understanding of cerebral metabolism and hemodynamics, these techniques have certain constraints. The major limitation of PET relates to its cost and complexity, factors which have restricted the widespread application of the technique. The short half-life of PET isotopes necessitates an on-site cyclotron, and the complexities of radiotracer synthesis require a radiochemist. Single photon emission tomography is a less costly, less cumbersome, and more accessible alternative, which in many circumstances is able to demonstrate the same information as PET.5l However, several limitations restrict the SPECT technique. First, the inability to measure metabolism directly may limit the value of SPECT, particularly in the study of ischemia when the normal coupling of CBF to metabolism may break down. In addition, recent evidence suggests that the fractional fixation of 99mTc-HMPAO may be altered in certain disease states, including cerebral ischemia.52 Second, SPECT is currently semiquantitative. Ongoing efforts are aimed at quantitative validation.33
11C, 13N, and 15O Tracers
Published in Garimella V. S. Rayudu, Lelio G. Colombetti, Radiotracers for Medical Applications, 2019
Roy S. Tilbury, Alan S. Gelbard
The short half-lives of 11C, 13N and 11C present challenges as well as opportunities for the radiochemist. To obtain labeled compounds in sufficient yields to carry out clinical or animal studies, large amounts of radioactivity must be produced and methods must be developed to synthesize compounds quickly and remotely in order to limit radiation exposure. Work is usually carried out by automated and remote procedures within a lead-shielded hot cell.
Peptide receptor radionuclide therapy in neuroendocrine neoplasms and related tumors: from fundamentals to personalization and the newer experimental approaches
Published in Expert Review of Precision Medicine and Drug Development, 2023
a) Multiple new radionuclide molecules which are more powerful and easily produced than routine 90Y/177Lu are being studied for their therapeutic potentialse.g.213Bi,67Cu,111In,161Tb. Recently a phase I trial which treated 33 treatment-naive patients, using 212Pb-DOTAMTATE [138]. 212Pb has a half-life of 10.6hrs and emits imageable gamma photons 238 and 300 KeV. Another benefit of 212Pb is 224Ra(half-life: 3.6 days) based generator systems which can selectively produce clinical-grade 212Pb, Pb shows suitable radiochemistry and forms a stable complex with DOTA and TCMC chelators [139]. As per primary results from this study 83.3% of patients who could complete all 4 cycles showed objective response as per RECIST1.1, no grade 4 and five grade 3 adverse effects were reported (back pain, dysarthria, dyspnea, acute kidney injury). All patients showed improvement in the quality of life, reduction of pain, shortness of breath in the majority of subjects, with an increase of energy. Multiple other α-emitting agents like211At in novel delivery systems like polymer nanoparticles are also being studied at pre-clinical level waiting to be translated into clinical studies.
Modeling of mass transfer in vacuum membrane distillation process for radioactive wastewater treatment using artificial neural networks
Published in Toxin Reviews, 2021
Elena-Niculina Dragoi, Yasser Vasseghian
Due to its disastrous effects when released, the radioactive materials (generated in the course of nuclear activities such as production of nuclear fuel, production and use of radioisotopes in nuclear medicine, industry and agriculture, and radiochemistry analysis (Mahmoud et al.2018) are considered very toxic and their treatment is of outmost importance. Low level radioactive wastewater (LLRWs) is one of the main types of radioactive wastewater in the nuclear power plants. This wastewaters always contains a small amount of long half-life nuclides, such as cobalt 60 (60Co), strontium 90 (90Sr), cesium 134 (134Cs), and cesium 137 (137Cs; Kim et al.2016) and a large amount of boric acid (about 500 mg/l) from the initial cooling of the nuclear reactor (Wen et al.2016b). During the process, the concentration of these wastewaters is initially changed by minimizing their volume and then solidified by cement, bitumen, or glass (Zakrzewska-Trznadel 2013). For these wastewaters, there are three basic principles of treatment (Zakrzewska-Trznadel 2013): (I) purification to bring them to the evacuation environmental conditions, (II) compression and volume reducing to reduce the solidification costs, and (III) recovery of valuable materials such as cobalt 60 (60Co), strontium 90 (90Sr), cesium 137 (137Cs), and boric acid (H3BO3; Table 1).
Why is the multiple stressor concept of relevance to radioecology?
Published in International Journal of Radiation Biology, 2019
B. Salbu, H. C. Teien, O. C. Lind, K. E. Tollefsen
To provide environmental impact (EIA) and risk assessment (RA) associated with radionuclide contamination of an ecosystem, information on source term and deposition, ecosystem processes and mobility, biological uptake, accumulation and effects is essential. In mixed contaminated areas where organisms are exposed to a cocktail of contaminants, i.e. multiple stressors, biological uptake and accumulation in organisms will depend on the interaction between stressors (toxicokinetics), while biological effects will depend on the competition between stressors to interact with key biological targets and interactions between different toxicity pathways leading to an adverse effect (toxicodynamics). Thus, not only the concentrations of the stressors, but also the elemental speciation will be essential for stressor interactions. Upon interaction with living organisms, ionizing radiation excites and ionizes predominantly water molecules and free radicals are induced. By recombination, the ROS formation may result in biological endpoints such as reproduction failure, mutation, morbidity, mortality, i.e. biological endpoints that also can be induced by other stressors such as metals and organics. Therefore, linking biological endpoints to one specific source could be rather questionable, and would at best be affected with considerable uncertainties. Thus, a joint collaboration between radiochemists and biologists is essential.