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New Trends
Published in Vlado Valković, Low Energy Particle Accelerator-Based Technologies and Their Applications, 2022
They described the new concept of energy amplification to extract nuclear energy with the help of accelerator induced nuclear cascades, extending to practical energy production the well-known “calorimeter” technique, widely used in High Energy Physics. The energy is produced from a nuclear fuel material disposed in a moderator medium through a process of breeding of a fissile element from a fertile element of the fuel material. After an initial phase, the rate between the concentrations of fissile and fertile elements reaches a substantial stability, resulting in a stable long-term energy production. The device must operate at relatively low neutron flux, in the 1014 cm−2 s−1 range, to ensure the correct performance of the breeding cycle and' to prevent the risk of criticality. Thorium as breeding fuel has considerable advantages when compared with uranium, in contrast with the full breeding based classic reactors for which the use of thorium presents serious difficulties. Thorium is more abundant than uranium, it generates much less transuranic actinides among the radioactive waste and the risk of nuclear proliferation is negligible. In the paper the basic concepts of the “Energy Amplifier, EA” are presented as well as alternative illustrative designs of the device. Some economic considerations are also discussed (Carminati et al. 1993; Rubbia et al. 1995) (Fig. 6.2).
Inhalation Toxicity of Metal Particles and Vapors
Published in Jacob Loke, Pathophysiology and Treatment of Inhalation Injuries, 2020
Inhalation exposures in humans, while infrequent, have caused sensitivity to heat, itching, and an increased awareness of odor and taste. In animals, intratracheal administration or inhalation exposure to fluorides or oxides, or a combination thereof, resulted in transient pneumonitis, subacute bronchiolitis, and regional bronchiolar stricturing (Stokinger, 1981). Cancers of the blood vessels, kidney, liver, and other organs have occurred after exposure to thorium used as a radiopaque medium (Stokinger, 1981). For example, Verhaack et al. (1974) reported 45 cases of tumors of the renal pelvis related to Thorotrast pyelography. The severity of the neoplastic effect, however, did not appear to be dose related.
Radiation Hormesis in Cancer
Published in T. D. Luckey, Radiation Hormesis, 2020
Thorium is one of the primordial radioactive elements that, with uranium, heat the interior of the earth. The half life of 232Th is 14 billion years (1.4 × 1010 year). It decays into 228Ra (half life 5.75 year); this decays to 228Ac (actinium with a 6.1 h half life), then to 228Th (half life 1.91 year) and 224Ra. 228Th decay is followed by a series of seven radionuclides emitting alpha, beta, and gamma rays within the next 4 d. Thorium and several of its progeny emit strong alpha rays, 3 to 10 MeV; this is enough to pass though 40 to 45 μm of tissue, equal to about one cell diameter.57 However, much of that energy may be expended in traversing the aggregate of bone, inorganic microparticulates, cell debris, and capsule surrounding the radionuclide; the calculated efficacy is dramatically decreased after it transverses these.
Mesothelioma mortality within two radiation monitored occupational cohorts
Published in International Journal of Radiation Biology, 2022
Michael T. Mumma, Jennifer L. Sirko, John D. Boice, William J. Blot
Radiation. Therapeutic doses of radiation and injection with Thorotrast, an alpha-particle emitting colloidal solution of thorium dioxide used as a diagnostic radiographic contrast medium, are likely causes of mesothelioma, including cancers of the pleura and peritoneum. However, cancer of the pleura is not increased among atomic bomb survivors, and large-scale studies of occupational groups exposed to low radiation levels are either negative or the increases are attributed to asbestos exposure. Associations between radiation and asbestosis (which is only caused by asbestos) indicate that jobs with relatively high radiation exposures are highly correlated with jobs with relatively high asbestos exposure. Over 83,000 IRs not employed at shipyards did not have an excess of mesothelioma or asbestosis, and there was no clear evidence of a radiation dose-response relationship in the overall cohort. Low-dose radiation received in these occupational setting was not found to be associated with mesothelioma.
Radium dial workers: back to the future
Published in International Journal of Radiation Biology, 2022
Nicole E. Martinez, Derek W. Jokisch, Lawrence T. Dauer, Keith F. Eckerman, Ronald E. Goans, John D. Brockman, Sergey Y. Tolmachev, Maia Avtandilashvili, Michael T. Mumma, John D. Boice, Richard W. Leggett
226Ra (228Ra (232Th commonly referred to as mesothorium (Keane et al. 1994). Figure 1 contains decay schemes for these two radium isotopes. Despite being chemically identical, 228Ra was cheaper than 226Ra. The processing of thorium ore results in the production of thorium nitrate, which was used at the time in the manufacture of incandescent gas mantles. 228Ra was a byproduct of this process that could be obtained locally, used after a year or two following extraction to allow in-growth of alpha-emitting progeny, necessary to achieve reasonable luminescence. Additionally, with a higher specific activity, 228Ra also had a ‘greater practical luminosity’ than 226Ra and was thus used in some locations to supplement 226Ra in dial paint (MLR 1926; Stewart 1929; Sharpe 1978). Retrospective analysis of USRC dial paint determined an average ratio of 228Ra to 226Ra of about 8.4 for paints used between 1919 and 1925, with other years’ paint likely 226Ra only (Keane et al. 1994).
The potential of PSMA-targeted alpha therapy in the management of prostate cancer
Published in Expert Review of Anticancer Therapy, 2020
Luca Filippi, Agostino Chiaravalloti, Orazio Schillaci, Oreste Bagni
Thorium-227 (227Th) represents another alpha-emitter with favorable properties for PSMA TAT [42]. 227Th can be obtained in large amounts through the beta-decay of 227Ac that, in its turn, can be produced by 226Ra irradiation in nuclear reactors. Hammer et al. utilized a specific chelator (i.e. 3,2-HOPO) in order to conjugate 227Th with a MoAb (i.e. BAY 2315493) directed toward PSMA, thus obtaining a PSMA-targeted 227Th-conjugate (PSMA-TTC) [43]. PSMA-TTC resulted capable to induce in vitro DNA damage, cell-cycle arrest, apoptosis and also presented strong antineoplastic efficacy in animal models bearing tumor xenografts.