Accelerator-Based Methods in Radio-Material 99Mo/99mTc Production Alternatives by Monte Carlo Method: The Scientific-Expedient Considerations in Nuclear Medicine

2019 ◽  
Vol 11 (01) ◽  
pp. 1930001 ◽  
Author(s):  
Abdollah Khorshidi

Some accelerator technologies are already used for commercial [Formula: see text]Mo-99mTc production, as the economic criteria are considered representative of the main differences between diverse technologies including accelerators and reactors. This study has provided a review of known and potential [Formula: see text]Mo production using conventional medical facilities. Accelerator-based method in 99mTc production via ([Formula: see text], [Formula: see text]) direct reaction on [Formula: see text]Mo was simulated using 18[Formula: see text]MeV proton beam. Meanwhile, a conceptual design for indirect [Formula: see text]Mo production via [Formula: see text]Mo([Formula: see text])[Formula: see text]Mo and [Formula: see text]Mo(n,[Formula: see text]2n)[Formula: see text]Mo reactions was investigated when an electron source of 35[Formula: see text]MeV by accelerator is used. These indirect reactions were explored via inserted [Formula: see text]Mo samples at different positions inside the lead region. Furthermore, Adiabatic Resonance Crossing (ARC) method based on proton accelerator via transmutation in [Formula: see text]Mo([Formula: see text]Mo was examined when the 30[Formula: see text]MeV proton beam is used. Saturation activity and yield were investigated using alternative proposed methods. The potential proliferation risk associated with accelerator technetium production is minimal. While accelerators could be turned into neutron sources which could in turn be used to irradiate [Formula: see text]U to breed plutonium, and centrifuges used to enrich [Formula: see text]Mo for targets could conceivably be turned to enriching uranium, this would result in very tiny global production capability particularly compared with research or power reactors. The potential of the fresh methods could provide a replacement or complement over current reactor-based supply sources in various radioisotopes production purposes.

2021 ◽  
Vol 167 ◽  
pp. 109454
Author(s):  
Frederick C. Hila ◽  
Cheri Anne M. Dingle ◽  
Alvie Asuncion-Astronomo ◽  
Charlotte V. Balderas ◽  
Marianna Lourdes Marie L. Grande ◽  
...  

1974 ◽  
Vol 22 ◽  
pp. 307 ◽  
Author(s):  
Zdenek Sekanina

AbstractIt is suggested that the outbursts of Periodic Comet Schwassmann-Wachmann 1 are triggered by impacts of interplanetary boulders on the surface of the comet’s nucleus. The existence of a cloud of such boulders in interplanetary space was predicted by Harwit (1967). We have used the hypothesis to calculate the characteristics of the outbursts – such as their mean rate, optically important dimensions of ejected debris, expansion velocity of the ejecta, maximum diameter of the expanding cloud before it fades out, and the magnitude of the accompanying orbital impulse – and found them reasonably consistent with observations, if the solid constituent of the comet is assumed in the form of a porous matrix of lowstrength meteoric material. A Monte Carlo method was applied to simulate the distributions of impacts, their directions and impact velocities.


Author(s):  
Makoto Shiojiri ◽  
Toshiyuki Isshiki ◽  
Tetsuya Fudaba ◽  
Yoshihiro Hirota

In hexagonal Se crystal each atom is covalently bound to two others to form an endless spiral chain, and in Sb crystal each atom to three others to form an extended puckered sheet. Such chains and sheets may be regarded as one- and two- dimensional molecules, respectively. In this paper we investigate the structures in amorphous state of these elements and the crystallization.HRTEM and ED images of vacuum-deposited amorphous Se and Sb films were taken with a JEM-200CX electron microscope (Cs=1.2 mm). The structure models of amorphous films were constructed on a computer by Monte Carlo method. Generated atoms were subsequently deposited on a space of 2 nm×2 nm as they fulfiled the binding condition, to form a film 5 nm thick (Fig. 1a-1c). An improvement on a previous computer program has been made as to realize the actual film formation. Radial distribution fuction (RDF) curves, ED intensities and HRTEM images for the constructed structure models were calculated, and compared with the observed ones.


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