Mahdieh Sadat Mousavi; Faezeh Rahmani
Abstract
Boron Neutron Capture Therapy (BNCT) is one of the promising treatment methods for some malignant tumors such as Glioblastoma Multiforme (GBM). One of the requirements of BNCT treatment is the accurate and real-time boron-concentration monitoring to ensure the efficacy of treatment and no leakage of ...
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Boron Neutron Capture Therapy (BNCT) is one of the promising treatment methods for some malignant tumors such as Glioblastoma Multiforme (GBM). One of the requirements of BNCT treatment is the accurate and real-time boron-concentration monitoring to ensure the efficacy of treatment and no leakage of boron. An accurate method for real-time calculation of the boron dose distribution mapping during irradiation is Single Photon Emission Computed Tomography (SPECT), in which the determination of boron distribution is based on the detection of 478 keV prompt gamma-rays generated through thermal neutron capturing by B-10. Tehran Research Reactor (TRR) is the only possible source for BNCT in Iran, so as the first approach, this BNCT-SPECT system has been evaluated for TRR. In this paper, an imaging system of BNCT-SPECT including four arrays of collimator/detector has been designed for real-time dosimetry as well as boron-10 concentration distribution map in the phantom that placed in front of the therapeutic neutron beam using the Monte Carlo simulation code MCNP6. Maximum Likelihood Expectation Maximization (MLEM) method has been used for image reconstruction which results 1 cm spatial resolution.
Sajjad Shahmaleki; Faezeh Rahmani
Abstract
In this research, the Tm content as codopant in CsI(Tl) was optimized for reducing the afterglow. As an experimental reference, CsI(Tl) and CsI(Tl-0.05%Eu) single crystals were grown by Bridgman method. The grown crystals were characterized through photoluminescence analysis, and the measurements of ...
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In this research, the Tm content as codopant in CsI(Tl) was optimized for reducing the afterglow. As an experimental reference, CsI(Tl) and CsI(Tl-0.05%Eu) single crystals were grown by Bridgman method. The grown crystals were characterized through photoluminescence analysis, and the measurements of charge collection time, energy resolution, photon light yield as well as the amount of afterglow were performed. It was observed that the change in codopant shifted the emission curve of Tl+. For CsI(Tl) codoped with Tm in the range of 0.02 to 0.1 mol%, the afterglow of 0.05 mol% Tm reduced in comparison with Tm-free CsI(Tl). The results showed that the Tm codopant resulted in a decrease of 32 to 42% in afterglow depending on the Tl concentration. The addition of various contents of Tm also decreased the light yield, up to 23%, and as well as the resolution about 2 to 33%. The light yield exhibited insignificant changes, whilst the measured energy resolution was about 8.8% at 662 keV. Overall, the improvement in the afterglow, as well as the insignificant reduction in both the energy resolution and light yield of CsI(Tl-Tm), may motivate some researchers to consider it as a good candidate for fast spectroscopy and high-frequency imaging applications.
Ali Taaghibi Khotbesara; Faezeh Rahmani; Farshad Ghasemi
Abstract
This work presents an alternative method for Mo-99 production as a parent nuclide of Tc-99m which is the most used radioisotope in diagnostic imaging processes. Regarding to some benefits of accelerator-based methods over reactor-based methods for Mo-99 production, the electron ...
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This work presents an alternative method for Mo-99 production as a parent nuclide of Tc-99m which is the most used radioisotope in diagnostic imaging processes. Regarding to some benefits of accelerator-based methods over reactor-based methods for Mo-99 production, the electron Linac-based method has been selected. In this way of production, two approaches (one-stage and two-stage) are available using photoneutron reaction in Mo-100 target using bremsstrahlung photons. The superiority of one-stage approach and optimal dimension of target has been demonstrated by nuclear simulation using MCNPX2.6 code. Thermal analysis of the optimized target has been performed by COMSOL software, which has been led to select the indirect cooling system. The final suggested conceptual design of the target includes nine Mo-100 stripe plates with 0.2, 3, and 30 cm in thickness, width and length, respectively which being surrounded by two copper clamps as the cooling ducts. The velocity of 2.5 m/s of inlet coolant (water) is sufficient for the suggested cooling system to satisfy the conditions of the turbulent regime as the desired cooling regime.
