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An investigation on the improvement of neutron radiography system of the tehran research reactor by using MCNPX simulations
, Article Nuclear Engineering and Technology ; Volume 53, Issue 10 , 2021 , Pages 3413-3420 ; 17385733 (ISSN) ; Zamzamian, M ; Fadaei, A. H ; Gharib, M ; Feghhi, A. H ; Sharif University of Technology
Korean Nuclear Society
2021
Abstract
Applying the available neutron flux for medical and industrial purposes is the most important application of research reactors. The neutron radiography system is used for non-destructive testing (NDT) of materials so that it is one of the main applications of nuclear research reactors. One of these research reactors is the 5 MW pool-type light water research reactor of Tehran (TRR). This work aims to investigate on materials and location of the beam tube (BT) of the TRR radiography system to improve the index parameters of BT. Our results showed that a through-type BT with 20 cm thick carbon neutron filter, 1.2 cm and 9.4 cm of the diameter of inlet (D1) and output (D2) BT, respectively...
A new method for determination of concentration profile in a transport column by gamma spectroscopy combined with genetic algorithm
, Article Progress in Nuclear Energy ; Volume 124 , 2020 ; Kazemi, Z ; Samadfam, M ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
A non-collimated gamma spectroscopy with fewer sampling (counting) and shorter sampling periods is developed and used to estimate the concentration profile of the radiotracers within the column. In this method, the radiotracer activity in the whole column is measured in a few different positions of the detector and then, by using an appropriate advection-dispersion model and the genetic algorithm, the concentration profile within the column is constructed. The concentration profile obtained by the new method fits very well to the experimentally obtained thin-section scanning results with RMSE less than 0.046. The uniqueness of the concentration profile obtained by the method was confirmed by...
Simulation of Intensity Modulated Radiation Therapy (IMRT) and Assessment of the Time Parameter
, M.Sc. Thesis Sharif University of Technology ; Vosoughi, Naser (Supervisor) ; Mahdavi, Rabi (Supervisor) ; Robat Jazi, Mostafa (Co-Advisor)
Abstract
It is necessary to evaluate dosimetry accuracy in the framework of advanced methods for radiation therapy such as Intensity Modulated Radiation Therapy (IMRT) to ensure reliability of a proposed treatment. The ability of the Monte Carlo codes to model linear accelerator (LINAC) and to calculate the exact dose distribution in clinical radiation therapy is one of the reasons to use such codes. The purpose of this project is to validate a treatment planning system with BEAMnrc and DOSXYZnrc Monte Carlo codes. In this study, the dose distribution obtained from DOSXYZnrc in considered to be thr main criterion with which the dose distribution obtained from treatment planning system is assessed and...
Assessment and comparison of اomogeneity and conformity indexes in step-and-shoot and compensator-based intensity modulated radiation therapy (IMRT) and three-dimensional conformal radiation therapy (3D CRT) in prostate cancer
, Article Journal of Medical Signals and Sensors ; Volume 7, Issue 2 , 2017 , Pages 102-107 ; 22287477 (ISSN) ; Shirani Tak Abi, K ; Nedaie, H. A ; Hassani, H ; Gharaati, H ; Samei, M ; Shahi, R ; Zarei, H ; Sharif University of Technology
Abstract
Intensity modulated radiation therapy (IMRT) and three-dimensional conformal radiation therapy (3D CRT) are two treatment modalities in prostate cancer, which provide acceptable dose distribution in tumor region with sparing the surrounding normal tissues. IMRT is based on inverse planning optimization; in which, intensity of beams is modified by using multileaf collimators and also compensators with optimum shapes in step and shoot (SAS) and compensator-based method, respectively. In the recent study, some important parameters were compared in two IMRT and 3D CRT methods. Prescribed dose was 80 Gy for both IMRT procedures and 70 Gy for 3D CRT. Treatment plans of 15 prostate cancer...
MIMO underwater visible light communications: Comprehensive channel study, performance analysis, and multiple-symbol detection
, Article IEEE Transactions on Vehicular Technology ; Volume 67, Issue 9 , 2018 , Pages 8223-8237 ; 00189545 (ISSN) ; Nabavi, P ; Salehi, J. A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
This paper presents a comprehensive study of underwater visible light communications (UVLC), from channel characterization, performance analysis, and effective transmission and reception methods. To this end, we first simulate the fading-free impulse response (FFIR) of UVLC channels using Monte Carlo numerical procedure to take into account the absorption and scattering effects; and then to characterize turbulence effects, we multiply the aforementioned FFIR by a fading coefficient modeled as a lognormal random variable (RV) for weak oceanic turbulence. Based on this general channel model, we analytically study the bit error rate (BER) performance of UVLC systems with binary pulse position...