Publications by authors named "Shiva Zarifi"

Introduction: A significant number of head computed tomography (CT) scans are performed annually. However, due to the close proximity of the thyroid gland to the radiation field, this procedure can expose the gland to ionising radiation. Consequently, this study aimed to estimate organ dose, effective dose (ED) and lifetime attributable risk (LAR) of thyroid cancer from head CT scans in adults.

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This study aimed to investigate the effect of bladder volume on the dosimetry of pelvic organs at risk (OARs) in patients treated with external beam radiation therapy. Twenty patients with locally advanced cervical cancer were selected. Two computed tomography-simulation scans were obtained, one with an empty bladder followed by one with a full bladder.

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Background And Objectives: There is significant interest and potential in the treatment of neuroendocrine tumors via peptide receptor radionuclide therapy (PRRT) using one or both of 90Y and 177Lu-labeled peptides. Given the presence of different tumor sizes in patients and differing radionuclide dose delivery properties, the present study aims to use Monte Carlo simulations to estimate S-values to spherical tumors of various sizes with 90Y and 177Lu separately and in combination. The goal is to determine ratios of 90Y to 177Lu that result in the largest absorbed doses per decay of the radionuclides and the most suitable dose profiles to treat tumors of specific sizes.

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Background: Due to the importance of choosing the applicable dosimetry method in radionuclide therapy, the present study was conducted to investigate the efficiency of the implementation of Dose Point Kernel (DPK) for dose optimization of Lu/Y Cocktail Radionuclides in internal Dosimetry.

Methods: In this study, simulations and calculations of DPK were performed using the GATE/GEANT4 Monte Carlo code. For specific liver dosimetry, the NCAT phantom and convolution algorithm-based Fast Fourier Transform method was used by MATLAB software.

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To validate the GATE Monte Carlo simulation code and to investigate the lateral scattering of proton pencil beams in the major body tissue elements in the therapeutic energy range. In this study, GATE Monte Carlo simulation code was used to compute absorbed dose and fluence of protons in a water cubic phantom for the clinical energy range. To apply the suitable physics model for simulation, different physics lists were investigated.

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Objective: This study aims to benchmark a Monte Carlo (MC) model of the 18 MV photon beam produced by the Siemens Oncor® linac using the BEAMnrc and DOSXYZnrc codes.

Methods: By matching the percentage depth doses and beam profiles calculated by MC simulations with measurements, the initial electron beam parameters including electron energy, full width at half maximum (spatial FWHM), and mean angular spread were derived for the 10×10 cm2 and 20×20 cm2 field sizes. The MC model of the 18 MV photon beam was then validated against the measurements for different field sizes (5×5, 30×30 and 40×40 cm2) by gamma index analysis.

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