Papers by Mohammad Taghi Bahreyni Toossi
The effect of glucose-coated gold nanoparticles on radiation bystander effect induced in MCF-7 and QUDB cell lines
Radiation and environmental biophysics, Nov 1, 2016
Due to biocompatibility and relative non-toxic nature, gold nanoparticles (GNPs) have been studie... more Due to biocompatibility and relative non-toxic nature, gold nanoparticles (GNPs) have been studied widely to be employed in radiotherapy as radio-sensitizer. On the other hand, they may enhance radiation-induced bystander effect (RIBE), which causes radiation adverse effects in non-irradiated normal cells. The present study was planned to investigate the possibility of augmenting the RIBE consequence of applying glucose-coated gold nanoparticles (Glu-GNPs) to target cells. Glu-GNPs were synthesized and utilized to treat MCF7 and QUDB cells. The treated cells were irradiated with 100 kVp X-rays, and their culture media were transferred to non-irradiated bystander cells. Performing MTT cellular proliferation test and colony formation assay, percentage cell viability and survival fraction of bystander cells were determined, respectively, and were compared to control bystander cells which received culture medium from irradiated cells without Glu-GNPs. Glu-GNPs decreased the cell viabili...
Iranian Journal of Medical Physics, 2011
Introduction: Nowadays ionizing radiation has a considerable contribution in medical diagnostic a... more Introduction: Nowadays ionizing radiation has a considerable contribution in medical diagnostic and treatment. Using ionizing radiation is increasing rapidly, so biological effects of ionizing radiation should be considered more. X-rays in the range of diagnostic radiology have hazardous effects and risks that are defined as random effects. These effects obey the LNT hypothesis that occur at low doses and include many types of cancer and genetic mutations. So it is very important to assess the risk of exposure in medical examinations. Cancer is one of these hazardous risks caused by low dose ionizing radiation that may occur during life after exposure. According to BEAR 7, low dose radiation is defined as radiation that produces doses near zero up to 100 mSv. Materials and Methods: This work was carried out in eight radiology centers in the Sabzevar county of Iran for 485 patients in eight typical x-ray examinations chosen for the study: chest PA, chest AP, lumbar spine AP, lumbar s...
Journal of Birjand University of Medical Sciences, 2017
The basic aim in radiography is to scan a clear image from the body organs, but the issue of the ... more The basic aim in radiography is to scan a clear image from the body organs, but the issue of the patient's protection against the harmful effects of ionizing radiation should never be neglected.The present study aimed at calculating the received drug to the perigonadic areas during radiography. In the current study thermoluminescence dosimeter was used to measure the dose absorbed by the skin.Dap values for each examination and also the patients demographic information such as age, body size, weight; and radiographic setting like mA, time, kVp , and focal spot distance from thefilm were recorded. Gonadal doses were calculated using PCXMC software (V: 2). Results: Maximum dose received by the testicles in the pelvis AP projection was 0.45 mGy and for the ovaries in abdomen PA it was, 0.306 mGy. Minimum dose received by the testicles and ovaries in lumbar LAT was 0.065 and 0.101, respectively. One of the ways for patients' gonadal dose reduction is to use appropriate shields for radiosensitive organs such as gonads. Hence,it is recommended to use appropriate shields for testicles because of their high radiosensitivity.
Research Square (Research Square), Nov 16, 2022
Journal of North Khorasan University of Medical Sciences
Journal of Biomedical Physics & Engineering, 2021
Background: The importance of cellular dosimetry in both diagnostic and radiation therapy is beco... more Background: The importance of cellular dosimetry in both diagnostic and radiation therapy is becoming increasingly recognized. Objective: This study aims to compare surviving fractions, which were predicted using Geant4 and contained three types of cancer cell lines exposed to 188Re with the experimentally surviving fraction determined by MTT assay. Material and Methods: In this comparative study, Geant4 was used to simulate the transport of electrons emitted by 188Re from the cell surface, cytoplasm, nucleus or medium around the cells. The nucleus dose per decay (S-value) was computed for models of single cell and random monolayer cell. Geant4-computed survival fraction (SF) of cancer cells exposed to 188Re was compared with the experimental SF values of MTT assay. Results: For single cell model, Geant4 S-values of nucleus-to-nucleus were consistent with values reported by Goddu et al. (ratio of S-values by analytical techniques vs. Geant4 = 0.811–0.975). Geant4 S-values of cytopla...
Iranian Journal of Medical Physics, 2018
Introduction: Craniospinal radiotherapy is a therapeutic technique for central nervous system (CN... more Introduction: Craniospinal radiotherapy is a therapeutic technique for central nervous system (CNS) tumors, which requires meticulous attention to technique and dosimetry.Treatment planning system (TPS) is one of the main equipment in radiotherapy; therefore, the evaluation of its accuracy is essential for dose calculation. The present study evaluates the validity of Isogray TPS in craniospinal irradiation techniques. Material and Methods: The computed tomography (CT) images of the brain and spine of the Rando phantom were acquired. Two techniques were designed. In technique 1, the whole CNS was irradiated with 6 MV photon beam. In technique 2, the brain and spine were irradiated with 6 MV photon and 18 MeV electron beam, respectively. The tumor and organs at risk doses were measured by thermoluminescent dosimeter (TLD). In addition, photon and electron dose measurements inside and outside the treatment field were accomplished using TLD, and then compared to the corresponding values...
Iranian Journal of Medical Physics, 2017
Introduction Quality control (QC) techniques are used in monitoring and maintenance of the compon... more Introduction Quality control (QC) techniques are used in monitoring and maintenance of the components of an x-ray system. QC of radiology devices plays a significant role in reduction of medication dose and optimization of image quality. This study aimed to conduct QC tests on randomly selected radiology devices, installed in diagnostic imaging departments of Iran. Materials and Methods In total, quality control tests were conducted on 51 conventional radiology devices installed in 20 cities of Iran in order to assess the accuracy of peak kilovoltage (kVp), exposure time, exposure linearity and reciprocity, reproducibility of exposure and determination of half-value layer (HVL) using a calibrated Mult-O-Meter. Results In this study, 38.6% of devices had intolerable variance of kVp accuracy. The results of 34.5% of devices were out of the acceptable limits in exposure time accuracy test. In 46.7% and 53.1% of devices, variance was greater than the acceptable range for exposure linea...
Iranian Journal of Medical Physics, 2014
Introduction Radiation-induced bystander effect (RIBE) is a phenomenon in which radiation signals... more Introduction Radiation-induced bystander effect (RIBE) is a phenomenon in which radiation signals are transmitted from irradiated cells to non-irradiated ones, inducing radiation effects in these cells. RIBE plays an effective role in radiation response at environmentally relevant low doses and in radiotherapy, given its impact on adjacent normal tissues or those far from the irradiated tumor. Reactive oxygen species contribute to RIBE induction. Therefore, the present study was conducted to investigate the possible inhibitory effects of garlic, as an antioxidant-containing plant, on RIBE. Materials and Methods MCF7 cells, treated with raw garlic extracts, were irradiated by 60Co gamma rays, and their culture medium was transferred to non-irradiated autologous bystander cells. Percentage cell viability and micronucleus formation in both irradiated and bystander cells were examined and compared with corresponding cell groups, not treated with garlic. Results Treatment with garlic ext...
Iranian Journal of Radiation Research, 2020
Background: Endoscopic retrograde cholangiopancreatography (ERCP) is now widely used in the diagn... more Background: Endoscopic retrograde cholangiopancreatography (ERCP) is now widely used in the diagnosis and treatment of gastrointestinal tract disorders. A large number of X-ray fluoroscopy and digital radiographs make ERCP as an interventional radiological procedure. In this study, patients' and examiner's entrance skin doses (ESDs) were measured during diagnosis and treatment procedures and patients' effective dose (ED) were calculated. Materials and Methods: Thermoluminescent dosimeters (TLDs) and dose area product meter (DAP) were used to measure ESDs of 30 patients and examiner and calculate patients' ED. Besides, to assess the effectiveness of an extra lead shield in decreasing examiner's ESDs, a lead cover was wrapped around the Xray tube. The data were analyzed with IBM SPSS Statistics version 16 software. Results: The mean DAP and fluoroscopy time (FT) of the diagnostic procedure were 4.09 Gy.cm and 32.4 s while those of the therapeutic procedure were 7.6...
Journal of Biomedical Physics & Engineering, 2016
Background EBT and EBT3 radioChromic films have been used in radiotherapy dosimetry for years. Ob... more Background EBT and EBT3 radioChromic films have been used in radiotherapy dosimetry for years. Objective The aim of the current study is to compare EBT and EBT3 radioChromic films in dosimetry of radiotherapy fields for treatment of parotid cancer. Methods Calibrations of EBT and EBT3 films were performed with identical setups using a 6 MV photon beam of a Siemens Primus linac. Skin dose was measured at different points in the right anterior oblique (RAO) and right posterior oblique (RPO) fields by EBT and EBT3 films on a RANDO phantom. Results While dosimetry was performed with the same conditions for the two film types for calibration and in phantom in parotid cancer radiotherapy, the measured net optical density (NOD) in EBT film was found to be higher than that from EBT3 film. The minimum difference between these two films under calibration conditions was about 2.9% (for 0.2 Gy) with a maximum difference of 35.5% (for 0.5 Gy). In the therapeutic fields of parotid cancer radiothe...
Iranian Journal of Medical Physics, 2012
Introduction Quality control is an important phenomenon in nuclear medicine imaging. A Jaszczak S... more Introduction Quality control is an important phenomenon in nuclear medicine imaging. A Jaszczak SPECT Phantom provides consistent performance information for any SPECT or PET system. This article describes the simulation of a Jaszczak phantom and creating an executable phantom file for comparing assessment of SPECT cameras using SIMIND Monte Carlo simulation program which is well-established for SPECT. Materials and Methods The simulation was based on a Deluxe model of Jaszczak Phantom with defined geometry. Quality control tests were provided together with initial imaging example and suggested use for the assessment of parameters such as spatial resolution, limits of lesion detection, and contrast comparing with a Siemens E.Cam SPECT system. Results The phantom simulation was verified by matching tomographic spatial resolution, image contrast, and also uniformity compared with the experiment SPECT of the phantom from filtered backprojection reconstructed images of the spheres and r...
Iranian Journal of Medical Physics, 2020
Introduction: In recent years, the number of complex coronary angiography (CA) is increasing rapi... more Introduction: In recent years, the number of complex coronary angiography (CA) is increasing rapidly. These procedures have a significant contribution to medical exposure to the general population. Exposure of patients to high doses of x-rays could cause deterministic effects on the skin. Therefore, the assessment of radiation doses of patients is of great importance. This study aimed to assess maximum entrance skin dose (MESD) of patients who underwent interventional cardiology procedures. Moreover, it was attempted to determine the correlation between MESD and other relevant dosimetric parameters. Material and Methods: The MESDs of 32 patients who underwent CA procedures were measured by an array of thermoluminescence dosimeters (TLDs). In this study, a Perspex tray consisting of 5 rows and 6 columns was used to hold the TLDs. Its long axis was perpendicular to the long axis of the table, and the top edges of the tray were approximately equal to the patient’s shoulders. Results: T...
Iranian Journal of Medical Physics, 2010
Introduction: The purpose of this work was to study the ability of MRI normoxic polymer gel dosim... more Introduction: The purpose of this work was to study the ability of MRI normoxic polymer gel dosimetry for evaluating the dose distribution in HDR brachytherapy of esophagial cancer at Imam Reza brachytherapy center (Mashhad, Iran). Materials and Methods: Initially, 2liters of normoxic gel (MAGIC) was fabricated and then poured into 12 calibration test tubes and placed in a perspex walled phantom. The gel phantom was irradiated with a brachytherapy remote-afterloader unit using a cobalt-60 brachytherapy source and the test tubes were irradiated with a range of known doses with a cobalt-60 teletherapy unit. Imaging was performed with a multi-spin-echo protocol and a T2 quantitative technique using a Siemens 1.5 T MRI machine. The MRI images were transferred to a computer and then image processing was performed in the MATLAB environment to extract R2 maps of the irradiated area. Results: In this study and at the reference point, the dose deviation between the gel dosimetry and the calc...
Journal of Biomedical Physics & Engineering, 2018
Background: One of the main causes of induction of secondary cancer in radiation therapy is neutr... more Background: One of the main causes of induction of secondary cancer in radiation therapy is neutron contamination received by patients during treatment. Objective: In the present study the impact of wedge and block on neutron contamination production is investigated. The evaluations are conducted for a 15 MV Siemens Primus linear accelerator. Methods: Simulations were performed using MCNPX Monte Carlo code. 30˚, 45˚ and 60˚ wedges and a cerrobend block with dimensions of 1.5 × 1.5 × 7 cm3 were simulated. The investigation were performed in the 10 × 10 cm2 field size at source to surface distance of 100 cm for depth of 0.5, 2, 3 and 4 cm in a water phantom. Neutron dose was calculated using F4 tally with flux to dose conversion factors and F6 tally. Results: Results showed that the presence of wedge increases the neutron contamination when the wedge factor was considered. In addition, 45˚ wedge produced the most amount of neutron contamination. If the block is in the center of the fi...
Iranian Journal of Medical Physics, 2012
Introduction Computed Tomography scans are a very important tool for diagnosis and assessment of ... more Introduction Computed Tomography scans are a very important tool for diagnosis and assessment of response to treatment in the practice of medicine. Ionizing radiation in medical imaging is undoubtedly one of the most powerful diagnostic tools in medicine. Yet, as with all medical interventions, there are potential risks in addition to the clear potential benefits. Materials and Methods Two reference dose quantities have been defined in order to promote the use of good technique in CT. These are weighted CT dose index (CTDIw) in (mGy) for a single slice in serial scanning or per rotation in helical scanning, and dose�length product (DLP) per complete examination (mGy.cm), All measurements were performed using a pencil shaped ionization chamber introduced into polymethyl methacrylate cylindrical brain and body phantoms. This survey was performed on 7 CT scanners in Khorasan Province-Iran. Results DLP for brain, chest, abdomen and pelvic examinations had a range of 255 - 1026, 76-127...
Journal of Biomedical Physics & Engineering, 2016
Background: Breast cancer is the most frequently diagnosed cancer and the leading global cause of... more Background: Breast cancer is the most frequently diagnosed cancer and the leading global cause of cancer death among women worldwide. Radiotherapy plays a significant role in treatment of breast cancer and reduces locoregional recurrence and eventually improves survival. The treatment fields applied for breast cancer treatment include: tangential, axillary, supraclavicular and internal mammary fields. Objective: In the present study, due to the presence of sensitive organ such as thyroid inside the supraclavicular field, thyroid dose and its effective factors were investigated. Materials and Methods: Thyroid dose of 31 female patients of breast cancer with involved supraclavicular lymph nodes which had undergone radiotherapy were measured. For each patient, three TLD-100 chips were placed on their thyroid gland surface, and thyroid doses of patients were measured. The variables of the study include shield shape, the time of patient’s setup, the technologists’ experience and qualific...
Iranian Journal of Basic Medical Sciences, 2018
Objective(s): Radiotherapy is one of the most effective modalities of cancer therapy, but clinica... more Objective(s): Radiotherapy is one of the most effective modalities of cancer therapy, but clinical responses of individual patients varies considerably. To enhance treatment efficiency it is essential to implement an individual-based treatment. The aim of present study was to identify the mechanism of intrinsic apoptosis pathway on radiosensitivity and normal tissue complications caused by the radiotherapy. Materials and Methods: Peripheral blood mononuclear cells from ten breast cancer patients were exposed to 6MV X-rays to deliver 1 and 2 Gy. Expression levels of Bax, Bcl-2, and Bax/Bcl-2 ratio were examined by relative quantitative RT-PCR. All the patients received similar tangential irradiation of the whole breast and conventional fractionation. Skin dosimetry was done by GAFChromic EBT-3 film and clinical radiosensitivity was determined using the acute reactions to radiotherapy of the skin according to Radiation Therapy Oncology Group score. All statistical analyses were perfor...
Iranian Journal of Medical Physics, 2018
Introduction: In recent years, the number of computed tomography (CT) scans, which is a high-dose... more Introduction: In recent years, the number of computed tomography (CT) scans, which is a high-dose technique, has increased significantly. Head and neck CT is performed frequently and thyroid, particularly in children, has always been considered a sensitive organ. In recent years, radiobiologists and health physicists have been more concerned about the safety of lenses of the eyes, as cataract is no longer considered a deterministic effect. Material and Methods: In the present study, incurred doses to the thyroid and lens of the eye of 140 patients who underwent common head and neck CT at five hospitals were measured by thermoluminescent dosimeters (TLD-100). The patients were divided into two age groups of pediatrics and adults. TLD chips were placed on the patient’s skin surface. For each patient, scan parameters, sex and age were recorded. Exposed TLDs were read by a manual TLD reader. Results: The verage absorbed dose of the thyroid, as well as the lenses of the left and right ey...
Iranian Journal of Medical Physics, 2016
Introduction Wedge modifiers are commonly applied in external beam radiotherapy to change the dos... more Introduction Wedge modifiers are commonly applied in external beam radiotherapy to change the dose distribution corresponding to the body contour and to obtain a uniform dose distribution within the target volume. Since the radiation dose delivered to the target must be within ±5% of the prescribed dose, accurate dose calculation by a treatment planning system (TPS) is important. The objective of the present study was to quantify the dose calculation accuracy of TiGRT TPS for physical wedged fields in radiotherapy. Materials and Methods A Semiflex™ ionization chamber was used for dose measurements in a water phantom; TiGRT TPS was also applied for dose calculations. The central axis (i.e., high dose-small dose gradient), build-up (i.e., high dose-large dose gradient), off-axis (i.e., high dose-small dose gradient), and out-of-field (i.e., low dose-small dose gradient) regions were evaluated in this study. Finally, the confidence limit values were obtained to quantify the dose calcula...
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Papers by Mohammad Taghi Bahreyni Toossi