Mohammad Taghi Bahreyni-Toossi
Medical Physics Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
[ 1 ] - In vivo Exposure Effects of 99mTc-methoxyisobutylisonitrile on the FDXR and XPA Genes Expression in Human Peripheral Blood Lymphocytes
Objective(s): In recent years, the application of radiopharmaceuticals in nuclear medicine has increased substantially. Following the diagnostic procedures performed in nuclear medicine departments, such as myocardial perfusion imaging, patients generally receive considerable doses of radiation. Normally, radiation-induced DNA damages are expected following exposure to a low-dose ionizing radia...
[ 2 ] - Bax/Bcl-2 expression ratio in prediction of response to breast cancer radiotherapy
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 ...
[ 3 ] - Assessment of the effects of radiation type and energy on the calibration of TLD-100
Introduction: In radiation therapy, knowing the dose rates to healthy organs and tumors is beneficial, and thermoluminescent dosimeter (TLD) allows for this possibility. This study was aimed at determining the dose-response differences of TLDs in various types of radiation, energy levels, and dose rate calibrated with other types of radiation beams and energy and dose levels. Materials and Meth...
[ 4 ] - Quality Control Assessment of Conventional Radiology Devices in Iran
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 tota...
[ 5 ] - Assessment of Dose Calculation Accuracy of TiGRT Treatment Planning System for Physical Wedged fields in Radiotherapy
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 ...
[ 6 ] - Evaluation of Organ and Effective Doses to Patients Arising From Some Common X-Ray Examinations by PCXMC Program in Sabzevar, Iran
Introduction The purpose of this study was to estimate organ and effective doses in patients undergoing some common X-ray examinations in Sabzevar, Iran. The effective dose is one of the best parameters for describing the amount of radiation dose received by a patient undergoing any diagnostic X-ray examination. The public dose from X-ray examinations depends on various factors, and its contrib...
[ 7 ] - Dose Measurements of Parotid Glands and Spinal Cord in Conventional Treatment of Nasopharyngeal Carcinoma Using RANDO Phantom and Thermoluminescent Dosimeters
Introduction Radiotherapy is regarded as the first treatment of choice for nasopharyngeal carcinoma. Despite the advantages of radiotherapy, patients may suffer from a wide range of side-effects due to the presence of many sensitive normal tissues in these regions. If the absorbed dose exceeds the tolerance level in parotid glands and the spinal cord, myelopathy, Lhermitte's sign and xerostomia...
[ 8 ] - An Investigation of the Effects of Raw Garlic on Radiation-induced Bystander Effects in MCF7 Cells
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. ...
[ 9 ] - Evaluation of Maximum Patient Skin Dose Arising from Interventional Cardiology Using Thermoluminescence Dosimeter in Mashhad, Iran
Introduction The increasing practice of interventional fluoroscopy in diagnosis and treatment of cardiovascular disease has risen attention to improve radiation protection of patients and cardiologists in these relatively high dose techniques. Therefore, nowadays there is an emphasis on the measurement of radiation dose received by patients and cardiologists arising from the relevant procedures...
[ 10 ] - Monte Carlo Study of the Effect of Backscatter Materail Thickness on 99mTc Source Response in Single Photon Emission Computed Tomography
Introduction SPECT projections are contaminated by scatter radiation, resulting in reduced image contrast and quantitative errors. Backscatter constitutes a major part of the scatter contamination in lower energy windows. The current study is an evaluation of the effect of backscatter material on FWHM and image quality investigated by Monte Carlo simulation. Materials and Methods SIMIND program...
[ 11 ] - Assessment of Patient Dose from CT Examinations in Khorasan, Iran
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 refe...
[ 12 ] - Diagnostic Reference Level Arising from Dental Panoramic Radiography
Introduction The present work describes a study in which, based on patient dose measurements, thermoluminescent dosimeters were used to obtain the diagnostic reference level arising from panoramic radiography. Materials and Methods Ten panoramic units and a sample of 15 patients per X-ray unit were studied. Two thermoluminescent dosimeter chips were placed on the skin surface of selected organs...
[ 13 ] - Simulation of a Quality Control Jaszczak Phantom with SIMIND Monte Carlo and Adding the Phantom as an Accessory to the Program
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 fo...
[ 14 ] - Excess Cancer Risk Assessment from Some Common X-Ray Examinations in Sabzevar County
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 lo...
[ 15 ] - Image Optimization in Single Photon Emission Computed Tomography by Hardware Modifications with Monte Carlo Simulation
Introduction: In Single Photon Emission Computed Tomography (SPECT), the projection data used for image reconstruction are distorted by several factors, including attenuation and scattering of gamma rays, collimator structure, data acquisition method, organ motion, and washout of radiopharmaceuticals. All these make reconstruction of a quantitative SPECT image very difficult. Simulation of a SP...
[ 16 ] - Evaluation of Dose Distribution Accuracy in HDR Brachytherapy of Esophagus Cancer Based on MRI Normoxic Polymer Gel Dosimetry
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 phanto...
[ 17 ] - An Assessment of Spinal Cord Dose Following Radiotherapy of Nasopharyngeal Cancer by TLD and Rando Phantom
Introduction: Nasopharyngeal carcinoma is one of the most common malignancies in the head and neck region and radiotherapy is its treatment of choice. In spite of the fact that it is widely used, due to the presence of many sensitive organs or tissues in this region, patients may suffer from a wide range of side effects. One such sensitive tissue is the spinal cord. If the absorbed dose to spin...
[ 18 ] - Monte Carlo Simulation of a Linear Accelerator and Electron Beam Parameters Used in Radiotherapy
Introduction: In recent decades, several Monte Carlo codes have been introduced for research and medical applications. These methods provide both accurate and detailed calculation of particle transport from linear accelerators. The main drawback of Monte Carlo techniques is the extremely long computing time that is required in order to obtain a dose distribution with good statistical accuracy. ...
[ 19 ] - Radiation Bystander Effects Mechanism
Introduction: Radiation Induced Bystander Effect (RIBE) which cause radiation effects in non-irradiated cells, has challenged the principle according to which radiation traversal through the nucleus of a cell is necessary for producing biological responses. What is the mechanism of this phenomenon? To have a better understanding of this rather ambiguous concept substantial number of original ...
[ 20 ] - Radiation Induced Bystander Effect
Introduction: Radiation effects observed in cells that are not irradiated are known as non-targeted effects. Radiation induced bystander effect (RIBE) as a kind of non-targeted effect has been introduced in recent years. RIBE occurs in unexposed cells which are related to adjacent or distant irradiated cells. RIBE contradict with "target theory" which necessitates radiation tr...
[ 21 ] - Assessment of Radiation Dose to the Lens of the Eye and Thyroid of Patients Undergoing Head and Neck Computed Tomography at Five Hospitals in Mashhad, Iran
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 i...
[ 22 ] - Evaluation of Dose Calculation Accuracy of Isogray Treatment Planning System in Craniospinal Radiotherapy
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...
[ 23 ] - Gonad, bone marrow and effective dose to the population of more than 90 towns and cities of Iran, arising from environmental gamma radiation
Background: Since 1996 the assessment of environmental gamma radiation dose in residential areas of Iranian towns and cities has been accomplished for 10 counties. As a practical method and based on the results of a pilot study, in order to attribute the final results to the whole residential area of a town five stations were selected for every town. The location of individual station wa...
[ 24 ] - Diagnostic Reference Levels for Computed Tomography Examinations in Iran: A Nationwide Radiation Dose Survey
Introduction: International Commission on Radiological Protection introduced three basic principles of radiation protection, namely justification, optimization, and dose limit. Medical exposure has no dose limits, and generally, diagnostic reference levels are used as a tool for optimization of patient protection. Material and Methods: Dosimetry was performed on 20 CT scanners located in 14 cit...
[ 25 ] - INF/IL-4 increases after the low doses of gamma radiation in BALB/c spleen lymphocytes
Introduction: The effects of the low dose of ionizing radiation are not thoroughly evident due to an unavoidable increase of occupational exposure and the widespread application of ionizing radiation in medical and industrial fields. The aim of this study was to investigate immune system responses following the low doses of ionizing radiation. Materia...
[ 26 ] - Use of Apoptotic Biomarkers to Predict Response to Radiotherapy in Breast Cancer Patients
Introduction: To enhance radiation therapy efficiency it is crucial 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: radiation-induced apoptosis in periphera...
[ 27 ] - Residual DNA double strand breaks correlates with excess acute toxicity from radiotherapy
Introduction: A high risk for development of severe side effects after radiotherapy may be correlated with high cellular radiosensitivity. To enhance radiation therapy efficiency a fast and reliable in-vitro test is desirable to identify radiosensitive patients. The aim of present study was to identify the mechanism of radiation induced DNA double-strand breaks (DSBs) and DSB r...
[ 28 ] - The role of dose fractionation in the level of Radiation- Induced Bystander Effect in QU-DB Cells
Introduction: Radiation effects induced in non-irradiated cells are termed radiation- induced bystander effects (RIBE). The present study intends to examine the RIBE response of QU-DB bystander cells to first, second and third radiation fractions and compare their cumulative outcome with an equal, single acute dose. Materials and Methods: This experimental ...
[ 29 ] - Absorbed dose of sensitive organs in maxillofacial region by different radiographic techniques: Panoramic, Waters, Caldwell and cone-beam computed tomography
BACKGROUND AND AIM: Due to increasing use of X-rays in diagnosis and treatment of diseases, this study aimed to measure and compares the absorbed dose in a number of sensitive organs of head and neck in different radiographic techniques.METHODS: Thermoluminescence dosimeter (TLD) and a male equivalent RANDO phantom were used to measure the absorbed dose in organs. The dosimeters were set in cer...
[ 30 ] - PHA stimulation may be useful for FDXR gene expression-based biodosimetry
Objective(s): Nowadays, ionizing radiation (IR) has a significant contribution to the diagnostic and therapeutic medicine, and following that, health risks to individuals through unexpected exposure is greatly increased. Therefore, biological and molecular technology for estimation of dose (biodosimetry) is taken into consideration. In biodosimetry methods stimulation ...
[ 31 ] - Assessment of Maximum Entrance Skin Dose of Patients Undergoing Cardiac Interventional Procedures and Its Correlation with Other Dosimetric Parameters
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. ...
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