Mahdi Momennezhad
Nuclear Medicine 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 ] - Evaluation of Personal Shields Used in Selected Radiology Departments
Introduction The purpose of this study was to evaluate personal shields in radiation departments of hospitals affiliated to Mashhad University of Medical Sciences. Materials and Methods First, the information related to 109 personal shields was recorded and evaluated by imaging equipment. Afterwards, the equivalent lead thickness (ELT) of 62 personal shields was assessed, using dosimeter and st...
[ 3 ] - Calculations of Linac Photon Dose Distributions in Homogeneous Phantom Using Spline
Introduction Relative dose computation is a necessary step in radiation treatment planning. Therefore, finding an approach that is both fast and accurate seems to be necessary. The purpose of this work was to investigate the feasibility of natural cubic spline to reconstruct dose maps for linear accelerator radiation treatment fields in comparison with those of the simulation. Materials and Met...
[ 4 ] - Evaluation of the Portal Imaging System Performance for an Elekta Precise Linac in Radiotherapy
Introduction: Electronic portal imaging devices (EPIDs) provide two- and three-dimensional planar and volumetric cone beam images to improve the accuracy of radiation treatment delivery. Periodic quality assurance (QA) of EPIDs is essential for dosimetric verification in radiotherapy. In this study, a QA program was implemented to evaluate the function of the EPID to be confident in applying co...
[ 5 ] - تأثیر کاهش اثر ساختگی فلز در برآورد توزیع دوز توسط نرم افزار طراحی درمان ISOgray
هدف: در بدن برخی از بیماران مبتلا به سرطان و تحت درمان با اشعه، اجسام خارجی فلزی وجود دارند که عدد اتمی آن ها تفاوت زیادی با عدد اتمی بافت های بدن دارد. این امر موجب ایجاد آرتیفکت در تصاویر، اختلاف زیاد در اعداد سی تی و خطا در محاسبات می شود. این مطالعه جهت بررسی تاثیر اصلاح آرتیفکت فلز بر تصاویر و مقایسه میزان دوز محاسباتی توسط سیستم طراحی درمان ISOgray با دوز اندازه گیری شده انجام گرفته ا...
[ 6 ] - Quality assessment of conventional X-ray diagnostic equipment by measuring X-ray exposure and tube output parameters in Great Khorasan Province, Iran
Introduction: Regular implementation of quality control (QC) program in diagnostic X-ray facilities may affect both image quality and patient radiation dose due to the changes in exposure parameters. Therefore, this study aimed to investigate the status of randomly selected conventional radiographic X-ray devices installed in radiology centers of Great Khorasan Province, Iran, to produce the da...
[ 7 ] - Dosimetric comparison of conventional and field-in-field techniques in early stage breast cancer radiotherapy
Introduction: Breast conserving surgery followed by adjuvant radiotherapy (RT) of the whole breast is accepted as the treatment of choice in early stage breast cancer. Due to breast irregularities, it is difficult to access homogenous dose distribution with conventional techniques. Currently, it is possible to use varied breast irradiation techniques, such as field- in-field (F...
[ 8 ] - An Empirical Transmitted EPID Dosimetry Method using a Back-Projection Algorithm
Background: The present study aimed to introduce a rapid transmission dosimetry through an electronic portal-imaging device (EPID) to achieve two-dimensional (2D) dose distribution for homogenous environments. Material and Methods: In this Phantom study, first, the EPID calibration curve and correction coefficients for field size were obtained from EPID and ionization chamber. Second, the...
[ 9 ] - Evaluation of Breast Cancer Radiation Therapy Techniques in Outfield Organs of Rando Phantom with Thermoluminescence Dosimeter
Background: Given the importance of scattered and low doses in secondary cancer caused by radiation treatment, the point dose of critical organs, which were not subjected to radiation treatment in breast cancer radiotherapy, was measured.Objective: The purpose of this study is to evaluate the peripheral dose in two techniques of breast cancer radiotherapy with two energies. Methods: Eight diff...
[ 10 ] - An Update of Couch Effect on the Attenuation of Megavoltage Radiotherapy Beam and the Variation of Absorbed Dose in the Build-up Region
Purpose: Fiber carbon is the most common material used in treating couch as it causes less beam attenuation than other materials. Beam attenuation replaces build-up region, reduces skin-sparing effect and causes target volume under dosage. In this study, we aimed to evaluate beam attenuation and variation of build-up region in 550 TxT radiotherapy couch.Materials and Methods: In this study, we ...
[ 11 ] - Utilization of Electronic Portal Imaging Device (EPID) For Setup Verification and Determination of Setup Margin in Head and Neck Radiation Therapy
Introduction: Radiation therapy involves a multistep procedure; therefore, the error in patient set up is an inherent part of the treatment. Main purpose of this study was to determine the clinical target volume (CTV) to planning target volume (PTV) in head and neck cancer patients. Material and Methods: A total of 15 patients who had daily p...
[ 12 ] - Contribution of 68Ga-PSMA PET/CT to targeting volume delineation of prostate cancer treated with conformal radiation therapy: Which SUV threshold is appropriate?
Introduction: Prostate-specific membrane antigen (PSMA) has been demonstrated as a promising tool for specific imaging of prostate cancer (PCa) via positron emission tomography-computed tomography (PET/CT) scanning. Radiation treatment planning (RTP) based on 68Ga-PSMA PET/CT scanning can also lead to some decision modifications. The specific goal o...
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