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دکتر مهدی صادقی

  • Iman Azinkhah *, Mahdi Sadeghi
    Introduction
    Complexity metrics have been suggested to characterize treatment plans based on machine parameters such as multileaf collimator (MLC) position. Several complexity metrics have been proposed and related to the Intensity-modulated radiation therapy (IMRT) quality assurance results. This study aims to evaluate aperture-based complexity metrics on MLC openings used in clinicaland establish a correlation between plan complexity and the gamma passing rate (GPR) for the IMRT plans.
    Material and Methods
    We implemented the aperture-based complexity metric on MLC openings of the IMRT treatment plan for breast  and central nervous system (CNS) cases . The modulation complexity score (MCS), the edge area metric (EAM), the converted area metric (CAM), the circumference/area (CPA), and the ratio monitor unit MU/Gy are evaluated in this study. The complexity score was calculated using Matlab. The MatriXX Evolution was used for dose verification. The dose distribution was  analyzed using the OmniPro-I'mRT program  and the gamma index was assessed using two criteria: 3%/3 mm and 3%/2 mm. The correlation between the calculated complexity score and the GPR  is analyzed using SPSS.
    Results
    The complexity score calculated by MCS, EAM, CAM, CPA, and MU/Gy shows breast plan is more complex than the CNS plan. The results of the correlation test of the complexity metric and GPR show that only the EAM metric shows a good correlation with GPR for both cases.
    Conclusion
    EAM strongly correlates with the gamma pass rate. The MCS, CAM, CPA, and MU/Gy have a weak correlation with the GPR.
    Keywords: Image Processing, Magnetic Resonance, Medical Imaging
  • I. Azinkhah, M. Sadeghi*
    Background

    Evaluation of Size-Specific Dose Estimation (SSDE) by patient's weight and Body Mass Index (BMI) instead of Anterior-Posterior (AP) and Lateral (LAT) diameter measurements in patient's images for lung computed tomography (CT).

    Materials and Methods

    Before the examination, the weight and BMI of all patients were measured and calculated. All AP and LAT diameters were measured from the axial images, and localizer and conversion factors (fsize) were calculated based on them. Volume Computed Tomography Dose Index (CTDIvol) and Dose Length Product (DLP) values were also recorded from the patient's examination summary. In this way, different SSDEs based on effective diameter (SSDEeff), water equivalent diameter(SSDEw), AP diameter (SSDEAP), LAT diameter (SSDELAT), sum of the AP and LAT diameters (SSDEAP+LAT), AP diameter in scout view (SSDEAPscout) and LAT diameter in scout view (SSDELATscout) are obtained. By Pearson statistical test the correlation between patients' BMI and weight with all types of SSDE calculation methods was examined.

    Results

    There was a statistically significant correlation between all measured and compared parameters, but the most correlation between BMI and weight with SSDEs was obtained with SSDEeff (R=0.825, P<0.05) and SSDEw (R=0.777, P<0.05), respectively. Also, the correlation between BMI and effective diameter (deff) (R=0913, P<0.05) is the highest among all types of diameters measured. The correlation of BMI with SSDEw and water equivalent diameter (dw) was (R=0.807, P<0.05), (R=0.909, P<0.05), respectively.

    Conclusion

    There seems to be a significant correlation between BMI andf_size so that we can estimate patients' SSDE without measuring AP and LAT diameters, even before a CT scan.

    Keywords: Size-Specific Dose Estimate, CT Scan, Patient's BMI, Body Diameter
  • Houshyar Seyedi, Amir Nikjou, Alireza Goosheh, Parvin Sarabadani, Mahdi Sadeghi *
    Niobium-90 (90Nb), a radioisotope of paramount importance in the field of nuclear medicine, has been effectively synthesized and separated from target materials through natZr(p,n)90Nb and 90Zr(p,n)90Nb reactions. The attainment of high-purity Niobium -90 necessitates the use of exceptionally pure zirconium-90 isotopes, prompting the establishment of a meticulously structured three-stage production process. In the initial phase, the enrichment of 90Zr stable is achieved through Electromagnetic Isotope Separation (EMIS). The resulting enriched zirconium oxide target material undergoes rigorous validation through X-ray Diffraction (XRD) analysis, confirming isotopic and chemical purities quantified at 99.22% and 99.85%, respectively. These purities are ascertained through advanced techniques, including gamma spectrometry and Particle-Induced X-ray Emission (PIXE). The subsequent stage involves the irradiation of target materials, prepared from natZrO2 and 90ZrO2 powders, within the cyclotron accelerator. The third and final phase, post-irradiation, encompasses an elaborate chemical purification process, employing ion-exchange method. This process refines Niobium -90 from the target materials. The assessment of Niobium-90 activity purity, derived from both natural and enriched sources, confirms purities of 98.69% and 100%, respectively, through meticulous examination using a High Purity Germanium (HPGe) detector.
    Keywords: 90Nb, 90Zr, EMIS, Chemical purification, Ion Exchange
  • Iman Azinkhah, Mahdi Sadeghi, PeymanSheikhzadeh, MalakehMalekzadeh
    Background

    Simulation of tomographic imaging systems with fan‑beam geometry, estimation of scattered beam profile using Monte Carlo techniques, and scatter correction using estimated data have always been new challenges in the field of medical imaging. The most important aspect is to ensure the results of the simulation and the accuracy of the scatter correction. This study aims to simulate 128‑slice computed tomography (CT) scan using the Geant4 Application for Tomographic Emission (GATE) program, to assess the validity of this simulation and estimate the scatter profile. Finally, a quantitative comparison of the results is made from scatter correction.

    Methods

    In this study, 128‑slice CT scan devices with fan‑beam geometry along with two phantoms were simulated by GATE program. Two validation methods were performed to validate the simulation results. The data obtained from scatter estimation of the simulation was used in a projection‑based scatter correction technique, and the post-correction results were analyzed using four quantities, such as: pixel intensity, CT number inaccuracy, contrast‑to‑noise ratio (CNR), and signal‑to‑noise ratio (SNR).

    Results

    Both validation methods have confirmed the appropriate accuracy of the simulation. In the quantitative analysis of the results before and after the scatter correction, it should be said that the pixel intensity patterns were close to each other, and the accuracy of the CT scan number reached <10%. Moreover, CNR and SNR have increased by more than 30%–65% respectively in all studied areas.

    Conclusion

    The comparison of the results before and after scatter correction shows an improvement in CNR and SNR while a reduction in cupping artifact according to pixel intensity pattern and enhanced CT number accuracy

    Keywords: Correction, computed tomography, geant4 application for tomographic emission, scatter
  • Goli Khaleghi, Mohammad Hosntalab, Mahdi Sadeghi, Reza Reiazi, Seied Rabi Mahdavi
    Background

    This study evaluated the performances of neural networks in terms of denoizing metal artifacts in computed tomography (CT) images to improve diagnosis based on the CT images of patients.

    Methods

    First, head‑and‑neck phantoms were simulated (with and without dental implants), and CT images of the phantoms were captured. Six types of neural networks were evaluated for their abilities to reduce the number of metal artifacts. In addition, 40 CT patients’ images with head‑and‑neck cancer (with and without teeth artifacts) were captured, and mouth slides were segmented. Finally, simulated noisy and noise‑free patient images were generated to provide more input numbers (for training and validating the generative adversarial neural network [GAN]).

    Results

    Results showed that the proposed GAN network was successful in denoizing artifacts caused by dental implants, whereas more than 84% improvement was achieved for images with two dental implants after metal artifact reduction (MAR) in patient images.

    Conclusion

    The quality of images was affected by the positions and numbers of dental implants. The image quality metrics of all GANs were improved following MAR comparison with other networks.

    Keywords: Denoizing, head‑and‑neck cancer, metal artifacts, neural networks
  • Milad Payandeh, Mahdi Sadeghi *, Dylan Richeson, Somayeh Gholami
    It is important to have accurate information regarding the dose distribution for treatment planning and to accurately deposit that dose in the tissue surrounding the brachytherapy source. However, the practical measurement of dose distribution for various reasons is associated with several problems. In this study, 6711 I-125, Micro Selectron mHDR-v2r Ir-192, and Flexisource Co-60 sources were simulated using the MCNP5 Monte Carlo method. To simulate the sources, the exact geometric characteristics of each source, the material used in them, and the energy spectrum of each source were entered as input to the program, and finally, the dosimetric parameters including dose rate constant, radial dose function, and anisotropy function were calculated for considered seeds according to AAPM, TG-43 protocol recommendation. Results obtained for dosimetric parameters of dose rate constant, radial dose function, and anisotropy function for I-125, Ir-192, and Co-60 sources agreed with other studies. According to the good agreement obtained between the parameters of TG43 and other studies, now these datasets can be used as input in the treatment planning systems and to validate their calculations.
    Keywords: Brachytherapy, Dosimetric parameters, TG-43 protocol, Monte Carlo simulation, MCNP5 code
  • سید احمد صحافی پور، الهام سعید زاده*، سید پژمان شیرمردی، مهدی صادقی، سمانه برادران
    کسر جذبی ویژه یکی از پارامترهای مهم جهت تخمین دز داخلی می باشد. در این مقاله کسر جذبی ویژه تعدادی از ارگان های بدن با استفاده از فانتوم وکسلی زوبال محاسبه گردیده است. از کد مونت کارلوی GATE ورژن 7.2 برای شبیه سازش فوتون ها و الکترون های تک انرژی مربوط به رادیوایزوتوپ لوتشیوم-177 استفاده شده است. سه ارگان کلیه، کبد و طحال به عنوان ارگان چشمه در این شبیه سازی در نظر گرفته شده اند و کسر جذبی ویژه این ارگان های چشمه با مقادیر بدست آمده از داده های مطالعات قبلی مقایسه شده اند. در بیشتر داده ها، اختلاف قابل قبول می باشد و بیشترین مقدار درصد اختلاف نسبی نتایج این مطالعه و مطالعات قبلی، مربوط به فوتون با انرژی  keV71 و در حالتی که طحال و کبد به عنوان ارگانهای چشمه و هدف در نظر گرفته شده بودند، برابر با 41% بدست آمد. با استفاده از مقادیر SAF بدست آمده، فاکتور S[1] که برای محاسبات دزیمتری در روش MIRD مورد استفاده قرار می گیرد، محاسبه و ارایه گردید.
    کلید واژگان: کسر جذبی ویژه, فاکتور S, کد GATE, MIRD, دزیمتری داخلی, فانتوم زوبال
    Seyed Ahmad Sahafi-Pour, Elham Saeedzadeh *, Seyed Pejman Shirmardi, Mahdi Sadeghi, Samaneh Baradaran
    Specific absorbed fraction is one of the important parameters for estimating the internal dose. In this paper, the specific absorbed fraction for a number of body organs has been calculated using the Zubal Voxel phantom. The GATE Monte Carlo code version 7.2 was used to simulate the single-energy photons and electrons related to the radioactive isotope 177Lu. kidney, liver, and spleen were considered as source organs in this simulation and the specific absorbed fractions of these source organs were compared with the values ​​obtained from previous studies. The most relative difference between the values of this study and previous studies was observed to be 41% and related to the photons with the energy of 71 keV when the spleen and liver were considered as the source and target organs, respectively. In most data, discrepancies are acceptable and the obtained data are consistent with the previous data and have been verified. Using the data obtained from this study, the S-factors used for dosimetric calculations in the MIRD method were calculated and presented.
    Keywords: Specific absorption fraction, S factor, GATE Code, MIRD, Internal dosimetry, Zobal phantom
  • گلی خالقی، محمد حسن طلب، مهدی صادقی*، رضا ریاضی، سید ربیع مهدوی

    این پژوهش می تواند در پرتودرمانی بیماران مبتلا به انواع مختلف سرطان با پروتزهای فلزی به منظور افزایش کیفیت تصاویر سی تی اسکن برای تشخیص بهتر ناحیه درمان و کاهش دز دریافتی، صورت گیرد. در این پژوهش به منظور کاهش اثر سیگنال اشیا فلزی ایجاد شده در تصاویر سی تی اسکن ناحیه دهان، پارامترهای کیفیت تصاویر سی تی اسکن سر و گردن 20 بیمار مبتلا به سرطان سر و گردن دارای سیگنال اشیا فلزی بررسی شده و میزان بهبود کیفیت تصاویر بیماران با تصاویر پس از اصلاح سیگنال اشیا فلزی مقایسه شده است، هم چنین میزان دز دریافتی بیماران نیز بررسی شده است. بدین منظور تصاویر اصلاح شده ای به وسیله دو مدل شبکه عصبی ساخته شده تا عملکرد شبکه های عصبی به وسیله پارامترهای کیفیت تصاویر ارزیابی گردد تا شبکه عصبی مطلوب پیدا شود. در شبکه عصبی مولد تخاصمی، در برخی نقاط مانند غدد بزاقی و اطراف دندان دارای فلز تا %61/94 بهبود کیفیت تصویر صورت گرفته که در مقایسه با شبکه عصبی لایه به لایه تا حدود %36/72 عملکرد بهتری داشته است.

    کلید واژگان: سیگنال اشیا فلزی, شبکه های عصبی, دز ناحیه دهان, پرتودرمانی, سی تی اسکن, پارامترهای کیفیت تصاویر
    Goli Khaleghi, Mohammad Hosntalab, Mahdi Sadeghi*, Reza Reiazi, Seyed Rabie Mahdavi

    In this study, in order to reduce the effects of metal artifacts caused by metal objects in CT scan images of the mouth area, we investigated the quality parameters of head and neck CT scan images of patients before and after the presence of artifacts and evaluated the changes in quality image parameters to improve the quality of radiotherapy after modifying the images. For this purpose, first, we provided CT scan images of 20 patients with head and neck cancers with and without metal objects in the mouth area and compared the absorbed dose in patients with and without metal objects. Then, in order to prevent the destructive effects of images with artifacts in diagnosis and treatment process in radiotherapy, we created modified images by two different neural network models and evaluated the performance of neural networks by image quality parameters to find the effective neural network. By generative adversarial neural network, in some places around salivary glands and teeth with metal, up to 94% improvement has been achieved in image quality metrics, which is up to 70% better than the convolutional neural network. This study can be done to improve the quality of treatment in radiotherapy on patients with different types of cancer, especially with metal prostheses, in order to improve the quality of CT scan images for better diagnosis and contouring of the therapeutic area and reduce the dose received by patients through radiotherapy.

    Keywords: Metal artifacts, Neural networks, bucal area dose, Radiotherapy, CT Scan, Quality image metrics
  • FATEMEH SOLTANI, SIMINDOKHT SHIRVANI ARANI, MAHDI SADEGHI *, SAMIRA HEIDARI, ALI BAHRAMI SAMANI, KAMAL YAVARI
    The purpose of the present work was to introduce 141Ce-EDTMP as a novel potential future pain palliative agent to patients suffering from disseminated skeletal metastases and diagnostic imaging radioisotope as well. Cerium-141 [T1/2 = 32.501 days, Eβ (max) = 0.580 (29.8%) and 0.435(70.2%) MeV, Eγ = 145.44 (48.2%) keV] possesses radionuclidic properties suitable for use in palliative therapy of bone metastases. 141Ce also has gamma energy of 145.44 keV, which resembles that of 99mTc. Therefore, the energy window is adjustable on the Tc-99m energy because of imaging studies. 141Ce can be produced through a relatively easy route that involves thermal neutron bombardment on natural CeO2 in medium flux research reactors (4–5×1013 neutrons/cm2·s). The requirement for an enriched target does not arise. Ethylenediamine (tetramethylene phosphonic acid) (EDTMP) was synthesized and radiolabeled with 141Ce. The experimental parameters were optimized to achieve maximum yields (>99%). The radiochemical purity of 141Ce-EDTMP was evaluated by radio-thin layer chromatography. The stability of the prepared formulation was monitored for one week at room temperature, and results showed that the preparation was stable during this period (>99%). Biodistribution studies of the complexes carried out in wild-type rats exhibited significant bone uptake with rapid clearance from blood. The images showed high uptake of complex in bone after 72h and 2 weeks clearly. The percentage injected dose per gram of tissue (%ID/g) for each organ or tissue was calculated. The results show significant bone uptake with rapid clearance from blood. The properties of produced 141Ce-EDTMP suggest applying a new efficient bone pain palliative therapeutic agent to overcome metastatic bone pains.
    Keywords: Cerium-141, Bone pain palliative, EDTMP, Radiopharmaceutical, Biodistribution
  • FATEMEH SOLTANI, KAMAL YAVARI, MAHDI SADEGHI*, ALI BAHRAMI SAMANI, SIMINDOKHT SHIRVANI ARANI
    In recent years, nanotechnology has gained serious attention for diagnosis, prevention and treatment roles. In this study we synthesized nanoceria or CeO2NPs (cerium oxide nanoparticles) and compared toxicity of cerium oxide powder in nano and bulk forms in two cancerous and one normal cell lines. The cell lines were cultured in a standard humidified incubator, at 37 °C in a 5% CO2 atmosphere, in RPMI 1640 medium. The cells were incubated with different concentrations of cerium oxide (from 2 μg/mL to 64 μg/mL) in bulk and nano forms. To determine the effect of cerium oxide on cell viability after 24 h, 48 h, and 72 h incubation, a MTT assay was performed using SKBR3 (human breast cancer cell line), A431 (Human epidermoid carcinoma cell line) and C2Cl2 (ATCC mouse skeletal muscle cell line) cells. Analysis of variance followed by Sidak post-hoc test, shows the toxicity of nanoceria is significantly deferent from bulk form on three cell lines in this study and is more on cancerous cells in compared to normal cells especially in higher level of concentrations after 24, 48 and 72 hours (All P<0.05). Additionally, the effect of cell lines, cerium oxide forms and concentrations cerium oxide leads in significantly the lowest amount of viability after 72 hours compared with 24 hours and 48 hours.
    Keywords: Cerium oxide, Nanoceria, MTT assay, C2Cl2 cells, A431 cells, SKBR3 cells
فهرست مطالب این نویسنده: 10 عنوان
  • دکتر مهدی صادقی
    دکتر مهدی صادقی
نویسندگان همکار
  • دکتر علی بهرامی سامانی
    : 2
    دکتر علی بهرامی سامانی
    دانشیار پژوهشکده چرخه سوخت هسته ای، پژوهشگاه علوم و فنون هسته ای سازمان انرژی اتمی ایران، تهران، ایران
  • دکتر سید پژمان شیرمردی
    : 1
    دکتر سید پژمان شیرمردی
    دانشیار پژوهشکده کاربرد پرتوها، پژوهشگاه علوم و فنون هسته ای سازمان انرژی اتمی ایران، تهران، ایران
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