در هنگام جستجو کلمه در قسمت عنوان میتوانید کلمات مورد جستجو را با کاراکتر (-) جدا کنید.
کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Nanomedicine Journal
- نوع مقاله: Journal Article
- کلمات کلیدی: Nanoparticles,Nanocomposite,Nuclear Medicine,radiation shielding
- چکیده:
- چکیده انگلیسی: Objective(s): The present study aimed to design new nanoparticle-based shielding materials for photons used in single-photon emission computed tomography and positron emission tomography facilities.
Materials and Methods: Initially, the mass attenuation coefficients and half value layer (HVL) of the composites were comprehensively investigated based on a silicon rubber containing various ratios of micro- and nano-barium sulfate (BaSO4), lead oxide (PbO), and tungsten oxide (WO3) particles at 60, 80, 100, 150, 200, 300, 400, 500, and 600 keV photon energies using the MCNP-X6 Monte Carlo (MC) code and WinXCOM software. In the second stage, the composites composed of 10 wt% and 20 wt% WO3 and PbO particles were constructed in a liquid silicone rubber-based matrix. The mass attenuation coefficients and HVL of the designed shields were experimentally assessed using Cs-137 and Am-241 radioactive sources.
Results: The particles sizes of PbO and WO3 were within the range of 50-200 nanometers. The MC and measurement results indicated that the linear attenuation coefficients of the composites were augmented with the addition of all the studied nano- and micro-particles. However, the PbO composites had more significant shielding properties compared to the BaSO4 and WO3 composites.
Conclusion: According to the results, the nanocomposites had better ability to shield γ-rays at both energies compared to the micro-composites.- انتشار مقاله: 19-03-1399
- نویسندگان: Reza Malekzadeh,Vahid Sadeghi Zali,Okhtay Jahanbakhsh,Murat Okutan,Asghar Mesbahi
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Medical Physics
- نوع مقاله: Journal Article
- کلمات کلیدی: modeling,Radiation Therapy,Complications,Acute Esophagitis,Concurrent Chemotherapy
- چکیده:
- چکیده انگلیسی: Introduction: The current study aimed to compare the performance of radiobiological models in predicting acute esophagitis (AE) complications after three-dimensional conformal radiation therapy (3D-CRT).
Material and Methods: Out of a total of 100 patients, 50 patients with concurrent chemotherapy and 50 patients without such therapy were treated with different total doses and a daily dose range of 1.8-2.4 Gy on the basis of 5 days a week for 3 months. Predictions of AE were based on Lyman–Kutcher–Burman (LKB) and equivalent uniform dose (EUD)-based radiobiological models. Consequently, 3 months of follow-upwere performed to monitor the complication incidence among the studied patients. Receiver operating characteristic (ROC) and univariable logistic regression analyses were carried out to determine the effect of mean dose, volume percentage, and weight loss percentage on the probability of AE grade ³ 2.
Results: The EUD-basedmodel showed a better concordance with the clinical data for all patients (area under the curve [AUC]=0.919) and the concurrent chemoradiotherapy (CCRT) group (AUC=0.986). For the radiation therapy group, the LKB model had a better performance than the EUD-based model (AUC=0.921). Grade ³ 2 esophagitis occurred 37.94±4.0 and 68.39±7.1 days after the initiation of radiation therapy in the chemoradiation and radiation therapy groups, respectively.
Conclusion: The EUD-basedmodel showed a higher agreement with the follow-up data. The incidence time of grade ³ 2 AE in the CCRT was approximately two times shorter than that in the non-CCRT group.- انتشار مقاله: 30-02-1398
- نویسندگان: Mostafa Alizade-harakiyan,Amir Ghasemi Jangjoo,Behnam Nasiri,Tohid Jafari-Koshki,Murat Okutan,Asghar Mesbahi
- مشاهده