نتایج جستجو برای: carlo

تعداد نتایج: 70255  

Journal: :Nuclear Physics B - Proceedings Supplements 2001

Background and purpose: Radiation therapy make an important contribution in the control and treatment of cancers. Lungs are the main organs at risk in esophageal cancer radiotherapy. Difference between the dose distribution due to the treatment planning system (TPS) and the patient's body dose is dependent on the calculation of the treatment planning system algorithm, which is more pronounced i...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه صنعتی امیرکبیر(پلی تکنیک تهران) - دانشکده ریاضی و کامپیوتر 1386

در این پایان نامه به بخش بندی تصاویر چندطیفی پرداخته می شود. برای این منظور روش جدیدی با عنوان مدل بر پایه مدل درختی معرفی می شود. این روش بر پایه خوشه بندی با استفاده از مدل های آمیخته متناهی و براورد پارامترها با استفاده از بیشینه کردن تابع درستنمایی و حل آن با الگوریتم em می باشد. تعیین تعداد خوشه ها بوسیله معیار انتخاب بیز که توسط bic تخمین زده می شود معیین می گردد. وابستگی مکانی پیکسل ه...

Journal: :journal of medical signals and sensors 0
daryoush shahbazi-gahrouei saba ayat

introduction: radioiodine therapy is an effective method for treating thyroid cancer carcinoma, but it has some affects on normal tissues, hence dosimetry of vital organs are important to weigh the risks and benefits of this method. the aim of this study is to measure the absorbed doses of important organs by mcnp (monte carlo n particle) simulation and comparing the results of different method...

Journal: :cell journal 0

objective: the passage of ionizing radiation in living cells creates clusters of damaged nucleotides in dna. in this study, dna strand breaks induced by the beta particle of iodine-131 (i-131), have been determined experimentally and compared to monte carlo simulation results as a theoretical method of determining131i damage. materials and methods: in this experimental study, in order to create...

Journal: :iranian journal of radiation research 0
m.b. tavakoli department of medical physics and medical engineering, school of medicine, isfahan university of medical sciences, isfahan, iran d. shahbazi-gahrouei department of medical physics and medical engineering, school of medicine, isfahan university of medical sciences, isfahan, iran m. hosseinpour department of medical physics and medical engineering, school of medicine, isfahan university of medical sciences, isfahan, iran

background: for an effective treatment planning in brachytherapy, it is necessary to know the accurate source dosimetric information such as air kerma strength, exposure rate constant, dose rate constant and redial dose distribution. the usual method to determine these factors is thermo luminescent dosimeter (tld) dosimetry. nowadays, another more accurate method is known to be the monte carlo ...

Journal: :iranian journal of medical physics 0
mehdi zehtabian ray medical engineering department, school of mechanical engineering, shiraz university, shiraz iran elham piruzan ray medical engineering department, school of mechanical engineering, shiraz university, shiraz iran zahra molaiemanesh ray medical engineering department, school of mechanical engineering, shiraz university, shiraz iran

introduction lead-based shields are the most widely used attenuators in x-ray and gamma ray fields. the heavy weight, toxicity and corrosion of lead have led researchers towards the development of non-lead shields. materials and methods the purpose of this study was to design multi-layered shields for protection against x-rays and gamma rays in diagnostic radiology and nuclear medicine. in this...

Journal: :iranian journal of medical physics 0
banafsheh zeinali rafsanjani m.sc. of nuclear engineering, medical radiation trends, faculty of mechanical engineering, shiraz university, shiraz, iran. reza faghihi assistant professor of medical radiation, radiation research center, faculty of mechanical engineering, shiraz university, shiraz, iran.

introduction: among different kinds of oral cavity cancers, the frequency of tongue cancer occurrence is more significant. brachytherapy is the most common method to cure tongue cancers. long sources are used in different techniques of tongue brachytherapy. the objective of this study is to asses the dose distribution around long sources, comparing different radioisotopes as brachytherapy sourc...

Journal: :iranian journal of medical physics 0
zahra anjomani m.sc. in medical physics, nuclear engineering dept., shahid beheshti university, tehran, iran hasan nedaie assistant professor, radiotherapy physics dept., tehran university of medical science, tehran, iran majid shariari associate professor, nuclear engineering dept, shahid beheshti university, tehran, iran

introduction: nowadays new radiochromic films have an essential role in radiotherapy dosimetry. properties such as high sensitivity, good reproducibility, high spatial resolution, easy readout and portability have made them attractive for dosimetry, especially in high-dose-gradient regions. material and methods: in this study, electron-beam dose distributions in homogenous and heterogeneous pha...

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