نتایج جستجو برای: inverse monte carlo
تعداد نتایج: 161249 فیلتر نتایج به سال:
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...
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...
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...
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 ...
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...
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...
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