نتایج جستجو برای: modulated
تعداد نتایج: 60877 فیلتر نتایج به سال:
introduction intensity modulated radiation therapy (imrt) has made a significant progress in radiation therapy centers in recent years. in this method, each radiation beam is divided into many subfields that create a field with a modulated intensity. considering the complexity of this method, the quality control for imrt is a topic of interest for researchers. this article is about the various ...
background and aim: this study investigated whether objective temporal processing paradigms including voice-onset-time, speech-in-noise, and amplitude modulated-broad-band noise (am-bbn) are sensitive to disrupted temporal processing in elderly listeners with normal hearing (age-related-temporal processing deficit). methods: we evaluated 15 adults aged 64–80 years using behavioural measures of ...
مقدمه: این مطالعه، با هدف تعیین دز جذبی هیپوکامپ در پرتودرمانی گلیومای مغزی با درجه ی بالا با استفاده از روش نقاشی دز و مقایسه ی آن با روش های پرتودرمانی تطبیقی سه بعدی و پرتودرمانی با شدت تعدیل شده (intensity-modulated radiation therapy یا imrt) انجام شد. روش ها: مطالعه ی حاضر در بخش پرتودرمانی بیمارستان میلاد اصفهان انجام شد. تصاویر magnetic resonance imaging (mri) 24 بیمار مبتلا به تومور گلی...
The first purpose of this paper is to shed some new light on the old question of selecting the number of beams in intensity-modulated radiation therapy (IMRT). The second purpose is to illuminate the related issue of discrete static beam angles versus rotational techniques, which has recently re-surfaced due to the advancement of volumetric modulated arc therapy (VMAT). A specific objective is ...
Volumetric modulated arc therapy (VMAT) has found widespread clinical application in recent years. A large number of treatment planning studies have evaluated the potential for VMAT for different disease sites based on the currently available commercial implementations of VMAT planning. In contrast, literature on the underlying mathematical optimization methods used in treatment planning is sca...
Weak microwave radiation (WMR) in our environment has raised health concerns in the public. Among those, communication frequencies are more than ever becoming widespread and their effects need thorough studies. A correct understanding of these effects in-vivo by in-vitro experiments shall preferentially use primary cells. In this study we compared non-modulated (CW) and modulated WMR exposure o...
The generation of coherent Terahertz (THz) radiation is studied which is produced from moving the relativistic electron beam through a helical wiggler with axial magnetic field. The relativistic electron beam is modulated via interacts with the beat wave of two laser beams that have frequency difference in THz range. When the modulated relativistic beam of electrons go through the helical wiggl...
مقدمه: در این مطالعه، مقایسه ای بین دز جذبی پاروتید و بافت حساس اطراف آن در انواع طراحی درمان های مختلف جهت دستیابی به تکنیک بهینه ی درمان انجام گردید. دز جذبی اعضای مختلف با استفاده از نرم افزار طراحی درمان اندازه گیری شد. روش ها: طراحی و انجام کانتورینگ بر روی اسکن 15 بیمار، با استفاده از نرم افزار tigrt صورت گرفت. 6 تکنیک مقایسه شدند. در نهایت، با مقایسه ی میانگین دز رسیده به هر عضو با استفا...
In this study a novel, user-independent automated planning technique was developed to objectively compare volumetric modulated arc therapy (VMAT) and intensity-modulated radiotherapy (IMRT) for nasopharyngeal carcinoma planning, and to determine which technique offers a greater benefit for parotid-sparing and dose escalation strategies. Ten patients were investigated, with a standard prescripti...
We study the treatment plan optimization problem for volumetric modulated arc therapy (VMAT). We propose a new column-generation-based algorithm that takes into account bounds on the gantry speed and dose rate, as well as an upper bound on the rate of change of the gantry speed, in addition to MLC constraints. The algorithm iteratively adds one aperture at each control point along the treatment...
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