نتایج جستجو برای: absolute dose
تعداد نتایج: 394859 فیلتر نتایج به سال:
BACKGROUND AND PURPOSE The QA of intensity modulated radiotherapy (IMRT) dosimetry is a laborious task. The goal of this work is to evaluate the dosimetric characteristics of a new 2D diode array (MapCheck from Sun Nuclear Corporation, Melbourne, Florida) and assess the role it can play in routine IMRT QA. MATERIAL AND METHODS Fundamental properties of the MapCheck such as reproducibility, li...
PURPOSE In 2008, a national intensity modulated radiation therapy (IMRT) dosimetry intercomparison was carried out for all 23 radiation oncology institutions in Switzerland. It was the aim to check the treatment chain focused on the planning, dose calculation, and irradiation process. METHODS A thorax phantom with inhomogeneities was used, in which thermoluminescence dosimeter (TLD) and ioniz...
خطرات پره اکلامپسی و متعاقب آن اکلامپسی به خوبی مشخص می باشد. آسپرین low-dose با کاهش انتخابی ترومبوکسان a2 سبب غلبه پروستاسیکلین شده و به این طریق از پره اکلامپسی و عوارض آن جلوگیری می نماید. در این مطالعه 150 خانم حامله در معرض پره اکلامپسی به طور رندوم به دو گروه دریافت کننده آسپرین (60 نفر) و دریافت کننده آسپرین (90 نفر) تقسیم شدند. پراکلامپسی فقط در 2 نفر از گروه آسپرینی دیده شد(3/3
Intensity-modulated radiotherapy treatment demands stringent quality assurance and accurate dose determination for delivery of highly conformal dose to the patients. Generally 3D dose distributions obtained from a treatment planning system have to be verified by dosimetric methods. Mainly, a comparison of two-dimensional calculated and measured data in several coplanar planes is performed. In p...
The purpose of this study was to develop dosimetry verification procedures for volumetric-modulated arc therapy (VMAT)-based total marrow irradiation (TMI). The VMAT based TMI plans were generated for three patients: one child and two adults. The planning target volume (PTV) was defined as bony skeleton, from head to mid-femur, with a 3 mm margin. The plan strategy similar to published studies ...
Linacs equipped with flattening filter-free (FFF) megavoltage photon beams are now commercially available. However, the commissioning of FFF beams poses challenges that are not shared with traditional flattened megavoltage X-ray beams. The planning system must model a beam that is peaked in the center and has an energy spectrum that is softer than the flattened beam. Removing the flattening fil...
AIMS The objective of this study was to measure to secretion of the selective serotonin uptake inhibitor citalopram in breast milk. METHODS The excretion of citalopram in breast milk was studied at steady-state conditions in two patients with depression and in one healthy volunteer after ingestion of a single dose citalopram. RESULTS Milk/serum concentration ratios based on single pairs of ...
A method of reconstructing three-dimensional, in vivo dose distributions delivered by intensity-modulated radiotherapy (IMRT) is presented. A proof-of-principle experiment is described where an inverse-planned IMRT treatment is delivered to an anthropomorphic phantom. The exact position of the phantom at the time of treatment is measured by acquiring megavoltage CT data with the treatment beam ...
IMRT plans are usually verified by phantom measurements: dose distributions are measured using film and the absolute dose using an ionization chamber. The measured and calculated doses are compared and planned MUs are modified if necessary. To achieve a conformal dose distribution, IMRT fields are composed of small subfields, or "beamlets." The size of beamlets is on the order of 1 x 1 cm2. The...
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