نتایج جستجو برای: dose volume constraints
تعداد نتایج: 787080 فیلتر نتایج به سال:
The Radiotherapy treatment planning optimization process based on a quasi-Newton algorithm with an object function containing dose-volume constraints is not guaranteed to converge when the dose value in the dose-volume constraint is a critical value of the dose distribution. This is caused by finite differentiability of the dose-volume histogram at such values. A closer look near such values re...
Introduction: Intensity Modulated Radiation Therapy (IMRT) planning dose calculation process depends on IMRT dose constraints. So, if there was any structure along the treatment beam path not delineated, it would not be taken into account during that calculation process. During IMRT routine practical work, it is noticed that there are some non-delineated normal tissue volumes that received un-a...
PURPOSE To evaluate the performance of a model-based optimisation process for volumetric modulated arc therapy, VMAT, applied to whole breast irradiation. METHODS AND MATERIALS A set of 150 VMAT dose plans with simultaneous integrated boost were selected to train a model for the prediction of dose-volume constraints. The dosimetric validation was done on different groups of patients from thre...
This paper presents a hybrid approach for developing radiation plans for high dose rate brachytherapy in cancer treatment. In order to take care of the computationally hard dose volume constraints, linear programming (LP) is alternated with heuristic neighborhood search which allows for a quick generation of multiple feasible treatment plans. The simulated annealing neighborhood search is guide...
LEO orbit space radiations in which the protons has the main contribution, have survived devastating effects on electronic components. The damage caused by ionizing protons on the satellite electrical components in the circuit LEO moves was reviewed. By studying the LEO orbit by Shieldose software, the worst-case scenario was evaluated for a satellite. Considering the electronic components base...
BACKGROUND To compare the differences in dose-volume data among coplanar intensity modulated radiotherapy (IMRT), noncoplanar IMRT, and helical tomotherapy (HT) among patients with hepatocellular carcinoma (HCC) and portal vein thrombosis (PVT). METHODS Nine patients with unresectable HCC and PVT underwent step and shoot coplanar IMRT with intent to deliver 46-54 Gy to the tumor and portal ve...
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