نتایج جستجو برای: Wedge
تعداد نتایج: 11897 فیلتر نتایج به سال:
background: in radiotherapy, wedge filters are used for optimizing the tumor dose distribution in patients. the attenuation in beam intensity due to the presence of wedge filter is compensated by means of a wedge factor measured at the central axis of the beam. the field size, depth and ssd dependence of wedge factor have been assessed for 9mv radiations of neptun pc linear accelerator. materia...
Objective Osteoarthritis is a degenerative disease of joints that causes degeneration and corrosion of joint surface. Because of osteoarthritis, the smooth and even movemvement of joints get interrupted. Osteoarthritis is the most common kind of arthritis and its prevalence is 19.3% in Iran. Patients with knee osteoarthritis usually have geno varum and hyperpronation of foot. The...
background: the presence of a wedge filter in the beam trajectory can modify the beam quality and cause some changes in the dosimetry parameters which are usually difficult to be measured directly and accurately. material and methods: in this study the mcnp-4c monte carlo code was used to simulate the 9 mv photon beam generated by a linear accelerator. upon getting a good agreement between the ...
introduction: nowadays, considerable developments in the field of radiotherapy have been achieved. they include the advances made in the equipments and treatment planning techniques which require highly complex calculations. such achievements have made it possible to treat cancer patients not only with higher radiation dose but also with higher precision and con...
Introduction: Wedge filters are commonly used in radiation oncology for eliminating hot spots and creating a uniform dose distribution in optimizing isodose curves in the target volume for clinical aspects. These are some limited standard physical wedges (15°, 30°, 45°, 60°), or creating an arbitrary wedge angle, like motorized wedge or dynamic wedge, ... The new formulation is...
background: in radiation therapy, the peripheral dose is important when anatomical structures with very low dose tolerances are involved. in this study, the two available calculation algorithms of the varian eclipse 8.6 treatment planning system(tps), the anisotropic analytic algorithm (aaa) and pencil-beam convolution (pbc) was used to compare measured and calculated peripheral dose distributi...
Introduction: Wedge filters are used in radiotherapy to modify photon beam and improve dose uniformity in the target volume. Determination of wedge dose distribution is important to improve treatment planning accuracy. The utilization of treatment planning software to obtain dose distribution is not always available. In this work an analytical model has been developed to calcu...
Introduction: Nowadays, considerable developments in the field of radiotherapy have been achieved. They include the advances made in the equipments and treatment planning techniques which require highly complex calculations. Such achievements have made it possible to treat cancer patients not only with higher radiation dose but also with higher precision and con...
introduction wedge modifiers are commonly applied in external beam radiotherapy to change the dose distribution corresponding to the body contour and to obtain a uniform dose distribution within the target volume. since the radiation dose delivered to the target must be within ±5% of the prescribed dose, accurate dose calculation by a treatment planning system (tps) is important. the objective ...
we describe a simple model that fits well with iranian economy, and extends a methodology which chary at el. (2007) demonstrated. in addition to four traditional wedges, we introduce additional trade wedge. we then evaluate the contribution of these wedges to the fluctuations in iran during last three years. because of international sanction, trading cost increases, and firms have difficulty to...
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