Siemens Virtual Wedge factor may drift significantly due to increase in output as dose rate decreases. This variation of output is caused by defective sample and hold boards in the dosimetry circuit due to radiation damage. In this note, we present a simple model based on the principle of Virtual Wedge operation and the measured output variation with dose rate to quantitatively describe Virtual...

A practical and accurate generalized procedure to reconstruct the isocenter dose D(iso) for 3D conformal radiotherapy (3DCRT) has been developed for X-ray open beams supplied by linacs of different manufacturers and equipped with aSi electronic portal imaging devices (aSi EPIDs). This paper reports an extension of the method, to be applied at the wedged X-ray beams characterized by the wedge at...

We used the two available calculation algorithms of the Varian Eclipse 7.3 three-dimensional (3D) treatment planning system (TPS), the anisotropic analytic algorithm (AAA) and pencil-beam convolution (PBC), to compare measured and calculated two-dimensional enhanced dynamic wedge (2D EDW) dose distributions, plus implementation of the dynamic wedge into the TPS. Measurements were carried out fo...

OBJECTIVES The aim of this study was to examine whether asymmetric loading influences macrophage elastase (MMP12) expression in different parts of a rat tail intervertebral disc and growth plate and if MMP12 expression is correlated with the severity of the deformity. METHODS A wedge deformity between the ninth and tenth tail vertebrae was produced with an Ilizarov-type mini external fixator ...

The use of electromagnetic induction lamps without electrodes has increased because of their long life and energy efficiency. The control of the ignition and luminosity of the lamp is provided by an electronic ballast. Beyond that, the electronic ballast also provides a power factor correction, allowing the minimizing of the lamps impact on the quality of service of the electrical network. The ...

Abstract Multilayer gradient absorbing materials are difficult to be modeled and simulated in practical applications. To solve this problem, a method of the inversion equivalent electromagnetic parameters multilayer based on annealing algorithm is proposed paper. The reflectivity material different forms polarization obliquely incident at angles calculated, then used calculate incidence angle s...

The MM50 Racetrack Microtron, suited for advanced three-dimensional conformal radiotherapy techniques, is a complex machine in various respects. Therefore, for a number of gantry angles, daily quality control of the absolute output and fluence profiles of the scanned beams are mandatory. For the applied photon beams, a fast method for these daily checks, based on dosimetric measurements with th...

Purpose: This study was to investigate the effect of irregularity in shape of field size of electron beam on the percentage depth dose and the output factor. Study the variety of the Percentage Depth Dose (PDD) and the output factors for rectangular and small field sizes when one of field dimensions less than the Practical Range (Rp) of the electron energy used. Compare the measured output fact...

background: the dosimetric performance of eclipse 6.5 three dimensional treatment planning system (3dtps) is evaluated by comparing the calculated and measured dose in two dimensions following the guide lines of american association for physicists in medicine task group 53. materials and methods: the calculations were performed by the 3dtps for symmetric as well as asymmetric fields for standar...