introduction: in diagnostic and therapeutic procedures, dosimetric studies are performed on the dosimetric systems in order to comply the radiation safety standards. monte carlo methods are used due to the high complexity and cost of patient-specific phantom construction. the high complexity of the digitized phantoms greatly increases the time and computational task of the monte carlo calculati...

Background: High-energy linear accelerator (linac) is a valuable tool and the most commonly device for external beam radiation treatments in cancer patients. In the linac head, high-energy photons with energies above the threshold of interaction produce photoneutrons. These photoneutrons deliver the extra dose to the patients in the planning treatment and increase the risk of secondary cancer.O...

We describe a method aiming at increasing the dynamic range of X-ray detectors. Two X-ray exposures of an object are acquired at different dose levels and constitute the only input data. The values of the parameters which are needed to process these images are determined from information contained in the images themselves; the values of two parameters are extracted from the input data. The two ...

In present study, a mathematical model of the vehicle–floating slab track (FST) interaction is established to investigate the coupled behaviour of vehicle–track system. The FST is modelled as the double Euler -Bernoulli beam including the rail and slab. The railway vehicle is simplified as a multi-rigid-body model. The wheel–rail interface is treated using a nonlinear Hertzian contact model, co...

The effect of gantry rotation on beam profiles of photon and electron beams is an important issue in quality assurance for radiotherapy. To address variations in the profiles of photon and electron beams at different gantry angles, a Dynamic Phantom scanner composed of a 20 x 12 x 6 cm3 scanning Lucite block was designed as a cross-beam-profile scanner. To our knowledge, differences between sca...

background: the advantages of proton beam in radiation therapy- like small lateral scattering as well as absence of exit dose tail in the organs which are after the tumor- make it capable of delivering more treatment doses to the target and much lesser to the critical tissues near it. materials and methods: in this study, the monte carlo mcnpx code has been used to simulate a slab head phantom ...

INTRODUCTION Dynamic image acquisition protocols are increasingly used in emission tomography for drug development and clinical research. As such, there is a need for computational phantoms to accurately describe both the spatial and temporal distribution of radiotracers, also accounting for periodic and non-periodic physiological processes occurring during data acquisition. METHODS A new 5D ...

In respect of imaging quality and patient safety, temperature rises and SAR distributions, which are caused by interaction of the applied electromagnetic fields during MR exams, are of high interest for implants in MR tomography [1]. High local SAR values are equivalent to high local temperature increases [2]. For developing support for radio frequency (RF) induced heating experiments, SAR valu...