background: gold nanoparticles (gnps) have been shown as a good radiosensitizer. in combination with radiotherapy, several studies with orthovoltage x-rays have shown considerable dose enhancement effects. this paper reports the dose enhancement factor (def) due to gnps in 18 megavoltage (mv) beams. materials and methods: different geometrical 50-nm gnps configurations at a concentration of 5 m...

background: exposure conditions in ct examinations are quite different from conventional xray. in ct examination higher dose is given to patient in comparison with the dose in other diagnostic examinations. in order to calculate organ effective dose in chest ct, monte carlo simulation has been used in this study. materials and methods: the impact survey data were used to determine the parameter...

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background: two protocols of aapm tg-51 and iaea trs-398 were compared followed by a measurement and monte carlo simulation of beam quality correction factor, kq, aapm tg-51 and iaea trs-398 protocols were compared for the absorbed dose to water for dw, and kq parameters. materials and methods: dose measurements by either protocols were performed with cylindrical and plane parallel chambers for...

today according to the competitive conditions, companies try to reduce their inventory level to diminish the costs. in companies inventory management and control should establish a balance between inventory level of spare parts, cost and the risk that arising from absence of part when is needed. it is clear that this level of spare parts inventory affected by facility characteristics and its re...

Background: For an effective treatment planning in brachytherapy, it is necessary to know the accurate source dosimetric information such as air kerma strength, exposure rate constant, dose rate constant and redial dose distribution. The usual method to determine these factors is thermo luminescent dosimeter (TLD) dosimetry. Nowadays, another more accurate method is known to be the Monte Carlo ...

Introduction: Monte Carlo calculation method is considered to be the most accurate method for dose calculation in radiotherapy. The purpose of this research is comparison between 6 MV Primus LINAC simulation output with commissioning data using EGSnrc and build a Monte Carlo geometry of 6 MV Primus LINAC as realistically as possible. The BEAMnrc and DOSXYZnrc (EGSnrc package) M...

background: obtaining high quality images in single photon emission tomography (spect) device  is the most important goal in nuclear medicine. because if image quality is low, the possibility of making a mistake in diagnosing and treating the patient will rise. studying effective factors in spatial resolution of imaging systems is thus deemed to be vital. one of the most important factors in sp...

introduction: in single photon emission computed tomography (spect), the projection data used for image reconstruction are distorted by several factors, including attenuation and scattering of gamma rays, collimator structure, data acquisition method, organ motion, and washout of radiopharmaceuticals. all these make reconstruction of a quantitative spect image very difficult. simulation of a sp...

introduction use of hadron therapy as an advanced radiotherapy technique is increasing. in this method, secondary particles are produced through primary beam interactions with the beam-transport system and the patient’s body. in this study, monte carlo simulations were employed to determine the dose of produced secondary particles, particularly neutrons during treatment. materials and methods i...