Papers by Hamid-Reza Sadoughi
Background & Objectives:The human living environment has some extent of ionizing radiation that d... more Background & Objectives:The human living environment has some extent of ionizing radiation that depends on the latitude and altitude of the region. Identifying the amount of this radiation can determine the suitable healthy living environment. In this study, for the first time, the outdoor radiation dose rate in the city of Bojnurd (North Khorasan Province, center latitude and longitude 27.37 and 2.57 degrees and elevation 1070 m above sea level), has been measured by survey meter. Materials and methods:In order to determine the amount of outdoor gamma radiation dose rate, in Bojnurd, a survey meter was used. Measurements for 30 points and four seasons of the year were done. Detector was placed on tripods and at a height of 1 m from the surface of the earth and each time, the dose rate was read at the desired location for 50 minutes. Results:Absorbed dose rate in different parts of the city and for the seasons of spring 133.5 nGy/h, summer 140.0 nGy/h, autumn 135.2 nGy/h and winter ...
Journal of experimental therapeutics & oncology, 2014
This study aimed to determine the efficacy of thermotherapy resulting from the presence of gold-g... more This study aimed to determine the efficacy of thermotherapy resulting from the presence of gold-gold sulfide nanoshells (GGS) in radio frequency electromagnetic field (13.56 MHz) onthe survival of CT26 colon carcinoma cells. GGS was synthesized and after characterizing and determining the features, the RF-radiation effects on aquatic environments were determined by recording temperature changes. To investigate the biological effects, cell survival rate due to GGS usage at five different concentrations, each one with applying three different exposure times of RF field, at CT26 cells were evaluated by MTT assay. In the presence of 100 mg/L GGS and 5 min RF exposure, increasing in temperature was recorded more than 60°C. A significant difference in cell survival rate was observed, when both GGS and RF field were applied with each other or separately (p<0.001). The GGS concentration of 25mg/L with a 4 min exposure causes cell death with the efficiency of 80 percent more than using th...
2007 29th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 2007
The user has requested enhancement of the downloaded file. All in-text references underlined in b... more The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately. Abstract -In this paper, a new piecewise modeling for approximation of ECG signal is presented. Most of the modeling methods are focused to obtain the best approximation of the entire ECG signal. The proposed method exploits the importance of different intervals of ECG signals, in particular QRS complex, by performing a segmented based modeling using Hermitian basis functions. This yields to weighting the approximation error of each segment based on its importance throughout the ECG complex. As the result shows the total error obtained in this method is almost halved in comparison with similar non-segmented method. This has a great impact in modeling the heart arrhythmias where a small error could mislead the diagnosis. The presented method uses only the 5 th order Hermitian basis functions which considerably reduce the total parameters needed to represent the ECG signal in comparison with other Hermitian based methods.
Relative dose computation is a necessary step in radiation treatment planning. Therefore, finding... more Relative dose computation is a necessary step in radiation treatment planning. Therefore, finding an approach that is both fast and accurate seems to be necessary. The purpose of this work was to investigate the feasibility of natural cubic spline to reconstruct dose maps for linear accelerator radiation treatment fields in comparison with those of the simulation.
Introduction Using ionization radiation for diagnostic and treatment fields has increased worldwi... more Introduction Using ionization radiation for diagnostic and treatment fields has increased worldwide dramatically. This issue causes an increase in the absorbed and collective doses in society noticeably. With regard to two main principles in radiation protection, i.e., justification and optimization, it is necessary to have imaging process with minimum dose to patients and personnel. For achieving this, it is vital to perform quality control tests regularly. On this topic, many studies have been performed and reported worldwide which show necessities and meaningfulness of QC tests. Materials and Methods In this study, Unfors Mult-O-Meter model 303 is used for surveying accuracy of kVp and time, linearity of exposure with mAs, and reproducibility of exposure. Results According to recommendations of AAPM (2002) and ICRP 103, in this study, 27% of apparatuses in accuracy of kVp, 45% in accuracy of timer, and 30% in accuracy of reproducibility were out of accepted range. Conclusion In surveyed apparatuses, both ends of operating range have large errors in therefore it is recommended that these devices should not be used in the mentioned regions. Performing strict quality control on all radioactive devices is one of the radiation protection priorities that should be done periodically .With regard to the results, repair, substitution or omition of some devices are suggested.
Radiotherapy dose calculations can be evaluated by Monte Carlo (MC) simulations with acceptable a... more Radiotherapy dose calculations can be evaluated by Monte Carlo (MC) simulations with acceptable accuracy for dose prediction in complicated treatment plans. In this work, Standard, Livermore and Penelope electromagnetic (EM) physics packages of GEANT4 application for tomographic emission (GATE) 6.1 were compared versus Monte Carlo N-Particle eXtended (MCNPX) 2.6 in simulation of 6 MV photon Linac. To do this, similar geometry was used for the two codes. The reference values of percentage depth dose (PDD) and beam profiles were obtained using a 6 MV Elekta Compact linear accelerator, Scanditronix water phantom and diode detectors. No significant deviations were found in PDD, dose profile, energy spectrum, radial mean energy and photon radial distribution, which were calculated by Standard and Livermore EM models and MCNPX, respectively. Nevertheless, the Penelope model showed an extreme difference. Statistical uncertainty in all the simulations was <1%, namely 0.51%, 0.27%, 0.27% and 0.29% for PDDs of 10 cm(2)× 10 cm(2) filed size, for MCNPX, Standard, Livermore and Penelope models, respectively. Differences between spectra in various regions, in radial mean energy and in photon radial distribution were due to different cross section and stopping power data and not the same simulation of physics processes of MCNPX and three EM models. For example, in the Standard model, the photoelectron direction was sampled from the Gavrila-Sauter distribution, but the photoelectron moved in the same direction of the incident photons in the photoelectric process of Livermore and Penelope models. Using the same primary electron beam, the Standard and Livermore EM models of GATE and MCNPX showed similar output, but re-tuning of primary electron beam is needed for the Penelope model.
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Papers by Hamid-Reza Sadoughi