15 research outputs found
The effects Of 50Hz, 0.6 mT extremely low frequency (ELF) electromagnetic field (EMF) on proliferation of the prostate cancer cell line, DU-145
No full textThe Role of MRSI in Target Volume Definition for Radiation Therapy of Prostate Cancer
No full textIntroduction: Recently, magnetic resonance spectroscopic imaging (MRSI), as a functional imaging method, has been used for clinical target volume definition. In this study, we used this method to define the target volume in prostate radiotherapy. Material and Method: In this study, we used images of 20 prostate cancer cases. MRSI and MRI images were fused with CT images. Then, treatment planning was preformed for each patient using three methods: CT, CT+MRI and CT+MRSI planning. Results: The volumes of MRICTV and MRIPTV were on average 12.83% and 8.97% lower than the corresponding CTCTV and CTPTV volumes, respectively. For MRSI, the CTV and PTV volumes were 21% and 27.41% greater than the corresponding CT-based volumes. Maximum dose to rectum showed a 0.58% increase in MRSI relative to CT, and 1.09% reduction in MRI relative to CT. Maximum dose variation in femoral heads showed a 5.4% increase in MRSI relative to CT and 0.67% reduction in MRI relative to CT. Discussion and Conclusion: Application of MRSI for target volume definition of prostate cancer leads to an increase in this volume in comparison to CT planning alone. In this imaging technique, protocol and resolution should be considered to determine the target volume exactly
Electron Beam Dosimetry in Heterogeneous Phantoms Using a MAGIC Normoxic Polymer Gel
No full textIntroduction: Nowadays radiosensitive polymer gels are used as a reliable dosimetry tool for verification of 3D dose distributions. Special characteristics of these dosimeters have made them useful for verification of complex dose distributions in clinical situations. The aim of this work was to evaluate the capability of a normoxic polymer gel to determine electron dose distributions in different slab phantoms in presence of small heterogeneities. Materials and Methods: Different cylindrical phantoms consisting gel were used under slab phantoms during each irradiation. MR images of irradiated gel phantoms were obtained to determine their R2 relaxation maps. 1D and 2D lateral dose profiles were acquired at depths of 1 cm for an 8 MeV beam and 1 and 4 cm for the 15 MeV energy, and then compared with the lateral dose profiles measured using a diode detector. In addition, 3D dose distributions around these heterogeneities for the same energies and depths were measured using a gel dosimeter. Results: Dose resolution for MR gel images at the range of 0-10 Gy was less than 1.55 Gy. Mean dose difference and distance to agreement (DTA) for dose profiles were 2.6% and 2.2 mm, respectively. The results of the MAGIC-type polymer gel for bone heterogeneity at 8 MeV showed a reduction in dose of approximately 50%, and 30% and 10% at depths 1 and 4 cm at 15 MeV. However, for air heterogeneity increases in dose of approximately 50% at depth 1 cm under the heterogeneity at 8 MeV and 20% and 45% respectively at 15 MeV were observed. Discussion and Conclusion: Generally, electron beam distributions are significantly altered in the presence of tissue inhomogeneities such as bone and air cavities, this being related to mass stopping and mass scattering powers of heterogeneous materials. At the same time, hot and cold scatter lobes under heterogeneity regions due to scatter edge effects were also seen. However, these effects (increased dose, reduced dose, hot and cold spots) at deeper depths, are compensated with the contributions of scattered electrons. Our study showed that normoxic polymer gels are reliable detectors for determination of electron dose distributions due to their characteristics such as tissue equivalence, energy independence, and 2D and 3D dose visualization capabilities
Effect of physical activity and 217-Hz extremely low frequency electromagnetic field on rat locomotor activity
No full textBackground: Nowadays the widespread use of cell phones has increased concerns about the biological effects of electromagnetic fields on human body. The purpose of the present study was to examine the role of physical activity in moderating the effects of extremely low frequency electromagnetic fields (ELF-EMF) emitted from cell phones on rat locomotor activity. Material and Methods: Male Albino-Wistar rats (no=70) were divided into seven groups: Short and Long- term physical activity; Control, ELF-EMF; Sham; Long-term physical activity+ELF-EMF; Short-term physical activity+ELF-EMF. Short and Long- term physical activity groups were forced to daily treadmill running (30 minutes) for one week and one month, respectively. ELF-EMF group was exposed to ELF-EMF cell phone simulator for three hours during the period. Having placed in the ELF-EMF simulator device, the physical activity+ELF-EMF groups were transferred to treadmill. Locomotor activity were analyzed as distance, time and speed of movement in open field apparatus. Results: The results showed that the ELF-EMF from cell phones can significantly decrease the locomotor activity in the exposed rats. On the other hand, short and long-term physical activity significantly increased motor activity in the trained rats (P≤0.05). However, there was no significant difference between the combination groups (Physical activity+ELF-EMF) and ELF group in locomotor activity. Conclusion: The results revealed that the physical activity could not prevent the decrease of locomotor activity caused by ELF-EMF from cell phone
Design Principles for Immersive Virtual Safety Training : An Action Design Research Project
No full textPublisher Copyright: © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2025.To tackle emerging challenges related with traditional safety training for practitioners that work onboard trains in society; for this research, we developed an immersive virtual safety training environment with Immersive Virtual Reality technology. We employed the Action Design Research (ADR) approach to design an Alpha prototype in close cooperation with end-users and software developers. The end-users were train operators and safety trainers at a train operating company in Sweden known as SJ. Two research cycles were executed to develop and evaluate the prototype. Consequently, by following the ADR method, we developed and proposed four design principles for immersive virtual safety training environments: (1) Design for Virtual Safety Realism, (2) Design for Virtual Boundary Crossing, (3) Design for Virtual Multimodal Feedback, and (4) Design for Virtual Touchpoints and Collaborative Reflection.Peer reviewe
Transient Rheological Behavior of Semisolid SEED-Processed 7075 Aluminum Alloys in Rapid Compression
No full text© 2018, The Author(s). The transient rheological behavior and microstructure evolution of semisolid SEED-processed 7075 aluminum alloys were studied using the rapid compression tests. The effects of the TiB2 grain refinement on the grain morphology and size of semisolid slurries were investigated. Results indicated that the grain refiner could reduce the grain size and improve the globularity of α-Al grains. The grain-refined alloy can be easily deformed at a wide range of solid contents (0.42 to 0.53 Fs), in which the deformation level appears to be independent from the solid content. Under the transient state, the apparent viscosity decreased with increasing shear rate to a minimum value and followed by an increase as the shear rate decreased. The apparent viscosity of the base alloy exhibited a dependency on the solid content, while the apparent viscosity of the grain-refined alloy in the decreasing or increasing shear rate periods was not substantially influenced by the solid content. The viscosity as a function of applied shear rate can be described using the power law viscosity model. The differences in the flow behavior index (n) and the consistency index (k) for two alloys were discussed
The Effect of Increased Electrical Field Strength of 950 MHz Waves on the EPSP Slope
No full textIntroduction: Over the last decade, exposure to electromagnetic waves due to base station antennas has increased. This study was planned to evaluate the effects of different electrical field strengths with 950 MHz waves of the GSM mobile phone system on the excitatory postsynaptic potentiation (EPSP) slope of the dentate gyrus long-term potentiation (LTP). Material and Methods: Twenty four naive male Wistar rats (3 months old, weighing 220 + 15 g) were randomly divided into three groups (sham–exposed, GSM with 50.4 V/m and GSM with 60 V/m electrical field strength). The exposure program was carried out for 10 sessions during 3 days. The animals were exposed to the electromagnetic field for 45 minutes in a plastic chamber. Immediately after the exposure, anesthesia was induced for LTP induction and the field potentials were recorded for 60 minutes, then the EPSP slope and maintenance were analyzed. Results: Our data showed that whole-body exposure to 950 MHz waves of the GSM mobile phone system with 60 V/m electrical field strength could change the EPSP slope in rat brain hippocampus. Discussion and Conclusion: Increasing the electrical field strength could change synaptic plasticity and LTP characteristics in rat brain hippocampus
Effects of Electromagnetic Stimulation on Gene Expression of Mesenchymal Stem Cells and Repair of Bone Lesions
No full textObjective
Most people experience bone damage and bone disorders during their lifetimes. The use of autografts is a suitable way for injury recovery and healing. Mesenchymal stem cells (MSCs) are key players in tissue engineering and regenerative medicine. Their proliferation potential and multipotent differentiation ability enable MSCs to be considered as appropriate cells for therapy and clinical applications. Differentiation of stem cells depends on their microenvironment and biophysical stimulations. The aim of this study is to analyze the effects of an electromagnetic field on osteogenic differentiation of stem cells.
Materials and Methods
In this experimental animal study, we assessed the effects of the essential parameters of a pulsatile electromagnetic field on osteogenic differentiation. The main purpose was to identify an optimum electromagnetic field for osteogenesis induction. After isolating MSCs from male Wistar rats, passage-3 (P3) cells were exposed to an electromagnetic field that had an intensity of 0.2 millitesla (mT) and frequency of 15 Hz for 10 days. Flow cytometry analysis confirmed the mesenchymal identity of the isolated cells. Pulsatile electromagnetic field-stimulated cells were examined by immunocytochemistry and real-time polymerase chain reaction (PCR).
Results
Electromagnetic field stimulation alone motivated the expression of osteogenic genes. This stimulation was more effective when combined with osteogenic differentiation medium 6 hours per day for 10 days. For the in vivo study, an incision was made in the cranium of each animal, after which we implanted a collagen scaffold seeded with stimulated cells into the animals. Histological analysis revealed bone formation after 10 weeks of implantation.
Conclusion
We have shown that the combined use of chemical factors and an electromagnetic field was more effective for inducing osteogenesis. These elements have synergistic effects and are beneficial for bone tissue engineering applications
Investigating the effects of electrical stimulation via gold nanoparticles on in vitro neurite outgrowth: Perspective to nerve regeneration
No full text
