Journal of Biomedical Physics and Engineering最新文献

Background: Smartphone users frequently connect to the Internet via mobile data or Wi-Fi. Over the past two decades, the worldwide percentage of people who connect to the Internet using their mobile phones has increased drastically.

Objective: This study aimed to evaluate the potential link between mobile cellular data/ and Wi-Fi use and adverse health effects.

Material and methods: This cross-sectional study was conducted on 2,796 employees (52% female and 48% male) of Shiraz University of Medical Sciences (SUMS), Shiraz, Iran. The sociodemographic data (e.g., gender, age, nationality, and education level) were collected for all the participants. They were also requested to provide information about their smartphone use including the characteristics of the connection to the Internet using their smartphones (mobile data and Wi-Fi). In addition, the participants' history of diabetes, hypertension, cardiac ischemia, myocardial infarction, renal failure, fatty liver, hepatitis, chronic lung disease, thyroid disease, kidney stone, gall bladder stone, rheumatoid disease, epilepsy, and chronic headache was recorded through face-to-face interviews.

Results: 94% of people participating in this study reported using mobile/Wi-Fi internet. The mean (±SD) Internet usage per day was 117.85±122.70 minutes including 76±98 minutes of mobile data and 42±81 minutes of Wi-Fi use.

Conclusion: Our findings showed no link between mobile phone Internet usage and the risk of the above-mentioned health problems. As in 2021, the global average daily time spent on the Internet using mobile phones was 155 minutes, the participants' lower use time could explain the failure to show any detrimental effects. Considering the study limitations, further large-scale studies are warranted.

Background: Electromagnetic induction hyperthermia is a promising method to treat the deep-seated tumors such as brain and prostatic tumors. This technique is performed using the induction of electromagnetic waves in the ferromagnetic cores implanted at the solid tumor.

Objective: This study aims at determining the conditions of the optimal thermal distribution in the different frequencies before performing the in vitro cellular study.

Material and methods: In this experimental study, the i-Cu alloy (70.4-29.6; wt%) was prepared and characterized and then the parameters, affecting the amount of induction heating in the ferromagnetic core, were investigated. Self-regulating cores in 1, 3, 6, and 9 arrangements in the water phantom with a volume of 2 cm³ were used as a replacement for solid tumor.

Results: Inductively Coupled Plasma (ICP) analysis and Energy Dispersive X-ray Spectroscopy (EDS) show the uniformity of the alloy after 4 times remeling by vacuum arc remelting furnace. The Vibrating Sample Magnetometer (VSM) shows that the Curie temperature (T_C) of the ferromagnetic core is less than 50 °C. Temperature profile with a frequency of 100-400 kHz for 30 min, was extracted by infrared imaging camera, indicating the increase temperature in the range of 42 °C to 46 °C.

Conclusion: The optimum conditions with used hyperthermia system are supplied in the frequency of 100 kHz, 200 kHz and 400 kHz with 6, 3 and 1 seeds, respectively. It is also possible to induce a temperature up to 50 °C by increasing the number of seeds at a constant frequency and power, or by increasing the applied frequency at a constant number of seeds.

Previous research has shown that children are more vulnerable to the adverse effects of radiofrequency electromagnetic fields (RF-EMFs) and blue light emitted from digital screens compared to healthy adults. This paper presents the findings of a cross-sectional study conducted in Yasuj, Iran, to investigate the screen time habits of children and adolescents and its potential impact on their health. A total of 63 participants, including 44 boys and 19 girls, were randomly selected for the study. The results showed that the average daily screen time for the children was 87.38 minutes, with a standard deviation of 49.58. When examining the specific purposes of screen time, it was found that the children spent an average of 17.54 minutes per day on screens for school assignments, 70 minutes per day for recreational purposes, and 23.41 minutes per day for contacting family, friends, and relatives. Our study highlights that a significant portion of the children's screen time was allocated to recreational activities. We observed some differences in screen time between girls and boys. Boys had a slightly higher overall daily screen time, primarily driven by more recreational screen time. However, girls spent slightly more time on screens for school assignments. The screen time for social interactions was similar for both genders. Our findings on the cognitive performance of children with different levels of screen time will be published in a separate paper.

Background: In Radiotherapy, computation of dose is important since in a small field with heterogeneity, dose is usually computed with discrepancies.

Objective: The present study was aimed to evaluate the dosimetry of treatment planning algorithms in lung equivalent heterogeneous medium for Volumetric Modulated Arc Therapy (VMAT) with step and shoot Intensity-Modulated Radiation Therapy (ss-IMRT), and dynamic Intensity-Modulated Radiation Therapy (d-IMRT).

Material and methods: In this experimental study, Computerized Imaging Reference System (CIRS) phantom was used with an inhomogeneous Racemosa wood cylinder for two types of tumors, namely, Left Lung Central Tumor (LCT) and Left Lung Peripheral Tumor (LPT) in the CIRS left lung cavity. The computed tomography (CT) datasets were employed with the generation of VMAT, d-IMRT and ss-IMRT plans for the LCT and LPT irradiated with 6 MV photon beams. In this study, the accuracy and efficacy of two algorithms: Monte Carlo (MC) and the Pencil Beam (PB), from the Monaco treatment planning system (TPS), were tested by using Gafchromic EBT3 films and CIRS thorax phantom.

Results: Regardless of treatment techniques, both algorithms exhibited higher divergence in LPT than LCT. In both LCT and LPT, the highest deviation was near the tumor-lung junction. However, the deviation was higher in the PB algorithm than MC algorithm, with a minimally acceptable variation of -0.8%.

Conclusion: The MC algorithm shows more consistency for EBT3 measured dose in lung equivalent heterogeneous medium. However, accurate dose predictions are complicated due to electronic disequilibrium within and at the interface of inhomogeneity. These constraints may cause variations from the anticipated outcomes of the treatments.

Background: The intravoxel incoherent motion (IVIM) model extracts both functional and structural information of a tissue using motion-sensitizing gradients.

Objective: The Objective of the present work is to investigate the impact of signal to noise ratio (SNR) and physiologic conditions on the validity of IVIM parameters.

Material and methods: This study is a simulation study, modeling IVIM at a voxel, and also done 10,000 times for every single simulation. Complex noises with various standard deviations were added to signal in-silico to investigate SNR effects on output validity. Besides, some blood perfusion situations for different tissues were considered based on their physiological range to explore the impacts of blood fraction at each voxel on the validity of the IVIM outputs. Coefficient variation (CV) and bias of the estimations were computed to assess the validity of the IVIM parameters.

Results: This study has shown that the validity of IVIM output parameters highly depends on measurement SNR and physiologic characteristics of the studied organ.

Conclusion: IVIM imaging could be useful if imaging parameters are correctly selected for each specific organ, considering hardware limitations.

Background: Many studies have investigated ankle sprain injury and it has been reported that in 80% of cases, ankle sprains lead to functional ankle instability (FAI). The conventional exercises for FAI rehabilitation neglect the associated neurocognitive dysfunction.

Objective: This study aims to evaluate the effect of Wii Fit Plus as a virtual reality training on neurocognitive function in athletes with FAI compared to athletes without FAI.

Material and methods: In this matched randomized clinical trial study, 25 athletes with unilateral FAI and 25 athletes without FAI were assigned to two groups randomly: 1) the intervention group, subjects performed the Wii training including balance and strengthening games three times a week for 12 sessions and 2) subjects in the control group received no intervention. Before and after the training, the neurocognitive function was assessed through the computerized-reaction time test based on the detection or identification of 'X' mark on a computer monitor. Between-groups and within-group comparisons were done by the independent T-test and paired T-test, respectively.

Results: A significant difference was observed in mean differences of neurocognitive function between athletes with and without FAI. Comprising before and after training was significant in the intervention group.

Conclusion: Based on the results, the information-processing speed of athletes with FAI increased after the training, utilized for rehabilitation protocols.

Background: The BEBIG Portio multi-channel applicator provides better target dose coverage and sparing organs-at-risk compared to a single-channel cylinder. However, artifacts and distortions of Portio in magnetic resonance images (MRI) have not yet been reported.

Objective: We aimed to quantify the artifacts and distortions in its 1.5-Tesla MR images before clinical use.

Material and methods: In this experimental study, we employed a gelatin-filled phantom to conduct our measurements. T2-weighted (T2W) images were examined for artifacts and distortions. Computed tomography (CT) images were used as a reference to assess image distortions. Artifact severity was measured by recording the full-width-at-half-maximum (FWHM) image pixel values at various positions along the length of the applicator/channels. CT and MRI-based applicator reconstruction accuracy were then compared, and signal-to-noise ratio (SNR) and contrast were also determined for the applicator images.

Results: The applicator distortion level for the Portio applicator was less than the image spatial resolution (0.5±0.5 pixels). The average FWHM for the tandem applicator images was 5.23±0.39 mm, while it was 3.21±0.37 mm for all channels (compared to their actual diameters of 5.0 mm and 3.0 mm, respectively). The average applicator reconstruction difference between CT and MR images was 0.75±0.30 mm overall source dwell positions. The image SNR and contrast were both acceptable.

Conclusion: These findings indicate that the Portio applicator has a satisfactory low level of artifacts and image distortions in 1.5-Tesla, T2W images. It may, therefore, be a promising option for MRI-guided multi-channel vaginal brachytherapy.

Background: Radiation therapy, the most common form of cancer treatment, can result in late complications, such as secondary breast and thyroid cancers.

Objective: This study aimed to evaluate the risk of secondary cancers using two radiobiological models of Excess Absolute Risk (EAR) and Excess Relative Risk (ERR) in patients with brain cancer undergoing radiotherapy for improved survival rates of cancer patients.

Material and methods: In this expository cross-sectional study, 45 patients under the age of 40 years underwent Whole Brain Radiotherapy (WBRT) using a compact accelerator in Shahid Ramezanzadeh Hospital, Yazd, Iran. Out-of-field organ dose measurement was performed using a Thermoluminescent Dosimeter (TLD) to determine the dose to thyroid and breast tissues. The risk of secondary cancers in these organs was calculated 3, 5, 10, 15, and 20 years after radiation therapy.

Results: The mean values of thyroid cancer risk in men and women were 0.418±0.509 and 0.274±0.306, respectively. ERR values of breast cancer in 3-, 5-, 10-, 15-, and 20-year women undergoing radiation therapy were 1.084±2.938, 0.594±1.407, 0.248±0.497, 0.138±0.248, and 0.091±0.148, respectively. EAR values of breast cancer in 3-, 5-, 10-, 15-, and 20-year women following radiation therapy were 0.064±0.060, 0.077±0.071, 0.119±0.100, 0.178±0.248, and 0.259±0.178, respectively.

Conclusion: After irradiation, the risk of secondary cancer is affected by factors, such as the patient's age and gender. The secondary thyroid cancer is higher than that of other organs, such as the breast, in the patients undergoing WBRT.

Background: Competitive sailing requires efforts pertinent to physiological limitations and coordination between different parts of the body. Such coordination depends on the torques applied by muscles to the joints.

Objective: This study aims to simulate the motion and provide a control law for the joint torques in order to track the desired motion paths.

Material and methods: In this analytical study, an inverse dynamics based control is employed in order to simulate the motion by tracking the desired movement trajectories. First, the dynamics equations are obtained using Lagrange method for 5 degrees of freedom (5 DOF) model. In the following, a robust control scheme with inverse dynamics method based on the Proportional-Integral-Derivative (PID) approach is employed to track the desired joint angles obtained from the experiment.

Results: The simulation results demonstrate the performance of the proposed control method. Low settling times are achieved for the entire joint, which is appropriate in comparison with the time period of each cycle (3.75 s). Also, the maximum torques required to be applied to the joints are in physiological range.

Conclusion: This study provided an appropriate model for the analysis of human movement in rowing sport. The model can also be cited in terms of basic biological theories in addition to practical computational uses in biomechanical engineering. Accordingly, the generated control signals can help to improve the interactive body movements during paddling and in designing robotic arms for automatic rowing.