Journal of Biomedical Physics and Engineering最新文献

Background: Functional Magnetic Resonance Imaging (fMRI) is a non-invasive neuroimaging tool, used in brain function research and is also a low-frequency signal, showing brain activation by means of Oxygen consumption.

Objective: One of the reliable methods in brain functional connectivity analysis is the correlation method. In correlation analysis, the relationship between two time-series has been investigated. In fMRI analysis, the Pearson correlation is used while there are other methods. This study aims to investigate the different correlation methods in functional connectivity analysis.

Material and methods: In this analytical research, based on fMRI signals of Alzheimer's Disease (AD) and healthy individuals from the ADNI database, brain functional networks were generated using correlation techniques, including Pearson, Kendall, and Spearman. Then, the global and nodal measures were calculated in the whole brain and in the most important resting-state network called Default Mode Network (DMN). The statistical analysis was performed using non-parametric permutation test.

Results: Results show that although in nodal analysis, the performance of correlation methods was almost similar, in global features, the Spearman and Kendall were better in distinguishing AD subjects. Note that, nodal analysis reveals that the functional connectivity of the posterior areas in the brain was more damaged because of AD in comparison to frontal areas. Moreover, the functional connectivity of the dominant hemisphere was disrupted more.

Conclusion: Although the Pearson method has limitations in capturing non-linear relationships, it is the most prevalent method. To have a comprehensive analysis, investigating non-linear methods such as distance correlation is recommended.

Background: At proton radiotherapy, the extracted beam from accelerator is not initially suitable for tumor treatment and a modification is needed for beam shape and energy due to tumor dimension and site. One clinical strategy is the use of double scattering systems known as passive dose delivery technique to generate proper flattening, transversely.

Objective: This work aims to design and simulate a new version of double scattering system and compare its performance with another available scatterer system, quantitatively.

Material and methods: In this analytical study, Monte Carlo FLUKA code is utilized to simulate the performance of proposed system in generating lateral flat beam. The simulation process is very close to real experimental condition, performed at proton beam irradiation room at Tohoku University in Japan. Moreover, the presence of secondary neutrons, produced due to protons collision with proposed scattering system, is considered as main issue.

Results: Final results represent that the proposed scattering system is robust to generate 40 mm flat region with an acceptable uniformity degree. Energy loss caused by current dual scatterer is more than simple ring technique, while the secondary neutrons produced by proposed system are larger than other system.

Conclusion: This study simulates the performance of a new dual ring double scattering system. Final results show that there is a close correlation between proposed system and current scattering system. The only concern is about the presence of secondary neutrons mainly at high energy proton particles.

Background: The reliability studies are limited to support ultrasound usage during dynamic conditions; for example, unstable sitting position.

Objective: This study aims to examine the reliability of ultrasound measurements of the lumbar multifidus and transversus abdominis during lying and unstable sitting positions in individuals with chronic low back pain (CLBP) and asymptomatic individuals considering abnormal lumbar lordosis.

Material and methods: In this observational study, intrarater within-day and between-day reliability of muscle thickness and contraction ratio of the lumbar multifidus and transversus abdominis muscles were assessed using ultrasound imaging. In total, 40 participants (27 with CLBP, 13 asymptomatic individuals) with abnormal lumbar lordosis were recruited. The degree of lumbar lordosis has been measured by a flexible ruler. The muscle thickness was assessed at lying and sitting on a gym ball for both muscles in three sessions.

Results: Both groups had well to high ICCs of thickness measurement and contraction ratio in the transversus abdominis and lumbar multifidus muscles during both static (ICC=0.71-0.99) and semi-dynamic conditions (ICC=0.73-0.98). The standard error of measurements and minimal detectable changes were rather small in both groups.

Conclusion: Ultrasound imaging is a highly reliable method to assess muscle thicknesses and contraction ratio of the transversus abdominis and lumbar multifidus during different conditions, even in patients with CLBP and abnormal lumbar lordosis.

Mobile health (m-health) is considered an undeniable part of health service delivery, planning, and marketing, which has dramatically changed due to the unique situation caused by the COVID-19 pandemic. The Forth International Congress of Mobile Health, from February 14^th to 16^th, 2021, in Shiraz, Iran, aimed to provide a venue to exchange ideas, techniques, relevant experiments, and applications with a particular focus on the COVID-19 pandemic impacts. More than 70 experts from different countries in engineering, biomedical sciences, and humanities presented their recent experiences in m-health advancements, particularly in response to the COVID-19 outbreak. In this article, highlights of the most valuable ideas presented at the congress are concisely summarized to give scientists, entrepreneurs, policymakers, and other stakeholders a better understanding of the growing opportunities, and challenges toward the development of m-health.

Background: Chemotherapy is typically the first-line treatment for the advanced stage of cancers. However, there are shortcomings with respect to conventional chemotherapy that limit therapeutic efficiency, including lack of tumor selectivity, systemic toxicity and drug resistance.

Objective: A multifunctional nanoplatform was build using of hydrogel co-loaded containing cisplatin and Iron oxide-gold core-shell nanoparticles. The Au shell comprises the light response and the iron core can be utilized as a negative contrast agent in nanocomplex.

Material and methods: In this experimental study, KB cells derived from the epithelial cells located in the nasopharynx were exposed to different levels of concentration of hydrogel co-loaded with cisplatin and Iron oxide-gold core-shell nanoparticles. Afterwards, the cytotoxicity was determined using MTT assay.

Results: The cytotoxicity results showed that this nanoplatforms has potent to create higher cytotoxicity in KB cells than free cisplatin, so that Fe-Au@Alg and Fe-Au@Alg with cisplatin mixed with laser irradiation exhibited a significant reduction in cell viability after 5 min.

Conclusion: Hydrogel co-loaded with cisplatin and Iron oxide-gold core-shell nanoparticles are stable construct to combine chemo-photothermal therapy. Therefore, they can be used as a computed tomography-traceable nanocarrie, enabling us to monitor the delivery of therapeutics.

Background: Independent Component Analysis (ICA) is the most common and standard technique used in functional neuroscience data analysis.

Objective: In this study, two of the significant functional brain techniques are introduced as a model for neuroscience data analysis.

Material and methods: In this experimental and analytical study, Electroencephalography (EEG) signal and functional Magnetic Resonance Imaging (fMRI) were analyzed and managed by the developed tool. The introduced package combines Independent Component Analysis (ICA) to recognize significant dimensions of the data in neuroscience. This study combines EEG and fMRI in the same package for analysis and comparison results.

Results: The findings of this study indicated the performance of the ICA, which can be dealt with the presented easy-to-use and learn intuitive toolbox. The user can deal with EEG and fMRI data in the same module. Thus, all outputs were analyzed and compared at the same time; the users can then import the neurofunctional datasets easily and select the desired portions of the functional biosignal for further processing using the ICA method.

Conclusion: A new toolbox and functional graphical user interface, running in cross-platform MATLAB, was presented and applied to biomedical engineering research centers.

Background: Calibration of Thermo Luminescent Dosimetry (TLD) in eye lens dosimeter requires a standard phantom. The use of anthropomorphic phantoms in calibration needs evaluation.

Objective: This study aimed to analyze the angular response of the TLD on the fabricated 3D anthropomorphic head phantom and Computerized Imaging Reference Systems (CIRS)- Computed Tomography (CT) dose phantom as a standard phantom irradiated with Cs-137 and to compare the absorbed dose and linear attenuation for both phantoms. H_p(3) analysis, conversion coefficient (h_pK(3)), and calibration factor (CF) are also investigated.

Material and methods: In this experimental study, the fabricated 3D printed anthropomorphic head phantom was analyzed using polylactic acid (PLA) with the skull and then filled with the artificial brain and cerebrospinal fluid (CSF) as a test phantom. TLD-700H and TLD Reader Harshaw 6600 plus were used to analyze the angular response of Cs-137 radiation and to determine the absorbed dose and linear attenuation coefficient of test and standard phantoms.

Results: The effect of the angle of radiation source towards TLD reading at the anthropomorphic head phantom has a similar value to the standard phantom with a calibration factor ranging from 0.82 to 1. The absorbed dose measurement and the linear attenuation coefficient of the anthropomorphic head phantom with the standard phantom have different values of 2.52 and 3.78%, respectively.

Conclusion: The fabricated 3D printed anthropomorphic head phantom has good potential as an alternative to standard phantoms for TLD calibration in eye lens dosimeter.

Background: Sleep apnea is one of the most common sleep disorders that facilitating and accelerating its diagnosis will have positive results on its future trend.

Objective: This study aimed to diagnosis the sleep apnea types using the optimized neural network.

Material and methods: This descriptive-analytical study was done on 50 cases of patients referred to the sleep clinic of Imam Khomeini Hospital in Tehran, including 11 normal, 13 mild, 17 moderate and 9 severe cases. At the first, the data were pre-processed in three stages, then The Electrocardiogram (ECG) signal was decomposed to 8 levels using wavelet transform convert and 6 nonlinear features for the coefficients of this level and 10 features were calculated for RR Intervals. For apnea categorizing classes, the multilayer perceptron neural network was used with the backpropagation algorithm. For optimizing Multi-layered Perceptron (MLP) weights, the Particle Swarm Optimization (PSO) evolutionary optimization algorithm was used.

Results: The simulation results show that the accuracy criterion in the MLP network is allied with the Backpropagation (BP) training algorithm for different types of apnea. By optimizing the weights in the MLP network structure, the accuracy criterion for modes normal, obstructive, central, mixed was obtained %96.86, %97.48, %96.23, and %96.44, respectively. These values indicate the strength of the evolutionary algorithm in improving the evaluation criteria and network accuracy.

Conclusion: Due to the growth of knowledge and the complexity of medical decisions in the diagnosis of the disease, the use of artificial neural network algorithms can be useful to support this decision.

Background: Substantial evidence indicates that exposure to extremely low frequency-electromagnetic fields (ELF-EMFs) affects male reproductive system.

Objective: The goal of this study was to evaluate the effects of long-term irradiation with ELF-EMF on sperm quality and quantity and testicular structure.

Material and methods: In this case-control study, sixty male Sprague-Dawley rats were randomly divided into six groups. Experimental groups were exposed to ELF-EMF (50 Hz EMF, 100 µT) for either 1 h/day for 52 days (Group 1), 4 h/day for 52 days (Group 3), 1 h/day for 5 days (Group 5), 4 h/day for 52 days (Group 7). Groups 2, 4, 6 and 8 were only sham exposed at durations equal to Groups 1, 3, 5 and 7, respectively.

Results: Both count and motility of sperms were significantly decreased in animals exposed to ELF-EMF (1 h/day for 52 days, 4 h/day for 52 day, and 4 h/day for 5 days) compared to the sham-exposed groups (P<0.05). Serum testosterone levels showed a significant decrease in the animals exposed to ELF-EMF (4 h/day for 5 days) compared to the control groups (P<0.05). A significant decrease was observed in the volume of the seminiferous tubules, seminiferous tubules epithelium and interstitial tissue in the animals exposed to ELF-EMF for 4 h/day for 5 days. Tubules length was also reduced by 18% in animals exposed to ELF-EMF (4 h/day for 5 days).

Conclusion: Our results show that ELF-EMF can reduce spermatocyte count and motility and is able to induce structural changes in testicular tissue.

Background: The effect of different types of substances on brain function is still challenging; however, many studies have shown the functional and structural damage to the brain under influence of substance abuse.

Objective: This study aimed to quantitatively compare the effect of opioid (Op), methamphetamine (Meth), cannabis (Can), and simultaneous methamphetamine and opioid (Multi-Drug (MD)) abuse on brain function. Furthermore, the impacts of pure Op and Meth abuse were considered with simultaneous substance abuse.

Material and methods: In this descriptive study, the electroencephalogram (EEG) signal was recorded from 52 participants in the Meth, Op, Can, and MD abusers, and the Healthy Control (HC) groups at rest state. EEG data were analyzed on the frequency domain with electrode-based, cortex-based, and hemisphere-based approaches.

Results: However, the power spectrum in the delta band in the Op group, the gamma band in the Can group, and the gamma and beta bands in the MD group more significantly increased compared to the HC group, the power spectrum values in the Meth group reduced in the alpha, beta, and gamma bands. Moreover, the power spectrum values in the MD group more significantly higher than the Meth and Op groups in the beta and gamma bands.

Conclusion: Since substance abuse in different types caused various changes in frequency components, the different power spectrum bands analysis in abusers can be reasonable to apply as a biomarker to detect the drug types.