Vol 9 No 3 (2022)


Original Article(s)

  • XML | PDF | downloads: 192 | views: 347 | pages: 160-169

    Purpose: Working Memory (WM) plays a crucial role in many cognitive functions of the human brain. Examining how the inter-regional connectivity and characteristics of functional brain networks modulate with increasing WM load could lead to a more in-depth understanding of the WM system.

    Materials and Methods: To investigate the effect of WM load alterations on the inter-regional synchronization and functional network characteristics, we used Electroencephalogram (EEG) data recorded from 21 healthy participants during an n-back task with three load levels (0-back, 2-back, and 3-back). The networks were constructed based on the weighted Phase Lag Index (wPLI) in the theta, alpha, beta, low-gamma, and high-gamma frequency bands. After constructing the fully connected, weighted, and undirected networks, the node-to-node connections, graph-theory metrics consisting of mean Clustering coefficient (C), characteristic path Length (L), and node strength were analyzed by statistical tests.

    Results: It was revealed that in the presence of WM load (2- and 3-back tasks) compared with the WM-free condition (0-back task) within the alpha range, the Inter-Regional Functional Connectivity (IRFC), functional integration, functional segregation, and node strength in channels located at the frontal, parietal and occipital regions were significantly reduced. In the high-gamma band, IRFC was significantly higher in the difficult task (3-back) compared to the easy and moderate tasks (0- and 2-back). Besides, locally clustered connections were significantly increased in 3-back relative to the 2-back task.

    Conclusion: Inter-regional alpha synchronization and alpha-band network metrics can distinguish between the WM and WM-free tasks. In contrast, phase synchronization of high-gamma oscillations can differentiate between the levels of WM load, which demonstrates the potential of the phase-based functional connectivity and brain network metrics for predicting the WM load level.

  • XML | PDF | downloads: 133 | views: 277 | pages: 170-175

    Purpose: Perceptual decision-making is the act of choosing one option from a set of alternatives based on available sensory information. Regarding the serious role of this act in human personal and social lives, the neurophysiological analysis of the brain during this type of decision is of great interest. In this research, the underlying neural mechanism of these decisions is investigated using a perceptual decision-making Electroencephalogram (EEG) dataset with a perceptual discrimination task.

    Materials and Methods: An online available dataset containing the pre-processed EEG signals of 24 healthy participants during the perceptual decision-making task of Random Dot Kinematograms was used. After a secondary pre-processing stage, clean EEG signal was divided into 1.3-second segments and averaged for Event-Related Potential (ERP) and Event-Related Spectral Perturbation (ERSP) calculations. The task engagement index was also calculated and averaged among all participants.

    Results: According to the results, the amplitude of the N200 component in O1 and O2 channels was larger for correct choices than incorrect ones. Furthermore, in the O2 channel, it was observed that the average alpha power near 200 milli-seconds after stimulus onset was slightly higher in high and low confidence choices than medium confidence choices. The beta band power in the PO2 channel was also higher for correct choices rather than incorrect ones in this interval. Moreover, the results represented that the task engagement index was higher in medium confidence choices, especially in occipital and parieto-occipital channels.

    Conclusion: The larger N200 amplitude and the higher beta power for correct choices, and the lower alpha power for medium confidence choices may be due to more attention of the individuals to the stimuli. This phenomenon can be observed in the task engagement indices as well. This could be because the user expended more efforts in medium confidence to bring one of the choices to the decision threshold.

  • XML | PDF | downloads: 118 | views: 173 | pages: 176-184

    Purpose: The present study aimed to investigate the quantitative pattern of brain waves with post-traumatic growth dimensions in patients admitted due to Coronavirus Disease (COVID-19). Post-traumatic growth is the mental experience of positive psychological changes caused by the individual as a result of coping with challenging situations.

    Materials and Methods: In this study, 66 individuals with COVID-19 who were admitted to Baharloo Hospital in Tehran as a stressful event were selected by convenience sampling and completed a post-traumatic growth inventory (PTGI) and their brain waves in rest were recorded.

    Results: The results showed that brain components are a good predictor of post-traumatic growth dimensions. Alpha-parietal, F3-Sensorimotor Rhythm (F3-SMR) and alpha asymmetry predicted new possibilities component, alpha-F3 and alpha asymmetry predicted relating to others component, F4-SMR predicted spiritual change component and alpha asymmetry significantly predicted the total post-traumatic growth score. Also, Quantitative Electroencephalogram (QEEG) components did not significantly predict the appreciation of life and personal strength component.

    Conclusion: According to the results, it can be said that more objective instruments such as Electroencephalogram )EEG( have good predictive power in complex psychological and multidimensional cases such as post-traumatic growth. The results of this study confirm the hypothesis that post-traumatic growth may reflect a process of active struggle to achieve new goals and perspectives. Accordingly, especially the more guided dimensions of post-traumatic growth (e.g., the new possibilities dimension) may be associated with the asymmetry of the frontal lobe of the brain. In contrast, the dimensions of appreciation of life and personal strength were not predicted by the brain component; these two components were slightly more abstract than the others and may lead to more / less neural network activity in functional Magnetic Resonance Imaging (fMRI) that is more observable.

  • XML | PDF | downloads: 183 | views: 144 | pages: 185-190

    Purpose: Dose Area Product (DAP) is a quantity for radiation risk assessment in diagnostic X-ray tests. Children's tissues are up to 10 times more sensitive to radiation than adults, and life expectancy is higher in children than adults, as well as a higher risk of hematopoietic and mass malignancies in them. Therefore, this study aimed to measure DAP values for X-ray fields adjusted by Birjand radio-technologists in chest X-rays of children under 12 years of age.

    Materials and Methods: 233 children from Birjand University hospitals who performed chest X-rays were included in the study. To collect data related to DAP, the DAP meter model KermaX plus SDP was used. It should be noted that no intervention was performed in the patient's imaging method and at the time of radiation and measurement of the DAP values, there was no need for the patient's presence. In the end, the measured DAP values were compared with DAP values of other studies. Data were analyzed using SPSS software version 22 at 5% error level using Anova, t-test, and Pearson correlation tests.

    Results: Out of 233 patients who were included in the study, 134 males (57.5%) and 99 females (42.5%) participated in the study, it should be noted that there was no significant difference between the mean of DAP in male and female (p=0.52). In our study, the average DAP was 5.78 ± 3.54 μGy.m2 and DAP values in the range of 0.55 μGy.m2 to 15.54 μGy.m2 that were higher than the average of other studies and there was a significant difference. There was a direct relationship between radiation field dimensions and DAP values so that as the dimensions of the radiation field increase, the DAP value increases. There was a significant difference between the mean DAP of the lowest and the highest age groups, lowest and the highest age groups, and lowest and the highest height groups of patients.

    Conclusion: In our study, it was observed that there is a significant relationship between patients' weight, age, and height, radiation field dimensions with DAP values. The amount of DAP in the present study was significantly higher than in other studies. The most important effective parameter in DAP is the radiation field size and if sufficient optimization is done in imaging parameters (kVp, mAS, field size), the DAP values will be greatly reduced.

  • XML | PDF | downloads: 98 | views: 207 | pages: 191-198

    Purpose: Deception is described as a deliberate endeavor to deceive others.  In this research, the main purpose is to survey the brain network between deception and telling the truth.

    Materials and Methods: Electroencephalography (EEG) data were collected from 17 subjects during a deception task in which the subjects had to classify the target stimuli deceptively while responding truthfully to other stimuli (non-targets). Functional Connectivity (FC) analysis was carried out in source space in order to attenuate the volume conduction effect. The coherence criterion was applied for calculating FC.

    Results: The results revealed that deception is associated with significantly greater connectivity between distant regions, including frontal-occipital and frontal-parietal connectivity. In addition, Anterior Cingulate Cortex (ACC) demonstrated significantly greater connectivity with regions of the frontal and occipital lobes. Besides, deception was accompanied by high number of strong connectivity between the left parietal and frontal lobes.

    Conclusions: The findings demonstrated that the FC studies in source space can strikingly assist in the investigation of deception.

  • XML | PDF | downloads: 123 | views: 119 | pages: 199-205

    Purpose: The concept of Quality Control (QC) is considered a regular method to control, stabilize, and inspect the function of the diagnostic imaging system. The objective of implementing the QC program is to produce high-quality images by applying a minimum dose of radiation based on the As Low As Reasonably Achievable (ALARA) principle. Therefore, this study aimed to evaluate the status of radiation protection in diagnostic radiology wards of educational hospitals affiliated with Hamadan University of Medical Sciences.

    Materials and Methods: In order to implement the QC programs, standard QC tests were performed for 11 devices at educational hospitals affiliated with Hamadan University of Medical Sciences. A Sweden QC kit called Pirranha was used to carry out the QC tests of X-ray devices, and the dosimetry of controlled areas. Also, the measurement of ambient dose in different places was performed by Graetz dosimeter made in Germany.

    Results: Voltage Reproducibility, Exposure time reproducibility, tube outlet Linearity, and tube outlet reproducibility tests in all radiology departments which were in accordance with standard criteria were accepted; however, about 10% of the total filtration resulted in different centers needed to be corrected. In terms of radiation protection, 5% of the centers had problems related to warning signs, dimensions of radiology rooms were not standard at 7% of wards and also required protection was not sufficient at 9 percent. Moreover, there were problems with 12% of radiology centers in terms of dosimetry results and the efficiency of different parts of the radiology device.

    Conclusion: QC programs performed by authorized companies are costly. But if these programs are done by qualified physicists in addition to reducing costs, we will see a significant increase in the accuracy and precision of the obtained results.

  • XML | PDF | downloads: 64 | views: 89 | pages: 206-213

    Purpose: The goal of the study was to identify earlier pathology of the Left Ventricle (LV) using Speckle Tracking Echocardiography (STE) without angiography results for detecting Coronary Artery Disease (CAD) patients who have need invasive coronary reperfusion.

    Materials and Methods: A total of seventy-five referral patients to angiography (mean age 57±9 years) with chest pain, underwent Two-Dimensional Echocardiography (2D-ECG). Conventional echocardiographic parameters were calculated for the assessment of LV function. End systole and early diastole longitudinal strain, strain rate, and velocity with 2D-STE were estimated to evaluate myocardial function. Discriminated analysis was performed to detect CAD patients from the healthy group.

    Results: According to the angiography results, patients were divided into CAD group (n=55) and healthy group (n=20). There was a significant decrease in longitudinal strain, strain rate, and velocity in patients with CAD compared to the healthy group (systolic longitudinal strain for CAD group -15.9±2.2% vs. -19.6±2.2% for healthy group and early diastolic longitudinal strain for CAD patients -9.5±1.2% vs. -12.0±1.3% for the healthy group) (P-value<0.05). Discriminate analysis of end-systolic and early diastolic longitudinal strain with 81.8% and 89.1% indicated the highest sensitivity, respectively.

    Conclusions: End systolic and early diastolic longitudinal strain parameters derived with the STE method are superior predictors for detecting CAD patients referred to angiography for revascularization.

  • XML | PDF | downloads: 109 | views: 136 | pages: 214-223

    Purpose: Breast cancer is one of the most prevalent diseases among women worldwide. One of the effective ways to reduce the risk of death from breast cancer is early detection by breast screening methods such as thermography. Thermography is non-invasive infrared imaging that detects early symptoms of breast angiogenesis based on the temperature difference and asymmetric patterns between left and right breasts. For better visual perception, it is essential to increase the medical image quality and contrast.

    Materials and Methods: Histogram Equalization (HE) is a common and effective technique for contrast enhancement that uses the whole dynamic range of gray levels. In this paper, we propose to apply the equalization technique to the object part of the image rather than the background. One way is to use Otsu's method for automatic image thresholding. A more efficient approach to extract the body region is to fit a bimodal Gaussian distribution on the temperature information and restrict the equalization on gray level ranges corresponding to temperatures between the mean minus/plus three times of standard deviation.

    Results: We compared the performance of the proposed approach with six conventional HE methods by using objective criteria, including Absolute Mean Brightness Error (AMBE), Peak Signal-to-Noise Ratio (PSNR), Structural Similarity Index (SSI), and Entropy.

    Conclusion: Based on objective measures, as well as subjective visual inspection of the results, the proposed Gaussian model-based HE has better performance in contrast enhancement and brightness preservation among other methods.

  • XML | PDF | downloads: 118 | views: 129 | pages: 224-230

    Purpose: Cold Atmospheric Plasma (CAP) has a wide application in medicine that has many biological effects on bacterial, fungal, yeast, and mammalian cells, particularly cancer cells. In this study, the in-vivo anti-tumor effect of an Atmospheric Pressure Jet Plasma (APJP) source is investigated.

    Materials and Methods: The Glioblastoma Multiforme (GBM) tumoric cells have been implanted in the rat brains. Then, cancerian cells are treated by direct CAP and the Temozolomide (TMZ) drug. Positron Emission Tomography (PET) imaging method is used for evaluating the tumor regions.

    Results: The PET imaging results showed that the GBM cell has a significant reduction in direct plasma treatment and TMZ drug just. This reduction can be clearly observed just five days after treatment. The calculated Brain to the Background Ratio (BBR) shows that the cancer cells in the plasma method are halved after five days. This amount is comparable to the TMZ method that makes two times decreasing in the cancer cells.

    Conclusion: The plasma method can be used as an effective method in treating and removing the GBM cells. Also, CAP has fewer side effects than chemical methods.

Technical Note

  • XML | PDF | downloads: 99 | views: 160 | pages: 231-236

    Purpose: During breast radiotherapy, the organs which are located out of the radiation field such as the thyroid are prone to secondary cancers. The present study aims to evaluate the risk of thyroid cancer in breast cancer radiotherapy in conventional and conformal radiation therapy.

    Materials and Methods: The data related to the thyroid dose in radiotherapy of breast cancer from the study by Behmadi et al. were used. In their study, the thyroid dose was measured on the Alderson RANDO phantom for four different breast cancer treatment plans and two photon energies. Using the Biological Effects of Ionizing Radiation (BEIR) VII model, the risk of thyroid cancer was estimated in conventional and conformal plans with two photon energies (6 and 15 MV) in breast cancer radiotherapy.

    Results: The Lifetime Attributable Risk (LAR) for thyroid cancer in the conventional technique was only 7.5% higher than that in the conformal technique. In the conventional treatment technique, LAR for thyroid cancer at 6 MV in all age groups was 17% higher than the 15 MV energy. However, the LAR for thyroid cancer in conformal technique at 15 MV energy was 50% higher than at 6 MV energy.

    Conclusion: Applying high energy for radiotherapy of breast cancer, in the conventional technique, could reduce the risk of thyroid cancer. But at high energies, the risk of thyroid cancer in the conformal technique is considerably higher than that at low energy. Therefore, it is suggested that the impact of energies be evaluated to reduce the risk of thyroid cancer in breast cancer radiotherapy.

Literature (Narrative) Review(s)

  • XML | PDF | downloads: 162 | views: 181 | pages: 237-245

    Purpose: Rapid Prototyping (RP) methods have for quite some time been utilized to construct complex 3-Dimensional (3D) models in the field of medicine since the 1900s. This paper intends to offer a thorough audit of different RP strategies, especially in Prosthodontics that are relied upon to carry numerous enhancements to this field.

    Materials and Methods: A pursuit was made using the Google scholar web and the PubMed database as a search engine. The keywords; ‘RP’, ‘rapid prototyping’, ‘3D printing’, ‘dentistry’ and ‘prosthodontics’, ‘stereolithography’, ‘selective laser sintering’, ‘fused deposition method’, and ‘inkjet-based system’ were looked at in the title/abstract of distributions. References of selected articles were additionally looked into for conceivable incorporation in the study. The selected articles utilized RP procedures in different fields of dentistry through various methods. Nonetheless, distributions concerning the dental utilization of RP advancements are as yet uncommon.

    Results: Although the concept of layering 3D objects is almost as old as human civilization, this technology has only lately been applied to the construction of 3D complex models in dentistry. Many additional methods appear to be on the horizon that could alter standard dentistry practises in the near future. More unit hours should be included in dentistry curriculums to familiarise dental professionals with the various advantages of this unique technology.

    Conclusion: Lately, RP using the property of adding substances or layering strategies have advanced quickly in different fields of dentistry as they can overcome known disadvantages of subtractive and regular procedures. RP has as of late proposed effective uses in different fields of dentistry, like fabrication of implant surgical guides, structures for Removable Partial Dentures (RPDs), Fixed Partial Dentures (FPDs), wax designs for the dental prosthesis, maxillofacial prosthesis, zirconia prosthesis, and molds for metal castings now as well for complete dentures.