Journal of Biomedical Physics & Engineering
Volume:12 Issue: 3, May-Jun 2022

Approximately 50% of dental amalgam is elemental mercury by weight. Accumulating body of evidence now shows that not only static magnetic fields (SMF) but both ionizing and non-ionizing electromagnetic radiations can increase the rate of mercury release from dental amalgam fillings. Iranian scientists firstly addressed this issue in 2008 but more than 10 years later, it became viral worldwide.

This review was aimed at evaluating available data on the magnitude of the effects of different physical stressors (excluding chewing and brushing) on the release of toxic mercury from dental amalgam fillings and microleakage.

The papers reviewed in this study were searched from PubMed, Google Scholar, and Scopus (up to 1 December 2019). The keywords were identified from our initial research matching them with those existing on the database of Medical Subject Headings (MeSH). The non-English papers and other types of articles were not included in this review.

Our review shows that exposure to static magnetic fields (SMF) such as those generated by MRI, electromagnetic fields (EMF) such as those produced by mobile phones; ionizing electromagnetic radiations such as X-rays and non- Ionizing electromagnetic radiation such as lasers and light cure devices can significantly increase the release of mercury from dental amalgam restorations and/or cause microleakage.

The results of this review show that a wide variety of physical stressors ranging from non-ionizing electromagnetic fields to ionizing radiations can significantly accelerate the release of mercury from amalgam and cause microleakage.

Modern radiotherapy techniques are using advanced algorithms; however, phantoms used for quality assurance have homogeneous density; accordingly, the development of heterogeneous phantom mimicking human body sites is imperative to examine variation between planned and delivered doses. This study aimed to analyze the accuracy of planned dose by different algorithms using indigenously developed heterogeneous thoracic phantom (HT). In this experimental study, computed tomography (CT) of HT was done, and the density of different parts was measured. The plan was generated on CT images of HCP with 6 and 15 Megavoltage (MV) photon beams using different treatment techniques, including three-dimensional conformal radiotherapy (3D-CRT), intensity-modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT). Plans were delivered by the linear accelerator, and the dose was measured using the ion chamber (IC) placed in HT; planned and measured doses were compared. Density patterns for different parts of the fabricated phantom, including rib, spine, scapula, lung, chest wall, and heart were 1.849, 1.976, 1.983, 0.173, 0.855, and 0.833 g/cc, respectively. Variation between planned and IC estimated doses with the tolerance (±5%) for all photon energies using different techniques. Acuros-XB (AXB) showed a slightly higher variation between computed and IC estimated doses using HCP compared to the analytical anisotropic algorithm (AAA). The indigenous heterogeneous phantom can accurately simulate the dosimetric scenario for different algorithms (AXB or AAA) and be also utilized for routine patient-specific QA.

Rosemary plant, with phenolic compounds, is known as an antioxidant herb and able to scavenge free radical agents in the biological environment; therefore, it is expected that the rosemary essential oil (R-EO) shows the radioprotective effect to protect individuals who are physically in contact with ionizing radiation. This study aimed to assess the radioprotective effect of R-EO on human peripheral blood mononuclear cells (PBMCs). In this experimental study, the toxicity of the rosemary essential oil on PBMCs was assessed by the 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide (MTT) assay. The cells were irradiated at 0. 25 and 200 cGy using a 6 MV X-ray linear accelerator. The survival, apoptosis, necrosis, and survival enhancement factors of cells were analyzed by MTT and flow cytometry analyses with a non-toxic concentration of the rosemary essential oil (IC10). Irradiation of cells in the presence of R-EO caused a significant increase in cell survival compared with the control in both 25 and 200 cGy radiation doses. Also, the percentages of apoptosis and necrosis of cells showed a significant decrease compared with the control. Rosemary essential oil as a natural and non-toxic compound could show favorable radioprotective effects in such a way that significantly increases the survival rate and decreases the percentage of apoptosis and necrosis of PBMCs.

Quantitative Electroencephalography (qEEG) is a non-invasive method used to quantify electrical activity over the cortex. QEEG provides an accurate temporal resolution of the brain activity, making it a useful tool for assessing cortical function during challenging tasks. This study aimed to investigate postural adjustments in older adults in response to an external perturbation. In this observational study, nineteen healthy older adults were involved. A 32-channel qEEG was employed to track alterations in beta power on the electrodes over the two sensory-motor areas. Integrated electromyographic activity (IntEMG) of the leg muscles was evaluated in response to perturbations under predictable and unpredictable conditions. The results indicated higher beta power during late-phase in the Cz electrode in both conditions. IntEMG was significantly greater in the tibialis anterior muscle during both conditions in the CPA epoch. In predictable condition, a positive correlation was found between the beta power over C4 (r = 0.560, p = 0.013) and C3 (r = 0.458, p = 0.048) electrodes and tibialis anterior muscle amplitude, and between beta power in C4 and gastrocnemius amplitude (r = 0.525, p = 0.021). In unpredictable condition, there was a positive correlation between beta power over the C4 and the tibialis anterior amplitude (r = 0.580, p = 0.009) and also it over the C3 and the tibialis anterior amplitude (r = 0.452, p = 0.049). Our findings demonstrate that sensorimotor processing occurs in the brain during response to perturbation. Furthermore, cortical activity appeared to be greatest during the recruitment of the muscles upon late-phase in older adults.

Melanoma is categorized as one of the most malignant, severe, and lethal cancers of the skin. Regarding the lack of efficiency of conventional therapies for most patients, novel therapeutic strategies are strongly required. The current study aimed to assess the impact of AZD6738- an ATR kinase inhibitor- in combination with 6 MV X-ray on the human melanoma cell line (A375). In this experimental study, cells were treated with different concentrations of AZD6738 for 24 and 48 h in the presence and absence of radiation (2 Gy, 4 Gy, and 6 Gy). The cell viability and cell proliferation assay were examined in both experimental and control groups by MTT and colony formation techniques, respectively. The results indicated that by increasing the concentration of AZD6738, the cell viability was markedly diminished in all treatment groups. As expected, the cell viability of the cells treated with AZD6738 and radiation was significantly lower than the group treated with AZD6738 alone. Besides, the combinatory treatment significantly decreased cell proliferation in the melanoma cell line. The combination of AZD6738 with radiation resulted in a significant increase in cytotoxicity by a 50% increase in cell death when used at concentrations of 0.3 µM, 1 µM, 1.51 µM, and 1.61 µM, respectively. The combination of AZD6738 with radiation possesses a synergistic effect on the reduction of the cell viability and proliferation of melanoma cells. This present study provides insight into the impact of Ataxia Telangiectasia and Rad3-related kinase (ATR) inhibition on the potential role of this kinase in the suppression of melanoma cell proliferation.

Radiation-induced hematopoietic suppression and myelotoxicity can occur due to the nuclear accidents, occupational irradiation and therapeutic interventions. Bone marrow dysfunction has always been one of the most important causes of morbidity and mortality after ionizing irradiation. This study aims to investigate the protective effect of telmisartan against radiation-induced bone marrow injuries in a Balb/c mouse model. In this experimental study, male Balb/c mice were divided into four groups as follow: group 1: mice received phosphate buffered saline (PBS) without irradiation, group 2: mice received a solution of telmisartan in PBS without irradiation, group 3: mice received PBS with irradiation, and group 4: mice received a solution of telmisartan in PBS with irradiation. A solution of telmisartan was prepared and administered orally at 12 mg/kg body weight for seven consecutive days prior to whole body exposing to a single sub-lethal dose of 5 Gy X-rays. Protection of bone marrow against radiation induced damage was investigated by Hematoxylin-Eosin (HE) staining assay at 3, 9, 15 and 30 days after irradiation. Histopathological analysis indicated that administration of telmisartan reduced X-radiation-induced damage and improved bone marrow histology. The number of different cell types in bone marrow, including polymorphonuclear /mononuclear cells and megakaryocytes significantly increased in telmisartan treated group compared to the only irradiated group at all-time points. The results of the present study demonstrated an efficient radioprotective effect of telmisartan in mouse bone marrow against sub-lethal X-irradiation.

The application of radar systems in telecommunications and aerospace science is important. However, engineering department’s staff various tissues are always under chronic radiation generated by the radar fields which may affect health. This study aims to evaluate the risk of radar wave exposure and to explore the effects and limitations. In this simulation study, an adult body model versus 1 watt source with a distance of 50 centimeters exposure has been simulated using the CST STUDIO SUITE. Furthermore, various physical and electrical properties of each tissue and organ for different frequencies and exposure times have been studied. The exposure dose limitations have been considered using the International Commission on Non-Ionizing Radiation Protection (ICNIRP) safety and health guide report. Total body absorbed doses for 4 GHz, 8 GHz, and 12 GHz frequency, and 6 min, 4 h, and 30 days exposure time, have been calculated as 1.136×10-5, 1.598×10-5, 1.58×10-3, 1.521×10-5, 3.122×10-5, 4.52×10-3, 4.1×10-5, 10-4, and 10-2, respectively. It has shown that the internal organs of the body and head will be under more risk by reducing radar frequencies from 12 GHz to 4 GHz. On the other hand, the higher frequency can cause a higher risk to the human skin. In addition, the maximum Specific Absorption Rate (SAR) for each case has been calculated. The results show that for this normalized source, the safety criteria have been respected, but for a higher source, the calculations must be repeated.

Breast cancer is considered one of the most common cancers in women caused by various clinical, lifestyle, social, and economic factors. Machine learning has the potential to predict breast cancer based on features hidden in data. This study aimed to predict breast cancer using different machine-learning approaches applying demographic, laboratory, and mammographic data. In this analytical study, the database, including 5,178 independent records, 25% of which belonged to breast cancer patients with 24 attributes in each record was obtained from Motamed cancer institute (ACECR), Tehran, Iran. The database contained 5,178 independent records, 25% of which belonged to breast cancer patients containing 24 attributes in each record. The random forest (RF), neural network (MLP), gradient boosting trees (GBT), and genetic algorithms (GA) were used in this study. Models were initially trained with demographic and laboratory features (20 features). The models were then trained with all demographic, laboratory, and mammographic features (24 features) to measure the effectiveness of mammography features in predicting breast cancer. RF presented higher performance compared to other techniques (accuracy 80%, sensitivity 95%, specificity 80%, and the area under the curve (AUC) 0.56). Gradient boosting (AUC=0.59) showed a stronger performance compared to the neural network. Combining multiple risk factors in modeling for breast cancer prediction could help the early diagnosis of the disease with necessary care plans. Collection, storage, and management of different data and intelligent systems based on multiple factors for predicting breast cancer are effective in disease management.

Low back pain is one of the most common problems for pregnant women during pregnancy. Most belts are designed for supporting the surface of the symphysis pubis or upper anterior iliac spine without any support in the lumbar region.

This study aimed to compare the related effects between the new design and the current belt on the pain and function of pregnant women.

In this randomized control trial study, 48 pregnant women with pelvic and lumbar pain participated. The participants were randomly divided into three groups: current belt, modified belt, and control. Pain intensity assessment, pelvic girdle (PG), and Oswestry disability index (ODI) questionnaires were utilized at the beginning of the study and three weeks later.

The pain intensity decreased more in the modified belt group than in the current belt group. ODI and PG scores decreased in two belt groups after three weeks of follow-up. However, this decrease was greater in the modified belt group, there was no statistically significant difference.

The disability decreased in both groups using the belts, and their function was improved. Accordingly, the use of a modified belt with lumbar and PG support can significantly reduce back and pelvic pain in pregnant women compared to the current pelvic belt.

Nowadays, the introduction of the so-called ‘diabetes technology’, either hardware/device or software, to different aspects of day-to-day living in patients with diabetes aims to improve blood glucose control and various lifestyle features. The coordination of vast context of diabetes education/training, particularly in the area of medical nutrition therapy, is considered as a great concern. On the other hand, Iranian food culture consists of a set of traditional dietary patterns and food consumption habit. The study was aimed to develop “the Comprehensive Mobile Application of Advanced Carbohydrate Counting and Diet- and Insulin-Regimen Planning” to help type 1 diabetic patients, improving their health status. The programming language of Kotlin, JavaScript, Node JS, and HTML5 was used for the mobile app development. The app was developed with the following abilities: 1) educating users on different aspects of disease control including, updated general treatment guidelines on physical activity, medical nutrition and insulin therapy, stress management, and the patient’s specific goals and dietary needs, 2) performing advanced carbohydrate counting using both picture-represented and kitchen-scale of carbohydrate foods as well as traditional Iranian foods, 3) recommending the patient’s specific insulin dose, either short- or rapid-acting, based on the carbohydrate content of the selected meal or the selected amount of Iranian foods, 4) recommending the personalized insulin dose needed for decreasing the high blood glucose levels, and 5) performing 3 and 4 simultaneously. Developing Carbulin was an effort to increase type 1 diabetes self-management using the traditional Iranian dietary pattern and menu.