Journal of Biomedical Physics & Engineering
Volume:10 Issue: 1, Jan-Feb 2020

Cervical spinal cord is important and radiosensitive. It is the most critical organ for the head and neck (H&N) cancer patients during radiotherapy. If the delivered dose to the cord is more than tolerance dose, demyelination may occur. Current study aims to analyze the post radiotherapy status of cord in the H&N cancer patients. In this analytical study, sixty patients who received more than 50 Gray (Gy) dose for more than 10 cm length of spinal cord participated in the study. All the patients were clinically examined and magnetic resonance imaging (MRI) was performed for patients who had demyelination symptoms. Adequate medical management was provided for all the patients having demyelination. Out of sixty patients, ten cases were reported with demyelination symptoms, and only six cases gave consent for this study. One patient was found to have irreversible demyelination while five patients had reversible demyelination. Demyelination may occur if long segment spinal cord receives dose more than tolerance limit. However target dose should not be compromised up to 54 Gy to spinal cord.

Hesperidin is a bioflavonoid glycoside mainly found in citrus fruit and has been shown radio-protective potential in various measurement systems.

In this article aims to investigate the radio-protective effect of hesperidin on the liver of Sprague Dawely rats.

In this clinical study, 40 male rats were selected randomly and divided into 8 groups. Group 1 did not receive radiation and hesperidin (sham control). Group 2 received only 100 mg/kg body weight (b.w) of hesperidin for 7 consecutive days (HES group); group 3 exposed to dose of 2Gy whole body gamma radiation (2Gy group), and group 4 and 5 received 50 and 100 mg/kg b.w of HES for 7 consecutive days before 2 Gy gamma radiation, respectively.Group 6 exposed to dose of 8Gy gamma radiation (8Gy group); group 7 and 8 received 50 and 100 mg/kg b.w of HES for 7 days before 8Gy gamma irradiation, respectively. Histopathological evaluation was perfomred 24 hours after radiation.

Administration of hesperidin (50 mg/kg b.w, 7 days) before 2Gy of gamma irradiation led to remove inflammatory mononuclear cells in the portal space. Microscopic findings in the groups receiving two doses of hesperidin (50 and 100 mg/kg b.w, orally, 7 days), before 8Gy of gamma radiation, were similar in a way that extreme dilation of central veins to be seen, however, there was no capillarization.

HES can be offered as a suitable radio-protector in radiotherapy patients and radiation workers.

Radiosensitization using nanoparticles is proposed as a novel strategy for treatment of different cancers. Superparamagnetic iron oxide nanoparticles (SPIONs) have been reported to enhance effects of radiotherapy in several researches. The objective of this research is to investigate the radiosensitization properties of polyglycerol coated SPIONs (PG-SPIONs) on U87-MG cancer cells. In this experimental study, polyglycerol coated SPIONs were synthesized by thermal decomposition method and characterized by FTIR, TEM and VSM analysis. Cellular uptake of nanoparticles by cells was examined via AAS. Cytotoxicity and radiosensitization of nanoparticles in combination with radiation were evaluated by MTT and colony assay, respectively. Mean size of nanoparticles was 17.9±2.85 nm. FTIR verified SPIONs coating by Polyglycerol and VSM showed that they have superparamagnetic behaviour. Viability significantly (P < 0.001) decreased at concentrations above 100µg/ml for SPIONs but not for PG-SPIONs (P > 0.05). Dose verification results by TLD for doses of 2 and 4 Gy were 2±0.19 and 4±0.12 Gy respectively. The combination index for all situations was less than 1 and the effect is antagonism. However, PG-SPIONs combination with 6 MV X-ray reduced survival of U87-MG cells compared to radiation alone but the effect is antagonism.

Glucose transporter (Glut), a cellular transmembrane receptor, has a key role in the metabolism of cell glucose and is also associated with various human carcinomas. In this study, we evaluated a magnetic resonance (MR) imaging contrast agent for tumor detection based on paramagnetic gadolinium oxide (Gd2O3) coated polycyclodextrin (PCD) and modified with glucose (Gd2O3@PCD-Glu) for the targeting of overexpressed glucose receptors. In this experimental study, 3T magnetic resonance imaging (MRI) scanner was used to assess the specific interactions between Glut1-overexpressing tumor cells (MDA-MB-231) and Gd2O3@PCD-Glu NPs. Furthermore, the capacity of transporting Gd2O3@PCD-Glu NPs to tumor cells was evaluated. It was found that the acquired MRI T1 signal intensity of MDA-MB-231 cells that were treated with the Gd2O3@PCD-Glu NPs increased significantly. Based on the results obtained, Gd2O3@PCD-Glu NPs can be applied in targeting Glut1-overexpressing tumor cells in vivo, as well as an MRI-targeted tumor agent to enhance tumor diagnosis. Results have shown that glucose-shell of magnetic nanoparticles has a key role in diagnosing cancer cells of high metabolic activity.

Amyloid fibrils are insoluble arranged aggregates of proteins that are fibrillar in structure and related to many diseases (at least 20 types of illnesses) and also create many pathologic conditions. Therefore understanding the circumstance of fibril formation is very important. This study aims to work on fibrillar structure formation of fibroin (as a model protein). In this experimental study, fibroin was extracted from bombyx mori silk cocoon, and the concentration was obtained by Bradford method. The protein was incubated in a wide range of times (0 min to 7 days) in specific acidity and thermal conditions (pH=1.6, T=70 °C). The assays of UV-vis spectroscopy with congo red, field emission scanning electron microscopy, transmission electron microscopy, atomic force microscopy and circular dichroism spectroscopy were employed to monitor the fibrillation process. Fibroin assemblies were formed upon the process of aggregation and fibril formation with a variety of morphology ranging from nanoparticles to elongated fibrils. The results showed progressive pathway of fibril formation.

During interventional cardiology processes, patients especially women and children receive high radiation doses due to their sensitivity. In this study, we evaluated a pediatric patient dose separately in those undergone intervention cardiac procedure. In this cross sectional study, a public hospital with 252 patients, Entrance Skin Dose (ESD) and Dose-Area Product (DAP) were recorded. Prior to the beginning of fluoroscopic procedure, the chest thickness and Body Mass Index (BMI) of patients were measured. Furthermore, kV, mAs, angle of tube and time of angiography and angioplasty were recorded. Children ratio to all patients underwent the cardiovascular imaging was 1.8. The means of patients’ ESD, DAP and fluoroscopy time were 178.3±17 mGy, 1123.6±11 μGycm2 and 281.4±181.2 s, respectively for coronary angiography. The females were 96.8 under 30 years and their dose mean was 276±37 mGy, 368±24 μGycm2 for ESD and DAP received, respectively with 376s fluoroscopy time. Mean mAs was 359±34 and kV was 71.23±2.7. Above all, a direct and significant correlation was found between the patients’ chest thickness with kV (p=0.037, r = 0.11) and mAs (p<0.001, r = 0.28) variations. The results demonstrated that the number of children referred to the cardiology department and also the dose rate received by them during this test was higher than the data provided for children in developing countries. Paying attention to the children’s perception of high-fluorescence time is necessary in comparison with total angiography time in order to reduce the number of radiation injuries among pediatrics.

Recently, multileaf collimators (MLC) have become an important part of any LINAC collimation system because they reduce the treatment planning time and improve the conformity. Important factors that affect MLCs collimation performance are leaves material composition and their thickness. In this study, we investigate main dosimetric parameters of a typical MLC including dose in the buildup point, physical penumbra as well as average and end leaf leakages. Effects of the leaves geometry and density on these parameters are evaluated. In this analytical study, calculations were performed by using phase space data for Varian ix just above MLC and BEAMnrc/DOSXYZnrc for SSD=100cm and in a water phantom. Based on the results, a new MLC with improved dosimetric parameters is proposed. The physical penumbra for proposed MLC is 4.7mm was compared to 5.16 mm for Millennium 120 leaf. Average leakage in our design is reduced to 1.16% compared to 1.73% for Millennium 120 leaf, the end leaf leakage suggested design also reduced to 4.86% compared to 7.26% for Millennium 120 leaf. The results show that the proposed MLC could improve the dosimetric parameters and conformity of treatment planning.

Recently, ultrasonic neuromodulation research has been an important and interesting issue. Ultrasonic neuromodulation is possible by the use of low-intensity transcranial focused ultrasound (tFUS) to stimulate or inhibit the neural structures. The primary capability of this method is the improvement in the treatment progress of certain neurological and psychiatric disorders noninvasively. tFUS is able to modulate ionic currents and neural depolarization, causing the alteration in electrical properties of neurons. The study aims to investigate the effect of tFUS waves on the electrical behavior of neurons using the simulation method. In the first part of this simulation study, the propagation of tFUS waves throughout the head was simulated to calculate the value of acoustic pressure at the cortex. In the second part, cortical neurons were simulated by a simple model of spiking neurons proposed by Izhikevich for three common dynamics. Then, the capacitance model was proposed to determine the alteration in the electrical behavior of the neurons during tFUS stimulation. At the resting state, the electric potential of the neuron’s membrane through the tFUS stimulation has an amplitude of about 30 mv with the similar oscillatory behavior of the acoustic waveform; while,the ultimate electrical behavior of the neuron’s membrane indicates a decrease in the electric potential when the neurons fire. The electrical behavior of the neuron and the range of its membrane voltage modulated during ultrasonic stimulation. The reduction in the amplitude of membrane potential was observed while neuron spikes.

Aging often results in thoracic kyphosis and adverse postural changes. This may interfere with physiologic activity of paraspinal muscles. Few styles of spinal orthosis have been already used to reduce thoracic kyphosis. This paper describes the development of a novel orthosis, which is designed based on the anatomy of the back muscles. This novel orthosis may potentiate muscle activity and balance control among older hyper kyphotic subjects. The object of this study was to design and preliminary testing of a new orthosis to potentiate muscle activity and balance control among older hyper kyphotic subjects. In this quasi-experimental study, a new postural control orthosis with a textile band structure was designed to provide an additional support for spine and muscles of the back. The functional impact of this orthosis was evaluated in six older hyper-kyphotic subjects. According to the results, the paraspinal muscles activity and balance control were significantly improved. The RMS sEMG of the lumbar and thoracic erector spinae muscles reduced significantly (p<0.05), and a significant improvement (p<0.05) was observed in the balance test when patients put on the novel orthosis (p<0.05). The new orthosis can considerably improve the paraspinal muscles activity at both the upper and lower lumbar levels. It can also recover balance control among elderly subjects.

Nowadays, image de-noising plays a very important role in medical analysis applications and pre-processing step. Many filters were designed for image processing, assuming a specific noise distribution, so the images which are acquired by different medical imaging modalities must be out of the noise. This study has focused on the sequence filters which are selected by a hybrid genetic algorithm and particle swarm optimization. In this analytical study, we have applied the composite of different types of noise such as salt and pepper noise, speckle noise and Gaussian noise to images to make them noisy. The Median, Max and Min filters, Gaussian filter, Average filter, Unsharp filter, Wiener filter, Log filter and Sigma filter, are the nine filters that were used in this study for the denoising of medical images as digital imaging and communications in medicine (DICOM) format. The model has been implemented on medical noisy images and the performances have been determined by the statistical analyses such as peak signal to noise ratio (PSNR), Root Mean Square error (RMSE) and Structural similarity (SSIM) index. The PSNR values were obtained between 59 to 63 and 63 to 65 for MRI and CT images. Also, the RMSE values were obtained between 36 to 47 and 12 to 20 for MRI and CT images. The proposed denoising algorithm showed the significantly increment of visual quality of the images and the statistical assessment.

Excessive range of adductory free moment of the ground reaction force may potentially increase the risk of lower extremity injuries by applying a higher torsional load transmitted to the proximal parts. It was hypothesized that the free moment pattern might be different between hyper-pronated and normal feet subjects. Moreover, a correlation would exist between peak adduction free moment and peak ankle-foot complex abduction at the stance phase of walking. In this cross sectional study, thirty female participants were divided into two groups of asymptomatic hyper-pronated and normal feet. Kinetic and kinematic data were collected using a single force plate and a six-camera motion analysis system during three successful free speed walking trials. Ensemble average curves were extracted from the time normalized individual trials of the stance phase for both free moment and peak ankle-foot complex abduction parameters. Significant differences in peak adductory free moment, peak ankle-foot complex eversion and peak ankle-foot complex abduction were found between normal and hyper-pronated groups (4.90±0.97 Vs. 5.94±0.88, P < 0.01), (3.30±0.95 Vs. 6.28±1.47, P < 0.01) and (4.52±1.16 Vs. 8.23±2.52, P < 0.01) respectively. A significant positive correlation was found between the peak adduction free moment and peak ankle-foot complex abduction in both groups, which was more strongly positive in hyper-pronated group (r = 0.745, p < 0.01 for normal group and r = 0.900, p < 0.01 for hyper-pronated group). As a good measure of torque which is transmitted to the lower extremity, may free moment be a useful biomechanical indicator for both clinical and research purposes.

Magnetic resonance imaging (MRI) using nanostructures has been a proper method for tumor targeting purposes. Different MRI nanomaterials, targeting agents and anticancer drugs have been used for targeting of tumors. This study aims to consider the MRI property of doxorubicin (DOX)-loaded gadolinium/13X zeolite/folic acid (Gd3+/13X/FA) nanocomposite. In this in vitro study, Gd3+/13X/FA/DOX nanocomposite was prepared and the X-ray diffraction, scanning electron microscopy and MTT assay were conducted to evaluate the physicochemical properties of the nanocomposite. MRI was performed at 25°C using a 1.5 T clinical system to determine the T1 relaxation times and subsequently, the T1 relaxivity. The size of the nanocomposite was in the range of 80-200 nm. The nanocomposite without DOX loading (Gd3+/13X/FA) showed compatibility for A549 cells for all concentrations while DOX-loaded nanocomposite was toxic for 62% of the cells at the concentration of 0.4 mg/ml. The T1 relaxivity of Gd3+/13X/FA/DOX nanocomposite was 4.0401 mM-1s-1. Gd3+/13X/FA/DOX nanocomposite shows a T1 relaxivity similar to the conventional gadolinium chelates, and a successful DOX loading.

A bystander effect is biological changes in non-irradiated cells by transmitted signals from irradiated bystander cells, which causes the radiation toxic effects on the adjacent non-irradiated tissues. This phenomenon occurs by agents such as ionizing radiation, ultraviolet radiation (UVR) and chemotherapy. The bystander effect includes biological processes such as damage to DNA, cell death, chromosomal abnormalities, delay and premature mutations and micronuclei production. The most involved genes in creating this phenomenon are cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), the nuclear factor of kappa B (NFkB) and Mitogen-Activated Protein Kinases (MAPKs).Radiation generated reactive oxygen species (ROS) can damage DNA, membranes and protein buildings. Studies have shown that Vitamin C, Hesperidin, and melatonin can reduce the number of ROS and have a protective role.Silver nanoparticles (Ag NPs) are the most abundant nanoparticles produced and when they enter cells, they can create DNA damage. Studies have shown that combined treatment with UVR and silver nanoparticles could form γ-H2AX and 8-hydroxy-2′-deoxyguanosine (8-OHdG) synergistically.This article reviews the direct and the bystander effects of UVR on the nuclear DNA, the effect of radioprotectors and Ag NPs on these effects.

Ankle-foot orthoses (AFOs) have been described to have positive effects on the gait biomechanics in stroke patients. The plantarflexion resistance of an AFO is considered important for hemiplegic patients, but the evidence is still limited. The purpose of this case series was to design and evaluate the immediate effect of an articulated AFO on kinematics and kinetics of lower-limb joints in stroke patients. The articulated AFO with the adjustment of plantarflexion resistance was designed. The spring generates a plantarflexion resistance of the ankle joint at initial stance phase. The efficacy of orthosis was evaluated on two stroke patients in 2 conditions: without an AFO and with the AFO. Results showed the immediate improvements for walking speed, stride length and angular changes of dorsiflexion of the paretic ankle joint during a gait cycle of both subjects using the AFO compared with barefoot walking. The AFO also was able to reduce the paretic knee extension in the single-support phase of the stance and increase the vertical COM displacement during stance phase on the affected leg. In conclusion, the designed AFO affect not only the movement of the ankle joint but also the movements of the knee joint and the vertical COM height. These changes indicate improvement of the first and the second rockers and swing phase gait but not third rocker function. Further investigation is recently underway to compare its effect compared with other AFOs on the gait parameters of hemiplegic patients.