فهرست مطالب

Journal of Biomedical Physics & Engineering
Volume:7 Issue: 2, Mar-Apr 2017

  • تاریخ انتشار: 1396/01/06
  • تعداد عناوین: 10
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  • M. A Hosseini_S. B Jia_M. Ebrahimi_Loushab Page 95
    Background
    The assessment of RBE quantity in the treatment of cancer tumors with proton beams in treatment planning systems (TPS) is of high significance. Given the significance of the issue and the studies conducted in the literature, this quantity is fixed and is taken as equal to 1.1.
    Objective
    The main objective of this study was to assess RBE quantity of proton beams and their variations in different depths of the tumor. This dependency makes RBE values used in TPS no longer be fixed as they depend on the depth of the tumor and therefore this dependency causes some changes in the physical dose profile.
    Materials And Methods
    The energy spectrum of protons was measured at various depths of the tumor using proton beam simulations and well as the complete simulation of a cell to a pair of DNA bases through Monte Carlo GEANT4. The resulting energy spectrum was used to estimate the number of double-strand breaks generated in cells. Finally, RBE values were calculated in terms of the penetration depth in the tumor.
    Results and
    Conclusion
    The simulation results show that the RBE value not fixed terms of the depth of the tumor and it differs from the clinical value of 1.1 at the end of the dose profile and this will lead to a non-uniform absorbed dose profile. Therefore, to create a uniform impact dose area, deep-finishing systems need to be designed by taking into account deep RBE values.
    Keywords: Proton Therapy, Relative Biological Radiation Effectiveness, Geant4, Absorbed Dose, Iso, effective Dose, DSB
  • V. Karami, M. Zabihzadeh Page 101
    Introduction
    Collimating the primary beam to the area of diagnostic interest (ADI) has been strongly recommended as an effective method to reduce patient’s radiation dose and to improve image quality during radiology practice. Lack or inadequate collimation results in excessive radiation dose to patients and deterioration image quality.
    Objective
    To assess the quality of beam collimation during lumbar spine radiography at two general hospitals in Ahvaz, Iran.
    Materials And Methods
    We retrospectively reviewed 830 digital antero-posterior (AP) lumbar spine radiographs in term of beam collimation. For each radiograph, the distance between current and optimal collimation was calculated (in cm). The area of ADI and total field size for each radiograph were also calculated (in cm2).
    Results
    The total mean ADI and irradiated region outside ADI for each radiograph were estimated 360 and 454 cm2, respectively. The total irradiated region outside ADI was 1.26 times more than ADI. In contrast to cranial regions outside ADI, caudal regions were more commonly included inside the primary beam (12% vs. 24.4%; P-value
    Conclusion
    Radiographers should make considerable effort to limit the primary beam to the ADI to reduce patient’s exposure and to increase image quality.
    Keywords: Beam Collimation, Lumbar Spine Radiography, Radiation Protection
  • M. B Shiran_M. Barzegar Marvasti_A. Shakeri Zadeh_M. Shahidi_N. Tabkhi_F. Farkhondeh_E. Kalantar_A. Asadinejad Page 107
    Background
    Hemodialysis is a process of removing waste and excess fluid from blood when kidneys cannot function efficiently. It often involves diverting blood to the filter of the dialysis machin to be cleared of toxic substances. Fouling of pores in dialysis membrane caused by adhesion of plasma protein and other toxins will reduce the efficacy of the filtre.
    Objective
    In This study, the influence of pulsed ultrasound waves on diffusion and the prevention of fouling in the filter membrane were investigated.
    Material and
    Methods
    Pulsed ultrasound waves with frequency of 1 MHz at an intensity of 1 W/cm2 was applied to the high flux (PES 130) filter. Blood and blood equivalent solutions were passed through the filter in separate experimental setups. The amount of Creatinine, Urea and Inulin cleared from both blood equvalent solution and human whole blood passed through High Flux (PES 130) filter were measured in the presence and absence of ultrasound irradiation. Samples were taken from the outlet of the dialyzer every five minutes and the clearance of each constituent was calculated.
    Results
    Statistical analysis of the blood equvalent solution and whole blood indicated the clearance of Urea and Inulin in the presence of ultrasound increased (p
    Conclusion
    It may be concluded that ultrasound, as a mechanical force, can increase the rate of clearance of some toxins (such as middle and large molecules) in the hemodialysis process.
    Keywords: Ultrasound, High Flux Dialyzer, Creatinine, Urea, Inulin
  • A. Naeeji_H. Mozdarani_A. Shabestani Monfared_F. Faeghi_A. A Ahmadi_M. Gholami_R. Behzadi_M. R Momtaz Page 117
    Background
    In many studies, chemicals and natural materials were tested to reduce the harmful effects of radiation. It is known that Famotidine and vitamin C reduce DNA damage.
    Objective
    The aim of this study was to evaluate the radioprotective effect of vitamin C, Cimetidine and Famotidine on gamma-radiation-induced damage on mouse bone marrow.
    Methods
    Six-to-seven week male NMRI mice (28 g ±3) were randomly divided into fourteen groups: control, 2Gy irradiation, six group drugs without irradition (Famotidine, Cimetidine, vitaminC, Fam-Cim, Fam-Vit, Cim-Vit), six groups received drugs and 2Gy radiation with a 60Co |γ|-ray source at room temperature 22 ± 2 °C. The mice were killed 48 hours after irradiation by cervical dislocation. Slides were prepared from bone marrow cells and stained in May-Granwald and Giemsa. Finally, the cells were counted with microscope, frequencies of polychromatic erythrocyte (PCE), normochoromatic erythrocyte (NCE) and their micronuclated cell were recorded. PCE / PCE NCE were calculated.
    Results
    There were significant differences of MNPCE/1000PCE, MNNCE/1000NCE and PCE/PCE㐡 among different groups with similar radiation doses (p≤0.01). Moreover, there were significant differences of MNPCE/1000PCE and PCE/PCE㐡 among different doses of radiation (p≤0.01). While considering MNNCE/1000NCE, there were no significant differences among silimar groups with radiation dose (p˃0.05).
    Conclusion
    Oral administration of Famotidine, vitamin C and Cimetidine demonstrate reliable and similar radioprotective effects. Additionally, the protective effect of single use of these drugs was similar to the combination form. Thus, the oral use of combination, 48 hours after irradiation cannot induce more radioprotective effect.
    Keywords: Micronuclei, Radiation, Radioprotection, Cimetidine, Vitamin C, Famotidine
  • A. Abbaszadeh_G. H Haddadi_Z. Haddadi Page 127
    Normal skin is composed of epidermis and dermis. Skin is susceptible to radiation damage because it is a continuously renewing organ containing rapidly proliferating mature cells. Radiation burn is a damage to the skin or other biological tissues caused by exposure to radiofrequency energy or ionizing radiation. Acute skin reaction is the most frequently occurring side effect of radiation therapy. Generally, any chemical/biological agent given before or at the time of irradiation to prevent or ameliorate damage to normal tissues is called a radioprotector. Melatonin is a highly lipophilic substance that easily penetrates organic membranes and therefore is able to protect important intracellular structures including mitochondria and DNA against oxidative damage directly at the sites where such a kind of damage would occur. Melatonin leads to an increase in the molecular level of some important antioxidative enzymes such as superoxide, dismotase and glutation-peroxidase, and also a reduction in synthetic activity of nitric oxide. There is a large body of evidence which proves the efficacy of Melatonin in ameliorating UV and X ray-induced skin damage. We propose that, in the future, Melatonin would improve the therapeutic ratio in radiation oncology and ameliorate skin damage more effectively when administered in optimal and non-toxic doses.
    Keywords: Radiation, Melatonin, Radiotherapy, Skin Damage
  • S. M J. Mortazavi_Z. Mostafavi Pour_M. Daneshmand_F. Zal_R. Zare_M. A Mosleh Shirazi Page 137
    Background
    Over the past few years, the rapid use of high frequency electromagnetic fields like mobile phones has raised global concerns about the negative health effects of its use. Adaptive response is the ability of a cell or tissue to better resist stress damage by prior exposure to a lesser amount of stress. This study aimed to assess whether radiofrequency radiation can induce adaptive response by changing the antioxidant balance.
    Materials And Methods
    In order to assess RF-induced adaptive response in tissues, we evaluated the level of GSH and the activity of GR in liver. 50 rats were divided into 5 groups. Three groups were pre-exposed to 915 MHz RF radiation, 4 hours per day for one week at different powers, as low, medium and high. 24 hours after the last exposure to radiation, they were exposed to 4 Gy sublethal dose of gamma radiation and then sacrificed after 5 hours. Their livers were removed, washed and were kept at -80o C until used.
    Results
    Our finding showed that pre-exposure to 915 MHz radiofrequency radiation with specific power could induce adaptive response in liver by inducing changes in the activity and level of antioxidant enzymes.
    Conclusion
    It can be concluded that pre-exposure to microwave radiation could increase the level of GSH and the activity of GR enzyme, although these increases were seen just in low power group, and the GR activity was indicated in medium power group. This increase protects tissue from oxidative damage induced by sublethal dose of gamma radiation.
    Keywords: Adaptive Response, RF Radiation, Antioxidant Enzymes, Glutathione Reductase (GR), Reduced Glutathione (GSH)
  • Y. Kiran Kumar_S. B Mehta_M. Ramachandra Page 143
    Background And Objective
    Cerebral Arteriovenous Malformation (CAVM) hemodynamic is disease condition, results changes in the flow and pressure level in cerebral blood vessels. Measuring flow and pressure without catheter intervention along the vessel is big challenge due to vessel bifurcations/complex bifurcations in Arteriovenous Malformation patients. The vessel geometry in CAVM patients are complex, composed of varying diameters, lengths, and bifurcations of various angles. The variations in the vessel diameter and bifurcation angle complicate the measurement and analysis of blood flow features invasively or non-invasively.
    Methods
    In this paper, we proposed a lumped model for the bifurcation for symmetrical and asymmetrical networks in CAVM patients. The models are created using MATLAB Simulation software for various bifurcation angles. Each bifurcation angle created using electrical network- RLC. The segmentation and pre-processing of bifurcation vessels are implemented using adaptive segmentation. The proposed network address clinicians problem by measuring hemodynamic non-invasively. The method is applicable for any types of bifurcation networks with different bifurcation angles in CAVM patients.
    Results
    In this work, we constructed a mathematical model, measured hemodynamic for 23 patients (actual and simulated cases) with 60 vessel bifurcation angles variations. The results indicate that comparisons evidenced highly significant correlations between values computed by the lumped model and simulated mechanical model for both networks with p
    Conclusion
    In this paper, we have modelled different bifurcation types and automatically display pressure and flow non-invasively at different node and at different angles of bifurcation in the complex vessel with help of bifurcation parameters, using lumped parameter model. We have simulated for different bifurcation angles and diameters of vessel for various imaging modality and model extend for different organs. This will help clinicians to measure haemodynamic parameters noninvasively at various bifurcations, where even catheter cannot be reached.
    Keywords: Bifurcation, AVM, Modelling, Lumped Parameter
  • H. Khastavaneh, H. Ebrahimpour Komleh Page 155
    Background
    Multiple Sclerosis (MS) is a degenerative disease of central nervous system. MS patients have some dead tissues in their brains called MS lesions. MRI is an imaging technique sensitive to soft tissues such as brain that shows MS lesions as hyper-intense or hypo-intense signals. Since manual segmentation of these lesions is a laborious and time consuming task, automatic segmentation is a need.
    Materials And Methods
    In order to segment MS lesions, a method based on learning kernels has been proposed. The proposed method has three main steps namely; pre-processing, sub-region extraction and segmentation. The segmentation is performed by a kernel. This kernel is trained using a modified version of a special type of Artificial Neural Networks (ANN) called Massive Training ANN (MTANN). The kernel incorporates surrounding pixel information as features for classification of middle pixel of kernel. The materials of this study include a part of MICCAI 2008 MS lesion segmentation grand challenge data-set.
    Results
    Both qualitative and quantitative results show promising results. Similarity index of 70 percent in some cases is considered convincing. These results are obtained from information of only one MRI channel rather than multi-channel MRIs.
    Conclusion
    This study shows the potential of surrounding pixel information to be incorporated in segmentation by learning kernels. The performance of proposed method will be improved using a special pre-processing pipeline and also a post-processing step for reducing false positives/negatives. An important advantage of proposed model is that it uses just FLAIR MRI that reduces computational time and brings comfort to patients.
    Keywords: Multiple Sclerosis Lesions, Automatic Segmentation, Learning Kernels, MRI, MS
  • M. Taheri_M. Darabyan_E. Izadbakhsh_F. Nouri_M. Haghani_S. A R. Mortazavi_G. Mortazavi_S. M J. Mortazavi_M. Moradi Page 163
    Background
    Due to rapid advances in modern technologies such as telecommunication technology, the world has witnessed an exponential growth in the use of digital handheld devices (e.g. smartphones and tablets). This drastic growth has resulted in increased global concerns about the safety of these devices. Smartphones, tablets, laptops, and other digital screens emit high levels of short-wavelength visible light (i.e. blue color region in the visible light spectrum).
    Material and
    Methods
    At a dark environment, Staphylococcus aureus bacteria were exposed to the light of the tablet and smartphone. The control samples were exposed to the same intensity of light generated by a conventional incandescent light bulb. The growth rate of bacteria was examined by measuring the optical density (OD) at 625 nm by using a spectrophotometer before the light exposure and after 30 to 330 minutes of light exposure.
    Results
    The growth rates of bacteria in both smartphone and tablet groups were higher than that of the control group and the maximum smartphone/control and tablet/control growth ratios were observed in samples exposed to digital screens’ light for 300 min (ratios of 3.71 and 3.95, respectively).
    Conclusion
    To the best of our knowledge, this is the first study that investigates the effect of exposure to light emitted from digital screens on the proliferation of Staphylococcus aureus and its association with acne pathogenesis. Our findings show that exposure to short-wavelength visible light emitted from smartphones and tablets can increase the proliferation of Staphylococcus aureus.
    Keywords: Smartphones, Tablets, Blue Light, Staphylococcus aureus, Acne
  • R. Boostani, M. Sabeti Page 169
    Objective
    In this research, a new approach termed as “evolutionary-based brain map” is presented as a diagnostic tool to classify schizophrenic and control subjects by distinguishing their electroencephalogram (EEG) features.
    Methods
    Particle swarm optimization (PSO) is employed to find discriminative frequency bands from different EEG channels. By deploying the energy of those selected frequency bands from different channels within each time frame (window) on the scalp geometry, a sort of two dimensional points along with their values are created; by applying Lagrange interpolation, an image can be constructed. Finally, by averaging the images belonging to successive time frames, an evolutionary-based brain map is created.
    Results
    In this study, twenty subjects from each group voluntarily participated and their EEG signals were caught from 20 channels. The energy of selected bands for different channels are arranged in a feature vector for each time frame and applied to Fisher linear discriminant analysis (FLDA) resulting in 83.74% diagnostic accuracy between the two groups. The achieved result by the proposed method was much higher than applying the energy of standard EEG bands (delta, theta, alpha, beta and gamma) to the same classifier which just provided 77.04% accuracy. Applying T-test to the achieved results supports the supremacy of the proposed method as an automatic powerful diagnostic tool.
    Conclusion
    The proposed brain map is capable of highlighting the same physiological and anatomical changes which are observed in fMRI, PET and CT as differentiable indicators between controls and schizophrenic patients
    Keywords: EEG Classification, Schizophrenia Disorder, Band Power, PSO