فهرست مطالب
Journal of Biomedical Physics & Engineering
Volume:6 Issue: 1, Jan-Feb 2016
- تاریخ انتشار: 1394/12/23
- تعداد عناوین: 6
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Page 1BackgroundEBT and EBT3 radioChromic films have been used in radiotherapy dosimetry for years.ObjectiveThe aim of the current study is to compare EBT and EBT3 radioChromic films in dosimetry of radiotherapy fields for treatment of parotid cancer.MethodsCalibrations of EBT and EBT3 films were performed with identical setups using a 6 MV photon beam of a Siemens Primus linac. Skin dose was measured at different points in the right anterior oblique (RAO) and right posterior oblique (RPO) fields by EBT and EBT3 films on a RANDO phantom.ResultsWhile dosimetry was performed with the same conditions for the two film types for calibration and in phantom in parotid cancer radiotherapy, the measured net optical density (NOD) in EBT film was found to be higher than that from EBT3 film. The minimum difference between these two films under calibration conditions was about 2.9% (for 0.2 Gy) with a maximum difference of 35.5% (for 0.5 Gy). In the therapeutic fields of parotid cancer radiotherapy at different points, the measured dose from EBT film was higher than the EBT3 film. In these fields the minimum and maximum measured dose differences were 16.0% and 25.5%, respectively.ConclusionEBT film demonstrates higher NOD than EBT3 film. This effect may be related to the higher sensitivity of EBT film over EBT3 film. However, the obtained dose differences between these two films in low dose range can be due to the differences in fitting functions applied following the calibration process.Keywords: RadioChromic film, EBT, EBT3, Radiotherapy, Parotid cancer
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Page 13BackgroundTherapeutic and diagnosis properties of radioactive gold nanoparticle (198-AuNPs) cause them to be suitable for detection and treatment of tumors.ObjectiveElectrical and optical properties of PEG-198AuNPs were examined in this paper. Polyethylene Glycol (PEG)-198 AuNPs can be used for treatment and diagnosis of small intestine tumors.MethodsWireless fluorescence capsule endoscopy will be able to detect emission lights of triggered Au by external light. First, the output electrical field was calculated by DDSCAT software. Secondly, tumor and distribution of PEG-198 gold nanoparticles were modeled using Monte Carlo simulation and finally dose delivered throughout a solid tumor when the PEG-198 gold nanoparticles linked to each cell was calculated.ResultsPolyethylene Glycol functionalized gold nanoparticles (AuNPs) possess optimized sizes (30 nm core diameter and 70 nm hydrodynamic diameters) to target individual tumor cells. Surface distribution to receive doses of up to 50Gy was simulated. Activities and absorbed doses by the tumors with 0.25cm and 0.5cm radius were 187.9mCi and 300mCi and 72 and 118 Gy,respectively.ConclusionTherapeutic and diagnosis properties of 198-AuNPs show that it can be used for treatment and detection of small bowel tumors in early stage of growing.Keywords: Radioactive gold nanoparticle, Wireless fluorescence capsule endoscopy, Small intestine, Polyethylene glycol, Dose, activity
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Page 21Background And ObjectiveProfessional radiation workers are occupationally exposed to long-term low levels of ionizing radiation. Occupational health hazards from radiation exposure, in a large occupational segment of the population, are of special concern. Biological dosimetry can be performed in addition to physical dosimetry with the aim of individual dose assessment and biological effects.MethodsIn this biodosimetry study, some hematological parameters have been examined in 40 exposed and 40 control subjects who were matched by gender, age and occupational records (±3 years) in Kermanshah hospitals in Iran (2013-2014). The occupational radiation dose was measured by personal dosimetry device (film badges). The data was analyzed using SPSS V.20 and statistical tests such as two-sided Students t-test.ResultsExposed subjects had a median exposure of 0.68±1.58 mSv/year by film badge dosimetry. Radiation workers with at least a 10-year record showed lower values of Mean Hemoglobin (Hb) and Mean Corpuscular Volume (MCV) compared to the control group (pConclusionAlthough the radiation absorbed doses were below the permissible limits based on the ICRP, this study showed the role of low-level chronic exposure in decreasing Hb and MCV in the blood of radiation workers with at least 10 years records. Therefore, the findings from the present study suggest that monitoring of hematological parameters of radiation workers can be useful as biological dosimeter, and also the exposed medical personnel should carefully follow the radiation protection instructions and radiation exposure should be minimized as possible.Keywords: Biological Dosimetry, Radiation Exposure, Radiation Dosimetry, Biological Effects
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Page 27BackgroundSubstantial evidence indicates that exposure to electromagnetic fields (EMF) above certain levels can affect human health through triggering some biological responses. According to WHO, short-term exposure to EMF at the levels present in the home/environment do not cause any apparent detrimental effects in healthy individuals. However, now, there is a debate on whether long-term exposure to low level EMF can evoke detrimental biological responses. Although based on the Communications Act of 1934, selling, advertising, using, or importing mobile jammers which block cell phone calls and text messages are illegal acts, in some countries these devices are being used for security purpose and for prevention of cheating during examinations.MethodsIn this study 30 male Wistar rats were randomly divided into 3 groups of 10 each. The control group received no radiation. The sham exposure group was exposed to a switched-off jammer device. After fasting for 12 hours, the exposure group was exposed to EMFs at a distance of 50 cm from the jammer. Blood samples were collected from the tail vein after 24, 48 and72 hours and fasting blood sugar was measured by using a common blood glucose monitor (BIONIME GM110, Taiwan). The significance level was considered 5% and SPSS Ver. 21 was used for statistical analysis. The data were analyzed by ANOVA followed by Tukeys test.ResultsA statistically significant difference was observed between blood sugar level in the control and exposure groups after 24, 48 and 72 hours of continuous irradiation (p values wereConclusionShort-term exposure to electromagnetic field generated by mobile phone jammer can reduce blood sugar level in adult male rats. These findings, in contrast with our previous results, lead us to this conclusion that the use of these signal blocking devices in very specific circumstances may have some therapeutic effects. However, further studies have to be performed to find out the exact mechanism by which Jammer EMFs reduce fasting blood sugar.Keywords: Electromagnetic fields, Mobile jammer, Fasting blood sugar
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Page 33Background And ObjectiveNumerical modeling of biological structures would be very helpful tool to analyze hundreds of human body phenomena and also diseases diagnosis. One physiologic phenomenon is blood circulatory system and heart hemodynamic performance that can be simulated by utilizing lumped method. In this study, we can predict hemodynamic behavior of one artery of circulatory system (anterior cerebral artery) when disease such as internal carotid artery occlusion is occurred.MethodPressure-flow simulation is one the leading common approaches for modeling of circulatory system behavior and forecasts of hemodynamic in numerous physiological conditions. In this paper, by using lumped model (electrical analogy), CV system is simulated in MATLAB software (SIMULINK environment).ResultsThe performance of healthy blood circulation and heart is modeled and the obtained results used for further analyses. The stenosis of internal carotid artery at different rates was, then, induced in the circuit and the effects are studied. In stenosis cases, the effects of internal carotid artery occlusion on left anterior cerebral artery pressure waveform are investigated.ConclusionThe findings of this study may have implications not only for understanding the behavior of human biological system at healthy condition but also for diagnosis of diseases in circulatory and cardiovascular system of human body.Keywords: Numerical modeling, Lumped method, Cardiovascular system, Internal carotid artery, Stenosis
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Page 41According to the World Health Organization (WHO), factors such as growing electricity demand, ever-advancing technologies and changes in social behaviour have led to steadily increasing exposure to man-made electromagnetic fields. Dental amalgam fillings are among the major sources of exposure to elemental mercury vapour in the general population. Although it was previously believed that low levels are mercury (i.g. release of mercury from dental amalgam) is not hazardous, now numerous data indicate that even very low doses of mercury cause toxicity. There are some evidence indicating that perinatal exposure to mercury is significantly associated with an increased risk of developmental disorders such as autism spectrum disorders (ASD) and attention-deficit hyperactivity disorder (ADHD). Furthermore, mercury can decrease the levels of neurotransmitters dopamine, serotonin, noreprenephrine, and acetylcholine in the brain and cause neurological problems. On the other hand, a strong positive correlation between maternal and cord blood mercury levels is found in some studies. We have previously shown that exposure to MRI or microwave radiation emitted by common mobile phones can lead to increased release of mercury from dental amalgam fillings. Moreover, when we investigated the effects of MRI machines with stronger magnetic fields, our previous findings were confirmed. As a strong association between exposure to electromagnetic fields and mercury level has been found in our previous studies, our findings can lead us to this conclusion that maternal exposure to electromagnetic fields in mothers with dental amalgam fillings may cause elevated levels of mercury and trigger the increase in autism rates. Further studies are needed to have a better understanding of the possible role of the increased mercury level after exposure to electromagnetic fields and the rate of autism spectrum disorders in the offspring.Keywords: Autism spectrum disorders (ASD), Maternal Exposure, Electromagnetic fields, Mothers, Mercury release, Dental amalgam