Showing papers in "Journal of biomedical physics & engineering in 2019"
TL;DR: The finding showed that the composite can be considered as a lead-free shielding material and nano-WO3 has a better ability to shield in comparison with the micro- WO3 fillers.
Abstract: Background : In recent years, there has been an increased interest toward non-lead radiation shields consisting of small-sized filler particles doped into polymer matrices. In this paper, we study a new polyvinyl alcohol (PVA)/WO 3 composite in the presence of high-energy gamma photons through simulation via the Monte Carlo N-Particle (MCNP) simulation code. Materials and Methods: An MCNP geometry was first designed in the software based on real-life conditions, and the generated geometry was validated by calculating the mass attenuation coefficient and making relative comparisons with standard tables. Using the lattice card in the MCNP input file, WO 3 was considered as a filler dispersed in a PVA polymer at sizes of 10 µm and 30 nm with a weight concentration of 50 wt%. By defining 10 6 -photons emitted from point sources corresponding to 662, 778, 964, 1112, 1170, 1130 and 1407 keV energy levels, and the F4 tally used to estimate the cell average flux, the values for mass attenuation coefficient and half-value layer (HVL) were calculated. Results: The results show that PVA/WO 3 composite can be considered to shield X and γ-rays in the mentioned energies. However, nano-WO 3 has a better ability to shield in comparison with the micro-WO 3 fillers. The differences in attenuation changed at different energy levels, ascribed to the dominance of pair production occurrence and photon interactions in the composite, which was in good agreement with previous studies. Conclusion: Our finding showed that the composite can be considered as a lead-free shielding material.
27 citations
TL;DR: By optimizing the implant design, life expectancy of the implant can be improved, which will avoid the revision of the hip implant in active adult patients, and the behavior of different implant designs when their cross-sections are varied is shown.
Abstract: Background: The hip joint is the largest joint after the knee, which gives stability to the whole human structure. The hip joint consists of a femoral head which articulates with the acetabulum. Due to age and wear between the joints, these joints need to be replaced with implants which can function just as a natural joint. Since the early 19th century, the hip joint arthroplasty has evolved, and many advances have been taken in the field which improved the whole procedure. Currently, there is a wide variety of implants available varying in the length of stem, shapes, and sizes. Material and Methods: In this analytical study of femur, circular, oval, ellipse and trapezoidal-shaped stem designs are considered in the present study. The human femur is modeled using Mimics. CATIA V-6 is used to model the implant models. Static structural analysis is carried out using ANSYS R-19 to evaluate the best implant design. Results: All the four hip implants exhibited the von Mises stresses, lesser than its yielded strength. However, circular and trapezoidal-shaped stems have less von Mises stress compared to ellipse and oval. Conclusion: This study shows the behavior of different implant designs when their cross-sections are varied. Further, these implants can be considered for dynamic analysis considering different gait cycles. By optimizing the implant design, life expectancy of the implant can be improved, which will avoid the revision of the hip implant in active adult patients
25 citations
TL;DR: Evaluation results are promising and show that the developed computer-based system could be used to quantify scoliosis by measuring Cobb angle, and is easy to use, less operator-dependent, accurate, and reliable.
Abstract: Background: Scoliosis is the most common type of spinal deformity. A universal and standard method for evaluating scoliosis is Cobb angle measurement, but several studies have shown that there is intra- and inter- observer variation in measuring cobb angle manually. Objective: Develop a computer- assisted system to decrease operator-dependent errors in Cobb angle measurement. Methods: The spinal cord in the given x-ray image of the spine is highlighted using contract-stretching technique. The overall structural curvature of the spine is determined by a semi-automatic algorithm aided by the operator. Once the morphologic curve of the spine is determined, in the last step the cobb-angle is estimated by calculating the angle between two normal lines to the spinal curve at the inflection points of the curve. Results: Evaluation results of the developed algorithms using 14 radiographs of patients ( 4 - 40 years old) with cobb angle ranges from 34 - 82 degrees, revealed that the developed algorithm accurately estimated cobb angle. Statistical analysis showed that average angle values estimated using the developed method and that provided by experts are statistically equal. The correlation coefficient between the angle values estimated using the developed algorithm and those provided by the expert is 0.81. Conclusion: Compared with previous algorithms, the developed system is easy to use, less operator-dependent, accurate, and reliable. The obtained results are promising and show that the developed computer-based system could be used to quantify scoliosis by measuring Cobb angle.
22 citations
TL;DR: If NRS was properly designed, implemented and finally evaluated, it could be used as an effective tool to improve nutrition and promote a healthy lifestyle.
Abstract: Background: Nutrition informatics has become a novel approach for registered dietitians to practice in this field and make a profit for health care. Recommendation systems considered as an effective technology into aid users to adjust their eating behavior and achieve the goal of healthier food and diet. The purpose of this study is to review nutrition recommendation systems (NRS) and their characteristics for the first time.Material and Methods: The systematic review was conducted using a comprehensive selection of scientific databases as reference sources, allowing access to diverse publications in the field. The process of articles selection was based on the PRISMA strategy. We identified keywords from our initial research, MeSH database and expert’s opinion. Databases of PubMed, Web of Sciences, Scopus, Embase, and IEEE were searched. After evaluating, they obtained records from databases by two independent reviewers and inclusion and exclusion criteria were applied to each retrieved work to select those of interest. Finally, 25 studies were included. Results: Hybrid recommender systems and knowledge-based recommender systems with 40% and 32%, respectively, were the mostly recommender types used in NRS. In NRS, rule-based and ontology techniques were used frequently. The frequented platform that applied in NRS was a mobile application with 28%.Conclusion: If NRS was properly designed, implemented and finally evaluated, it could be used as an effective tool to improve nutrition and promote a healthy lifestyle. This study can help to inform specialists in the nutrition informatics domain, which was necessary to design and develop NRS.
17 citations
TL;DR: In this article, the antimicrobial effects of a carbon nanoparticles-polypyrrole nanocomposite (C-PPy) upon laser irradiation were investigated to destroy the pathogenic gram-negative Pseudomonas aeruginosa.
Abstract: Background: Nowadays, it is needed to explore new routes to treat infectious bacterial pathogens due to prevalence of antibiotic-resistant bacteria. Antimicrobial photothermal therapy (PTT), as a new strategy, eradicates pathogenic bacteria. Objective : In this study, the antimicrobial effects of a carbon nanoparticles-polypyrrole nanocomposite (C-PPy) upon laser irradiation were investigated to destroy the pathogenic gram-negative Pseudomonas aeruginosa . Material and Methods: In this experimental study, the bacterial cells were incubated with 50, 100 and 250 µg mL -1 concentrations of C-PPy and irradiated with a 808-nm laser at two power densities of 0.5 and 1.0 W cm -2 . CFU numbers were counted for the irradiated cells, and compared to an untreated sample (kept in dark). To explore the antibacterial properties and mechanism(s) of C-PPy, temperature increment, reactive oxygen species formation, and protein and DNA leakages were evaluated. Field emission scanning electron microscopy was also employed to investigate morphological changes in the bacterial cell structures. Results: The results showed that following C-PPy attachment to the bacteria surface, irradiation of near-infrared light resulted in a significant decrement in the bacterial cell viability due to photothermal lysis. Slightly increase in protein leakage and significantly increase intracellular reactive oxygen species (ROS) were observed in the bacteria upon treating with C-PPy. Conclusion: Photo-ablation strategy is a new minimally invasive and inexpensive method without overdose risk manner for combat with bacteria.
15 citations
TL;DR: Substantial evidence that tinnitus network can be successfully detected by consistent measures of the brain networks based on EEG functional connectivity is provided.
Abstract: Background: Tinnitus known as a central nervous system disorder is correlated with specific oscillatory activities within auditory and non-auditory brain areas. Several studies in the past few years have revealed that in the most tinnitus cases, the response pattern of neurons in auditory system is changed due to auditory deafferentation, which leads to variation and disruption of the brain networks. Objective: In this paper, we introduce an approach to automatically distinguish tinnitus individuals from healthy controls based on whole-brain functional connectivity and network analysis. Material and Methods: The functional connectivity analysis was applied to the resting state electroencephalographic (EEG) data of both groups using Weighted Phase Lag Index (WPLI) for various frequency bands in 2-44 Hz frequency range. In this case- control study, the classification was performed on graph theoretical measures using support vector machine (SVM) as a robust classification method. Results: Experimental results showed promising classification performance with a high accuracy, sensitivity, and specificity in all frequency bands, specifically in the beta2 frequency band. Conclusion: The current study provides substantial evidence that tinnitus network can be successfully detected by consistent measures of the brain networks based on EEG functional connectivity.
14 citations
TL;DR: In this article, the authors used the Kirby-Bauer disk diffusion method to test the susceptibility of Staphylococcus aureus and Pseudomonas aeruginosa to electromagnetic waves emitted by mobile phone simulator with a frequency of 900 MHz.
Abstract: Background: The increasing use of telecommunication devices such as Wi-Fi modems and mobile phones in the recent years can change the cellular structure of microorganisms so the generation of electromagnetic waves has led to concern in the community whenever be exposed to these fields and may have harmful effects on human health.Material and Methods: Standard strains of bacteria were prepared on Mueller-Hinton agar for bacterial growth to obtain 0.5 McFarland turbidity (1.5 A— 108 CFU) of bacteria. Antibiotic susceptibility testing using the Kirby-Bauer disk diffusion method was done. For Staphylococcus aureus and Pseudomonas aeruginosa, antibiotics susceptibility test was conducted. The test group was exposed to electromagnetic waves emitted by mobile phone simulator with a frequency of 900 MHz and the control group didin’t exposed.Results: The results revealed that increasing duration of exposure to electromagnetic waves emitted by the mobile simulators with a frequency of 900 MHz especially after 24 h of exposure, can increase bacterial resistance in S. aureus, and P. aeruginosa.Conclusion: Several factors can cause bacterial resistance against antibiotics. One of these factors is the electromagnetic waves emitted from mobile simulator with a frequency of 900 MHz, which can increase the permeability of the cell wall of bacteria.
9 citations
TL;DR: Limited data about the NASA astronaut Scott Kelly show that exposure to space radiation can induce telomere length to regain length, and these differences can possibly indicate the necessity of a minimum dose/dose-rate for induction of adaptive response.
Abstract: Telomere length and stability is a biomarker of aging, stress, and cancer. Shortening of telomeres and high level of DNA damages are known to be associated with aging. Telomere shortening normally occurs during cell division in most cells and when telomeres reach a critically short length, DNA damage signaling and cellular senescence can be triggered. The induction of an adaptive response by space radiation was first documented in 2003. Telomere length alterations are among the most fascinating observations in astronauts and residents of high background radiation areas. While study of the chronic exposure to high levels of background ionizing radiation in Kerala, India failed to show a significant influence on telomere length, limited data about the NASA astronaut Scott Kelly show that exposure to space radiation can induce telomeres to regain length. Interestingly, his telomeres shortened again only a couple of days after returning to Earth. The difference between these situations may be due to the differences in radiation dose, dose-rate, and/or type of radiation. Moreover, Scott Kelly’s spacewalks (EVA) could have significantly increased his cumulative radiation dose. It is worth noting that the spacewalks not only confer a higher dose activity but are also characterized by a different radiation spectrum than inside the space craft since the primary particles would not interact with the vehicle shell to generate secondary radiation. Generally, these differences can possibly indicate the necessity of a minimum dose/dose-rate for induction of adaptive response (the so called Window effect).
9 citations
TL;DR: In this article, the authors used 2D correlation spectra to distinguish between normal and carious human teeth in the presence of vibrational bands in 437.87 cm-1, 581.89 cm 1, 953.73 cm 1 and 1054.3 cm 1 with smaller intensity than in carious spectra.
Abstract: Background: Carious lesions are formed by a complex process of chemical interaction between dental enamel and its environment. They can cause cavities and pain, and are expensive to fix. It is hard to characterize in vivo as a result of environment factors and remineralization by ions in the oral cavity. Objectives: The development of a technique that gives early diagnosis which is non-invasive, is of crucial importance for publichealth. Raman spectroscopy is a technique that can fulfil these requirements. The main goal of this work was to use Raman spectroscopy to differentiate between normal and carious human teethinvivo. The samples used in this study were collected by traditional human teeth. Method: An in vivo Raman spectroscopy system andspecialized fiber optic probe has been designed to obtain spectra from tissue. Theseprobes are filtered to reduce the background signal from the fiber optics and the collection fiberutilizes beam steering to optimize the collection effectiv. Results: In order to detect any demineralization and carious versus sound pit and fissure enamel, the spectral data sets are analyzed by the proposed scheme to demonstrate the utility of generalized 2D correlation spectra. Potential applications of this 2D correlation approach are then explored. The Raman spectra in the normal tissue showed thepresence of vibrational bands in 437.87 cm-1, 581.89 cm-1, 953.89 cm-1 and 1054.73 cm-1 with smaller intensity than in the carious spectra. Image construction from the peak intensity produced chemical maps of apatite concentration. Conclusion: Such two-dimensional correlation spectra emphasize spectral features not readily observable in conventional one-dimensional spectra.No correlation is observed in mode-to-mode intensity fluctuations indicating that the changes inmode intensities are completely independent. Theoreticalcalculations provide convincing evidence that the fluctuationsare not the result of diffusion, orientation or local electromagnetic field gradients but rather are the result of subtle variations ofthe excited-state lifetime, energy and geometry of the molecule and producing a signature response for carious detection.
9 citations
TL;DR: According to the outcomes of this work, MAGICA polymer gel can be recommended as a reliable dosimeter to investigate the dosimetric effect of GNP size and also a useful method to validate the current radiobiological and simulation studies.
Abstract: Background: Gold nanoparticles (GNPs) are among the most promising radiosensitive materials in radiotherapy. Studying the effective sensitizing factors such as nanoparticle size, concentration, surface features, radiation energy and cell type can help to optimize the effect and possible clinical application of GNPs in radiation therapy. In this study, the radiation sensitive polymer gel was used to investigate the dosimetric effect of GNP size in megavoltage (MV) photon beam radiotherapy. Material and Methods: GNPs with the size of 30nm, 50nm and 100nm in diameter were used. Transmission electron microscope (TEM) and dynamic light scattering (DLS) were applied to analyze the size of nanoparticles. The MAGICA polymer gel was synthesized and impregnated with different sizes of GNPs. The samples were irradiated with 6MV photon beam and 24 hours after irradiation, they were read using a Magnetic Resonance Imaging (MRI) scanner. Macroscopic Dose Enhancement Factor (DEF) was measured to compare the effect of GNP size. The MAGICA response of the 6MV x-ray beam was verified comparing Percentage Depth Dose (PDD) curve extracted from polymer gel dosimetry and Treatment Planning System (TPS). Results: MAGICA polymer gel dose response curve was linear in the range of 0 to 10 Gy. DEFs by adding 30nm, 50nm and 100nm GNPs were 1.1, 1.17 and 1.12, respectively. PDD curves of polymer gel dosimeter and treatment planning system were in good agreement. Conclusion : The results indicated a substantial increase in DEF uses a MV photon beam in combination with GNPs of different sizes and it was inconsistent with previous radiobiological studies. The maximum DEF was achieved for 50nm GNPs in comparison with 30nm and 100nm leading to the assumption of self-absorption effect by larger diameters. According to the outcomes of this work, MAGICA polymer gel can be recommended as a reliable dosimeter to investigate the dosimetric effect of GNP size and also a useful method to validate the current radiobiological and simulation studies.
9 citations
TL;DR: Arbutin is a strong radioprotector for reducing the radiation effect on the whole-body tissues by measuring ALP, ALT and AST enzyme activity levels.
Abstract: Background : Medical use of ionizing radiation has direct/indirect undesirable effects on normal tissues. In this study, the radioprotective effect of arbutin in megavoltage therapeutic x-irradiated mice was investigated using serum alkaline phosphatase (ALP), alanine aminotransferase (ALT), and asparate amniotransferase (AST) activity measurements. Material and Methods: In this analytical and experimental lab study, sixty mice (12 identical groups) were irradiated with 6 MV x-ray beam (2 and 4 Gy in one fraction). Arbutin concentrations were chosen 50, 100, and 200 mg/kg and injected intraperitoneal 2 hours before irradiation. Samples of peripheral blood cells were collected and serum was separated on the 1, 3, and 7 days post-x-radiation; in addition, the level of ALP, ALT, and AST were measured. Data were analyzed using one-way ANOVA, and Tukey HSD test. Results: X-radiation (2 and 4 Gy) increased the ALT and AST activity levels on the 1, 3, and 7 days post- irradiation, but the ALP level significantly increased on the 1 and 7 days and decreased on the third day compared to the control group (P< 0.001). ALP, ALT and AST activity levels in “2 and 4 Gy x irradiation + distilled water” groups were significantly higher than “2 and 4 Gy irradiation + 50, 100, and 200 mg/kg arbutin” groups on the first and seventh day post-irradiation (P< 0.001). Conclusion: Arbutin is a strong radioprotector for reducing the radiation effect on the whole-body tissues by measuring ALP, ALT and AST enzyme activity levels. Furthermore, the concentration of 50 mg/kg arbutin showed higher radioprotective effect.
TL;DR: An Android app for estimating MOL via analyzing the surface EMG signal and evaluation results revealed that the presented app performed as well as MegaWin 3.0 software in estimating M OL.
Abstract: Background : Electromyography (EMG) signal processing and Muscle Onset Latency (MOL) are widely used in rehabilitation sciences and nerve conduction studies. The majority of existing software packages provided for estimating MOL via analyzing EMG signal are computerized, desktop based and not portable; therefore, experiments and signal analyzes using them should be completed locally. Moreover, a desktop or laptop is required to complete experiments using these packages, which costs. Objective: Develop a non-expensive and portable Android application (app) for estimating MOL via analyzing surface EMG. Material and Methods: A multi-layer architecture model was designed for implementing the MOL estimation app. Several Android-based algorithms for analyzing a recorded EMG signal and estimating MOL was implemented. A graphical user interface (GUI) that simplifies analyzing a given EMG signal using the presented app was developed too. Results : Evaluation results of the developed app using 10 EMG signals showed promising performance; the MOL values estimated using the presented app are statistically equal to those estimated using a commercial Windows-based surface EMG analysis software (MegaWin 3.0). For the majority of cases relative error <10%. MOL values estimated by these two systems are linearly related, the correlation coefficient value ~ 0.93. These evaluations revealed that the presented app performed as well as MegaWin 3.0 software in estimating MOL. Conclusions : Recent advances in smart portable devices such as mobile phones have shown the great capability of facilitating and decreasing the cost of analyzing biomedical signals, particularly in academic environments. Here, we developed an Android app for estimating MOL via analyzing the surface EMG signal. Performance is promising to use the app for teaching or research purposes.
TL;DR: Deciding on techniques and energies required for preparing an acceptable treatment plan in terms of scattering and neutron contamination is a key issue that may affect the probability of secondary cancer in a patient.
Abstract: Background: Given the importance of scattered and low doses in secondary cancer caused by radiation treatment, the point dose of critical organs, which were not subjected to radiation treatment in breast cancer radiotherapy, was measured. Objective: The purpose of this study is to evaluate the peripheral dose in two techniques of breast cancer radiotherapy with two energies. Methods: Eight different plans in two techniques (conventional and conformal) and two photon energies (6 and 15 MeV) were applied to Rando Alderson Phantom’s DICOM images. Nine organs were contoured in the treatment planning system and specified on the phantom. To measure the photon dose, forty-eight thermoluminescence dosimeters (MTS700) were positioned in special places on the above nine organs and plans were applied to Rando phantom with Elekta presice linac. To obtain approximately the same dose distribution in the clinical organ volume, a wedge was used on planes with an energy of 6 MeV photon. Results: Point doses in critical organs with 8 different plans demonstrated that scattering in low-energy photon is greater than high-energy photon. In contrast, neutron contamination in high-energy photon is not negligible. Using the wedge and shield impose greater scattering and neutron contamination on patients with low-and high-energy photon, respectively. Conclusion: Deciding on techniques and energies required for preparing an acceptable treatment plan in terms of scattering and neutron contamination is a key issue that may affect the probability of secondary cancer in a patient.
TL;DR: Bladder cumulated activity was the most contribution in the effective dose of patients scanned with 99m Tc-DTPA, and using a hybrid planar/SPECT method can cause an increase in accumulated activity accuracy for the region of interest.
Abstract: Introduction: In this study, organ radiation doses were calculated for the renal agent 99m Tc-DTPA in children. Bio-kinetic energy of 99m Tc-DTPA was evaluated by scintigraphy and estimates for absorbed radiation dose were provided using standard medical internal radiation dosimetry (MIRD) techniques. Material and Methods: In this applied research, fourteen children patients (6 males and 8 females) were imaged using a series of planar and SPECT images after injecting with technetium-99m diethylenetriaminepentaacetic acid ( 99m Tc-DTPA). A hybrid planar/SPECT method was used to plot time-activity curves to obtain the residence time of the source organs and also MIRDOSE software was used to calculate the absorbed dose of every organ. P-values were calculated using t-tests in order to make a comparison between the adsorbed doses of male and female groups.. Results: Mean absorbed doses (µGy/MBq) for urinary bladder wall, kidneys, gonads, liver and adrenals were 213.5±47.8, 12.97±6.23, 12.0±2.5, 4.29±1.47, and 3.31±0.96, respectively. Furthermore, the mean effective dose was 17.5±3.7 µSv/MBq. There was not any significant difference in the mean absorbed dose of the two groups. Conclusion: Bladder cumulated activity was the most contribution in the effective dose of patients scanned with 99m Tc-DTPA. Using a hybrid planar/SPECT method can cause an increase in accumulated activity accuracy for the region of interest. Moreover, patient-specified internal dosimetry is recommended.
TL;DR: It is proposed that Wi-Fi exposure acted on bacteria in stressful manner by increasing antibiotic resistance and motility of Escherichia coli 0157H7, as well as enhancing biofilm formation by EscherICHia coli, Staphylococcus aureus and Staphyllococcus epidermis.
Abstract: Background: The radiation emitted from electromagnetic fields (EMF) can cause biological effects on prokaryotic and eukaryotic cells, including non-thermal effects. Objective: The present study evaluated the non-thermal effects of wireless fidelity (Wi-Fi) operating at 2.4 GHz part of non-ionizing EMF on different pathogenic bacterial strains (Escherichia coli 0157H7, Staphylococcus aureus, and Staphylococcus epidermis). Antibiotic resistance, motility, metabolic activity and biofilm formation were examined. Material and Methods: In this case-control study, a Wi-Fi router was used as a source of microwaves and also bacterial cells were exposed to Wi-Fi radiation continuously for 24 and 48 hours. The antibiotic susceptibility was carried out using a disc diffusion method on Muller Hinton agar plates. Motility of Escherichia coli 0157H7 was conducted on motility agar plates. Cell metabolic activity and biofilm formation were performed using 3-(4, 5-Dimethylthiazol-2yl)-2, 5-diphenyltetrazolium bromide (MTT) assay and crystal violet quantification, respectively. Results: The exposure to Wi-Fi radiation altered motility and antibiotic susceptibility of Escherichia coli 0157H7. However, there was no effect Wi-Fi radiation on antibiotic susceptibility of Staphylococcus aureus and Staphylococcus epidermis. On the other hand, the exposed cells, as compared to the unexposed control, showed an increased metabolic activity and biofilm formation ability in Escherichia coli 0157H7, Staphylococcus aureus and Staphylococcus epidermis. Conclusion: These results proposed that Wi-Fi exposure acted on bacteria in stressful manner by increasing antibiotic resistance and motility of Escherichia coli 0157H7, as well as enhancing biofilm formation by Escherichia coli 0157H7, Staphylococcus aureus and Staphylococcus epidermis. The findings may have implications for the management of serious diseases caused by these infectious bacteria.
TL;DR: The results indicate that a drop in dose before the air cavities and in the air zone occurs due to the lack of scattered radiation, and the rise in dose was due to to the passage of more radiation from the air cavity and dose deposition after theAir cavity.
Abstract: Background: Considering that some vital organs exist in the head and neck region, the treatment of tumors in this area is a crucial task. The existence of air cavities, namely sinuses, disrupt the radiotherapy dose distribution. The study aims to analyze the effect of maxillary, frontal, ethmoid and sphenoid sinuses on radiotherapy dose distribution by Monte Carlo method. Materials and Methods: In order to analyze the effect of the cavities on dose distribution, the maxillary, frontal, ethmoid and sphenoid sinus cavities were simulated with (3×3.2×2) cm 3 , (2×2×3.2) cm 3 , (1×1×1.2) cm 3 and(1×1×2) cm 3 dimensions. Results: In the analysis of the dose distribution caused by cavities, some parameters were observed, including: inhomogeneity of dose distribution in the cavities, inhomogeneity of dose on the edges of the air cavities and dispersion of the radiations after the air cavity. The amount of the dose in various situations showed differences: before the cavity a 0.64% and a 2.76% decrease, a 12.06% and a 17.17% decrease in the air zone, and a 2.25% and a 5.9% increase after the cavity. Conclusion: The results indicate that a drop in dose before the air cavities and in the air zone occurs due to the lack of scattered radiation. Furthermore, the rise in dose was due to the passage of more radiation from the air cavity and dose deposition after the air cavity. The changes in dose distribution are dependent on the cavity size and depth. As a result, this has to be noted in the treatment planning and MU calculations of the patient.
TL;DR: Run-length matrix features not only have high potential for characterization but also can help physicians to diagnose kidney failure after transplantation.
Abstract: Background: The ability to monitor kidney function after transplantation is one of the major factors to improve care of patients. Objective: Authors recommend a computerized texture analysis using run-length matrix features for detection of changes in kidney tissue after allograft in ultrasound imaging. Material and Methods: A total of 40 kidney allograft recipients (28 male, 12 female) were used in this longitudinal study. Of the 40 patients, 23 and 17 patients showed increased serum creatinine (sCr) (increased group) and decreased sCr (decreased group), respectively. Twenty run-length matrix features were used for texture analysis in three normalizations. Correlations of texture features with serum creatinine (sCr) level and differences between before and after follow-up for each group were analyzed. An area under the receiver operating characteristic curve (Az) was measured to evaluate potential of proposed method. Results: The features under default and 3sigma normalization schemes via linear discriminant analysis (LDA) showed high performance in classifying decreased group with an Az of 1. In classification of the increased group, the best performance gains were determined in the 3sigma normalization schemes via LDA with an Az of 0.974 corresponding to 95.65% sensitivity, 91.30% specificity, 93.47% accuracy, 91.67% PPV, and 95.45% NPV. Conclusion: Run-length matrix features not only have high potential for characterization but also can help physicians to diagnose kidney failure after transplantation.
TL;DR: This report tries to convince the readers to accept the author’s opinion that exposure to the 5G high frequencies is not a real concern, and states that as the outermost layer of the authors' epidermis, the outer layer of the skin, is basically dead cells, therefore the living cells in their skin are not damaged by 5G radiofrequency radiation.
Abstract: Received: 24 July 2019 Accepted: 30 July 2019 Areport published in the New York Times “The 5G Health Hazard, That Isn’t, How one scientist and his inaccurate chart led to unwarranted fears of wireless technology” addressed the controversies over the safety of 5G technology. Unfortunately, the approach of New York Times in this report is not scientific. William J. Broad in his report published July 16, 2019 criticized Dr. Bill P Curry for not considering the so called “protective effect of human skin”. As a consultant and physicist, in 2000 Bill P Curry was invited to study the health risks associated with the use of laptops and wireless networks in 250,000 students in Broward County public schools in Florida. His graph labeled “Microwave Absorption in Brain Tissue (Grey Matter)” showed that electromagnetic fields are “likely to be a serious health hazard.” Broad blames Dr. Curry for not considering the low penetration of high frequencies and hence not paying attention to the shielding effect of the human skin “His analysis failed to recognize the protective effect of human skin. At higher radio frequencies, the skin acts as a barrier, shielding the internal organs, including the brain, from exposure. Human skin blocks the even higher frequencies of sunlight”. It seems that the author believes that as the outermost layer of our epidermis, the outer layer of our skin, is basically dead cells, therefore the living cells in our skin are not damaged by 5G radiofrequency radiation. Given this consideration, this report tries to convince the readers to accept the author’s opinion that exposure to the 5G high frequencies is not a real concern. Moving to ionizing radiation, alpha particle can be a good analogy for this claim. However, the depth of penetration in human tissue (skin, muscle and tissues with high water content) for a frequency of 10 GHz which lies in 5G frequency spectrum is about a few mm. Given this consideration, high frequency 5G radiofrequency electromagnetic fields (RF-EMF) easily penetrate living skin cells and can make them severely damaged. Moreover, stating “Human skin blocks the even higher frequencies of sunlight” is misleading the people because although skin blocks the sunlight, this exposure increases the risk of skin cancer. The non-ionizing 5G RF-EMF can behave like high LET ionizing radiations which have the maximum energy deposition per unit distance. Considering the low penetration and very high energy deposition per unit distance of 5G, this can lead to generation of high levels of free radicals in a short distance which in turn increases the risk of skin cancer. It’s worth noting that Yakymenko et al. have reported that among 100 peer-reviewed studies regarding the oxidative effects of low-intensity radiofrequency radiation that were available at the time of their study, in general, 93 confirmed that radiofrequency radiation induced oxidative effects in biological systems [1]. Editorial
TL;DR: Whether cancer treatments could be more successful if immune system is boosted, not destroyed by the treatments such as chemotherapy is discussed.
Abstract: Abscopal effect, a radiobiology term meaning “away from target”, was practically unheard of just ten years ago. This effect describes the elimination and cure of a non-treated tumor when another part of the body is irradiated. Successful treatment of cancer in patients with multiple metastatic foci has sporadically been reported. Abscopal effect after radiotherapy has been introduced as the key factor which induced an anticancer response in these metastatic lesions. Moreover, not receiving chemotherapy is reported to have a role in cancer regression after radiotherapy. Given this consideration, it can be hypothesized that standard radiotherapy doses, which usually classified as high-dose, may cause cancer cells to expose or release their sequestered antigens that had been previously masked. Furthermore, radiotherapy can decrease the suppressive effect of regulatory T cells which usually down modulate immune responses against cancers. Moreover, some data show that low dose total-body irradiation (TBI) alone (without standard localized high dose radiotherapy) may cause suppression of distant metastasis of tumor cells. Induction of a “whole body abscopal effect” can be involved in suppression of distant metastasis. Here we discuss whether cancer treatments could be more successful if immune system is boosted, not destroyed by the treatments such as chemotherapy.
TL;DR: In this study, representative techniques for segmentation of abnormal tissues are reviewed and, as experimental results demonstrate, the methods based on deep learning techniques perform better than other methods that are usually based on handy feature engineering techniques.
Abstract: Nowadays, medical image modalities are almost available everywhere. These modalities are bases of diagnosis of various diseases sensitive to specific tissue type. Usually physicians look for abnormalities in these modalities in diagnostic procedures. Count and volume of abnormalities are very important for optimal treatment of patients. Segmentation is a preliminary step for these measurements and also further analysis. Manual segmentation of abnormalities is cumbersome, error prone, and subjective. As a result, automated segmentation of abnormal tissue is a need. In this study, representative techniques for segmentation of abnormal tissues are reviewed. Main focus is on the segmentation of multiple sclerosis lesions, breast cancer masses, lung nodules, and skin lesions. As experimental results demonstrate, the methods based on deep learning techniques perform better than other methods that are usually based on handy feature engineering techniques. Finally, the most common measures to evaluate automated abnormal tissue segmentation methods are reported.
TL;DR: IMRT plans were superior to 3D-CRT plans in terms of estimated NTCP for studied critical organs, and different mathematical models provided different quantitative outcome for TCP of prostate cancer plans.
Abstract: Purpose: In the current study, using different radiobiological models, tumor control probability (TCP) and normal tissue complication probability (NTCP) of radiotherapy plans were calculated for three-dimensional conformal radiation therapy (3D-CRT) and intensity modulated radiation therapy (IMRT) of prostate cancer. Methods and Materials: 10 prostate plans were randomly selected among patients undergoing radiation therapy of prostate cancer. For each patient, 3D-CRT and IMRT plans were designed to deliver, on average 76 Gy and 82 Gy to planning target volume, respectively. Using different radiobiological models including Poisson, equivalent uniform dose (EUD) and Lyman-Kutcher-Burman (LKB), TCP and NTCP were calculated for prostate and critical organs including bladder, rectum and femoral heads. Results: IMRT plans provided significantly lower NTCP for bladder, rectum and femoral heads using LKB and EUD models (p-value <0.05). The EUD-calculated TCP for prostate cancer revealed no considerable improvement for IMRT plans relative to 3D-CRT plans. However, the TCPs calculated by Poisson model were dependent on α/β, and higher TCP for IMRT relative to 3D-CRT was seen for α/β higher than 5. Conclusion: It can be concluded that IMRT plans were superior to 3D-CRT plans in terms of estimated NTCP for studied critical organs. On the other hand, different mathematical models provided different quantitative outcome for TCP of prostate cancer plans. More clinical studies are suggested to confirm the accuracy of studied radiobiological models.
TL;DR: The radiation dose received by patient during HSG examination in the study environment is investigated in order to enhance optimization of procedures and the associated dose, thereby minimizing radiation risks.
Abstract: Background: Hysterosalpingography (HSG) is an indispensable tool for diagnosing infertility in females. The procedure exposes female reproductive organs to ionizing radiation as the genitals are irradiated during the process. Investigating patient absorbed dose during the procedures is essential for effective radiological protection of the patient. Objective: This study aims to investigate the radiation dose received by patient during HSG examination in the study environment in order to enhance optimization of procedures and the associated dose, thereby minimizing radiation risks. Material and Methods: The prospective pilot study, was conducted in four tertiary healthcare institutions in Southwest Nigeria. Thermoluminescence dosimeter (TLD 100) was used to determine the Entrance Surface Dose (ESD) of 80 patients presented for HSG investigation. The corresponding effective dose, ovary, uterus and urinary bladder doses were evaluated using PCXMC software. Results: The mean entrance surface doses (ESD) obtained from the four centers were 18.58±6.31 mGy, 15.18±2.27 mGy, 17.44±3.43 mGy and 34.24±11.98 mGy for SW1, SW2, SW3 and SW4 centers, respectively. The corresponding mean of effective doses were 1.54±0.63 mSv, 1.24±0.28 mSv, 1.41±0.30 mSv and 2.53±0.94 mSv for SW1, SW2, SW3 and SW4 centers, respectively. The resulting mean doses to the ovary, urinary bladder and uterus were also presented. Conclusion: The results obtained in general are comparable with international standards. It was, however, recommended that study centers with high doses should conduct dose audit in order to enhance patient safety.
TL;DR: The high T2/T1 relaxivity ratio of the iron oxide-4A nanocomposite confirms it’s potential to act as a T2 contrast agent.
Abstract: Background : Magnetic resonance imaging (MRI) contrast agents have an important role to differentiate healthy and diseased tissues. Access and design new contrast agents for the optimal use of MRI are necessary. This study aims to evaluate iron oxide–4A nanocomposite ability to act as a magnetic resonance imaging contrast agent. Materials and Methods: Iron oxide–4A nanocomposite (F4A) was synthesized. MTT assay was used to consider the nanocomposite safety for cell culture. The T1 and T2 relaxation times were measured using a 1.5 Tesla clinical MRI scanner. Then the corresponding relaxivities were determined. Results : The average particle diameter of the nanocomposite was 50 to 100 nm based on scanning electron microscope (SEM) image. A linear relationship between relaxation rates and the Fe concentration of the nanocomposite was obtained. The T1 and T2 relaxivities of the nanocomposite were calculated 5.413 and 1092.1 mM -1 .s -1 , respectively which led to the T2/T1 relaxivity ratioof 201.75. Conclusion : The high T2/T1 relaxivity ratio of the iron oxide–4A nanocomposite confirms it’s potential to act as a T2 contrast agent.
TL;DR: It is believed that providing and expanding the required equipment, gated radiotherapy will be a routine technique for treatment of chest and abdominal tumors in all clinical radiotherapy centers in the world by considering benefits of respiratory gating techniques in increasing efficiency of patient treatment in the near future.
Abstract: One of the most important challenges in treatment of patients with cancerous tumors of chest and abdominal areas is organ movement. The delivery of treatment radiation doses to tumor tissue is a challenging matter while protecting healthy and radio sensitive tissues. Since the movement of organs due to respiration causes a discrepancy in the middle of planned and delivered dose distributions. The moderation in the fatalistic effect of intra-fractional target travel on the radiation therapy correctness is necessary for cutting-edge methods of motion remote monitoring and cancerous growth irradiancy. Tracking respiratory milling and implementation of breath-hold techniques by respiratory gating systems have been used for compensation of respiratory motion negative effects. Therefore, these systems help us to deliver precise treatments and also protect healthy and critical organs. It seems aspiration should be kept under observation all over treatment period employing tracking seed markers (e.g. fiducials), skin surface scanners (e.g. camera and laser monitoring systems) and aspiration detectors (e.g. spirometers). However, these systems are not readily available for most radiotherapy centers around the word. It is believed that providing and expanding the required equipment, gated radiotherapy will be a routine technique for treatment of chest and abdominal tumors in all clinical radiotherapy centers in the world by considering benefits of respiratory gating techniques in increasing efficiency of patient treatment in the near future. This review explains the different technologies and systems as well as some strategies available for motion management in radiotherapy centers.
TL;DR: The direct and the bystander effects of UVR on the nuclear DNA, the effect of radioprotectors and Ag NPs on these effects are reviewed.
Abstract: 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.
TL;DR: The results show that the primary collimator has the largest contribution to production of neutrons and in all of the accelerators, the neutron strength also increases with increasing energy.
Abstract: Introduction: Considering the importance of photoneutron production in linear accelerators, it is necessary to describe and measure the photoneutrons produced around modern linear accelerators.Material and Methods: The main components of the head of Siemens Primus Plus linac were simulated using MCNPX 2.7.0 code. The contribution of different components of the linac in photoneutron production, neutron source strength, neutron source strength and photon and electron spectra were calculated for the flattening filter and flattening filter free cases for the 18 MV photon beam, and was scored for three fields of 5 A— 5 cm2, 10 A— 10 cm2 and 20 A— 20 cm2 in size.Results: The results show that the primary collimator has the largest contribution to production of neutrons. Moreover, the photon fluence for the flattening filter free case is 8.62, 6.51 and 4.62 times higher than the flattening filter case for the three fields, respectively. The electron fluences for the flattening filter free case are 4.62, 2.93 and 2.79 times higher than with flattening filter case for the three fields under study, respectively. In addition to these cases, by increasing the field size, the contribution of neutron production related to the jaws is reduced, so that when the field size increases from 5 A— 5 cm2 to 20 A— 20 cm2, a 17.93% decrease in photoneutron production was observed.Conclusion: In all of the accelerators, the neutron strength also increases with increasing energy. The calculated neutron strength was equal to 0.83A—1012 neutron Gy −1 at the isocenter.
TL;DR: HES can be offered as a suitable radio-protector in radiotherapy patients and radiation workers and remove inflammatory mononuclear cells in the portal space in Sprague Dawely rats.
Abstract: Background: Hesperidin is a bioflavonoid glycoside mainly found in citrus fruit and has been shown radio-protective potential in various measurement systems. Objective: In this article aims to investigate the radio-protective effect of hesperidin on the liver of Sprague Dawely rats. Material and Methods: 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. Results: 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. Conclusion: HES can be offered as a suitable radio-protector in radiotherapy patients and radiation workers.
TL;DR: In this article, the authors found that the radiation scattering from patient is the main cause of dose near the edge of treatment field, while the leakage radiation has the main contribution at large distances from the treatment field.
Abstract: Received: 21 January 2018 Accepted: 28 March 2018 Along with chemotherapy and surgery, radiotherapy remains as an important modality in tumor treatment, as it is used to treat approximately 50% of all patients with localized cancer [1-3]. However, the use of radiotherapy inevitably leads to exposing the organs/tissues that are entirely or partially excluded from the treatment volume [4]. Therefore, out-of-field regions receive dose values due to secondary radiation sources, including scattered radiation from collimators and beam modifiers, photon leakage through the treatment head of the linear accelerator (Linac), and internal patient radiation scattering [5]. In a study by Kase, et al. [6], it was found that the radiation scattering from patient is the main cause of dose near the edge of treatment field, while the leakage radiation has the main contribution at large distances from the edge of treatment field. Although dose value in out-of-field region is smaller than that in-field region, these doses can induce secondary malignancies with a long-latency period (particularly in radiosensitive tissue/organs) [7-8]. Furthermore, knowledge of the peripheral dose can be of very interest when considering radiation therapy for patients with pregnancy or patients with cardiac pacemaker. Therefore, accurate measurement of the peripheral dose to normal tissue outside the target volume is essential, to have an adequate clinical decision for patients with implanted electronic devices or pregnant patients as well as more accurate estimation of the radiation-induced secondary cancer risk. Generally, it has been accepted that the dose calculation accuracy in out-of-field regions by treatment planning systems (TPSs) is poor. This can be found out by reviewing the specified protocols for quality assurance and commissioning of TPSs, which suggest an agreement criterion of up to 50% in the low dose/small dose gradient region of photon beams between the TPS calculations and experimental measurements [9-10]. There are several factors which can affect poor performance of TPSs in out-of-field regions, including the lack of TPS commissioning for out-of-field regions, the limitations of TPSs in modelling the dose contributions from contaminated electrons originated from the collimator assembly, flattening filter, and secondary scattered photons from the Linac’s head [11-12]. Editorial
TL;DR: It is demonstrated that the TS is a key parameter for measuring the maximum and minimum SI and also TS plays the role in determining the maximum linear relationship between the MRI contrast agent concentration and SI in an in vivo perfusion study.
Abstract: Background: The relationship between the concentration of contrast agents and signal intensity (SI) are affected by some image parameters, phase-encoding scheme, magnetic field strength, image sequences, and iron oxide nanoparticles used and Gd-DTPA as MRI contrast agents. Objective: In this article, the effect of saturation times (TSs) on the maximum and minimum SI, and also the linear relationship between the concentration of the contrast agent and SI are evaluated. Additionally, we evaluated the concentration of contrast agent that results the minimum SI using a saturation recovery TurboFLASH sequence. Material and Methods: A phantom was designed to hold vials with different concentrations of Gd-DTPA (0–19.77mmol/L). The mean SI was acquired from the nine central pixels of every vial at various TSs. Results: This study shows that the maximum SI in an image is dependent on short TSs (up to 400ms) and independent of long TSs (400–1000ms). The result also shows that the concentration at which a maximum linear relationship between concentration and SI is maintained that gave an R 2 equal to 0.95 and 0.99 dependent on the TS. Moreover, the outcome demonstrates that as TS increases, the concentration of the contrast agent decreases. This causes SI to be minimized. Conclusion: This study demonstrated that the TS is a key parameter for measuring the maximum and minimum SI and also TS plays the role in determining the maximum linear relationship between the MRI contrast agent concentration and SI in an in vivo perfusion study.
TL;DR: The proposed quantitative radiomic framework yielded promising results, which can guide physicians to make better and more precise decisions and increase the chance of treatment success.
Abstract: Background: Selection of the best treatment modalities for lung cancer depends on many factors, like survival time, which are usually determined by imaging. Objectives: To predict the survival time of lung cancer patients using the advantages of both radiomics and logistic regression-based classification models.Material and Methods: Fifty-nine patients with primary lung adenocarcinoma were included in this retrospective study and pre-treatment contrast-enhanced CT images were acquired. The patients lived more than 2 years were classified as the ‘Alive’ class and otherwise as the ‘Dead’ class. In our proposed quantitative radiomic framework, we first extracted the associated regions of each lung lesion from pre-treatment CT images for each patient via grow cut segmentation algorithm. Then, 40 radiomic features were extracted from the segmented lung lesions. In order to enhance the generalizability of the classification models, the mutual information-based feature selection method was applied to each feature vector. We investigated the performance of six logistic regression-based classification models. Results: It was observed that the mutual information feature selection method can help the classifier to achieve better predictive results. In our study, the Logistic regression (LR) and Dual Coordinate Descent method for Logistic Regression (DCD-LR) models achieved the best results indicating that these classification models have strong potential for classifying the more important class (i.e., the ‘Alive’ class). Conclusion: The proposed quantitative radiomic framework yielded promising results, which can guide physicians to make better and more precise decisions and increase the chance of treatment success.