Measuring the dose�width product and proposing the local diagnostic reference level in panoramic dental radiography: a multi-center study from Iran

Objective: Although radiation exposure associated with dental radiography is relatively low, patient exposure must be kept practically low. Therefore, it is necessary for each country to establish its own diagnostic reference levels (DRLs) suitable for its equipment and practice. In the present study, dose-width product (DWP) values for panoramic dental radiography were measured and a local DRL was established. Methods: Five panoramic devices from five radiology clinics of Kashan, Iran were selected to measure the DWP values of panoramic dental radiography. To investigate the DWP values, the parameters of each patient�s exposure (e.g., tube voltage, tube current, and exposure time) at these five radiology clinics were extracted. Then, the dose value received by each patient was measured based on a CT pencil chamber. Finally, the overall median DWP values for the patients with small, medium, and large sizes were obtained, and these values were considered as the local DRLs for panoramic dental radiography. Results: A total of 99 adult patients were included in the present study. The findings demonstrated that the median and third-quartile DWP values for these five radiology clinics ranged from 42.3 to 94.3 and 49.7 to 142.8 mGy mm, respectively. The local DRL values, which were established as the overall median DWP values, were 43.4, 52.0, and 80.3 mGy mm for the adults with small, medium, and large sizes, respectively. Conclusion: The local DRL proposed in this study for the adult with standard/medium size was lower than those proposed by other reports and seemed acceptable for panoramic radiography in Kashan, Iran. © 2020, Japanese Society for Oral and Maxillofacial Radiology and Springer Nature Singapore Pte Ltd

Measuring the dose–width product and proposing the local diagnostic reference level in panoramic dental radiography: a multi-center study from Iran

Objective: Although radiation exposure associated with dental radiography is relatively low, patient exposure must be kept practically low. Therefore, it is necessary for each country to establish its own diagnostic reference levels (DRLs) suitable for its equipment and practice. In the present study, dose-width product (DWP) values for panoramic dental radiography were measured and a local DRL was established. Methods: Five panoramic devices from five radiology clinics of Kashan, Iran were selected to measure the DWP values of panoramic dental radiography. To investigate the DWP values, the parameters of each patient’s exposure (e.g., tube voltage, tube current, and exposure time) at these five radiology clinics were extracted. Then, the dose value received by each patient was measured based on a CT pencil chamber. Finally, the overall median DWP values for the patients with small, medium, and large sizes were obtained, and these values were considered as the local DRLs for panoramic dental radiography. Results: A total of 99 adult patients were included in the present study. The findings demonstrated that the median and third-quartile DWP values for these five radiology clinics ranged from 42.3 to 94.3 and 49.7 to 142.8 mGy mm, respectively. The local DRL values, which were established as the overall median DWP values, were 43.4, 52.0, and 80.3 mGy mm for the adults with small, medium, and large sizes, respectively. Conclusion: The local DRL proposed in this study for the adult with standard/medium size was lower than those proposed by other reports and seemed acceptable for panoramic radiography in Kashan, Iran. © 2020, Japanese Society for Oral and Maxillofacial Radiology and Springer Nature Singapore Pte Ltd

Numerical Solutions of Duffing Van der Pol Equations on the Basis of Hybrid Functions

In the present work, a new approximated method for solving the nonlinear Duffing-Van der Pol (D-VdP) oscillator equation is suggested. The approximate solution of this equation is introduced with two separate techniques. First, we convert nonlinear D-VdP equation to a nonlinear Volterra integral equation of the second kind (VIESK) using integration, and then, we approximate it with the hybrid Legendre polynomials and block-pulse function (HLBPFs). The next technique is to convert this equation into a system of ordinary differential equation of the first order (SODE) and solve it according to the proposed approximate method. The main goal of the presented technique is to transform these problems into a nonlinear system of algebraic equations using the operational matrix obtained from the integration, which can be solved by a proper numerical method; thus, the solution procedures are either reduced or simplified accordingly. The benefit of the hybrid functions is that they can be adjusted for different values of n and m, in addition to being capable of yield greater correct numerical answers than the piecewise constant orthogonal function, for the results of integral equations. Resolved governance equation using the Runge-Kutta fourth order algorithm with the stepping time 0.01 s via numerical solution. The approximate results obtained from the proposed method show that this method is effective. The evaluation has been proven that the proposed technique is in good agreement with the numerical results of other methods

The effect of date palm seed extract as a new potential radioprotector in gamma-irradiated mice

Objective: Date palm seed extract (DPSE) has various compounds revealing antioxidant features. This study aimed to evaluate the radioprotective effect of DPSE in total body gamma irradiation. Materials and Methods: At first, chemical characteristics of DPSE were analyzed by ultraviolet, visible and Fourier transform infrared spectroscopy. Then, the toxicity of DPSE was assessed. For this purpose, 60 mice were divided into five groups, and each of the groups were injected by the doses of 100, 200, 300, 400, and 500 mg/kg, respectively. At the termination of the experiment, mortality rate and weight loss of all mice were evaluated over a period of 30 days. Finally, the radioprotective effect of DPSE was evaluated by dividing 36 mice into three groups: control, test, and placebo and then were irradiated by Cobalt-60. Results: According to the findings, there was no mortality due to DPSE. Furthermore, for the maximum dose of 500 mg/kg, the number of mice surviving at the termination of the experiment with and without injection of DPSE was reported as 83 and 41, respectively. In addition, a significant difference was obtained between radiated mice with and without DPSE injection (P = 0.035). Conclusion: The findings showed that DPSE injected into mice before irradiation has no toxicity and could protect mice from lethal effects of total body irradiation. The use of DPSE as a new radioprotector agent in the human needs further studies, particularly clinical trials. © 2018 Journal of Cancer Research and Therapeutics | Published by Wolters Kluwer-Medknow

Investigation of the Field Size Effect on Wedge Field Isodose Curves Angle for Two Energies; 6 & 18 MV, produced by VARIAN 2100C Linac

Introduction: Nowadays,  considerable developments  in  the field  of  radiotherapy have  been  achieved.  They  include  the  advances  made  in  the  equipments  and  treatment  planning  techniques  which  require  highly complex calculations. Such achievements have made it possible to treat cancer patients not only  with  higher  radiation  dose  but  also  with  higher  precision  and  consequently  increasing  the  chance  of  curing the cancer. However, the conventional techniques requiring physical wedge are still being used  but with a lesser frequency. One of the wedge parameters needed to be measured is the wedge angle. It is  the angle that the horizontal line creates with the tilted isodose curve at a specific depth and for a certain  field size.   In this study, the variation of wedge angle for different field sizes was evaluated using dosimetric and  mathematical method.  Material and Methods: For the wedge fields with a dimension of 6×6 to 20×20 cm 2 , the wedge angle  for  two  photon  energies  of  6  and  18  MV  was  measured  by  the  dosimetric  method.  For  these  measurements, the conventional wedges having the nominal wedge angle of 15, 30, 45 & 60 were used.  The theoretical method suggested by Saw et al. is also used to indirectly calculate the slope of isodose  curve  by  the  dose  profile  and  percent  depth  dose  data.  The  dose  profile,  percentage  depth  dose  and  isodose curves were drawn for all the field sizes and the tilt of isodose curve at 10 cm depth, according to  international definition, is considered as the wedge angle. The data were obtained using the theoretical  equation of wedge angle and it was compared to the dosimetric data.  Results: The result obtained in this work shows that the wedge angle increases with the field size. For a  6×6 cm 2 field size, the calculated wedge angle has the highest difference in comparison to the nominal  wedge angle. The difference is equal to 14.7 degree for a 45° wedge and a 6 MV photon. The highest  difference for a 45° wedge angle, a field size of 10×10 cm 2 and a 6 MV photon is 9.2 degree. Comparing  the calculated and measured wedge angles shows a maximum difference of 4 degree for 6 and 18 MV  photon beams.  Discussion  and  Conclusion:  The  wedge  angle  varies  with  field  size.  In  order  to  get  a  better  dose  distribution in the conventional radiotherapy, it is necessary to use the appropriate wedge angle which  generates the desired slope for the isodose line and for the specific field size

Specification of Bacteriophage Isolated Against Clinical Methicillin-Resistant Staphylococcus Aureus

Objectives: The emergence of resistant bacteria is being increasingly reported around the world, potentially threatening millions of lives. Amongst resistant bacteria, methicillin-resistant Staphylococcus aureus (MRSA) is the most challenging to treat. This is due to emergent MRSA strains and less effective traditional antibiotic therapies to Staphylococcal infections. The use of bacteriophages (phages) against MRSA is a new, potential alternate therapy. In this study, morphology, genetic and protein structure of lytic phages against MRSA have been analysed. Methods: Isolation of livestock and sewage bacteriophages were performed using 0.4 mum membrane filters. Plaque assays were used to determine phage quantification by double layer agar method. Pure plaques were then amplified for further characterization. Sulfate-polyacrylamide gel electrophoresis and random amplification of polymorphic DNA were run for protein evaluation, and genotyping respectively. Transmission electron microscope was also used to detect the structure and taxonomic classification of phage visually. Results: Head and tail morphology of bacteriophages against MRSA were identified by transmission electron microscopy and assigned to the Siphoviridae family and the Caudovirales order. Conclusion: Bacteriophages are the most abundant microorganism on Earth and coexist with the bacterial population. They can destroy bacterial cells successfully and effectively. They cannot enter mammalian cells which saves the eukaryotic cells from lytic phage activity. In conclusion, phage therapy may have many potential applications in microbiology and human medicine with no side effect on eukaryotic cells

Efficacy of percutaneous and transcutaneous posterior tibial nerve stimulation on idiopathic overactive bladder and interstitial cystitis/painful bladder syndrome: A systematic review and meta-analysis

Objectives Percutaneous and transcutaneous posterior tibial nerve stimulation (PTNS and TTNS) showed a promising effect on overactive bladder (OAB) and interstitial cystitis/painful bladder syndrome. We aimed to give a systematic review and meta-analysis on the efficacy and safety of these therapeutic methods as well. Methods We searched studies available on PubMed, Embase, Cochrane, Scopus, Web of Science, and ProQuest on March 31, 2021, to find both published and unpublished studies. The retrieved articles were screened by two independent researchers and then the selected studies were critically appraised by Cochrane risk-of-bias tool for randomized trials, and Joanna Briggs Institute's checklist for quasi-experimental studies. Finally, the results of studies were synthesized using Review Manager (RevMan) 5.4 statistical software when the data were homogenous. The meta-analysis was performed by calculating the effect size (mean difference) and their 95% confidence intervals (CIs). Results Of the total 3194 publications, 68 studies were included in our qualitative evaluation and 9 studies (11 trials) in the quantitative stage. When TTNS or PTNS were compared to sham, placebo, no treatment, or conservative management, a decrease in frequency of urination was observed in both TTNS (mean difference [MD]: -3.18, 95% CI: -4.42 to -1.94, and p < 0.00001), and PTNS (MD: -2.84, 95% CI: -4.22 to -1.45, and p < 0.00001), and overall TTNS or PTNS (MD: -2.95, 95% CI: -4.01 to -1.88, and p < 0.00001). Significant improvements in mean voiding volume (MVV) and decreasing nocturia were also observed. Conclusions Nerve stimulations either PTNS or TTNS appear to be effective interventions in treating refractory idiopathic OAB in terms of daily voiding frequency, MVV, urgency episodes, and nighttime voiding frequency. However, our result did not show any improvement in terms of urinary incontinence, postvoid residual volume or urge incontinence, and maximum cystometric capacity which emphasized the efficacy of these modalities on dry-OAB rather than wet-OAB

Unsteady natural convection within a porous enclosure of sinusoidal corrugated side walls

Numerically investigation of free convection within a porous cavity with differential heating has been performed using modified corrugated side walls. Sinusoidal hot left and cold right walls are assumed to receive sudden differentially heating where top and bottom walls are insulated. Air is considered as working fluid and is quiescent, initially. Numerical experiments reveal 3 distinct stages of developing pattern including initial stage, oscillatory intermediate and finally steady state condition. Implicit Finite Volume Method with TDMA solver is used to solve the governing equations. This study has been performed for the Rayleigh numbers ranging from 100 to 10,000. Outcomes have been reported in terms of isotherms, streamline, velocity and temperature plots and average Nusselt number for various Ra, corrugation frequency and corrugation amplitude. The effects of sudden differential heating and its resultant transient behavior on fluid flow and heat transfer characteristics have been shown for the range of governing parameters. The present results show that the transient phenomena are enormously influenced by the variation of the Rayleigh Number with corrugation amplitude and frequency