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Byline: Musa. Joya, Hassan. Nedaie, Ghazale. Geraily, Hadi. Rezaei, Awaz. Bromand, Mahdi. Ghorbani, Peyman. Sheikhzadeh Purpose: According to the revised Task Group number 43 recommendations, a brachytherapy source must be [...]

Introduction: This study proposes various designs of partial-ring geometry totalbody positron emission tomography (PET) scanners which maintain an extended axial field of view (AFOV) while remaining cost-effective, without sacrificing image quality. Methods: The total-body uEXPLORER PET scanner was simulated using the GATE Monte Carlo code. Partial-ring PET configurations were simulated, reducing the number of detectors by 25% in both the transaxial and axial directions. The sensitivity, noise equivalent count rate (NECR), and image quality of the partialring configurations were compared to those of the full-ring configuration. Results: The system sensitivity of partial-ring designs was 0.61 and 0.77 times that of the full-ring detector PET for detector reduction in the axial and transaxial directions, respectively. Notably, despite the higher sensitivity, the 10 mm sphere could not be detected in the transaxial reduction mode. When considering all spheres except the 10 mm one, the mean relative error of contrast recovery (CR) for the same time duration was 2% for detector reduction in the axial direction, whereas it increased to 9% for reduction in the transaxial direction. Conclusion: The results show that reducing the number of detectors in total-body PET scanners can significantly lower manufacturing costs associated with long AFOV PET systems. Although the reduced detector configuration resulted in lower sensitivity, the image quality of the NEMA phantom was found to be superior in the axial reduction mode compared to the transaxial reduction mode. Additionally, the image quality exhibited only a slight difference from that of the full-ring scanner. [ABSTRACT FROM AUTHOR]

Background and Aim: Increasing of resistant bacteria is a major concern globally. The emergence of XDR gram-negative bacteria is a more serious problem due to treatment limitations. This study aimed to evaluate the frequency of extensively drug-resistant (XDR) gram-negative bacterial isolates in different clinical samples from Payvand Clinical and Specialty Laboratory, Tehran, Iran, for 6 months by VITEK 2 system. Materials and Methods: During March 2020-September 2020, different clinical samples were collected from patients referred to Payvand Clinical and Specialty Laboratory. Bacterial identification and antimicrobial susceptibility test (AST) were performed applying an automated VITEK 2 system. The frequency of identified bacteria, their resistance to common antibiotics and also XDR bacteria were calculated and reported, respectively. Results: Overall, 4125 urine specimens, 34 sputum samples, and 1 tracheal aspirate tube were submitted to Payvand Laboratory during 6 months. Of them, 486 urine, 32 sputum, and a tracheal aspirate tube samples were culture positive. Gram-negative isolated bacteria were included in this study. Based on AST, 63.3% of the isolated Klebsiella pneumoniae, 100% of Pseudomonas aeruginosa, and all Acinetobacter baumannii isolates were susceptible to amikacin and colistin. Totally, 31 XDR gram-negative bacteria, including: K. pneumonia (ssp. pneumonia (n=20), and ozaenae (n=2), Escherichia coli (n=3), P. aeruginosa (n=5), and A. baumannii (n=1) were identified from 18 urine samples, 12 sputum specimens, and a tracheal aspirate tube. Conclusion: The rate of XDR bacteria was high in the investigated laboratory in this study. Therefore, accurate screening and antimicrobial stewardship is recommended in different medical centers of Iran. [ABSTRACT FROM AUTHOR]

Introduction: The present study investigated the correlations between the patient's dose-area product (DAP) values and cardiologist's dose using Monte Carlo simulation. During angiography procedures, patients are exposed to the primary beam; however, the cardiologist is irradiated by the scattered radiation arising from the table and the surrounding equipment. Accordingly, the cardiologist's dose is directly related to the patient's dose. Material and Methods: This study investigated 25 cardiac angiography procedures. In each procedure, the DAP readings and the cardiologist dose as measured using an electronic personal dosimeter placed over the apron were recorded. Moreover, the DAP values and dose received by the cardiologist in the chest region were calculated using the Monte Carlo N-Particle extended code. For the validation of the simulated spectrum, dosimetric measurements were made using a Farmer ionization chamber and a phantom. Results: The data obtained from 18 simulations showed that there was a strong linear relationship (R²=0.71) between the two variables of cardiologist's dose and patient's DAP. Likewise, the obtained results of dosimetry conducted on the patients in 25 cardiac angiography procedures revealed that there was a strong relationship (R²=0.78) between the two variables. Conclusion: The reported correlation rates show the appropriateness of the physician radiation exposure to total patient's DAP. With respect to the strong correlation coefficient obtained from the simulation method, it is recommended that this method should be verified by dosimetry. The findings of this study showed a linear relationship between the cardiologist's dose and the total dose of the patient. [ABSTRACT FROM AUTHOR]

Abstract Background Sleep patterns and habits in high school students in Iran have not been well studied to date. This paper aims to re-address this balance and analyse sleep patterns and habits in Iranian children of high school age. Methods The subjects were 1,420 high school students randomly selected by stratified cluster sampling. This was a self-report study using a questionnaire which included items about usual sleep/wake behaviours over the previous month, such as sleep schedule, falling asleep in class, difficulty falling asleep, tiredness or sleepiness during the day, difficulty getting up in the morning, nightmares, and taking sleeping pills. Results The mean duration of night sleep was 7.7 h, with no difference between girls, boys, and school year (grade). The mean time of waking in the morning was not different between genders. About 9.9% of the girls and 4.6% of the boys perceived their quality of sleep as being bad, and 58% of them reported sleepiness during the day. About 4.2% of the subjects had used medication to enhance sleep. The time of going to bed was associated with grade level and gender. Sleep latency was not associated with gender and grade leve, l and 1.4% experienced bruxism more than four times a week. Conclusion Our results are in contrast with that of previous studies that concluded sleep duration is shorter in Asia than in Europe, that boys woke-up significantly later than girls, and that the frequency of sleep latency category was associated with gender and grade level. The magnitude of the daytime sleepiness, daytime sleepiness during classes, sleep latency, and incidences of waking up at night represent major public health concerns for Iran.

Two electron-deficient dienes are reacted with a series of twelve electron-poor and electron-rich dienophiles to give the corresponding Diels-Alder adducts. It is demonstrated that in the case of normal Diels-Alder cycloadditions, the frontier molecular orbital (FMO) theory could predict the relative reactivities between dienophiles, while in the case of inverse-electron demand Diels-Alder reactions, it could not.

The concentration of fluoride and nitrate in groundwater is usually higher than that of surface water. The main objective of this study was to estimate the health-risk assessment associated with fluoride, nitrate, and nitrite in drinking water in Sanandaj and its villages. The number of samples in the Sanandaj and its rural was 106. The average concentration of fluoride in urban and rural drinking water was 0.22 mg/l and 0.27 mg/l, respectively. Fluoride concentration was also close to urban and rural drinking water. The concentration of nitrate in urban and rural drinking water was in the range between 0.28–27.77 mg/l and 1.28–80 mg/l, respectively. The concentration of nitrate reported in rural samples was higher than that of urban samples. The maximum concentration of nitrate reported in this study was 80 mg/l. The mean CDI for nitrate in the men, women, and children was 0.4258, 0.5110, and 1.1454, respectively. The findings of this study indicated that all three groups studied were exposed to nitrate contact hazards (HQ > 1). Therefore, the HQ in each of the three groups was higher than 1, which should be carefully monitored and necessary measures should be performed. [ABSTRACT FROM AUTHOR]

A study is conducted to demonstrate that electron poor dienes and oxadines participate in (4+1)-cycloadditions with dialkoxy carbenes. The [4 + 1] cycloaddition between a carbene and a diene to give a cyclopentene derivative is the five-membered ring equivalent of the Diels-Alder reaction.

In recent years, the use of gold nanoparticles in radiation therapy has been introduced as a new approach in radiotherapy. The aim of this study is to investigate the effect of gold nanoparticles (GNPs) in plaque brachytherapy for choroidal melanoma using Monte Carlo (MC) simulation. MCNPX code was used for simulation of human eye, Pd (model 200) brachytherapy source and the 20 mm COMS eye plaque that was loaded with 24 Pd seeds and standardized by Collaborative Ocular Melanoma Study (COMS). The tumour was defined from the inner surface of choroid with 0.55 cm height and latticed with gold nanospheres and it was filled with different concentrations of 5, 10 and 15 mg/g GNPs, separately. Dose rate and dose enhancement factor in tumour and normal tissues of the eye (without gold) was examined for this case and compared with gold-water mixture of the same concentrations distributed in the tumour. The results show that with increasing the concentration of GNPs, the dose in the tumour increases and the dose to the normal tissues decreases. Furthermore, the time that is required to deliver the prescribed dose to the tumour decreases. In the gold nanosphere case for 5, 10 and 15 mg/g concentrations, the DEF in the apex of the tumour are 1.28, 1.46, 1.44 and at the distance of 6.5 mm in the normal tissue (outside the tumour) this factor would be 0.82, 0.73 and 0.68. The comparison between two cases of gold nanospheres and gold-water mixture shows that when the gold concentrations are defined as mixed with water, the dose enhancement in the first depths are higher than when the gold-nanoparticles are distributed inside the tumour. Furthermore due to more reduced particle flux for water-mixture case, by an increase in the depth the dose enhancement in gold-nanosphere increases compared with gold-water mixture case. [ABSTRACT FROM AUTHOR]

Objectives: Precise determination of dose distribution around low-energy brachytherapy sources as well as considering tissue heterogeneity is crucial for optimized treatment planning. This study is aimed at determination and mathematically formulation of American Association of Physicists in Medicine Task Group No. 43 (AAPM TG-43) dosimetry parameters of 125I seed (model 6711) and calculation of dose difference caused by neglecting lung heterogeneity in permanent implant brachytherapy.Materials and Methods: Using MCNPX 2.6.0 code, 125I seed (model 6711) was simulated in a cubic water environment, and its dosimetry parameters mentioned in AAPM TG-43 protocol were obtained. After benchmarking of parameters and comparison with prior studies, mathematical equations were fitted to the data, and a specific set of 125I seeds was simulated on a plane in simulated lung and water environments. Appropriate photon histories were considered to achieve data with maximum accuracy (max error 1%). In the end, isodose curves, profiles, depth dose, and dose difference between lung and water environments were obtained.Results: For 125I seed (model 6711), radial dose function and anisotropy functions were obtained precisely with R2 > 0.99, all in good agreement with previous studies and protocol. In addition, percentage dose difference between inhomogeneous lung and homogenous water environments in a 5 cm distance was calculated and presented as D (r) function with R2 > 0.99.Conclusions: Considering practical difficulties in dose calculations, 125I seed dosimetry parameters and lung heterogeneity corrections can be obtained precisely by MCNPX. Equations presented in this study are recommended to be considered in future studies based on lung permanent implantation. [ABSTRACT FROM AUTHOR]