Psychometric properties and factor structure of the Repetitive Thinking Questionnaire: Persian versions of the RTQ-31 and RTQ-10.

INTRODUCTION: Repetitive thinking as a transdiagnostic factor plays an essential role in the development and maintenance of emotional disorders. Two versions of the Repetitive Thinking Questionnaire (RTQ-31 and RTQ-10) are the best-known measures used for assessing repetitive thinking in clinical and non-clinical samples. The present study was conducted to evaluate the psychometric properties and factor structure of Persian versions of them. METHODS: Participants were 592 students assessed with the RTQ-31, the RTQ-10, the Ruminative Response Scale, the Perseverative Thinking Questionnaire, the Beck Depression Inventory-second edition, the Beck Anxiety Inventory, and the Depression, Anxiety, Stress Scale-21. Exploratory and confirmatory factor analysis were used to determine construct validity. RESULTS: The findings showed that the RTQ-31 and the RTQ-10 demonstrated excellent internal consistency and good test-retest reliability (α = 0.946: r = 0.844) and (α = 0.903: r = 0.776) respectively. Also, five items from the original version were omitted due to inadequate factor loadings. This study showed that the resulting 26-item version has a two-factor structure, while the short version has a one-dimensional structure. Finally, it was found that repetitive thinking has a positive and powerful relationship with other measures of rumination and with symptoms of depression, anxiety, and stress. CONCLUSION: Persian versions of the RTQ have good factor structures and psychometric properties and can be used in clinical populations and related studies.

Psychometric properties and factor structure of the Repetitive Thinking Questionnaire: Persian versions of the RTQ-31 and RTQ-10

Abstract Introduction: Repetitive thinking as a transdiagnostic factor plays an essential role in the development and maintenance of emotional disorders. Two versions of the Repetitive Thinking Questionnaire (RTQ-31 and RTQ-10) are the best-known measures used for assessing repetitive thinking in clinical and non-clinical samples. The present study was conducted to evaluate the psychometric properties and factor structure of Persian versions of them. Methods: Participants were 592 students assessed with the RTQ-31, the RTQ-10, the Ruminative Response Scale, the Perseverative Thinking Questionnaire, the Beck Depression Inventory-second edition, the Beck Anxiety Inventory, and the Depression, Anxiety, Stress Scale-21. Exploratory and confirmatory factor analysis were used to determine construct validity. Results: The findings showed that the RTQ-31 and the RTQ-10 demonstrated excellent internal consistency and good test-retest reliability (α = 0.946: r = 0.844) and (α = 0.903: r = 0.776) respectively. Also, five items from the original version were omitted due to inadequate factor loadings. This study showed that the resulting 26-item version has a two-factor structure, while the short version has a one-dimensional structure. Finally, it was found that repetitive thinking has a positive and powerful relationship with other measures of rumination and with symptoms of depression, anxiety, and stress. Conclusion: Persian versions of the RTQ have good factor structures and psychometric properties and can be used in clinical populations and related studies.

A Monte Carlo evaluation of dose distribution of commercial treatment planning systems in heterogeneous media.

INTRODUCTION: Calculations from a treatment planning system (TPS) in heterogeneous regions may present significant inaccuracies due to loss of electronic equilibrium. The purpose of this study is to evaluate and quantify the differences of dose distributions computed by some of the newest dose calculation algorithms, including collapsed cone convolution (CCC), fast Fourier transform (FFT) convolution, and superposition convolution, in heterogeneity of the lung. MATERIALS AND METHODS: A 6-MV Siemens Primus linear accelerator was simulated by MCNPX Monte Carlo (MC) code, and the results of percentage depth dose (PDD) and dose profile values were compared with measured data. The ISOgray TPS was used and PDDs of CCC, FFT, and superposition convolution algorithms were compared with the results obtained by MCNPX code. CT2MCNP software was used to convert the computed tomography images of the lung tissue to MC input files, and dose distributions from the three algorithms were compared to MC method. RESULTS: For PDD curves in buildup region, the maximum underdosage of ISOgray TPS was at the surface (19%) and comes in closer agreement when depth increases (average 7.08%). Dose differences (DD) between different algorithms and MC were typically 4.81% (range: 1.95% to 7.30%), -1.55% (range: -5.14% to 5.26%) and 4.96% (range: 2.00% to 7.4%) in the lung for the CCC, FFT, and superposition algorithms, respectively. The difference between monitor units and maximum dose calculated using the three algorithms were 0.5% and 1.61%, respectively. The maximum DD of 7% was observed between MC and TPS results. CONCLUSION: Significant differences were found when the calculation algorithms were compared with MC method in lung tissue, and this difference is not negligible. It is recommended to use of MC-based TPS for the treatment fields including lung tissue.

Effect of computed tomography number-relative electron density conversion curve on the calculation of radiotherapy dose and evaluation of Monaco radiotherapy treatment planning system.

The accuracy of a computed tomography (CT)-relative electron density (RED) curve may have an indirect impact on the accuracy of dose calculation by a treatment planning system (TPS). This effect has not been previously quantified for input of different CT-RED curves from different CT-scan units in the Monaco TPS. This study aims to evaluate the effect of CT-RED curve on the dose calculation by the Monaco radiotherapy TPS. Four CT images of the CIRS phantom were obtained by different CT scanners. The accuracy of the dose calculation in the three algorithms of the Monaco TPS (Monte Carlo, collapse cone, and pencil beam) is also evaluated based on TECDOC 1583. The CT-RED curves from the CT scanners were transferred to the Monaco TPS to audit the different algorithms of the TPS. The dose values were measured with an ionization chamber in the CIRS phantom. Then, the dose values were calculated by the Monaco algorithms in the corresponding points. For the Monaco TPS and based on TECDOC 1583, the accuracy of the dose calculation in all the three algorithms is within the agreement criteria for most of the points evaluated. For low dose regions, the differences between the calculated and measured dose values are higher than the agreement criteria in a number of points. For the majority of the points, the algorithms underestimate the calculated dose values. It was also found that the use of different CT-RED curves can lead to minor discrepancies in the dose calculation by the Monaco TPS, especially in low dose regions. However, it appears that these differences are not clinically significant in most of the cases.

Antibacterial oxidized starch/ZnO nanocomposite hydrogel: Synthesis and evaluation of its swelling behaviours in various pHs and salt solutions.

In this study, oxidized starch hydrogels have been fabricated, and then ZnO nanoparticles were added to swollen oxidized starch hydrogels through the in-situ process. The purpose of this work was to study the effect of ZnO nanoparticles on swelling behavior of oxidized starch hydrogels, as well as investigation their potential to be used in the antibacterial applications. The obtained results showed that the swelling behavior of the nanocomposite hydrogels was dependent on pH conditions. And at pH 7 the highest swelling was observed for samples because of the carboxylate anions created from samples constituent. The ZnO nanoparticles formation in the hydrogels was established with FT-IR spectroscopy, X-ray diffraction and scanning electron microscopy (SEM). SEM micrographs showed the construction of ZnO nanoparticles with a size range of 35-70 nm within the hydrogel matrix. Also, the swelling behaviours of the nanocomposite hydrogels were studied in several pH values and salt solutions. The swelling capacity of the ZnO nanocomposite hydrogels was reliant on the abundance of the zinc oxide nanoparticles in the oxidized starch hydrogels matrix. Furthermore, these oxidized starch/ZnO nanocomposite hydrogels showed smart swelling behaviours in NaCl, CaCl2 and AlCl3 aqueous solutions and their swelling ratio reduced with a growth of the salt concentration and valence of the cations. The swelling capacity for the resulted compounds in diverse salt solutions with the equal concentration was in order of NaCl > CaCl2 > AlCl3. Also, the antibacterial activities of the ZnO nanocomposite hydrogels were proven against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The nanocomposite hydrogels confirmed fine antibacterial properties. The developed oxidized starch/ZnO nanocomposite hydrogels have the potential to be used for biomedical use.

Monte Carlo calculations and experimental measurements of the TG-43U1-recommended dosimetric parameters of 125I (Model IR-Seed2) brachytherapy source.

A new design of 125I (Model IR-Seed2) brachytherapy source has been manufactured recently at the Applied Radiation Research School, Nuclear Science and Technology Research Institute in Iran. The source consists of six resin beads (0.5 mm diameter) that are sealed in a cylindrical titanium capsule of 0.7 mm internal and 0.8 mm external diameters. This work aims to evaluate the dosimetric parameters of the newly designed 125I source using experimental measurements and Monte Carlo (MC) simulations. Dosimetric characteristics (dose rate constant, radial dose function, and 2D and 1D anisotropy functions) of the IR-Seed2 were determined using experimental measurements and MC simulations following the recommendations by the Task Group 43 (TG-43U1) report of the American Association of Physicists in Medicine (AAPM). MC simulations were performed using the MCNP5 code in water and Plexiglas, and experimental measurements were carried out using thermoluminescent dosimeters (TLD-GR207A) in Plexiglas phantoms. The measured dose to water in Plexiglas data were used for verification of the accuracy of the source and phantom geometry in the Monte Carlo simulations. The final MC simulated data to water in water were recommended for clinical applications. The MC calculated dose rate constant (Λ) of the IR-Seed2 125I seed in water was found to be 0.992 ± 0.025 cGy h-1U-1. Additionally, its radial dose function by line and point source approximations, gL(r) and gp(r), calculated for distances from 0.1 cm to 7 cm. The values of gL(r) at radial distances from 0.5 cm to 5 cm were measured in a Plexiglas phantom to be between 1.212 and 0.413. The calculated and measured of values for 2D anisotropy function, F(r, θ), were obtained for the radial distances ranging from 1.5 cm to 5 cm and angular range of 0°-90° in a Plexiglas phantom. Also, the 2D anisotropy function was calculated in water for the clinical application. The results of these investigations show that the uncertainty of the experimental data is within ± 7% between the measured and simulated data in Plexiglas. Based on these results, the MC-simulated dosimetric parameters of the new 125I source model in water are presented for its clinical applications in brachytherapy treatments.