Search

With the use of traditional thermoluminescence dosimeters (TLDs), this study was carried out to determine the effective dose and its trend in order to ensure radiation safety at interventional cardiology practices in Bangladeshi hospitals. Between 2015 and 2019, 1015 radiation workers in Bangladesh who were under observation for their personal dose equivalent were reported. There were 417 physicians among them, while the remaining personnel included radiological technologists, physicists, and other medical staff members. To measure the exposure dose, a conventional TLD-100 (LiF:Mg, Ti) was used. A Harshaw TLD reader (Model 4500) was used to read the TLDs on a quarterly basis. All of the monitored workers, who made up around 19.11% of the total, had ionizing radiation exposure below the limit established by international organizations. The Mann–Kendall trend test and Sen's slope estimator were also applied to the annual collective effective doses, and it showed a decreasing trend over the time frame. The current state of occupational exposure and its trends show that most workplaces have effective radiation protective measures in place. [ABSTRACT FROM AUTHOR]

Background Purpose Methods Results Conclusions Proton beam therapy, when integrated with MRI guidance, presents complex dosimetric challenges due to interactions with magnetic fields. Prior research has emphasized the nuanced impact of magnetic fields on dosimetry. For thermoluminescent dosimeters (TLDs) the electron‐return effect, alongside small air cavities surrounding the pellets, can lead to nonuniform dose distributions. Future MR‐guided proton therapy will require reliable methods for end‐to‐end tests and dosimetric audits, which so far are often performed using TLDs equipped with phantoms. This implicates the necessity of accounting for these interactions.This study investigates the influence of magnetic fields on TLDs at two proton energies, using magnetic field strengths of 0, 0.25, and 1T$1 \,\mathrm{T}$, aiming to clarify their impact on dose measurement accuracy.The study was conducted at a synchrotron‐based ion beam therapy beam line, enhanced by a resistive dipole magnet for creating magnetic fields up to 1T$1 \,\mathrm{T}$ to simulate MR‐guided proton therapy. Individual correction factors were applied for TLD measurements. The impact of air gaps on the TLD signal was evaluated using three dedicated TLD holders with air gaps of 0.1, 0.25, and 0.5 mm surrounding the TLD pellets using the highest available proton energy of 252.7MeV$252.7 \,\mathrm{M}\mathrm{e\mathrm{V}}$. Additionally, the influence of the magnetic field strength on the TLD response was evaluated for two proton energies of 97.4MeV$97.4 \,\mathrm{M}\mathrm{e\mathrm{V}}$ and 252.7MeV$252.7 \,\mathrm{M}\mathrm{e\mathrm{V}}$.The study found no statistically significant variation in TLD dose response attributable to changes in the air gap or the presence of magnetic fields. A power analysis indicated an upper limit on a potential change in dose‐response as small as 1.5%.The findings suggested that the impact of air gap variations and magnetic field strengths on the TLD response was below the detection threshold of TLD sensitivity. This emphasizes the suitability of TLDs for dose measurement in MR‐guided proton therapy, indicating that additional correction factors may not be necessary despite the influence of magnetic fields. [ABSTRACT FROM AUTHOR]

One of the challenges of individual dosimetry in Iran is the absence of standard radiation fields with different energies for calibration. For dosimetry in the photon fields, only the standard fields of Co-60 and Cs-137 sources, located in the (SSDL) can be utilized. This study aims to determine energy response of a personal thermoluminescence dosimeter (TLD) designed for determining the personal dose-equivalent, Hp(10), in order to investigate whether the calibration curve in the Co-60 gamma field can be utilized for assessing the dose-equivalent in the photon fields with different energies. To do this, first, the TLD dosimeters (an appropriate plastic badge including a TLD-100 chip) are irradiated with a few Hp(10) values using the Co-60 source in the Karaj SSDL. The badges are placed on a water phantom (slab), one meter distant from the source. Then, MCNP4C code is used to calculate the energy response at 662 keV and 1.25 MeV energies. Next, these responses are validated with the experimental data. Finally, the calculation is carried out for several other energies in the range of 20 keV to 1.25 MeV. Obtained results show that for the energies more than 400 keV, The response of the dosimeter is independent of the photon energy, within 10% uncertainty. On the other hand, for the energies smaller than 400 keV, a significant dependence on the energy is observed; such that in 40 keV the response is about 2 times larger than that at 1.25 MeV. Consequently, a method to reduce this uncertainty is needed. [ABSTRACT FROM AUTHOR]

Background Tenofovir/lamivudine/dolutegravir (TLD) is the preferred first-line antiretroviral therapy (ART) regimen for people with HIV (PWH), including those who were previously virologically suppressed on nonnucleoside reverse transcriptase inhibitors (NNRTIs). We sought to estimate the real-world effectiveness of the TLD transition in Ugandan public-sector clinics. Methods We conducted a prospective cohort study of PWH aged ≥18 years who were transitioned from NNRTI-based ART to TLD. Study visits were conducted on the day of TLD transition and 24 and 48 weeks later. The primary end point was viral suppression (<200 copies/mL) at 48 weeks. We collected blood for retrospective viral load (VL) assessment and conducted genotypic resistance tests for specimens with VL >500 copies/mL. Results We enrolled 500 participants (median age 47 years; 41% women). At 48 weeks after TLD transition, 94% of participants were in care with a VL <200 copies/mL (n = 469/500); 2% (n = 11/500) were lost from care or died; and only 2% (n = 9/500) had a VL >500 copies/mL. No incident resistance to DTG was identified. Few participants (2%, n = 9/500) discontinued TLD due to adverse events. Conclusions High rates of viral suppression, high tolerability, and lack of emergent drug resistance support use of TLD as the preferred first-line regimen in the region. Clinical Trials Registration NCT04066036. [ABSTRACT FROM AUTHOR]

This paper explores the implementation of machine learning-based algorithms for TL dose assessment. It focuses on the radiation field classification, performance quotient evaluation, and shallow and deep dose equivalent assessment of ANN and LGBM, in comparison to the traditional method of DT. We evaluate these algorithms based on the element response data measured by TLD. A data set was built for training, and the base element responses of test categories were amplified, and normalized to 1 mSv Cs-137 within the range of ±3 %. Both algorithms consist of five subset models for classifying radiation fields and identifying ratios of mixed fields. The LGBM showed the best accuracy in classifying considered radiation fields and the lowest performance quotients. By comparing the tolerance levels of deep dose and shallow dose equivalents among the three algorithms, the LGBM yields the smallest difference between the predicted and true dose equivalents. This smaller difference implies the LGBM offers the least bias and standard deviation in the expected value, giving higher accuracy and precision in dose assessment over the traditional DT method. The findings from this study further contribute to the adoption of ML-based algorithms for TL dose assessment, underscoring its importance in the field.

Background: The general practice for all radiographic procedures is to use Lead Shielding to optimise radiation dose to the patient. The American Association of Physicists (AAPM) in Medicine in 2019 however, made a recommendation on the use of gonad and foetal shielding. The authors have noticed that very few papers on this topic come from developing countries, hence this study embarked on. The aim of our study was to evaluate internal scatter with Lead and without Lead Shielding in an anthropomorphic phantom during Computed Tomography of the brain, chest, abdomen, and pelvis. Methods: The methodology was based on examinations of a RANDO phantom brain, chest, abdomen and pelvis on a General Electric Optima 660 scanner; which had a 128-channel multidetector row. Examinations were performed with Lead and without Lead Shielding equivalence of 0.35 mm, and the internal scatter measured using Thermoluminescent Dosimeters. The collected data was analysed descriptively to determine the mean and standard deviation. The T-tests and two-way analysis of variance (ANOVA) were used to compare the means. Results: The findings of this study revealed that internal scatter was highest closest to the exposed area with higher internal scatter observed for thicker areas of the phantom. Although slightly higher readings were recorded without Pb shielding, a non-statistical significance was observed for all internal scatter measurements regardless of whether Lead Shielding was used or not. Conclusions: A non-statistical significance for Computed Tomography examinations with and without Lead Shielding in confirmation with the AAPM positional statement. [ABSTRACT FROM AUTHOR]

Thermoluminescent dosimeters (TLD) and optically stimulated luminescent dosimeters (OSLD) are practical, accurate, and precise tools for point dosimetry in medical physics applications. The objective of this study is to investigate the luminescence properties—both OSL and TL—of lithium fluoride (LiF) doped with magnesium (Mg), copper (Cu), and phosphorous (P) (LiF: Mg, Cu, P), commercially known as TLD-100H. The goal is to devise a methodological approach for dose measurement that allows for obtaining two independently measured dose values at each irradiation point, thereby improving accuracy and precision. The luminescence properties of TLD-100H were studied using a beta irradiation source (90Sr/90Y) integrated into the TL/OSL DA-15 automated Risø reader. This study identified the ideal experimental conditions for optimal dose evaluation and used them for dosimeter calibration across doses ranging from 0.5 to 4.0 Gy. The results demonstrated that, under optimal measurement parameters, the OSL and residual thermoluminescence (ResTL) signals—correlated to two trap systems within the dosimeter—exhibited high reproducibility, stability over multiple cycles, and high precision and accuracy (≤2%). Specifically, the OSL response showed good linear behavior across the investigated dose range, while the ResTL signal exhibited linear behavior between 0.5 and 2 Gy and sublinear behavior for doses >2 Gy. [ABSTRACT FROM AUTHOR]

We report a case of a 54-year-old female diagnosed with HIV and antiretroviral therapy (ART) for the same. Seven years ago, she suffered from fever, cough and weight loss, was diagnosed with pulmonary tuberculosis and also seropositive for HIV. She suffered from Herpes Zoster infection, after which her ART regimen was changed to TLD (tenofovir, lamivudine and dolutegravir). The patient presented with two episodes of pyoderma gangrenosum (PG), which were biopsy-proven, corresponding to a rise in CD4 counts above 500. She responded to glucocorticoids, both systemic and topical.

Reputația numelor de domenii de Internet se referă la evaluarea credibilității, securității și fiabilității unui domeniu pe baza comportamentului și a caracteristicilor istorice ale acestuia. Aceasta implică analizarea factorilor care influențează calitatea percepută, securitatea și riscurile asociate pentru a determina reputația unui domeniu. Domeniile de nivel superior (TLD) reprezintă cel mai înalt nivel din ierarhia sistemului de nume de domenii. Reputația domeniului influențează clasamentele motoarelor de căutare, experiența utilizatorului și securitatea online. Registrele de domenii TLD, organizațiile și persoanele fizice au nevoie de sisteme de monitorizare automată a reputației domeniilor deținute din motive de securitate, în special atunci când utilizează date cu caracter personal, pentru a proteja utilizatorii și a menține o prezență online pozitivă. Principalele obiective ale acestui studiu includ identificarea parametrilor Sistemului de Nume de Domenii (DNS) relevanți pentru stabilirea reputației și analiza impactului stărilor unui domeniu asupra reputației, utilizând setul de date deținut de Registrul de domenii .ro.

A TLD is a passive damping device that works by dissipating energy through the sloshing of the liquid and the effect of wave breaking, thereby controlling the vibrations of the structure. One of the applications where TLDs are of great interest is in the case of industrial chimneys since these structures often have a very low natural frequency, which can be easily achieved in a control device of this type. The main objective of this study is to evaluate the behaviour of an annular TLD composed of multiple cells through laboratory tests and investigate if it is adequate to design it as an agglomeration of smaller rectangular TLDs. The influence of the amplitude of displacement on the behaviour of the annular TLD will also be analysed. The tests were performed on a shaking table and recurring with pendulums of the same length but of different masses. Three reservoirs were studied as TLDs: a rectangular one, a cell of an annular TLD and a quarter-ring of an annular TLD. This study concluded that the analytical methods developed in previous studies were, in general, adequate for the design of a rectangular TLD and that it was reasonable to design the annular TLD studied as a combination of rectangular ones, as its cells were a close match to a rectangle of similar dimensions. It was also concluded that a compartmentalised annular TLD is an adequate solution for the vibration control of structures with high displacements. [ABSTRACT FROM AUTHOR]

Background: Dosimetry in ultra‐high dose rate (UHDR) electron beamlines poses a significant challenge owing to the limited usability of standard dosimeters in high dose and high dose‐per‐pulse (DPP) applications. Purpose: In this study, Al2O3:C nanoDot optically stimulated luminescent dosimeters (OSLDs), single‐use powder‐based LiF:Mg,Ti thermoluminescent dosimeters (TLDs), and Gafchromic EBT3 film were evaluated at extended dose ranges (up to 40 Gy) in conventional dose rate (CONV) and UHDR beamlines to determine their usability for calibration and dose verification in the setting of FLASH radiation therapy. Methods: OSLDs and TLDs were evaluated against established dose‐rate–independent Gafchromic EBT3 film with regard to the potential influence of mean dose rate, instantaneous dose rate, and DPP on signal response. The dosimeters were irradiated at CONV or UHDR conditions on a 9‐MeV electron beam. Under UHDR conditions, different settings of pulse repetition frequency (PRF), pulse width (PW), and pulse amplitude were used to characterize the individual dosimeters' response in order to isolate their potential dependencies on dose, dose rate, and DPP. Results: The OSLDs, TLDs, and Gafchromic EBT3 film were found to be suitable at a dose range of up to 40 Gy without any indication of saturation in signal. The response of OSLDs and TLDs in UHDR conditions were found to be independent of mean dose rate (up to 1440 Gy/s), instantaneous dose rate (up to 2 MGy/s), and DPP (up to 7 Gy), with uncertainties on par with nominal values established in CONV beamlines (± 4%). In cross‐comparing the response of OSLDs, TLDs and Gafchromic film at dose rates of 0.18–245 Gy/s, the coefficient of variation or relative standard deviation in the measured dose between the three dosimeters (inter‐dosimeter comparison) was found to be within 2%. Conclusions: We demonstrated the dynamic range of OSLDs, TLDs, and Gafchromic film to be suitable up to 40 Gy, and we developed a protocol that can be used to accurately translate the measured signal in each respective dosimeter to dose. OSLDs and powdered TLDs were shown to be viable for dosimetric measurement in UHDR beamlines, providing dose measurements with accuracies on par with Gafchromic EBT3 film and their concurrent use demonstrating a means for redundant dosimetry in UHDR conditions. [ABSTRACT FROM AUTHOR]

We report a case of a 54-year-old female diagnosed with HIV and antiretroviral therapy (ART) for the same. Seven years ago, she suffered from fever, cough and weight loss, was diagnosed with pulmonary tuberculosis and also seropositive for HIV. She suffered from Herpes Zoster infection, after which her ART regimen was changed to TLD (tenofovir, lamivudine and dolutegravir). The patient presented with two episodes of pyoderma gangrenosum (PG), which were biopsy-proven, corresponding to a rise in CD4 counts above 500. She responded to glucocorticoids, both systemic and topical. [ABSTRACT FROM AUTHOR]

Thermoluminescence dosimeter (TLD) is widely used as a personal and medical dosimeter. Several TLD materials show the characteristics of mass energy absorption coefficient and energy response relative to ICRU (International Commission on Radiation Units and Measurements) issue material as an equivalent material for human body soft tissue. This research aims to analyze the effect of Dy3+ dopant on the mass-energy absorption coefficient and relative energy response of Lithium Magnesium Borate (LMB) materials. The simulation was carried out using Monte Carlo N-Particle (MCNP) software. Calculations based on simulation and theoretical results will be compared statistically using paired t-tests. The study showed that adding a Dy3+ dopant to TLD material made of Lithium Magnesium Borate (LMB) only affected the mass-energy absorption coefficient and relative energy response for low radiation energy. Adding Dy3+ dopant increased the mass energy absorption coefficient and relative energy response in a reasonably small value. Based on these results, LMBDy3+ produces a better mass-energy absorption coefficient value for TLD materials. The results of the statistical tests show a significant difference in the mass energy absorption coefficient value. At the same time, there is no significant difference between the simulation results and theoretical calculations for the relative energy response.

Aiming at the characteristics of short pulse time and high instantaneous dose rate of pulsed X-ray, a TLD-based few-channel spectrometer is studied. In this paper, the basic structure and principle of the spectrometer are introduced, the absorption plates and detectors of the spectrometer are selected. The energy response matrix of the few-channel spectrometer for single energy photons of different energies is simulated by Monte Carlo method and its influence on the energy resolution of the spectrometer is analyzed. The maximum entropy method is used to verify the pulsed X-ray spectrum resolution. The results show that the TLD-based few-channel spectrometer can be used to measure short pulse and high dose rate pulse X-ray energy spectrum, and it is also suitable for other high dose rate radiation fields.

Introduction: In this study, TLD 600 and TLD 700 pairs were used to measure the neutron dose of Elekta Precise medical linac. To this end, the optimum moderate thickness for the conversion of fast to thermal neutrons were evaluated. Materials and methods: 241Am-Be and 252Cf sources were simulated to calculate the optimum thicknesses of the moderator for the conversion of maximum fast neutrons (FN) into thermal neutrons (TN). Pair TLDs were used to measure F&TN doses for three different field sizes at four depths of the medical linac. Results: The maximum thickness of the moderator was optimized at 6 cm. The measurement results demonstrated that the TN dose increased with the expansion of field size and depth. The FN dose, which was converted TN, exhibits behaviors comparable to the TN due to its nature. Conclusion: This study presents the optimum thickness for the moderator to convert FN into TN and measure F&TN using TLDs.

Copyright of Journal of Isotopes is the property of Journal of Isotopes Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Tuned liquid dampers (TLDs) have been successfully installed on different types of structures for vibration mitigation against wind or earthquake forces. However, the effectiveness of TLDs in mitigating the dynamic responses of buildings with large mass eccentricity has not been well investigated. Method: In this study, a scaled-down one-bay 3-story structure with a 1 m span length and a total height of 2.65 m was constructed and subjected to free vibration and harmonic excitations. TLDs with mass ratios ranging from 1 to 5% were installed on the roof of the building. Moreover, to impose in-plane torsional moments to the reference structure, the location of floors' mass was shifted 0.15 m and 0.3 m away from the geometric centroid. The peak displacement and acceleration responses (PDR and PAR) were measured at the roof level of the reference structure with and without the effect of the torsional moment. Results: The obtained results indicated that, at the resonance frequency (RF), TLDs could successfully mitigate the PDRs and PARs even at the presence of torsional moments. Moreover, TLDs reduced the PDRs more than the PARs. Besides, an increase in the mass ratio up to 5% enhanced the effectiveness of TLDs in reducing the peak responses. [ABSTRACT FROM AUTHOR]

The aim of this study was to experimentally measure organ doses for computed tomography (CT) procedures using thermoluminescence dosimeters (TLDs) on a RANDO anthropomorphic phantom and verify the measured doses using CT-Expo software. The phantom was irradiated using clinical CT scan protocols routinely used for specific procedures in the radiology department. Fifty TLD chips were used in this study. The scanning parameters (kVp, mA, s) used to scan the phantom were used as input parameters for CT-Expo dose estimations. The TLD measured organ doses varied between 3.97 mGy for the esophagus and 56.22 mGy for the brain. High doses were recorded in the brain (37.80–56.22 mGy) and the eye lens (29.94–36.16 mGy). Comparing the organ dose measurements between TLD and CT-Expo, the maximum organ dose difference was obtained for the eye lens. A comparison between the two methods for the other organs were all less than 32 %. The effective doses from the TLD measurements for the head, chest, and abdominopelvic CT examinations were 2.78, 6.67, and 17 mSv, respectively and CT-Expo were 2.20, 10.30, and 16.70 mSv, respectively. The experimental and computational results are comparable, and the reliability of the TLD measurements and CT-Expo dose calculator has been proven. A reason for the difference in dose measurements between the two methods has been attributed to the dissimilarity in the organ position in the Rando anthropomorphic phantom and the standard mathematical phantom used by CT-Expo. The experimental and computational results have been found to be comparable. [ABSTRACT FROM AUTHOR]

Copyright of Romanian Journal of Information Technology & Automatic Control / Revista Română de Informatică și Automatică is the property of National Institute for Research & Development in Informatics - ICI Bucharest and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This virtual workshop was convened by the National Heart, Lung, and Blood Institute, in partnership with the Office of Strategic Coordination of the Office of the National Institutes of Health Director, and held September 2 to 3, 2020. The intent was to assemble a multidisciplinary group of experts in basic, translational, and clinical research in neuroscience and cardiopulmonary disorders to identify knowledge gaps, guide future research efforts, and foster multidisciplinary collaborations pertaining to autonomic neural mechanisms of cardiopulmonary regulation. The group critically evaluated the current state of knowledge of the roles that the autonomic nervous system plays in regulation of cardiopulmonary function in health and in pathophysiology of arrhythmias, heart failure, sleep and circadian dysfunction, and breathing disorders. Opportunities to leverage the Common Fund's SPARC (Stimulating Peripheral Activity to Relieve Conditions) program were characterized as related to nonpharmacologic neuromodulation and device-based therapies. Common themes discussed include knowledge gaps, research priorities, and approaches to develop novel predictive markers of autonomic dysfunction. Approaches to precisely target neural pathophysiological mechanisms to herald new therapies for arrhythmias, heart failure, sleep and circadian rhythm physiology, and breathing disorders were also detailed.

Thermoluminescent dosimeters (TLD) and optically stimulated luminescent dosimeters (OSLD) are practical, accurate, and precise tools for point dosimetry in medical physics applications. The objective of this study is to investigate the luminescence properties—both OSL and TL—of lithium fluoride (LiF) doped with magnesium (Mg), copper (Cu), and phosphorous (P) (LiF: Mg, Cu, P), commercially known as TLD-100H. The goal is to devise a methodological approach for dose measurement that allows for obtaining two independently measured dose values at each irradiation point, thereby improving accuracy and precision. The luminescence properties of TLD-100H were studied using a beta irradiation source (90Sr/90Y) integrated into the TL/OSL DA-15 automated Risø reader. This study identified the ideal experimental conditions for optimal dose evaluation and used them for dosimeter calibration across doses ranging from 0.5 to 4.0 Gy. The results demonstrated that, under optimal measurement parameters, the OSL and residual thermoluminescence (ResTL) signals—correlated to two trap systems within the dosimeter—exhibited high reproducibility, stability over multiple cycles, and high precision and accuracy (≤2%). Specifically, the OSL response showed good linear behavior across the investigated dose range, while the ResTL signal exhibited linear behavior between 0.5 and 2 Gy and sublinear behavior for doses >2 Gy.

A sodium sulphate/silica (Na2SO4/SiO2) composite was prepared by a sol-gel procedure using a geode as the silica source. The prepared sample was characterized by XRD, XRF and IR techniques. The Na2SO4/SiO2 has an orthorhombic phase, and an average crystalline size is about 51 nm. Thermoluminescence characteristics of Na2SO4/SiO2 were studied at different parameters. The glow curve resulting from Na2SO4/SiO2 showed one clear peak between 150 oC to 200 oC, depending on the energy. The general peak structure of the TL glow curve remains unchanged as a result of repeated cycles of irradiation at various X–ray energies, and exhibits good linearity over the used exposure. There were no significant changes in the TL reading after ten times of reuse, and the fading was observed at 56% after 15 days of irradiation and after one month about 82.3% of the TL signal was lost, and the value of Zeff of Na2SO4/SiO2 was found to be 13.56.

The sway frequency is an important component of the dynamic characteristics of trees. Video-based methods can be used to measure the sway frequencies of trees. The key to successfully measuring tree sway frequency using video methods lies in whether the tracking method employed is appropriate. Based on six algorithms, i.e., Boosting, TLD, MIL, KCF, MOSSE and CSR-DCF, the tracking performance and accuracy of tree sway frequency measurements were investigated under two conditions: artificial excitation and environmental excitation. The results show that the following: (1) In terms of the tracking speed of tree sway, MOSSE > KCF > CSR-DCF > Boosting > MIL > TLD. (2) The TLD algorithm is not suitable for tree sway tracking. Boosting, MIL, MOSSE, KCF and CSR-DCF can be used for tree sway tracking. (3) Boosting, MIL and MOSSE are suitable for measuring the sway frequency of artificially excited branches and environmentally excited trees. (4) KCF and CSR-DCF algorithms are not suitable for the measurement of branch sway frequency under artificial excitation conditions but can be used for the measurement of tree sway frequency under environmental excitation conditions. However, it should be noted that this experiment only takes a Betula platyphylla Sukaczev tree and a Betula platyphylla Sukaczev branch as the research object to verify the effectiveness and feasibility of each tracking method, and does not verify the generalization ability of the above methods (on multiple tree species and multiple trees). [ABSTRACT FROM AUTHOR]

In chest computed tomography (CT), the breasts located within the scan range receive a substantial radiation dose. Due to the risk of breast-related carcinogenesis, analyzing the breast dose for justification of CT examinations seems necessary. The main goal of this study is to overcome the limitations of conventional dosimetry methods, such as thermoluminescent dosimeters (TLDs) by introducing the adaptive neuro-fuzzy inference system (ANFIS) approach. In this study, the breast dose of 50 adult female patients who underwent chest CT examinations was measured directly by TLDs. Then, the ANFIS model was developed with four inputs including dose length product (DLP), volumetric CT dose index (CTDIvol), total mAs, and size-specific dose estimate (SSDE), and one output (TLD dose). Additionally, multiple linear regression (MLR) as a traditional prediction model was used for linear modeling and its results were compared with the ANFIS. The TLD reader results showed that the breast dose value was 12.37 ± 2.46 mGy. Performance indices of the ANFIS model, including root mean square error (RMSE) and correlation coefficient (R), were calculated at 0.172 and 0.93 for the testing dataset, respectively. Also, the ANFIS model had superior performance in predicting the breast dose than the MLR model (R = 0.805). This study demonstrates that the proposed ANFIS model is efficient for patient dose prediction in CT scans. Therefore, intelligence models such as ANFIS are suggested to estimate and optimize patient dose in CT examinations. [ABSTRACT FROM AUTHOR]

A TLD is a passive damping device that works by dissipating energy through the sloshing of the liquid and the effect of wave breaking, thereby controlling the vibrations of the structure. One of the applications where TLDs are of great interest is in the case of industrial chimneys since these structures often have a very low natural frequency, which can be easily achieved in a control device of this type. The main objective of this study is to evaluate the behaviour of an annular TLD composed of multiple cells through laboratory tests and investigate if it is adequate to design it as an agglomeration of smaller rectangular TLDs. The influence of the amplitude of displacement on the behaviour of the annular TLD will also be analysed. The tests were performed on a shaking table and recurring with pendulums of the same length but of different masses. Three reservoirs were studied as TLDs: a rectangular one, a cell of an annular TLD and a quarter-ring of an annular TLD. This study concluded that the analytical methods developed in previous studies were, in general, adequate for the design of a rectangular TLD and that it was reasonable to design the annular TLD studied as a combination of rectangular ones, as its cells were a close match to a rectangle of similar dimensions. It was also concluded that a compartmentalised annular TLD is an adequate solution for the vibration control of structures with high displacements.

Increased HIV drug resistance (HIVDR) with antiretroviral therapy (ART) rollout may jeopardize therapeutic options, especially in this era of transition to fixed-dose tenofovir-lamivudine-dolutegravir (TLD). We studied acquired HIVDR (ADR) patterns and describe potentially active drugs after first- and second-line failure in resource-limited settings (RLS) like Cameroon. A laboratory-based study with 759 patients (≥15 years) experiencing virological failure was carried out at the Chantal Biya International Reference Centre (CIRCB), Yaoundé, Cameroon. Socio-demographic, therapeutic and immunovirological data from patient records were analysed according to HIV-1 genotypic profiles. Median (IQR) ART-duration was 63 (50–308) months. Median CD4 and viremia were 153 (IQR:50–308) cells/mm3 and 138,666 (IQR:28,979–533,066) copies/mL, respectively. Overall ADR was high (93.4% first-line; 92.9%-second-line). TDF, potentially active in 35.7% of participants after first-line and 45.1% after second-line, suggested sub-optimal TLD-efficacy in second-line (64.3%) and third-line (54.9%). All PI/r preserved high efficacy after first-line failure while only DRV/r preserved high-level efficacy (87.9%) after second-line failure. In this resource-limited setting (RLS), ADR is high in ART-failing patients. PI/r strategies remain potent backbones for second-line ART, while only DRV/r remains very potent despite second-line failure. Though TLD use would be preferable, blind use for second- and third-line regimens may be sub-optimal (functional monotherapy with dolutegravir) with high risk of further failure, thus suggesting strategies for selective ART switch to TLD in failing patients in RLS. [ABSTRACT FROM AUTHOR]

Concern about the radiation dose to children from diagnostic radiology examinations has recently been popularly expressed, particularly related to Computed Tomography (CT) procedures. The common belief is that children receive higher doses compared to adults since the optimization of the procedure settings for different anatomies are not always implemented (i.e., FOV, kV and mA not optimized for children). Since the dosimetric quantities related to effective dose are essentially defined for adults, it becomes important to study and propose methods applicable also to pediatric cases. In current clinical and radiological practice, sizes, shapes, and data for pediatric organs are commonly derived from adult ones, but these statements do not reduce dosimetric problems at the definition of scaling algorithms. The aim of this study is to analyze the differences in pediatric vs adult dosimetry, starting from measured organ doses in cone-beam computed tomography (CBCT) procedures for maxillofacial region. Two different anthropomorphic phantoms (child vs adult phantoms) were scanned, acquiring all data: results will be presented in terms of organ and derived doses, discussing approaches and differences. [ABSTRACT FROM AUTHOR]

In this paper, parametric forced tuned solid ball dampers (TSBD) are considered for vibration control of engineering structures in an untypical way. The special feature of the presented investigation is to evaluate the potential application of parametric forcing of the rolling cylindrical or spherical body in the runway for reducing the vertical vibrations of a vibration-prone main system. Typically, tuned solid ball dampers are applied to structures that are prone to horizontal vibrations only. The coupled nonlinear differential equations of motion are derived and the phenomenon of parametric resonance of the rolling body in the runway is analyzed. A criterion for avoiding parametric resonance is given to achieve the optimal damping effect of the TSBD. In the second part of the article, a method for the targeted use of parametric resonance to reduce the vertical vibrations of engineering structures is presented and verified, considering a biaxially harmonic excited pedestrian bridge. It is shown that, with a suitable choice of damper parameters, a stable vibration of the rolling body in the runway is formed over the course of the vibration despite the occurrence of parametric resonance and that the maximum vertical vibration amplitudes of the main system can be reduced up to 93%. Hence, the here presented untypical application of parametric forced TSBD for reducing the vertical forced vibrations of vibration-prone main systems could be successfully demonstrated. [ABSTRACT FROM AUTHOR]

An essential step in evaluating and comparing the performance of two passive radiation dosimeter types, thermosluminescent (TLD) and optically stimulated luminescence (OSL), used by workers in environments with ionizing radiation for individual radiological monitoring and control of external exposure at various times (cumulative dose for 1 month), is to compare the measured dose accuracy, energy response, and coefficient of variation.In fact this performance study consists in determining the accuracy of both R(10) and R(0.07) which are considered as the ratios of the measured dose (Hp(10) or Hp(0.07)) to the delivered dose (Hp(10) or Hp(0.07)) for each photon energy. The validity of the results of this test is based on the acceptance limits of the ICRP and the international standard IEC-62387. The relative energy response used is normalized to the 137Cs 662 keV energy to find which energy response is closest to the ideal case, and the coefficient of variation that allows to determine the statistical fluctuation of the Hp(10) and Hp(0.07) doses.The results of the accuracy test for the OSL and TLD dosimeters are acceptable because they fall within the ICRP limits. For the energy response, the OSL performs better than the TLD for Hp(10) and Hp(0.07), and for the coefficient of variation, the OSL satisfies the requirements of ISO 62387 for both Hp(10) and Hp(0.07), while the TLD satisfies these requirements only for the measurement of Hp (0.07).

A rapidly changing landscape of antiretrovirals and their procurement at scale has permitted the evaluation of new optimised second-line antiretroviral therapy (ART) in low- and middle-income countries. D2EFT is an open-label randomised controlled non-inferiority phase IIIB/IV trial in people living with HIV-1 (PWH) whose first-line non-nucleoside reverse transcriptase inhibitor (NNRTI)-based ART is failing. At inception, it compared a standard of care of boosted darunavir with two nucleos(t)ide reverse transcriptase inhibitors (NRTIs) to the novel NRTI-sparing regimen of boosted darunavir with dolutegravir. Implemented in 2017, participating sites were across Africa, Asia and Latin America. Around the time of implementation, the World Health Organization updated its treatment guidelines and recommended scaling up tenofovir disoproxil fumarate-lamivudine-dolutegravir (TLD). This situation pushed D2EFT investigators to consider the impact of the roll-out of TLD on the D2EFT research question. The protocol team agreed it was important to study TLD in second-line when an NNRTI regimen was failing, and focused on options to expedite the work by studying the question within the existing trial and network. All key issues (statistical, programmatic and financial) were reviewed to assess the benefits and risks of adding a third arm to the ongoing study, as opposed to developing a new randomised clinical trial with the same control arm and within the same network. The development of a new trial was deemed to be longer than adding a third arm, and to create a challenging situation with two competing clinical trials at the same sites which would slow down recruitment and impair both trials. On the other hand, adding a third arm would be demanding in terms of operationalisation, increased sample size and statistical biases to control. The optimal strategy was deemed to be the addition of a third arm, arriving retrospectively at a simplified multi-arm multi-stage clinical trial design to achieve statistical validity. The D2EFT study maintains additional value in a quickly evolving second-line ART strategy allowed by the progress in global access to ART.

Supplemental Digital Content is Available in the Text. Background: Recycling tenofovir and lamivudine/emtricitabine with dolutegravir (TLD) after failure of non-nucleoside transcriptase inhibitor first-line antiretroviral therapy is more tolerable and scalable than dolutegravir plus optimized nucleoside reverse transcriptase inhibitors. Studies have demonstrated TLD's efficacy as second line, but long-term follow-up is limited. Methods: ARTIST is a single arm, prospective, interventional study conducted in Khayelitsha, South Africa, which switched 62 adults with 2 viral loads >1000 copies/mL from tenofovir, lamivudine/emtricitabine, and an non-nucleoside transcriptase inhibitor to TLD. We report efficacy to 72 weeks and, in a post hoc analysis, evaluated viral load trajectories of individuals with viremic episodes. Results: Virologic suppression was 86% [95% confidence interval (CI) 74 to 93], 74% (95% CI: 61 to 84), and 75% (95% CI: 63 to 86) <50 copies/mL and 95%, 84%, and 77% <400 copies/mL at week 24, 48, and 72, respectively, with 89% (50/56) resistant (Stanford score ≥15) to tenofovir and/or lamivudine preswitch. No participants developed integrase-inhibitor resistance. Of the 20 participants not suppressed at week 24 and/or 48, 2 developed virologic failure, 1 switched regimen (adverse event), 2 were lost to follow-up, 1 missed the visit, 1 transferred out, 9 resuppressed <50 copies/mL with enhanced adherence counseling, and 4 remained viremic (3 with <200 copies/mL) at week 72. Conclusions: Recycling NRTIs with dolutegravir was effective for most participants to 72 weeks. Most with viremia did not develop virologic failure and subsequently suppressed with enhanced adherence counseling or continued to have low-level viremia. No integrase-inhibitor resistance was detected despite low-level viremia in a minority of participants. [ABSTRACT FROM AUTHOR]

The Korea Retrospective Dosimetry network (KREDOS) performed an inter-laboratory comparison to confirm the harmonization and reliability of the results of retrospective dosimetry using mobile phone. The mobile phones were exposed to 192Ir while attached to the human phantoms in the field experiment, and the exposure doses read by each laboratory were compared. This paper describes the reference dosimetry performed to present the reference values for inter-comparison and to obtain additional information about the dose distribution. Reference dosimetry included both measurement using LiF:Mg,Cu,Si and calculation via MCNP simulation to allow a comparison of doses obtained with the two different methodologies. When irradiating the phones, LiF elements were attached to the phones and phantoms and irradiated at the same time. The comparison results for the front of the phantoms were in good agreement, with an average relative difference of about 10%, while an average of about 16% relative difference occurred for the back and side of the phantom. The differences were attributed to the different characteristics of the physical and simulated phantoms, such as anatomical structure and constituent materials. Nevertheless, there was about 4% of under-estimation compared to measurements in the overall linear fitting, indicating the calculations were well matched to the measurements.

Background Personnel radiation monitoring equipment monitors the level of exposure to radiation and personnel will have to wear a personnel device for radiation detection while working. Personnel monitoring equipment is usually worn by a worker for 3 months.

PET/MRI technology has expanded the boundaries of investigation in nuclear medicine, supported by the high sensitivity of solid-state PET detectors. Nonetheless, the coil positioning might lead to an increased exposure period of the worker to the injected patient. This procedure does not occur on PET/CT and, therefore, exposure period is reduced on such scanner. The aim of our study was to evaluate the dosimetry of two occupationally exposed individuals (OEI) working at the Center of Nuclear Medicine of Hospital das Clínicas of the University of Sao Paulo. We used thermoluminescent (TLD) dosimeters in pulse, whole-body and crystalline for PET/MRI and PET/CT procedures during five months of clinical and research routine. We also monitored the time for positioning/removing the patient on both scanners. For this study, OEI1 performed 76 PET/MRI studies and 102 PET/CT studies while OEI2 performed 26 and 56 PET/MRI and PET/CT studies, respectively. We found no evidence of differences for the whole-body dose values between both scanners (p = 0.22). The average time of patient management (positioning/removing the patient) was 14.38, and 3.81 minutes for PET/MRI and PET/CT, respectively. When the normalization by the number of PET/CT studies was applied, we found no statistical difference for effective and equivalent dose values. Our study encourages future investigations on nursing staff, which is a critical population that is exposed to ionizing radiation, mainly on dynamic studies, due to the synchronized injection with the protocol starting.

Background In 2019, the World Health Organization (WHO) recommended combined tenofovir disoproxil fumarate, lamivudine, and dolutegravir (TLD) as the preferred first-line regimen for adults and adolescents with human immunodeficiency virus (HIV), regardless of childbearing status. Nevertheless, final eligibility is determined by local policies, which may vary from WHO recommendations. We examined TLD transition by sex across 5 HIV care programs in sub-Saharan Africa supported by the United States President's Emergency Plan for AIDS Relief (PEPFAR) Methods The African Cohort Study (AFRICOS) enrolls people with HIV engaged in care in Uganda, Kenya (South Rift Valley and Kisumu West), Tanzania, and Nigeria. People with HIV with ≥1 study visit after the country introduced TLD were included. We generated Kaplan-Meier curves to compare TLD transition by sex from (1) the time countries introduced TLD and (2) the time of TLD eligibility according to local policies. Results Among 2476 participants enrolled through September 2021 at 4 sites in sub-Saharan Africa and eligible to transition to TLD, fewer women (68%) than men (80%; P <.001) were taking TLD. Kaplan-Meier analysis showed that time to transition varied by site, with women in Tanzania transitioning at the same rate as men. In Nigeria, women initially had a slower transition but caught up to men. After adjustment for local policies, women in Kisumu West transitioned at the same rate as men. In South Rift Valley and Uganda, women were less likely to be transitioned. Conclusions Although TLD has been the WHO's preferred regimen since 2019, transition of women to potentially lifesaving TLD has been slower than for men at certain clinical sites, even after accounting for local eligibility criteria. [ABSTRACT FROM AUTHOR]

To ensure optimal prescribing practices in the dolutegravir-era in Cameroon, we compared first-line virological response (VR) under tenofovir + lamivudine + dolutegravir (TLD) according to prior exposure to tenofovir + lamivudine + efavirenz (TLE). A facility-based survey was conducted among patients initiating antiretroviral therapy (ART) with TLD (I-TLD) versus those transitioning from TLE to TLD (T-TLD). HIV viral load was performed and unsuppressed participants (VL > 1000 copies/mL) had genotyping performed by Sanger sequencing. Of the 12,093 patients followed, 310 (mean-age: 41 ± 11 years; 52.26% female) complied with study criteria (171 I-TLD vs. 139 T-TLD). The median ART-duration was 14 (12–17) months among I-TLDs versus 28 (24.5–31) months among T-TLDs (15 (11–19) on TLE and 14 (9–15) on TLD), and 83.15% (148/178) were at WHO clinical stages I/II. The viral suppression rate (<1000 copies/mL) was 96.45%, with 97.08% among I-TLDs versus 95.68% among T-TLDs (p = 0.55). VR was similar in I-TLD versus T-TLD at <400 copies/mL (94.15% versus 94.42%) and age, gender, residence, ART-duration, and WHO stages were not associated with VR (p > 0.05). Genotyping was successful for 72.7% (8/11), with no major mutations to integrase inhibitors found. VR is optimal under first-line TLD after 14 months, even among TLE-exposed, thus confirming the effectiveness of transitioning from TLE to TLD in similar settings, supported by strong pharmacological potency and genetic barrier of dolutegravir. [ABSTRACT FROM AUTHOR]

This study aimed to determine the effective doses of the cardiologist, nurses, and technical staff in the pediatric angiography laboratory during their diagnostic and therapeutic applications. This study also compares the radiation dose in the applications performed in the country with the effective doses exposed on a world scale. A total of 39 coronary angiography (CA) + percutaneous transluminal angioplasty (PTCA) methods were performed in the pediatric angiography laboratory during the study. The radiation dose received for each person in a single application was determined, and the total dose values were measured in sequential applications. If the annual workload is taken into consideration, it is calculated that the person with a high workload may be exposed to a dose of 1384.7 µSv per year. Furthermore, from the total effective dose values, the doses per procedure were calculated to be in the range of 6.5 to 11.1 µSv. These results are consistent with the literature. [ABSTRACT FROM AUTHOR]

This is a study on a deep, liquid‐containing tank, such as an overhead water tank on a building, with a vertically submerged stretched membrane (SSM). Here, instead of the sloshing mode, which can become detuned and also affords a low damper mass ratio, the impulsive liquid–membrane interacting system is designed to serve as a dynamic vibration absorber. The requirement of tuning the frequency of the impulsive liquid–membrane interacting system to the structural frequency can be achieved without any imposition on the tank dimensions, which are generally fixed from the tank's functional requirements. The system frequency would remain unchanged so long the membrane would remain submerged below a minimum liquid depth, thereby allowing fluctuation of liquid level within a prescribed range of the tank depth. The formulation for obtaining the frequency of the impulsive liquid–membrane interacting system is derived, using the sub‐domain partition approach. It is seen that through suitable adjustment of the design parameters of the membrane, the proposed tank damper can be tuned to both short‐period and to long‐period structures. Further, the impulsive liquid mass, which otherwise has no role to play in the damping mechanism of a tuned liquid damper (TLD), is here utilized to absorb and dissipate the vibrational energy. Through a time‐domain study considering recorded seismic accelerograms, the significant control effectiveness of the proposed damper system is illustrated. Further, the results obtained from the equivalent mechanical model of the structure–damper system are compared with those from a finite element analysis of the fluid–structure system in the ANSYS Workbench environment. [ABSTRACT FROM AUTHOR]

A rapidly changing landscape of antiretrovirals and their procurement at scale has permitted the evaluation of new optimised second-line antiretroviral therapy (ART) in low- and middle-income countries. D2EFT is an open-label randomised controlled non-inferiority phase IIIB/IV trial in people living with HIV-1 (PWH) whose first-line non-nucleoside reverse transcriptase inhibitor (NNRTI)-based ART is failing. At inception, it compared a standard of care of boosted darunavir with two nucleos(t)ide reverse transcriptase inhibitors (NRTIs) to the novel NRTI-sparing regimen of boosted darunavir with dolutegravir. Implemented in 2017, participating sites were across Africa, Asia and Latin America. Around the time of implementation, the World Health Organization updated its treatment guidelines and recommended scaling up tenofovir disoproxil fumarate-lamivudine-dolutegravir (TLD). This situation pushed D2EFT investigators to consider the impact of the roll-out of TLD on the D2EFT research question. The protocol team agreed it was important to study TLD in second-line when an NNRTI regimen was failing, and focused on options to expedite the work by studying the question within the existing trial and network. All key issues (statistical, programmatic and financial) were reviewed to assess the benefits and risks of adding a third arm to the ongoing study, as opposed to developing a new randomised clinical trial with the same control arm and within the same network. The development of a new trial was deemed to be longer than adding a third arm, and to create a challenging situation with two competing clinical trials at the same sites which would slow down recruitment and impair both trials. On the other hand, adding a third arm would be demanding in terms of operationalisation, increased sample size and statistical biases to control. The optimal strategy was deemed to be the addition of a third arm, arriving retrospectively at a simplified multi-arm multi-stage clinical trial design to achieve statistical validity. The D2EFT study maintains additional value in a quickly evolving second-line ART strategy allowed by the progress in global access to ART. [ABSTRACT FROM AUTHOR]

Summary: The hydrodynamic characteristics of rectangular tanks with internal damping devices, including baffles and paddles, are investigated using shaking table tests excited by colored noise. The complex second‐order blind identification method is employed to decouple fluid sloshing responses and to obtain mode shapes. The modal frequency and damping ratio are also identified by the modified Bayesian spectral density approach. The influence of baffle angle, paddle width, liquid depth, and excitation amplitude on the natural frequency and damping ratio of tuned liquid dampers (TLDs) is analyzed. Results show that the natural frequency is reduced due to the added mass produced by the damping devices, and the reduction increases gradually with the increase in the size of the damping devices, indicating that the influence of the added mass should be considered in the design. This result is essentially different from the conclusion of the existing finding that the modal frequency of TLD increases continuously with the increase in the baffle angle. Therefore, the tuning of TLD cannot be realized by rotating the baffles. Moreover, the damping ratio of TLD with paddles shows a nonlinear relationship with the fluid response. The nonlinear empirical model fitted by the test results can predict the damping ratio with high accuracy and can be used in the preliminary design of TLD for the wind‐induced vibration control of super‐tall buildings. [ABSTRACT FROM AUTHOR]

Ionizing radiation has enough energy to damage DNA and increase human risk of developing cancer. Radiation protection must be assured to all the people of the hospital, from the employing authority to the workers carrying out radiological procedures. This work aims to evaluate the radiation safety in diagnostic procedures using X-ray, in Mekelle city, in the case of governmental and non-governmental hospitals. All the data are collected by observation and interviewing the staff members of each facility, measuring the dose rate at the controlled and supervised areas, the outputs and leakage of the X-ray machines. The collected data are evaluated both qualitatively and quantitatively. The result shows that 25.9 % of the radiation workers are females, and 74.1 % of them are males. As concerns the educational background, 37 % of the workers are bachelor degree holders, and 63 % are possessors of university diplomas. Thermoluminescence dosimeters (TLD) produce a file on the procedures being practiced for the assessment of personal doses. A need for such a file has also been touched to ensure the uniformity in processing of dosimeters, recording and reporting of doses by different TLD. It was noticed that there is a problem in using the existing protective devices during the radiotherapy practice. To improve the radiation safety procedure, the lifetime of the X-ray machine has to be limited. Also, it is necessary to adjust the maintenance and service shop to control the X-ray machine. At the same time, the radiation workers must permanently update their knowledge and skills. [ABSTRACT FROM AUTHOR]

Introduction: Human immunodeficiency virus HIV causes a well-known global disease, acquired immunodeficiency syndrome (AIDS), which has a high disease burden in Africa. HIV infection is known to be associated with oxidative stress, which may contribute to disease severity. However, the effect of HAART is equivocal, and requires more studies. 8-hydroxy-2-deoxyguanosine (8-OHdG), a useful biomarker to assess oxidative DNA damage in biological fluids, was therefore measured in this study., Objectives: The study measured 8-OHdG in HIV seronegative and seropositive participants and correlated it with the duration of HAART., Research Question: Does HIV infection have an effect on oxidative DNA damage? Does HAART have an effect on oxidative DNA damage? Does HAART duration have an effect on oxidative DNA damage?, Methods: This was a cross-sectional study consisting of 99 participants in 4 strata: 20 HIV seronegative, 25 HAART naïve, 26 on HAART <5 years, and 28 on HAART >5 years. Those on HAART were all on Tenofovir, Lamivudine, and Dolutegravir (TLD) combination. The questionnaires were administered, and blood samples were collected from all the participants. The serum 8-OHdG was measured with enzyme-linked immunosorbent assay in all the participants. The universal biosafety standards were strictly adhered to. The data were collected and analyzed with SPSS 2016 version., Results/discussion: The serum levels of 8-OHdG of the participants were shown below. Our findings showed higher 8-OHdG in HIV patients than the Controls and is much higher in HAART naïve when compared with those on HAART (p = 0.005). The serum 8-OHdG and HAART duration were compared and showed a statistically significant negative correlation (r = - 0.331, p= 0.014)., Conclusion: This study found that HIV infection causes oxidative DNA damage which is more in patients who have not started HAART than those on HAART. This showed that the TLD-HAART regimen reduces HIV-associated oxidative stress over time, though not completely. This finding further supports a critical role of oxidative stress in HIV infection, a protective effect of HAART, and a potential role of antioxidants that requires further research., Competing Interests: The Authors declare that no competing interest exists, (Copyright © 2024 by West African Journal of Medicine.)

This retrospective study provides an insight into the levels of radiation exposure of six nuclear medicine (NM) staff (four technologists and two nurses) performing routine diagnostic 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography-computed tomography (PET/CT) at the University Clinical Centre of the Republic of Srpska, Department of Nuclear Medicine and Thyroid Disorders, Banja Luka, Bosnia and Herzegovina. Data analysis included monthly staff exposure measured with personal thermoluminescent dosimeters (TLD) between June and December 2018, quantified in terms of normalised dose for the whole body [Hp(10)] and dominant hand [Hp(0.07)] and their comparison between each staff member and between the two groups (technologists and nurses). The study goal was to establish how our Department compared with reports from other PET/CT centres worldwide in terms of annual number of procedures and exposure limits and whether there could be room for further improvements in radiation protection. The number of procedures rose considerably from 208 in 2016 to 876 in 2019 and was 423 in the observed seven-month period. Mean individual whole-body exposure dose per GBq of injected 18F-FDG activity, [Hp(10)/A] was 18.55 μSv/GBq for the four technologists and 15.61 μSv/GBq for the two nurses. Mean dominant-hand exposure dose per GBq of injected 18F-FDG activity [Hp(0.07)/A] was 16.99 μSv/GBq and 25.44 μSv/GBq for the two groups, respectively. The average annual cumulative dose for all staff was (1.06±0.29) mSv for Hp(10) and (1.15±0.32) mSv for Hp(0.07). These results are comparable with those of similar studies. Staff doses were well below the annual limits. Nurses received slightly higher extremity doses than technologists. In view of the increasing trends in the number of PET/CT procedures, dose monitoring should be continued to identify exposure hotspots and maintain doses as low as possible.

Increased HIV drug resistance (HIVDR) with antiretroviral therapy (ART) rollout may jeopardize therapeutic options, especially in this era of transition to fixed-dose tenofovir-lamivudine-dolutegravir (TLD). We studied acquired HIVDR (ADR) patterns and describe potentially active drugs after first- and second-line failure in resource-limited settings (RLS) like Cameroon. A laboratory-based study with 759 patients (≥15 years) experiencing virological failure was carried out at the Chantal Biya International Reference Centre (CIRCB), Yaoundé, Cameroon. Socio-demographic, therapeutic and immunovirological data from patient records were analysed according to HIV-1 genotypic profiles. Median (IQR) ART-duration was 63 (50–308) months. Median CD4 and viremia were 153 (IQR:50–308) cells/mm3 and 138,666 (IQR:28,979–533,066) copies/mL, respectively. Overall ADR was high (93.4% first-line; 92.9%-second-line). TDF, potentially active in 35.7% of participants after first-line and 45.1% after second-line, suggested sub-optimal TLD-efficacy in second-line (64.3%) and third-line (54.9%). All PI/r preserved high efficacy after first-line failure while only DRV/r preserved high-level efficacy (87.9%) after second-line failure. In this resource-limited setting (RLS), ADR is high in ART-failing patients. PI/r strategies remain potent backbones for second-line ART, while only DRV/r remains very potent despite second-line failure. Though TLD use would be preferable, blind use for second- and third-line regimens may be sub-optimal (functional monotherapy with dolutegravir) with high risk of further failure, thus suggesting strategies for selective ART switch to TLD in failing patients in RLS.

In this paper, parametric forced tuned solid ball dampers (TSBD) are considered for vibration control of engineering structures in an untypical way. The special feature of the presented investigation is to evaluate the potential application of parametric forcing of the rolling cylindrical or spherical body in the runway for reducing the vertical vibrations of a vibration-prone main system. Typically, tuned solid ball dampers are applied to structures that are prone to horizontal vibrations only. The coupled nonlinear differential equations of motion are derived and the phenomenon of parametric resonance of the rolling body in the runway is analyzed. A criterion for avoiding parametric resonance is given to achieve the optimal damping effect of the TSBD. In the second part of the article, a method for the targeted use of parametric resonance to reduce the vertical vibrations of engineering structures is presented and verified, considering a biaxially harmonic excited pedestrian bridge. It is shown that, with a suitable choice of damper parameters, a stable vibration of the rolling body in the runway is formed over the course of the vibration despite the occurrence of parametric resonance and that the maximum vertical vibration amplitudes of the main system can be reduced up to 93%. Hence, the here presented untypical application of parametric forced TSBD for reducing the vertical forced vibrations of vibration-prone main systems could be successfully demonstrated.

Background: The out-of-the-field absorbed dose affects the probability of primary second radiation-induced cancers. This is particularly relevant in the case of pediatric treatments. There are currently no methods employed in the clinical routine for the computation of dose distributions from stray radiation in radiotherapy. To overcome this limitation in the framework of conventional teletherapy with photon beams, two computational tools have been developed--one based on an analytical approach and another depending on a fast Monte Carlo algorithm. The purpose of this work is to evaluate the accuracy of these approaches by comparison with experimental data obtained from anthropomorphic phantom irradiations. Materials and Methods: An anthropomorphic phantom representing a 5-year-old child (ATOM, CIRS) was irradiated considering a brain tumor using a Varian TrueBeam linac. Two treatments for the same planned target volume (PTV) were considered, namely, intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT). In all cases, the irradiation was conducted with a 6-MV energy beam using the flattening filter for a prescribed dose of 3.6 Gy to the PTV. The phantom had natLiF : Mg, Cu, P (MCP-N) thermoluminescent dosimeters (TLDs) in its 180 holes. The uncertainty of the experimental data was around 20%, which was mostly attributed to the MCP-N energy dependence. To calculate the out-of-field dose, an analytical algorithm was implemented to be run from a Varian Eclipse TPS. This algorithm considers that all anatomical structures are filled with water, with the exception of the lungs which are made of air. The fast Monte Carlo code dose planning method was also used for computing the out-of-field dose. It was executed from the dose verification system PRIMO using a phase-space file containing 3x109 histories, reaching an average standard statistical uncertainty of less than 0.2% (coverage factor k = 1) on all voxels scoring more than 50% of the maximum dose. The standard statistical uncertainty of out-of-field voxels in the Monte Carlo simulation did not exceed 5%. For the Monte Carlo simulation the actual chemical composition of the materials used in ATOM, as provided by the manufacturer, was employed. Results: In the out-of-the-field region, the absorbed dose was on average four orders of magnitude lower than the dose at the PTV. For the two modalities employed, the discrepancy between the central values of the TLDs located in the out-of-the-field region and the corresponding positions in the analytic model were in general less than 40%. The discrepancy in the lung doses was more pronounced for IMRT. The same comparison between the experimental and the Monte Carlo data yielded differences which are, in general, smaller than 20%. It was observed that the VMAT irradiation produces the smallest out-of-the-field dose when compared to IMRT. Conclusions: The proposed computational methods for the routine calculation of the out-of-the-field dose produce results that are similar, in most cases, with the experimental data. It has been experimentally found that the VMAT irradiation produces the smallest out-of-the-field dose when compared to IMRT for a given PTV. [ABSTRACT FROM AUTHOR]

Proton therapy enables to deliver highly conformed dose distributions owing to the characteristic Bragg peak and the finite range of protons. However, during proton therapy, secondary neutrons are created, which can travel long distances and deposit dose in out-of-field volumes. This out-of-field absorbed dose needs to be considered for radiation-induced secondary cancers, which are particularly relevant in the case of pediatric treatments. Unfortunately, no method exists in clinics for the computation of the out-of-field dose distributions in proton therapy. To help overcome this limitation, a computational tool has been developed based on the Monte Carlo code TOPAS. The purpose of this work is to evaluate the accuracy of this tool in comparison to experimental data obtained from an anthropomorphic phantom irradiation. An anthropomorphic phantom of a 5-year-old child (ATOM, CIRS) was irradiated for a brain tumor treatment in an IBA Proteus Plus facility using a pencil beam dedicated nozzle. The treatment consisted of three pencil beam scanning fields employing a lucite range shifter. Proton energies ranged from 100 to 165 MeV. A median dose of 50.4 Gy(RBE) with 1.8 Gy(RBE) per fraction was prescribed to the initial planning target volume (PTV), which was located in the cerebellum. Thermoluminescent detectors (TLDs), namely, Li-7-enriched LiF : Mg, Ti (MTS-7) type, were used to detect gamma radiation, which is produced by nuclear reactions, and secondary as well as recoil protons created out-of-field by secondary neutrons. Li-6-enriched LiF : Mg,Cu,P (MCP-6) was combined with Li-7-enriched MCP-7 to measure thermal neutrons. TLDs were calibrated in Co-60 and reported on absorbed dose in water per target dose (μGy/Gy) as well as thermal neutron dose equivalent per target dose (μSv/Gy). Additionally, bubble detectors for personal neutron dosimetry (BD-PND) were used for measuring neutrons (>50 keV), which were calibrated in a Cf-252 neutron beam to report on neutron dose equivalent dose data. The Monte Carlo code TOPAS (version 3.6) was run using a phase-space file containing 1010 histories reaching an average standard statistical uncertainty of less than 0.2% (coverage factor k = 1) on all voxels scoring more than 50% of the maximum dose. The primary beam was modeled following a Fermi–Eyges description of the spot envelope fitted to measurements. For the Monte Carlo simulation, the chemical composition of the tissues represented in ATOM was employed. The dose was tallied as dose-to-water, and data were normalized to the target dose (physical dose) to report on absorbed doses per target dose (mSv/Gy) or neutron dose equivalent per target dose (μSv/Gy), while also an estimate of the total organ dose was provided for a target dose of 50.4 Gy(RBE). Out-of-field doses showed absorbed doses that were 5 to 6 orders of magnitude lower than the target dose. The discrepancy between TLD data and the corresponding scored values in the Monte Carlo calculations involving proton and gamma contributions was on average 18%. The comparison between the neutron equivalent doses between the Monte Carlo simulation and the measured neutron doses was on average 8%. Organ dose calculations revealed the highest dose for the thyroid, which was 120 mSv, while other organ doses ranged from 18 mSv in the lungs to 0.6 mSv in the testes. The proposed computational method for routine calculation of the out-of-the-field dose in proton therapy produces results that are compatible with the experimental data and allow to calculate out-of-field organ doses during proton therapy. [ABSTRACT FROM AUTHOR]

Background Personnel radiation monitoring equipment monitors the level of exposure to radiation and personnel will have to wear a personnel device for radiation detection while working. Personnel monitoring equipment is usually worn by a worker for 3 months. Aim This study aims to evaluate the knowledge of radiology students about personnel radiation monitoring devices and their use. Materials and Methods A questionnaire-based cross-sectional study was performed in the College of Paramedical Sciences, Teerthanker Mahaveer University, Delhi–Road Moradabad, Uttar Pradesh, India. This questionnaire-based study was performed for the period time of 1 year from June 2020 to May 2021. A validated questionnaire was circulated among undergraduate and postgraduate radiology students. Result In this study the questionnaire was filled by a total of 140 students who were pursuing bachelor's and master's degree programs, including 61% (86) males and 39% (54) females from the radiology department. According to the data master's knowledge levels are greater than the bachelor's level. The level of knowledge of monitoring devices among MRIT (M.Sc. in Radiology and Imaging Technology) second year (81%) is more than those of MRIT first year (80%), BRIT (B.Sc. in Radiology and Imaging Technology) third year (65%), and BRIT second year (66%). Conclusion It is concluded that there is a lack of awareness about personnel radiation monitoring systems. The level of knowledge of personnel radiation monitoring devices among students remains at a medium level from the results of our students as it has been concluded that master's knowledge level is greater than the bachelor's level. The level of knowledge of monitoring devices increases with the age of the students and the year completed. [ABSTRACT FROM AUTHOR]