scholarly journals Comparison of the radiochromic EBT2 responses for4 MV LINAC in calibration processes

2019 ◽  
Vol 7 (2A) ◽  
Author(s):  
Sabrina Donato Silva ◽  
André L.S Castro ◽  
Thais Melo Mendes ◽  
Luciana B. Nogueira ◽  
Tarcisio Passos Ribeiro Campos
Keyword(s):  
Quality Control ◽  
Calibration Curve ◽  
Absorbed Dose ◽  
Public Health Problem ◽  
Radiochromic Film ◽  
Global Public Health ◽  
Linear Accelerators ◽  
Radiochromic Films ◽  
Water Phantom ◽  
Solid Water

Actually, cancer has gained a larger dimension and become a global public health problem. Radiotherapy (RT) is a neoplasia treatment and RT linear accelerators must undergo a strict dose quality control. Water or solid water phantoms can be used with this intuit. In recent years, radiochromic films with equivalent tissue composition have been widely used as dosimeters in the medical field. In this work the proposal was to analyze two distinct radiochromic film responses in water and solid water phantoms, a LINAC spectrum of 4MV beam. Solid water phantom, water phantom and EBT2 Radiochromic films were set in two distinct process of calibration. Films were exposed to a set of absorbed doses established by distinct monitor units (MU) specified in RT-center. Mathematical relations between the degree of red-intensity from digitized films and the absorbed dose for both methods were established. The coefficients of the polynomial function of the calibration curve were determined from the Origin software. The uncertainty of both processes was analyzed. The efficiency of the two calibration processes was set up. The adjustment of the calibration curve provided the coefficients of the second-order equation that relates the dose absorbed with the optical density of the film. The uncertainty regarding the calibration performed in water and solid water and the dose-error accuracy are in agreement with the literature. Both water and solid water were effective in calibration and can be used in routines of quality-control measurements. The results show that EBT2-radiochromic films are suitable to for dose-calibration in RT.

scholarly journals Dose profile evaluation of a 137Cs source using a solid water phantom

2020 ◽  
Vol 8 (3) ◽  
Author(s):  
Caio Fernando Teixeira Portela ◽  
Thêssa Cristina Alonso ◽  
Arnado Prata Mourão
Keyword(s):  
Visible Light ◽  
Beam Energy ◽  
Maximum Dose ◽  
Absorbed Dose ◽  
Radiochromic Film ◽  
Radiochromic Films ◽  
Water Phantom ◽  
Dose Profile ◽  
Cesium 137 ◽  
Solid Water

The precision in the dose values delivered in irradiation processes is essential for the efficiency and quality control of these processes. Radiochromic films can be used to record doses and the calibration of these films must be performed so that they can be used as dosimeters. The planning and control of the radiation released in a process allows to adjust the desired dose in the irradiated object. The photons in the primary beam interact with the matter of the object and the beam energy is attenuated due to these interactions. The attenuation depends on the characteristics of the beam and the composition of the irradiated matter. When a beam of photons propagates on an object, it tends to deposit more energy close to the surface and after reaching the maximum dose value, it decreases the dose values with depth. The films used in this work are of the Gafchromic External Beam Therapy (EBT) type, insensitive to visible light and can be prepared in places where sunlight and artificial light exists. Like many other dosimeters, which follow certain protocols, radiochromic films can provide an absolute dose measurement. Radiochromic films are characterized by their linearity, reproducibility, uniformity, sensitivity, and stability after irradiation. For the realization of the experiments, a part of the film to be irradiated was removed designated as background (BG). BG represents a piece of radiochromic film that will not change and reflects changes in film absorption in relation to environmental conditions such as temperature, visible light and scanning light, for example and that must be handled from it way that the film radiated. In this work, irradiations of a solid water phantom were performed using a source of cesium-137 with the deposition of a maximum absorbed dose value of 2.0 Gy. The phantom was placed 1,0 m far from the source collimator. Radiochromic films were placed inside the phantom to obtain the depth variation dose profile and axial dose profiles measured at 1.0 cm depth in the phantom. The dose variation profile in depth allowed to verify that the maximum dose value happened at a depth between 10 and 13 mm, very close to the surface due to the beam energy range (keV). The axial profiles presented a flatness of about 9.4 cm with a total field of 12 cm in diameter. 

scholarly journals A Novel Simple Phantom for Verifying the Dose of Radiation Therapy

2015 ◽  
Vol 2015 ◽  
pp. 1-5
Author(s):  
J. H. Lee ◽  
L. T. Chang ◽  
A. C. Shiau ◽  
C. W. Chen ◽  
Y. J. Liao ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Correction Factor ◽  
Scatter Correction ◽  
Absorbed Dose ◽  
Clinical Tests ◽  
Thermoluminescent Dosimeters ◽  
Water Phantom ◽  
Audit System ◽  
Solid Water ◽  
The Difference

A standard protocol of dosimetric measurements is used by the organizations responsible for verifying that the doses delivered in radiation-therapy institutions are within authorized limits. This study evaluated a self-designed simple auditing phantom for use in verifying the dose of radiation therapy; the phantom design, dose audit system, and clinical tests are described. Thermoluminescent dosimeters (TLDs) were used as postal dosimeters, and mailable phantoms were produced for use in postal audits. Correction factors are important for converting TLD readout values from phantoms into the absorbed dose in water. The phantom scatter correction factor was used to quantify the difference in the scattered dose between a solid water phantom and homemade phantoms; its value ranged from 1.084 to 1.031. The energy-dependence correction factor was used to compare the TLD readout of the unit dose irradiated by audit beam energies with60Co in the solid water phantom; its value was 0.99 to 1.01. The setup-condition factor was used to correct for differences in dose-output calibration conditions. Clinical tests of the device calibrating the dose output revealed that the dose deviation was within 3%. Therefore, our homemade phantoms and dosimetric system can be applied for accurately verifying the doses applied in radiation-therapy institutions.

15 years of 106 Ru eye plaque dosimetry at Memorial Sloan-Kettering Cancer Center and Weill Cornell Medical Center using radiochromic film in a Solid Water phantom

2018 ◽  
Vol 4 (4) ◽  
pp. 045017 ◽  
Author(s):  
Samuel Trichter ◽  
Christopher G Soares ◽  
Marco Zaider ◽  
J Keith DeWyngaert ◽  
Larry A DeWerd ◽  
...  
Keyword(s):  
Medical Center ◽  
Radiochromic Film ◽  
Cancer Center ◽  
Water Phantom ◽  
Solid Water ◽  
Eye Plaque

External Auditing on Absorbed Dose Using a Solid Water Phantom for Domestic Radiotherapy Facilities

2010 ◽  
Vol 28 (1) ◽  
pp. 50 ◽  
Author(s):  
Chang Heon Choi ◽  
Jung-In Kim ◽  
Jong Min Park ◽  
Yang Kyun Park ◽  
Kun-Woo Cho ◽  
...  
Keyword(s):  
Absorbed Dose ◽  
Water Phantom ◽  
Solid Water

Modulation of the drug resistance by Platonia insignis Mart. extract, ethyl acetate fraction and Morelloflavone/Volkensiflavone (biflavonoids) in Staphylococcus aureus strains overexpressing efflux pump genes

2020 ◽  
Vol 21 ◽  
Author(s):  
Andressa Kelly Ferreira e Silva ◽  
Antonielly Campinho dos Reis ◽  
Emanuelly Elanny Andrade Pinheiroc ◽  
Jonas Nascimento de Sousa ◽  
Felipe Araújo de Alcântara Oliveira ◽  
...  
Keyword(s):  
Natural Products ◽  
Ethyl Acetate ◽  
Native Species ◽  
Efflux Pump ◽  
Public Health Problem ◽  
Ethyl Acetate Fraction ◽  
Multidrug Resistant ◽  
Global Public Health ◽  
Minimal Inhibitory Concentrations ◽  
Subinhibitory Concentrations

Background: Microbial resistance to antibiotics is a global public health problem, which requires urgent attention. Platonia insignis is a native species from the eastern Brazilian Amazon, used in the treatment of burns and wounds. Objectives: To evaluate the antimicrobial activity of the hydroalcoholic extract of P. insignis (PIHA), the ethyl acetate fraction (PIAE), and its subfraction containing a mixture of biflavonoids (BF). Moreover, the effect of these natural products on the antibiotic activity against S. aureus strains overexpressing efflux pump genes was also evaluated. Methods: Minimal inhibitory concentrations were determined against different species of microorganisms. To evaluate the modulatory effect on the Norfloxacin-resistance, the MIC of this antibiotic was determined in the absence and presence of the natural products at subinhibitory concentrations. Inhibition of the EtBr efflux assays were conducted in the absence or presence of the natural products. Results: PIHA showed a microbicidal effect against S. aureus and C. albicans, while PIAE was bacteriosctatic for S. aureus. PIAE and BF at subinhibitory concentrations were able to reduce the MIC of Norfloxacin acting as modulating agents. BF was able to inhibit the efflux of EtBr efflux in S. aureus strains overexpressing specific efflux pump genes. Conclusion: P. inignisis a source of efflux pump inhibitors, including volkensiflavone and morelloflavone which were able to potentiate the Norfloxacin activity by NorA inhibition, being also able to inhibit QacA/B, TetK and MsrA. Volkensiflavone and morelloflavone could be used as adjuvant in the antibiotic therapy of multidrug resistant S. aureus strains overexpressing efflux pumps.

4H-1,3-Benzothiazin-4-one a Promising Class Against MDR/XDR-TB

2019 ◽  
Vol 19 (8) ◽  
pp. 567-578 ◽  
Author(s):  
Marcus Vinicius Nora de Souza ◽  
Thais Cristina Mendonça Nogueira
Keyword(s):  
Treatment Time ◽  
Public Health Problem ◽  
New Drugs ◽  
Global Public Health ◽  
Synthesis Mechanism ◽  
Highly Active ◽  
Latent Disease ◽  
Resistant Strains ◽  
Chemical Class ◽  
Global Public Health Problem

Nowadays, tuberculosis (TB) is an important global public health problem, being responsible for millions of TB-related deaths worldwide. Due to the increased number of cases and resistance of Mycobacterium tuberculosis to all drugs used for the treatment of this disease, we desperately need new drugs and strategies that could reduce treatment time with fewer side effects, reduced cost and highly active drugs against resistant strains and latent disease. Considering that, 4H-1,3-benzothiazin-4-one is a promising class of antimycobacterial agents in special against TB-resistant strains being the aim of this review the discussion of different aspects of this chemical class such as synthesis, mechanism of action, medicinal chemistry and combination with other drugs.

Application of Inherent Risk of Contagion (IRC) framework & modelling to aid local Covid-19 response & mitigation: Viewpoint (Preprint)

2020 ◽  
Author(s):  
Helmi Zakariah ◽  
Fadzilah bt Kamaluddin ◽  
Choo-Yee Ting ◽  
Hui-Jia Yee ◽  
Shereen Allaham ◽  
...  
Keyword(s):  
Public Health ◽  
Public Health Problem ◽  
Analytical Framework ◽  
Vulnerable Population ◽  
Contact Tracing ◽  
Global Public Health ◽  
Inherent Risk ◽  
Transmission Area ◽  
Current Outbreak ◽  
Novel Coronavirus

UNSTRUCTURED The current outbreak of coronavirus disease 2019 (COVID-19) caused by the novel coronavirus named SARS-CoV-2 has been a major global public health problem threatening many countries and territories. Mathematical modelling is one of the non-pharmaceutical public health measures that plays a crucial role for mitigating the risk and impact of the pandemic. A group of researchers and epidemiologists have developed a machine learning-powered inherent risk of contagion (IRC) analytical framework to georeference the COVID-19 with an operational platform to plan response & execute mitigation activities. This framework dataset provides a coherent picture to track and predict the COVID-19 epidemic post lockdown by piecing together preliminary data on publicly available health statistic metrics alongside the area of reported cases, drivers, vulnerable population, and number of premises that are suspected to become a transmission area between drivers and vulnerable population. The main aim of this new analytical framework is to measure the IRC and provide georeferenced data to protect the health system, aid contact tracing, and prioritise the vulnerable.

Perceived Experiences of Community Violence Among Adolescents: A School Survey From Rio de Janeiro, Brazil

2021 ◽  
pp. 088626052110051
Author(s):  
Claudia L. de Moraes ◽  
Érika B. dos Santos ◽  
Michael E. Reichenheim ◽  
Stella R. Taquette ◽  
Luciane Stochero ◽  
...  
Keyword(s):  
Public Schools ◽  
Community Violence ◽  
Rio De Janeiro ◽  
Public Health Problem ◽  
Cross Sectional Study ◽  
Global Public Health ◽  
Cross Sectional ◽  
Interpersonal Aggression ◽  
Adolescent Students ◽  
Management Actions

Community violence (CV) is a global public health problem due to its high frequency and severe consequences. Although CV is one of the leading causes of death among adolescents, little is known about the everyday CV situations that do not lead to death. This study aimed to estimate the frequency of exposure to and involvement in CV situations among adolescent students from public and private schools in the city of Rio de Janeiro, Brazil. This was a cross-sectional study of 693 individuals in their second year of high school selected through stratified multistage random sampling. Information about their exposure to and involvement in CV was collected through a self-completed multidimensional questionnaire in the classrooms. For approximately 30% of the adolescents, someone close to them had been murdered, and 40% had already seen the corpse of a victim of homicide. Seventeen percent reported having been directly involved in CV situations. Approximately 38%, 13%, and 25% had been victims of robberies, interpersonal aggression, and death threats to either themselves or their relatives, respectively. Many of these situations occurred more than once. In general, CV was more frequently reported by boys and by those who did not live with both parents. Adolescents from higher economic classes experienced more interpersonal aggression and felt a greater need to carry a gun. Those who belonged to the lower economic classes and studied in public schools were more exposed to lethal violence than other students. The results call attention to the very high percentage of adolescent students that are involved in CV situations as well as to the differences in violence rates among population subgroups. Such findings should be considered when planning CV prevention and management actions in schools and other socialization spaces for adolescents.

scholarly journals Associations between gestational diabetes mellitus and the neurodevelopment of offspring from 1 month to 72 months: study protocol for a cohort study

BMJ Open ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. e040305
Author(s):  
Chao Li ◽  
Ping Zhou ◽  
Yixi Cai ◽  
Bin Peng ◽  
Yongfang Liu ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Cohort Study ◽  
Gestational Diabetes ◽  
Gestational Diabetes Mellitus ◽  
Public Health Problem ◽  
Multiple Linear Regression Model ◽  
Preschool Age ◽  
Control Group ◽  
Global Public Health ◽  
Open Access Journals

IntroductionGestational diabetes mellitus (GDM) is a common gestational disease and an important global public health problem. GDM may affect the short-term and long-term health of offspring, but the associations between GDM and the neurodevelopment of offspring of mothers with GDM (OGDM) are still unclear, and studies based on the Chinese population are lacking. We aim to determine the associations between GDM and the neurodevelopment of OGDM by studying a cohort of OGDM and offspring of non-GDM mothers.Methods and analysisThe single-centre prospective cohort study is being conducted in China over 7 years. A total of 490 OGDM (GDM group) and 490 fromof healthy mothers (control group) will be enrolled during the same period. Baseline characteristics, neuropsychological development scores and clinical data at specific time points (at 0, 1, 3, 6, 12, 24, 36, 48, 60 and 72 months old) will be collected from the children in both groups until the age of 6 years. The associations between GDM and the neurodevelopment of OGDM from infancy to preschool age will be analysed using a multiple linear regression model adjusted for confounders. In addition, we will compare longitudinal data to further assess the effects of GDM on neurodevelopmental trajectories.Ethics and disseminationThe study has been approved by the Ethics Committee of the Children’s Hospital of Chongqing Medical University (Approval Number: (2019) Institutional Review Board (IRB) (STUDY) No. 85). The findings of this study will be disseminated through open access journals, peer-reviewed journals and scientific meetings.Trial registration numberNCT03997396.

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