303 research outputs found
Design and Implementation of a Monte Carlo Framework for Assessment of Spoiler Applications in Abutting Electron Fields
Background: Field matching problems in abutting electron fields can be man-aged by using spoilers. Objective: The aim of this study was to design a Monte Carlo framework for the assessment of spoiler application in abutting electron fields. Material and Methods: In this experimental study, a Siemens Primus treatment head was simulated for a 5 MeV electron beam using BEAMnrc, DOSXYZnrc and EGSnrc user codes. Validation of beam model was done by measurement using a MP3-M water tank and a Semi-flex Chamber-31010 (PTW, Freiburg, Germany). An in-house routine was developed to calculate the combined isodose curves result-ing from simulated adjacent fields. The developed framework was analyzed using PMMA and chromium spoilers. Results: The penumbra width increased from 27.5 mm for open fields to 42 mm for PMMA and 40 mm for chromium. The maximum junction dose reduced from 115% for open fields to 107% for PMMA and 108% for chromium. R90 reduced about 6 mm for PMMA and 3 mm for chromium. Uniformity index reduced from 93% to 77% for both spoilers. Surface dose increased from 79% to 89% for PMMA and 88% for chromium. Conclusion: Using spoilers, penumbra width at the surface was increased, size and depth of hot spots as well as the therapeutic range were reduced and dose homo-geneity at the junction of abutting electron fields was improved. For both spoilers, the uniformity index reduced, and surface percent dose increased. The results of this research can be used to optimize dose distribution in electron beam treatment using abutting fields
Evaluation of Therapeutic Properties of a Low Energy Electron Beam Plus Spoiler for Local Treatment of Mycosis Fungoides: A Monte Carlo Study
Background: When using low-energy electron beams for the treatment of skin
lesions, such as Mycosis Fungoides (MF), a beam spoiler is used to decrease electron
therapeutic depth (R90) while increasing the surface dose.
Objective: The aim of this study was to evaluate the characteristics of a 5 MeV
electron beam when using a spoiler for the local treatment of MF skin lesions by
Monte Carlo (MC) simulation.
Methods: A Siemens Primus treatment head and an acrylic spoiler, positioned at
the end of applicator, were simulated using BEAMnrc, an EGSnrc user code. The
modelled beam was validated by measurement using MP3-M water tank, Roos parallel
plate chamber and Semi flex Chamber-31013 (all from PTW, Freiburg, Germany).
For different spoiler thicknesses, dose distributions in water were calculated for 2
field sizes and were compared to those for the corresponding open fields.
Results: For a 1.3 cm spoiler, therapeutic range changed from 1.5 cm (open
field) to 0.5 cm and 0.4 cm for 10 × 10 cm2
and 20 × 20 cm2
field sizes, respectively.
Maximum increase in penumbra width was 2.8 and 3.8 cm for 10 × 10 cm2
and 20 ×
20 cm2
field sizes, respectively. Maximum increase in bremsstrahlung contamination
was %2 in both field sizes.
Conclusion: R90 decreased exponentially with increase in spoiler thickness. The
effect of field size on penumbra was much larger for spoiled beam compared to the
open beam. The results of this research can be applied to optimize the radiation treatment
of MF patients in our hospital
Applications in Integral Equations through Common Results in C*-Algebra-Valued Sb-Metric Spaces
We study some common results in C*-algebra-valued Sb-metric spaces. We also present an interesting application of an existing and unique result for one type of integral equation.Basque Government, Grant IT1155-22
Face Recognition Using Eigenfaces:Effectof the Different SVM Core Functions
ABSTRACT This study has been established based on the combination of the Principal Componen
Anomalous left coronary artery from the pulmonary artery presenting with aborted sudden death in an octogenarian: a case report
<p>Abstract</p> <p>Introduction</p> <p>We report a rare coronary anomaly presenting with aborted sudden death in an octogenarian. An anomalous left coronary artery from the pulmonary artery is a rare coronary anomaly which usually presents in the first year of life. Survival into adulthood and the elderly years is extremely rare.</p> <p>Case presentation</p> <p>An 85-year-old Caucasian woman was brought to our hospital following cardiopulmonary arrest. After prolonged resuscitation and stabilization of our patient, further evaluation revealed an anomalous left coronary artery from pulmonary artery syndrome. She was discharged on medication.</p> <p>Conclusion</p> <p>An anomalous left coronary artery from the pulmonary artery can present in elderly and even octogenarian patients. Careful history, physical examination and an appropriate invasive study are needed to confirm the diagnosis.</p
Generalized Contractive Mappings and Weakly α
The aim of this paper is to present some coincidence and common fixed point results for generalized (ψ, φ)-contractive mappings using partially weakly G-α-admissibility in the setup of G-metric space. As an application of our results, periodic points of weakly contractive mappings are obtained. We also derive certain new coincidence point and common fixed point theorems in partially ordered G-metric spaces. Moreover, some examples are provided here to illustrate the usability of the obtained results
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