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(1 - 8 of 8)
- Title
- Effect of preparation temperature on crystal structure properties on nanophase Fe-substituted hydroxyapatite.
- Creator
- Kathriarachchi, Vindu, Kyriacou, Andreas, Khanal, Suraj P., Leventouri, Theodora, Graduate College
- Date Issued
- 2012-03-30
- PURL
- http://purl.flvc.org/fcla/dt/3342385
- Format
- Document (PDF)
- Title
- Crystal structure studies of cone snail shells by powder x-ray diffraction.
- Creator
- Khanal, Suraj P., Kathriarachchi, Vindu, Kyriacou, Andreas, Leventouri, Theodora, Graduate College
- Date Issued
- 2011-04-08
- PURL
- http://purl.flvc.org/fcla/dt/3165805
- Subject Headings
- Snails, Shells, X-rays --Diffraction
- Format
- Document (PDF)
- Title
- A method of verification of the total treatment time for the APBI (Accelerated Partial Breast Irradiation) devices: CONTURA Multilumen Balloon and SAVI Applicator.
- Creator
- Kyriacou, Andreas, Charles E. Schmidt College of Science, Department of Physics
- Abstract/Description
-
A simple method to verify the total treatment time generated by the treatment planning system (TPS) when the CONTURA MLB or the SAVI applicator are used for APBI treatments has been developed. The method compares the time generated by the TPS to a predicted time, calculated by inserting parameters obtained from the TPS in equations generated in this Thesis. The equations were generated by linearly fitting data from clinical cases that had been treated using the Contura MLB or the SAVI...
Show moreA simple method to verify the total treatment time generated by the treatment planning system (TPS) when the CONTURA MLB or the SAVI applicator are used for APBI treatments has been developed. The method compares the time generated by the TPS to a predicted time, calculated by inserting parameters obtained from the TPS in equations generated in this Thesis. The equations were generated by linearly fitting data from clinical cases that had been treated using the Contura MLB or the SAVI applicator at the Lynn Cancer Institute of the Boca Raton Regional Hospital. The parameters used were the PTV coverage, Air Kerma Strength, Balloon Volume (Contura data fit) and Evaluation PTV (SAVI data fit). As an outcome of this research, it is recommended that the plan should be reevaluated when the percent difference between the generated and the predicted times exceeds 5% for the Contura MLB, or 10% for the SAVI.
Show less - Date Issued
- 2011
- PURL
- http://purl.flvc.org/FAU/3332254
- Subject Headings
- Cancer, Radiotherapy, Breast, Cancer, Radiotherapy, Breast, Cancer, Treatment
- Format
- Document (PDF)
- Title
- Simultaneous x-ray and neutron diffraction Rietveld refinements of nanophase Fe substituted hydroxyapatite.
- Creator
- Kyriacou, Andreas, Charles E. Schmidt College of Science, Department of Physics
- Abstract/Description
-
The effect of Fe substitution on the crystal structure of hydroxyapatite (HAp) is studied by applying simultaneous Rietveld refinements of powder x-ray and neutron diffraction patterns. Fe is one of the trace elements replacing Ca in HAp, which is the major mineral phase in bones and teeth. The morphology and magnetic properties of the Fe-HAp system are also studied by transmission electron microscopy and magnetization measurements. Samples of Ca(5-x)Fex(PO4)3OH with 0
Show moreThe effect of Fe substitution on the crystal structure of hydroxyapatite (HAp) is studied by applying simultaneous Rietveld refinements of powder x-ray and neutron diffraction patterns. Fe is one of the trace elements replacing Ca in HAp, which is the major mineral phase in bones and teeth. The morphology and magnetic properties of the Fe-HAp system are also studied by transmission electron microscopy and magnetization measurements. Samples of Ca(5-x)Fex(PO4)3OH with 0< x < 0.3 were prepared. Single phase HAp was identified in x-ray diffraction patterns (XRD) of samples with x < 0.1 inferring that the solubility limits are less than 0.1. Hematite ((Sa(B-Fe2O3) is identified as a secondary phase for higher Fe content. The refined parameters show that Fe is incorporated in the HAp structure by replacing Ca in the two crystallographic sites with a preference at the Ca2 site. This preference explains the small effect of the Fe substitution on the lattice constants of HAp. The overall decrease of the lattice constants is explained by the ionic vi size difference of Ca and Fe. The increasing trend of the a-lattice constant with x in the Fe substituted samples is attributed to a lattice relaxation caused by the substitution of the 4- and 6-fold Fe at the 7- and 9-fold Ca1 and Ca2 sites. This Ca local geometry reduction is indicated by a slight increase of the Ca1-O3 and Ca2-O1 bond lengths. Above the solubility limit x = 0.05, the Fe is partitioned in and out of the HAp structure with increasing nominal Fe content x. The excess Fe is oxidized to hematite. The TEM analysis and magnetic measurements support the results of the simultaneous Rietveld refinements. The TEM images show no significant effect on the morphology and size of the HAp particles upon Fe incorporation. The particles are either spheres or short rods of dimensions 20-60 nm. Hematite particles are imaged in the samples with x exceeding the solubility limit. These particles
Show less - Date Issued
- 2012
- PURL
- http://purl.flvc.org/FAU/3342204
- Subject Headings
- X-rays, Diffraction, Rietveld method, Nanostructured materials, Biomedical materials
- Format
- Document (PDF)
- Title
- Accurate verification of balloon rotation correction for the contura® multi-lumen device for accelerated partial breast irradiation.
- Creator
- Kyriacou, Andreas, Benda, R., Vargas, C., Lyden, M., Vicini , F., Leventouri, Theodora, Graduate College, Kasper, M.
- Date Issued
- 2011-04-08
- PURL
- http://purl.flvc.org/fcla/dt/3171046
- Subject Headings
- Breast --Cancer --Radiotherapy, Brachytherapy, Breast Neoplasms --surgery
- Format
- Document (PDF)
- Title
- A Comparative Analysis of Monte Carlo and Collapsed Cone Dose Calculation Algorithms for Monaco 3D Treatment Plans.
- Creator
- Pereira, Shakeel, Kyriacou, Andreas, Florida Atlantic University, Department of Physics, Charles E. Schmidt College of Science
- Abstract/Description
-
The Monaco treatment planning system offers three different dose calculation algorithms for use in calculating 3D treatment plans. These include Monte Carlo (MC), Collapsed Cone (CC) and the pencil beam algorithms. The aim of this study is an in-depth analysis of Monte Carlo and Collapsed Cone dose calculation methods to find the optimal parameters for clinical use for both algorithms. An end-to-end phantom with inhomogeneities was scanned and the DICOM images were imported into Monaco for...
Show moreThe Monaco treatment planning system offers three different dose calculation algorithms for use in calculating 3D treatment plans. These include Monte Carlo (MC), Collapsed Cone (CC) and the pencil beam algorithms. The aim of this study is an in-depth analysis of Monte Carlo and Collapsed Cone dose calculation methods to find the optimal parameters for clinical use for both algorithms. An end-to-end phantom with inhomogeneities was scanned and the DICOM images were imported into Monaco for contouring and planning. Treatment plans were then created in Monaco for both MC and CC using different permutations of variables for approximately 400 plans. These variables include CT Slice thickness, grid size, statistical uncertainty, and beam energy. Following planning the end-to-end phantom was then irradiated on an Elekta Linac and plans for each beam energy were created. Clinical beam data was then compared to the computed plans for each dose calculation method.
Show less - Date Issued
- 2022
- PURL
- http://purl.flvc.org/fau/fd/FA00014019
- Subject Headings
- Radiotherapy, Radiotherapy Dosage, Radiation dosimetry
- Format
- Document (PDF)
- Title
- A New Mechanical and Radiation Isocenter Adjustment Approach Using the Isopoint.
- Creator
- Irons, Tristan, Kyriacou, Andreas, Florida Atlantic University, Department of Physics, Charles E. Schmidt College of Science
- Abstract/Description
-
The Winston-Lutz has been the standard test for isocenter convergence, however, any adjustments needed – in case the test fails – are time consuming since the source of error is not readily available from the results. Isopoint by the Aktina Medical company has been developed to address this problem via decoupling the mechanical from the radiation isocenter and providing the user with information that was inaccessible before. The focus of this research is to perform optimization of the...
Show moreThe Winston-Lutz has been the standard test for isocenter convergence, however, any adjustments needed – in case the test fails – are time consuming since the source of error is not readily available from the results. Isopoint by the Aktina Medical company has been developed to address this problem via decoupling the mechanical from the radiation isocenter and providing the user with information that was inaccessible before. The focus of this research is to perform optimization of the isocenter by using the Isopoint and to confirm the validity of its results, as well as to find how much time is saved via this new technology. The data for this project was collected on a 2012 Elekta Synergy, a Varian 21ix, and a 2021 Elekta Versa through partnership with GenesisCare. Our findings indicate that the Isopoint will allow for more accurate and speedy adjustments of the LINAC (Linear Accelerator) and will be integral in the future of this field.
Show less - Date Issued
- 2023
- PURL
- http://purl.flvc.org/fau/fd/FA00014259
- Subject Headings
- Medical physics
- Format
- Document (PDF)
- Title
- An Algorithm to Determine IMRT Optimization Parameters within the Elekta Monaco® Treatment Planning System that Increases Dose Homogeneity and Dose Conformity in the Planning Target Volume.
- Creator
- Gregorisch, David, Pella, Silvia, Kyriacou, Andreas, Florida Atlantic University, Department of Physics, Charles E. Schmidt College of Science
- Abstract/Description
-
An algorithm to determine IMRT optimization parameters within the Elekta Monaco® treatment planning system that increases dose homogeneity and dose conformity in the planning target volume was developed. This algorithm determines IMRT optimization parameters by calculating the difference between two pairs of dose points along the target volume’s dose volume histogram: Dmax – Dmin, and D2 – D98. The algorithm was tested on the Elekta Monaco® Treatment Planning System at GenesisCare of Coconut...
Show moreAn algorithm to determine IMRT optimization parameters within the Elekta Monaco® treatment planning system that increases dose homogeneity and dose conformity in the planning target volume was developed. This algorithm determines IMRT optimization parameters by calculating the difference between two pairs of dose points along the target volume’s dose volume histogram: Dmax – Dmin, and D2 – D98. The algorithm was tested on the Elekta Monaco® Treatment Planning System at GenesisCare of Coconut Creek, Florida using CT data from 10 anonymized patients with non-small cell lung cancer of various tumor sizes and locations. Nine iterations of parameters were tested on each patient. Once the ideal parameters were found, the results were evaluated using the ICRU report 83 homogeneity index as well as the Paddick conformity index. As an outcome of this research, it is recommended that at least three iterations of IMRT optimization parameters should be calculated to find the ideal parameters.
Show less - Date Issued
- 2022
- PURL
- http://purl.flvc.org/fau/fd/FA00013990
- Subject Headings
- Radiotherapy, Algorithm, Medical physics
- Format
- Document (PDF)
