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- Title
- Dosimetric Consequences From Minimal Displacements In Abpi With Savi Applicators.
- Creator
- Chandrasekara, Shereen, Pella, Silvia, Leventouri, Theodora, Graduate College
- Abstract/Description
-
Purpose: To highlight the importance of provide proper solid immobilization initially and in every treatment in ABPI with brachytherapy. Materials and Methods: 100 patients receiving brachytherapy treatments in ABPI using the Savi applicators were considered for the study. The CT scans used in the initial plan was compared with every scan obtained before each treatment. Each of these scans were exported in the planning system and registered with the initial plan. Dosimetric evaluations were...
Show morePurpose: To highlight the importance of provide proper solid immobilization initially and in every treatment in ABPI with brachytherapy. Materials and Methods: 100 patients receiving brachytherapy treatments in ABPI using the Savi applicators were considered for the study. The CT scans used in the initial plan was compared with every scan obtained before each treatment. Each of these scans were exported in the planning system and registered with the initial plan. Dosimetric evaluations were performed with their consequences to the ribs and the skin surface. Results: Making the dosimetric comparison for the critical points on the ribs and skin due to very small changes in the interfractionation position revealed dramatic differences in the maximum dose to these critical organs. The cavity's volume manifested changes between fractions as well as the distances to the two critical organs. Therefore the maximum dose manifested variance between 10 and 32 in both of the sites Conclusions: This study demonstrates that using CT scan before each treatment will minimize the risk of delivering undesired high doses to the critical organs. This reveals the urgent need of increasing and improving the immobilization methods when treating ABPI with Savi. In 30 of the cases re-planning was necessary between fractions therefore we conclude that in each case the treatment and planning teams must be prepared for re-plan as needed.
Show less - Date Issued
- 2015
- PURL
- http://purl.flvc.org/fau/fd/FA00005872
- Format
- Document (PDF)
- Title
- A Computational Study on different penalty approaches for constrained optimization in radiation therapy treatment planning with a simulated annealing algorithm.
- Creator
- Mohammadi Khoroushadi, Mohammad Sadegh, Shang, Charles, Ouhib, Zoubir, Graduate College, Leventouri, Theodora, Kalantzis, Georgios
- Abstract/Description
-
Simulated Annealing algorithm is utilized for Intensity Modulated Radiation Therapy IMRT optimization. The goal in IMRT is to give the prescribed radiation dose to the tumor while minimizing the dose given to normal organs.
- Date Issued
- 2015
- PURL
- http://purl.flvc.org/fau/fd/FA00005891
- Format
- Document (PDF)
- Title
- Should we use RapidArc (VMAT) for breast radiotherapy? A Dosimetric comparison of IMRT versus VMAT optimization.
- Creator
- Moshiri Sedeh, Nader, Pella, Silvia, Leventouri, Theodora, Graduate College
- Abstract/Description
-
Purpose: The purpose of this study is to compare the dose-volumetric results of intensity modulated radiation therapy (IMRT) with RapidArc (RA Varian Medical Systems, Palo Alto, CA) for whole breast irradiation. Methods: 25 patients previously treated for whole left breast (either RapidArc plan or IMRT) were the subjects of this planning study. Eclipse v 11.0.47 was used to make all retrospective plans using the same contours, energy, machine and normalization. Prescription dose to the...
Show morePurpose: The purpose of this study is to compare the dose-volumetric results of intensity modulated radiation therapy (IMRT) with RapidArc (RA Varian Medical Systems, Palo Alto, CA) for whole breast irradiation. Methods: 25 patients previously treated for whole left breast (either RapidArc plan or IMRT) were the subjects of this planning study. Eclipse v 11.0.47 was used to make all retrospective plans using the same contours, energy, machine and normalization. Prescription dose to the planning target volume was 5000 Gy in 25 fractions. All plans were normalized such that 100% covered 95% of planning target volume (PTV). Results: V10, V20 and Dmean Gy of left lung significantly differed between the two plans (p-value <0.0001, =0.0473 and <0.0001 respectively), but V30 Gy did not (p-value 0.463). V25, D33 and Dmean Gy of heart significantly differed between the two plans (p-value =0.034, <0.0001 and 0.01 respectively), but V10 Gy did not (p-value 0.058). V5 of both right breast and right lung significantly differed between the two plans (p-value <0.0007 and =0.0112, respectively). Also Dmean of both right breast and right lung significantly differed between the two plans (p-value <0.0001 for both). The mean conformity index did not significantly differ, p-value 0.142. There was a significant difference between the mean MUs of the two plans as well, p-value <0.0001.
Show less - Date Issued
- 2015
- PURL
- http://purl.flvc.org/fau/fd/FA00005901
- Format
- Document (PDF)
- Title
- Comparison of Treatment Plans Calculated using Ray Tracing (RT) and Monte Carlo (MC) Algorithms for Lung Cancer Patients Having Undergone Radiotherapy with Cyberknife.
- Creator
- Pennington, Andreea, Selvaraj, Raj, Graduate College, Leventouri, Theodora, Kirkpatrick, Steven, Oliveira, Silvana
- Abstract/Description
-
Purpose/ Objectives: The latest publications indicate that the Ray Tracing algorithm significantly overestimates the dose delivered as compared to the Monte Carlo MC algorithm. The purpose of this study is to quantify this overestimation and to identify significant correlations between the RT and MC calculated dose distributions.
Materials/Methods: Preliminary results are based on 50 preexisting RT algorithm dose optimization and calculation treatment plans prepared on the Multiplan treatment...
Show morePurpose/ Objectives: The latest publications indicate that the Ray Tracing algorithm significantly overestimates the dose delivered as compared to the Monte Carlo MC algorithm. The purpose of this study is to quantify this overestimation and to identify significant correlations between the RT and MC calculated dose distributions.
Materials/Methods: Preliminary results are based on 50 preexisting RT algorithm dose optimization and calculation treatment plans prepared on the Multiplan treatment planning system Accuray Inc., Sunnyvale, CA. The analysis will be expanded to include 100 plans. These plans are recalculated using the MC algorithm, with high resolution and 1 uncertainty. The geometry and number of beams for a given plan, as well as the number of monitor units, is constant for the calculations for both algorithms and normalized differences are compared.
Results: MC calculated doses were significantly smaller than RT doses. The D95 of the PTV was 27 lower for the MC calculation. The GTV and PTV mean coverage were 13 and 39 less for MC calculation. The first parameter of conformality, as defined as the ratio of the Prescription Isodose Volume to the PTV Volume was on average 1.18 for RT and 0.62 for MC. Maximum doses delivered to OARs was reduced in the MC plans. The correlation of the ratio of air in PTV to the PTV with the difference in PTV coverage had a coefficient of -0.54.
Conclusions: The preliminary results confirm that the RT algorithm significantly overestimates the dosages delivered confirming previous analyses.
Show less - Date Issued
- 2014
- PURL
- http://purl.flvc.org/fau/fd/FA00005162
- Format
- Document (PDF)
