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Comparison of Treatment Plans Calculated using Ray Tracing (RT) and Monte Carlo (MC) Algorithms for Lung Cancer Patients Having Undergone Radiotherapy with Cyberknife.
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.
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Date Issued
2014
PURL
http://purl.flvc.org/fau/fd/FA00005162
Format
Document (PDF)
Comparison of treatment plans calculated using ray tracing and Monte Carlo algorithms for lung cancer patients having undergone radiotherapy with cyberknife
Title
Comparison of treatment plans calculated using ray tracing and Monte Carlo algorithms for lung cancer patients having undergone radiotherapy with cyberknife.
Creator
Pennington, Andreea, Selvaraj, Raj, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Physics
Abstract/Description
The purpose of this research is to determine the feasibility of introducing the Monte Carlo (MC) dose calculation algorithm into the clinical practice. Unlike the Ray Tracing (RT) algorithm, the MC algorithm is not affected by the tissue inhomogeneities, which are significant inside the chest cavity. A retrospective study was completed for 102 plans calculated using both the RT and MC algorithms. The D95 of the PTV was 26% lower for the MC calculation. The first parameter of conformality, as...
Show moreThe purpose of this research is to determine the feasibility of introducing the Monte Carlo (MC) dose calculation algorithm into the clinical practice. Unlike the Ray Tracing (RT) algorithm, the MC algorithm is not affected by the tissue inhomogeneities, which are significant inside the chest cavity. A retrospective study was completed for 102 plans calculated using both the RT and MC algorithms. The D95 of the PTV was 26% lower for the MC calculation. The first parameter of conformality, as defined as the ratio of the Prescription Isodose Volume to the PTV Volume was on average 1.27 for RT and 0.67 for MC. The results confirm that the RT algorithm significantly overestimates the dosages delivered confirming previous analyses. Correlations indicate that these overestimates are largest for small PTV and/or when the ratio of the volume of lung tissue to the PTV approaches 1.
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Date Issued
2014
PURL
http://purl.flvc.org/fau/fd/FA00004316
Subject Headings
Computer graphics, Diagnostic imaging, Image guided radiation therapy, Lung cancer -- Treatment, Lungs -- Cancer -- Radiotherapy, Monte Carlo method
Format
Document (PDF)
Dosimetric Consequences of the Parotid Glands Using CT-To-CBCT Deformable Registration During IMRT For Late Stage Head And Neck Cancers
Title
Dosimetric Consequences of the Parotid Glands Using CT-To-CBCT Deformable Registration During IMRT For Late Stage Head And Neck Cancers.
Creator
Conill, Annette L., Selvaraj, Raj, Kalantzis, Georgios, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Physics
Abstract/Description
Patients receiving Intensity Modulated Radiation Therapy (IMRT) for late stage head and neck (HN) cancer often experience anatomical changes due to weight loss, tumor regression, and positional changes of normal anatomy (1). As a result, the actual dose delivered may vary from the original treatment plan. The purpose of this study was (a) to evaluate the dosimetric consequences of the parotid glands during the course of treatment, and (b) to determine if there would be an optimal timeframe...
Show morePatients receiving Intensity Modulated Radiation Therapy (IMRT) for late stage head and neck (HN) cancer often experience anatomical changes due to weight loss, tumor regression, and positional changes of normal anatomy (1). As a result, the actual dose delivered may vary from the original treatment plan. The purpose of this study was (a) to evaluate the dosimetric consequences of the parotid glands during the course of treatment, and (b) to determine if there would be an optimal timeframe for replanning. Nineteen locally advanced HN cancer patients underwent definitive IMRT. Each patient received an initial computerized tomography simulation (CT-SIM) scan and weekly cone beam computerized tomography (CBCT) scans. A Deformable Image Registration (DIR) was performed between the CT-SIM and CBCT of the parotid glands and Planning Target Volumes (PTVs) using the Eclipse treatment planning system (TPS) and the Velocity deformation software. A recalculation of the dose was performed on the weekly CBCTs using the original monitor units. The parameters for evaluation of our method were: the changes in volume of the PTVs and parotid glands, the dose coverage of the PTVs, the lateral displacement in the Center of Mass (COM), the mean dose, and Normal Tissue Complication Probability (NTCP) of the parotid glands. The studies showed a reduction of the volume in the PTVs and parotids, a medial displacement in COM, and alterations of the mean dose to the parotid glands as compared to the initial plans. Differences were observed for the dose volume coverage of the PTVs and NTCP of the parotid gland values between the initial plan and our proposed method utilizing deformable registration-based dose calculations.
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Date Issued
2015
PURL
http://purl.flvc.org/fau/fd/FA00004491
Subject Headings
Cancer -- Radiation therapy, Head -- Cancer -- Treatment, Medical physics, Neck -- Cancer -- Treatment, Radiation dosimetry
Format
Document (PDF)