Dataset Information

Safety and benefit of using a virtual bolus during treatment planning for breast cancer treated with arc therapy.

ABSTRACT:

Purpose

This study evaluates the benefit of a virtual bolus method for volumetric modulated arc therapy (VMAT) plan optimization to compensate breast modifications that may occur during breast treatment.

Methods

Ten files were replanned with VMAT giving 50 Gy to the breast and 47 Gy to the nodes within 25 fractions. The planning process used a virtual bolus for the first optimization, then the monitors units were reoptimized without bolus, after fixing the segments shapes. Structures and treatment planning were exported on a second scanner (CT) performed during treatment as a consequence to modifications in patient's anatomy. The comparative end-point was clinical target volume's coverage. The first analysis compared the VMAT plans made using the virtual bolus method (VB-VMAT) to the plans without using it (NoVB-VMAT) on the first simulation CT. Then, the same analysis was performed on the second CT. Finally, the level of degradation of target volume coverage between the two CT using VB-VMAT was compared to results using a standard technique of forward-planned multisegment technique (Tan-IMRT).

Results

Using a virtual bolus for VMAT does not degrade dosimetric results on the first CT. No significant result in favor of the NoVB-VMAT plans was noted. The VB-VMAT method led to significant better dose distribution on a second CT with modified anatomies compared to NoVB-VMAT. The clinical target volume's coverage by 95% (V95%) of the prescribed dose was 98.9% [96.1-99.6] on the second CT for VB-VMAT compared to 92.6% [85.2-97.7] for NoVB-VMAT (P = 0.0002). The degradation of the target volume coverage for VB-VMAT is not worse than for Tan-IMRT: the median differential of V95% between the two CT was 0.9% for VMAT and 0.7% for Tan-IMRT (P = 1).

Conclusion

This study confirms the safety and benefit of using a virtual bolus during the VMAT planning process to compensate potential breast shape modifications.

SUBMITTER: Tyran M

PROVIDER: S-EPMC6123145 | biostudies-literature | 2018 Sep

REPOSITORIES: biostudies-literature

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Publications

Safety and benefit of using a virtual bolus during treatment planning for breast cancer treated with arc therapy.

Tyran Marguerite M Tallet Agnes A Resbeut Michel M Ferre Marjorie M Favrel Veronique V Fau Pierre P Moureau-Zabotto Laurence L Darreon Julien J Gonzague Laurence L Benkemouche Ahcene A Varela-Cagetti Leonel L Salem Naji N Farnault Bertrand B Acquaviva Marie-Aimee MA Mailleux Hugues H

Journal of applied clinical medical physics 20180630 5

<h4>Purpose</h4>This study evaluates the benefit of a virtual bolus method for volumetric modulated arc therapy (VMAT) plan optimization to compensate breast modifications that may occur during breast treatment.<h4>Methods</h4>Ten files were replanned with VMAT giving 50 Gy to the breast and 47 Gy to the nodes within 25 fractions. The planning process used a virtual bolus for the first optimization, then the monitors units were reoptimized without bolus, after fixing the segments shapes. Structu ...[more]

PMID: 29959819

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Project description:BackgroundThe Halcyon is a new machine from the Varian company. The purpose of this study was to evaluate the dosimetry of the Halcyon in treatment of bilateral breast cancer with volumetric modulated arc therapy.MethodsOn CT images of 10 patients with bilateral breast cancer, four Halcyon plans with different setup fields were generated, and dosimetric comparisons using Bonferroni's multiple comparisons test were conducted among the four plans. Whole and partial arc plans on the Trilogy and the Halcyon, referred to as T-4arc, T-8arc, H-4arc and H-8arc, were designed. The prescription dose was 50 Gy in 2-Gy fractions. All plans were designed with the Eclipse version 15.5 treatment planning system. The dosimetric differences between whole and partial arc plans in the same accelerator were compared using the Mann-Whitney U test. The better Halcyon plan was selected for the further dosimetric comparison of the plan quality and delivery efficiency between the Trilogy and the Halcyon.ResultsHalcyon plans with high-quality megavoltage cone beam CT setup fields increased the Dmean, D2 and V107 of the planning target volume (PTV) and the V5 and Dmean of the heart, left ventricle (LV) and lungs compared with other Halcyon setup plans. The mean dose and low dose volume of the heart, lungs and liver were significantly decreased in T-8arc plans compared to T-4arc plans. In terms of the V5, V20, V30, V40 and Dmean of the heart, the V20, V30, V40 and Dmean of the LV, the V30, V40, Dmax and Dmean of the left anterior descending artery (LAD), and the V5 and V40 of lungs, H-8arc was significantly higher than H-4arc (p < 0.05). Compared with the Trilogy's plans, the Halcyon's plans reduced the high-dose volume of the heart and LV but increased the mean dose of the heart. For the dose of the LAD and the V20 and V30 of lungs, there was no significant difference between the two accelerators. Compared with the Trilogy, plans on the Halcyon significantly increased the skin dose but also significantly reduced the delivery time.ConclusionFor the Halcyon, the whole-arc plans have more dosimetric advantages than partial-arc plans in bilateral breast cancer radiotherapy. Although the mean dose of the heart and the skin dose are increased, the doses of the cardiac substructure and other OARs are comparable to the Trilogy, and the delivery time is significantly reduced.

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Dataset Information

Safety and benefit of using a virtual bolus during treatment planning for breast cancer treated with arc therapy.

Purpose

Methods

Results

Conclusion

Publications

Safety and benefit of using a virtual bolus during treatment planning for breast cancer treated with arc therapy.

Similar Datasets

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