Comparative Study of Plan Robustness for Breast Radiotherapy: Volumetric Modulated Arc Therapy Plans with Robust...

Area of Science:

• Radiation Oncology
• Medical Physics
• Radiotherapy Planning

Background:

• Manual flash (MF) is the current standard for breast radiotherapy planning.
• A prior study suggested Robust Optimized (RO) volumetric modulated arc therapy (VMAT) plans are more robust than MF plans.
• Further investigation with a larger sample size is needed to validate these findings.

Purpose of the Study:

• To compare the plan robustness of RO and MF VMAT techniques for breast radiotherapy.
• To evaluate dose variations to the clinical target volume (CTV) and organs at risk (OARs) under different scenarios.
• To determine if RO offers superior robustness compared to MF in a larger patient cohort.

Main Methods:

• Retrospective analysis of 34 female breast radiotherapy patients.
• Evaluation of plan robustness using measured volume/dose differences (ΔV/ΔD) between nominal and worst-case scenarios.
• Statistical comparison of robustness values between RO and MF approaches using paired sample t-tests.

Main Results:

• RO approach demonstrated smaller ΔV/ΔD values for most CTV and OAR parameters compared to MF.
• Statistically significant improvements (p < 0.001-0.012) in ΔV/ΔD were observed for RO across various CTV parameters and heart dose metrics.
• Both techniques yielded clinically acceptable plans, but RO showed enhanced robustness.

Conclusions:

• The Robust Optimized (RO) approach is generally more robust than Manual Flash (MF) for breast radiotherapy planning.
• RO VMAT may offer improved robustness and potentially enhance workflow efficiency due to a simpler planning process.
• These findings support the consideration of RO as a potentially superior alternative to MF in clinical practice.