Retrospective dosimetric comparison of VMAT versus t-IMRT for patients with carbon dioxide tissue expanders undergoing left sided PMRT using the recent ESTRO-ACROP target volume delineation

Introduction: The Aeroform tissue expander device (ATED) is a novel alternative system for patients who have had mastectomy breast cancer (BC) and require adjuvant radiation therapy (RT), investigations are required when used during RT. We aim to compare RT dosimetry outcomes using volumetric modulated arc (VMAT) versus tangential intensity-modulated (t-IMRT) techniques planning post-mastectomy (PMRT), the recent European Society Radiation Oncology – Advisory Committee on Practice (ESTRO-ACROP) target volume delineation consensus guideline.1 Methods: Five with left-sided BC undergoing PMRT ATED in-situ were identified. Retrospectively, their CT-simulation scans utilised delineate chest wall (CW) nodal volumes. A dose of 50.4Gy in 28 fractions was prescribed four plans generated. Dosimetry all volumes organs at risk extracted, paired means compared. Results: When comparing VMAT t-IMRT techniques, there no statistically significant difference PTV50.4 D95% or D2% coverage. Within plans, excluding internal mammary nodes (IMN) leads higher heart mean V25 significantly lower than t-IMRT. There whether IMN included not. ipsilateral lung V20 t-IMRT, but not V5. V20. contralateral V5, even included. different between right if excluded. Conclusion: shown clear advantage over prescribing in-situ.