Comparison among four immobilization devices for whole breast irradiation with Helical Tomotherapy

Abstract

PurposeTo evaluate the repositioning accuracy of 4 immobilization devices (ID) used for whole breast Helical Tomotherapy treatments: arm float with VacFix® (Par Scientific, Denmark), all-in-one® (AIO®) system (Orfit, Belgium), MacroCast thermoplastic mask (Macromedics, The Netherlands) and BlueBag® system with Arm-Shuttle (Elekta, Sweden). Materials and methodsTwenty four women with breast cancer with PTV including the breast/chest wall and lymph nodes were involved in this study (6 women per group). Pretreatment registration results were first collected using automatic bone registration + manual adjustment on the vertebra followed by independent registrations on different ROIs representing each treated area (axillary, mammary chain, clavicular, breast/chest wall). The differences in translations and rotations between reference registration and the above mentionned ROIs were calculated. A total of 120 MVCT images were analyzed. ResultsSignificant differences were found between IDs (p < 0.0001), ROIs (p = 0.0002) and the session number (p < 0.0001) on the observed shifts, when examining 3D translation vectors. 3D-vectors were significantly lower for the BlueBag® than for the VacFix® or for the AIO® (p < 0.0001), but differences were not significant compared to the mask (p = 0.674). Finally, setup margins were overall smaller for the BlueBag® than for other IDs, with values ranging from 1.53 to 1.91 mm on the mammary chain area, 4.52–6.07 mm on the clavicular area, 2.71–4.62 mm on the axillary area, and 3.39–5.10 mm on the breast. ConclusionWe demonstrated in this study that the BlueBag® combined with arm shuttle is a robust solution for breast and nodes immobilization during HT treatments.