ESTRO meets Asia 2024 - Abstract Book

S82

Interdisciplinary – Breast

ESTRO meets Asia

Results:

The 3DCRT and hybrid plans both had target coverage V95%>98%, while the butterfly plans required re normalizing to fulfill V95%=98%, in most cases due to the one optimization restriction. All plans were within national dose constraints. The hybrid plans had lowest mean dose to ipsilateral lung and heart, as well as highest dose coverage of CTV. V95% outside the CTV was smallest for butterfly plans with CI = 0.77. Hybrid and 3DCRT plans had CI of 0.74 and 0.63, respectively. Hybrid plans were most homogenous with HI = 6.27. 3DCRT and butterfly plans had HI of 8.82 and 9.74, respectively. See Figure 1. Mean dose to contralateral lung and breast did not differ notably for the three techniques. Low dose bath (V5Gy) for contralateral lung were negligible, while V5Gy for contralateral breast was largest for hybrid plans at 0.28%. See Table 1. Delivery time for 3DRT plans was approximately 1 minute longer than hybrid and butterfly plans, mainly due to change in energy of support fields. Geometrical shifts and swelling showed no notable difference between hybrid and 3DRT, while butterfly was less robust. Gamma analysis for all delivered plans for patient specific QA performed >95% (3%, 3 mm, global dose) concluding that the machine can safely deliver all techniques.