Program Information
Dosimetric Impact of Boost Partial Breast Irradiation with External Beam in Organs-At-Risk Dosimetry for Patients Treated with Whole Breast Irradiation of the Left Breast
A Bejarano Buele*, S Bradley , A Lisher , Lawrence Cancer Center, Lawrence, KS
Presentations
SU-I-GPD-T-578 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose: The treatment of breast cancer after breast-conserving surgery typically includes Whole Breast Irradiation (WBI) followed by a Boost Partial Breast Irradiation (BPBI). The purpose of this study is to determine the impact of different types of external beam boost irradiation on dose delivered to Organs at Risk (OARs).
Methods: This study included 10 datasets of patients treated in the supine position with 3D-CRT WBI of the left breast. Dose composites included the WBI plan and one of three types of boost irradiation plans: single electron beam, two photon tangents, and two photon tangents with one conformal arc. The WBI patients were treated with 50 Gy delivered in 25 fractions and the boost volume prescription was 10 Gy to be delivered in 5 fractions.
Results: In terms of boost volume coverage, the “electron” and “photon tangents with arc” plans obtained the best conformities with 3.0 and 2.3 for the Standard CI and 0.4 and 0.5 for Paddick’s CI respectively. There is no significant addition of V25 volume in normal tissue added by the addition of a BPBI plan in contrast to a WBI treatment only. However, detailed analysis of OARs indicate an increase in volume of low dose regions specially for V5 in the heart, with 43.94% and 59.49% increase from the WBI plan for electrons and tangents with arc plans respectively.
Conclusion: Plans using electrons and photon tangents with one arc are more conformal to the boost volume while increasing the low dose region in OARs. Photon tangents for BPBI add minimal dose to OARs from the primary WBI treatment while irradiating more breast tissue.
Contact Email: