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Dosimetric Comparison of Hybrid Plan, 3DCRT and VMAT in Patients with Left-Sided Breast Cancer

S Ahn1*, E Ju1,2, N Jung1, Y Kim2, (1) Department of Radiation Oncology, Kangwon National University Hospital, Chuncheon-si, Republic of Korea, (2) Department of Bio-medical Science, Graduate School of Korea University, Sejong, Republic of Korea, (3) Department of Radiation Oncology, Asan Medical Center, Seoul, Republic of Korea


(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose: The purpose of this study is to evaluate the radiation treatment plan quality in the hybrid volumetric modulated arc therapy by comparing it with the volumetric modulated arc therapy(VMAT) and three-dimensional conformal radiation therapy(3DCRT).

Materials and
Methods: A total of 10 left-sided breast cancer patients who were treated with a hybrid plan were included in this study. The prescription dose was 260 cGy in 16 fractions. To compare the plan quality, V5Gy, V20Gy, V30Gy, Dmax, and Dmean were calculated for contralateral lung, ipsilateral lung, contralateral breast, and heart. In the case of PTV, Dmax, Dmean, and V95% were evaluated. The statistical significance was evaluated by the Wilcoxon signed-rank test.

Results: In the case of the comparison of the hybrid plan with the VMAT plan, there is no significant difference. However, In the case of the comparison of the hybrid plan with the 3DCRT plan, Dmax, and Dmean of the contralateral lung, V5Gy of ipsilateral lung, Dmax of heart and PTV were significantly different (p<0.05). The V5Gy of the ipsilateral lung was 31.5%, 76.7%, and 65.3%, and the averages of Dmax of the heart were 101.5%, 89.1%, and 93.2% in 3DCRT, VMAT, and hybrid plan, respectively.

Conclusion: The hybrid plan in left-sided breast cancer radiation therapy has been to significantly reduce the volume received a low dose of the ipsilateral lung and maximum dose of the heart compared with the 3DCRT plan. In addition, the volume received a low dose of both lungs has been reduced in the hybrid plan compared with the VMAT plan. Therefore, it has been verified that the hybrid plan can be applied as a planning technique to compensate for the disadvantage of 3DCRT and VMAT.




TH- External Beam- Photons: treatment planning/virtual clinical studies

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