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A IMRT Method Sparing of Cardiac Structures Compared to Volumetric Modulated Arc Radiotherapy

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T Sun

T Sun*, l XiuTong , G Zhang , Y Yin , Shandong Cancer Hospital Affiliated to Shandong,Shandong Cancer Hospital, Jinan, Shandong


SU-I-GPD-T-332 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: Cardiac irradiation increases the risk of coronary artery disease in patients with left-sided breast cancer. The aim of this study was to find the best treatment plan sparing heart dose by compare two different fields IMRT plans and VMAT plans.

Methods: Ten patients with left breast cancer were treated with radical mastectomy and radiotherapy sequaciously involving the supraclavicular region and the chest wall. For each patient, three treatment techniques including 4f-IMRT, 6f-IMRT and VMAT were designed. In 4f-IMRT plans, 0°、40° and two tangential fields were designed to the PTV. 0° and 40° fields were fixed jaw on the supraclavicular region, the caudal border of two fields was set at the inferior border of the supraclavicular region. In 6f-IMRT plans, the same four fields as in 4f-IMRT plans and two additional fields (300 and 160 degrees) were designed. The two additional fields were fixed jaw to irradiate partial chest wall ( see fig in support).VMAT plans were designed dual arc from around 300 to 160 degrees. The dose distribution in the target, the dose to the OAR were compared.

Results: For the target volume of 100% prescription dose, there was no statistical difference between three plans. 6f-IMRT plans showed the lowest values in mean dose and V40Gy to the heart. VMAT plans could reduce the V40Gy of the heart compared to 4f-IMRT plans. No statistical differences were observed in V20Gy, V30Gy of the left lung and V30Gy of the heart among three plans. V5Gy, V10Gy of the left lung increased significantly in VMAT plans and no statistically significant differences were observed in these indexes for 4f-IMRT versus 6f-IMRT plans. 6f-IMRT plans showed the lowest values in mean dose of the left lung.

Conclusion: 6f-IMRT plans resulted in the lowest dose in heart while not increasing the dose to the lungs.

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