Program Information
Operated Left Breast and Chest Wall Radiotherapy: A Dosimetric Comparison Between 3DCRT,IMRT and VMAT
B Sarkar1*, S Roy2 , A Munshi3 , A Pradhan4 , (1) AMRI Cancer Centre and GLA university, Mathura, Kolkata, West bengal, (2) AMRI Cancer Centre,Kolkata, Kolkata, West bengal, (3) Fortis Memorial Research Institute, Gurgon, haryana, (4) GLA University, Mathura, Uttar Pradesh
Presentations
SU-E-T-583 (Sunday, July 12, 2015) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose:To evaluate the comparative dosimetric efficacy between field and field 3DCRT(FnF), multiple field Intensity modulated radiotherapy (SnS IMRT) and, partial arc volumetric modulated arc therapy (VMAT) in case of post operative left side breast and chest wall irradiation.
Methods:CT study set of fifteen post-operative left breast and chest wall patient was tested for a treatment plan of 50Gy in 25 fraction using partial arc VMAT, SnSIMRT and tangential beam 3DCRT . 3DCRT FnF gantry angle was ranging for left medial tangential 290±17⁰ and Lt lateral tangential l14°±12⁰. For IMRT four fixed beam at gantry angle G130⁰ G110⁰ G300⁰ and G330⁰ was used, in case of insufficient dose another beam G150⁰ was added. In case of partial arc VMAT , lateral tangential arc G130⁰-G100⁰ and medial tangential arc G280⁰-G310⁰. Inverse optimization was opted to cover at least 95%PTV by 95% prescription dose (RxD) and a strong weightage on reduction of heart and lung dose. PTV coverage was evaluated for it’s clinically acceptability depending on the tumor spatial location and its quadrant. Out of the three plans, any one was used for the actual patient treatment.
Results: Dosimetric analysis done for breast PTV, left lung, heart and the opposite breast. PTV mean dose and maximum dose was 5129.8±214.8cGy, 4749.0±329.7cGy, 5024.6±73.4cGy and 5855.2±510.7cGy, 5340.7±146.1cGy, 5347.2±196.8cGy for FnF, VMAT and IMRT respectively. Ipsilateral lung volume receiving 20Gy and 5Gy was 23.6±9.5cGy and 32.7±10.3cGy for FnF, 18.6±8.7cGy and 38.8±15.2cGy for VMAT and 25.7±9.6cGy and 50.7±8.4cGy for IMRT respectively. Heart mean and 2cc dose was 867.9±456.7cGy and 5038.5±184.3cGy for FnF, 532.6±263cGy and 3632.1±990.6 for VMAT, 711±229.9cGy and 4421±463.7cGy for IMRT respectively. VMAT shows minimum contralateral breast dose 168±113.8cGy.
Conclusion: VMAT shows a better tumor conformity, minimum heart, ipsilateral lung and opposite breast dose. Cardiac Toxicity and risk of contralateral breast cancer can be reduce using VMAT.
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