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Dosimetric Comparison to Organs at Risk Sparing Using Volumetric-Modulated Arc Therapy Versus Intensity-Modulated Radiotherapy in Postoperative Radiotherapy of Left-Sided Breast Cancer

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J Zhang

L Qiao1 , J Xie2 , J Cheng3 , N Liang4 , G Deng5 , J Zhang6*, J Zhang7 , H Luo8 , (1) Department of Oncology, Shandong University School of Medicine, Jinan, Shandong, (2) Department of Radiation Oncology, Qianfoshan Hospital Affiliated to Shandon, Jinan, Shandong, (3) Department of Radiation Oncology, Qianfoshan Hospital Affiliated to Shandon, Jinan, Shandong, (4) Department of Radiation Oncology, Qianfoshan Hospital Affiliated to Shandon, Jinan, Shandong, (5) Department of Oncology, Shandong University School of Medicine, Jinan, Shandong, (6) Department of Radiation Oncology, Qianfoshan Hospital Affiliated to Shandon, Jinan, Shandong, (7)Division of Oncology, Department of Graduate, Weifang Medical College, 2610, Jinan, Shandong(8) Division of Oncology, Department of Graduate, Weifang Medical College, 2610, Jinan, Shandong

Presentations

SU-E-P-51 (Sunday, July 12, 2015) 3:00 PM - 6:00 PM Room: Exhibit Hall


Purpose: To compare the dosimetric characteristics of volumetric-modulated arc therapy (VMAT) and intensity-modulated radiotherapy (IMRT) techniques in treatment planning for left-sided breast cancer patients with modified radical mastectomy.

Methods: Twenty-four left-sided breast cancer patients treated with modified radical mastectomy were selected in this study. The planning target volume (PTV) was generated by using 7-mm uniform expansion of the clinical target volume (CTV) in all direction except the skin surface. The organs at risk (OARs) included heart, left lung, right lung, and right breast. Dose volume histograms (DVHs) were utilized to evaluate the dose distribution in PTV and OARs.

Results: Both VMAT and IMRT plans met the requirement of PTV coverage. VMAT was superior to IMRT in terms of conformity, with a statistically significant difference (p=0.024). Mean doses, V5 and V10 of heart and both lungs in VMAT plans were significantly decreased compared to IMRT plans (P<0.05), but in terms of heart volume irradiated by high doses (V30 and V45), no significant differences were observed (P>0.05). For right breast, VMAT showed the reduction of V5 in comparison with IMRT (P<0.05). Additionally, the mean number of monitor units (MU) and treatment time in VMAT (357.21, 3.62 min) were significantly less than those in IMRT (1132.85, 8.74 min).

Conclusion: VMAT showed similar PTV coverage and significant advantage in OARs sparing compared with IMRT, especially in terms of decreased volumes irradiated by low doses, while significantly reducing the treatment time and MU number.


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