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Cardiac Dose Control and Optimization Strategy for Left Breast Cancer Radiotherapy with Non-Uniform VMAT Technology

S Zhang, Z Pan, J Qiu*, Department of Radiation Oncology, Fudan University Huadong Hospital, Shanghai, 21


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

Room: AAPM ePoster Library

Purpose: project aims to develop a novel planning technique, named non-uniform VMAT (NU-VMAT), to integrate advantages and to eliminate pitfalls in both volumetric-modulated arc therapy(VMAT) and intensity-modulated radiation therapy(IMRT). It is anticipated that NU-VMAT will improve the planning quality and the treatment delivery efficiency, which’s re-optimization control effect on cardiac dose in left side breast cancer radiation treatment were researched.

Methods: on comprehensive analysis of IMRT and VMAT techniques, optimization of intensity modulation functions, definition of objective functions and development of core algorithms, the NU-VMAT modeling and optimization algorithm were established and integrated with the clinical treatment planning system (TPS) via the Enterprise Security Application Programming Interface (ESAPI).
A retrospective study of 14 patients with breast-conserving left breast cancer undergoing radiotherapy was made, the prescribed dose was 50Gy to the planning target volume (PTV). Dosimetric parameters, total monitor units (MU) and delivery time were calculated for plan quality and delivery efficiency comparison.

Results: prospective study of 14 randomly selected cases of breast cancer showed that: (1) the dose distribution requirements of the target and normal tissues could be met by the three techniques; (2) the minimum mean cardiac dose( heart mean dose:538.00±45.61,794.57±52.42,562.63±60.93 cGy by IMRT, VMAT and NU-VMAT retrospectively, p=0.531) could be obtained by using NU-VMAT technique distinguished of VMAT and IMRT, which was conducive to protecting the heart; (3)The total mean MU (245.7±11.1) for VMAT was significantly less than those for IMRT (864.4±171.2) (p<0.05), and was comparable with those for NU-VMAT(261.6±41.5) per fraction. The beam-on time required in NU-VMAT was only 30.3% of IMRT for the same prescribed radiation dose (p<0.05).

Conclusion: was proved that NU-VMAT could help improve the mechanical efficiency and protect normal tissues, especially heart tissues, and reduce the radiation dose of heart in the process of left breast cancer radiotherapy after breast conserving surgery.


Breast, Optimization, Intensity Modulation


Not Applicable / None Entered.

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