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Dosimetric Impact of Leaf Interdigitation in Breast Cancer Fixed-Field Intensity-Modulated Radiation Therapy

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J Duan

Shandong Cancer Hospital Affiliated to Shandong University, Jinan, Shandong province


SU-I-GPD-T-335 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: The aim of this work is to study the dosimetric impact of leaf interdigitation in breast cancer fixed-field intensity-modulated radiation therapy (ssIMRT).

Methods: Fifteen previously treated breast cancer patients were re-planned for 5 field ssIMRT with and without leaf interdigitation using Monaco 3.3 TPS on the Elekta Synergy linear accelerator. The prescription dose of PTV was 50Gy/25 fractions. Various dosimetric variables, such as PTV coverage, OAR sparing, delivery efficiency and optimization time, were evaluated for each plan.

Results: For each patient, all plans were clinically acceptable with a high and similar PTV coverage. Interdigitation did not improve the coverage, HI and CI for PTV. Regarding OARs, sparing was equal with and without interdigitation. Interdigitation shown an increase in MUs and segments. As expected, leaf interdigitation saved the optimization time.

Conclusion: This study shows that leaf interdigitation does not improve plan quality when performing ssIMRT treatment plan for breast cancer. However, it influences delivery efficiency and optimization time. Interdigitation may gain efficiency for dosimetrist when designing the breast cancer ssIMRT plans.

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