2869 - The Dosimetric Feasibility of Lattice Radiotherapy for Cervical Cancer with a Novel X - Ray and ? - Ray Combined Approach
Presenter(s)
W. Wang1, Z. F. Wang2, and L. Zhao3; 1Department of Radiation Oncology, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi, China, 2Department of Radiation Oncology, Xijing Hospital, Air Force Medical University, Xi’an, China, 3Department of Radiation Oncology, Xijing Hospital, Air Force Medical University, xi an, shan xi, China
Purpose/Objective(s): A new radiotherapy platform that integrates a linear accelerator (linac) and a gamma - knife has been put into clinical use (NMPA: 20223050973; FDA: K210921). This platform offers a novel radiotherapy technique that combines X - rays and ? - rays. The present study aims to explore the dosimetric advantages of this technique for lattice radiotherapy (LRT) in patients with Cervical cancer.
Materials/Methods: Retrospective treatment plans of three cervical cancer patients were selected for comparison with combined plans. The treatment involved two plans: the LRT plan at a dose of 15 Gy in 1 fraction (15Gy/1F) and the conventional plan at 50 Gy in 25 fractions (50Gy/25F). The LRT plans incorporated (6, 7, 8) high - dose vertices, each with a diameter of 1.2 cm and a separation of 3 cm, positioned within the GTV. The clinical plans were created using a technology company's treatment planning system with the VMAT technique. The combined plans were generated using the RT PRO TPS (OUR United Corp., Xi’an, China). Specifically, a focusing gamma plan was developed to cover the vertices, and a linac plan was optimized to cover the PTV.Dosimetric comparisons were conducted between the clinical plans and the combined plans. The aim was to evaluate the ability of the technique to deliver high doses to the vertices while minimizing the dose to the non - lattice target volume within the GTV.
Results: Compared to the clinical plans, the combined plans exhibited higher D0.5cc values (78.6 Gy vs 70.4 Gy, 77.9 Gy vs 70.1 Gy, 77.7 Gy vs 70.4 Gy) and Dmean values (71.2 Gy vs 68.3 Gy, 71.5 Gy vs 68.4 Gy, 71.0 Gy vs 68.5 Gy) at the vertices. Simultaneously, the combined plans showed lower doses at the GTV margin (53.8 Gy vs 58.1 Gy, 54.1Gy vs 59.1 Gy, 54.1 Gy vs 59.0 Gy) and higher D10/D90 ratios of the GTV (1.15 vs 1.12, 1.17 vs 1.13, 1.19 vs 1.13). These results demonstrate the feasibility of achieving very high dose fall - offs within the GTV.
Conclusion: Leveraging the physical properties of X - rays and ? - rays, this novel radiotherapy technique emerges as a favorable treatment alternative for lattice radiotherapy of cervical cancer.