Study of feasibility of MRI-guided cardiac stereotactic radiotherapy using VMAT-like technique
10.3760/cma.j.cn113030-20240425-00153
- VernacularTitle:基于类VMAT技术磁共振引导心脏放射消融计划可行性探究
- Author:
Weige WEI
1
;
Hang YU
;
Qing XIAO
;
Jialu LAI
;
Guangjun LI
;
Sen BAI
Author Information
1. 四川大学华西医院放射物理技术中心，成都 610041
- Keywords:
Stereotactic cardiac radiotherapy;
Magnetic resonance linac;
VMAT-like techniques;
Plan quality;
Magnetic field-induced dosimetric effects
- From:
Chinese Journal of Radiation Oncology
2024;33(12):1098-1105
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To investigate the dosimetric feasibility of cardiac stereotactic body radiotherapy (CSBRT) using volumetric-modulated arc radiotherapy (VMAT)-like technique on the Unity MR-linac.Methods:A retrospective analysis was conducted on 12 refractory arrhythmia patients who underwent CSBRT at West China Hospital, Sichuan University, from April 2021 to December 2022. Four different treatment plans were designed for each patient based on the average phase of 4DCT: VMAT plan based on a linear accelerator, VMAT-like plan with magnetic field based on Unity, VMAT-like plan without magnetic field based on a Unity, and static intensity-modulated radiation therapy (IMRT) plan with 7 beams based on Unity. The VMAT-like plans used static IMRT beams evenly distributed at 30 angles. Evaluation metrics included conformity index (CI), homogeneity index (HI), gradient index (GI), dosimetric parameters of organs at risk (OAR), optimization time, and monitor unit (MU). These metrics among groups were analyzed using the Wilcoxon paired signed-rank test.Results:The CI of the VMAT plan was better than that of the VMAT-like plan with magnetic field (0.84 vs. 0.81, P=0.005). The GI of the VMAT-like plan without magnetic field was significantly lower than that of VMAT-like plan with magnetic field ( P=0.015). The CI and HI of the IMRT plan were both inferior to VMAT-like plan with magnetic field ( P=0.034). The average dose to the heart and lungs in VMAT-like plan with magnetic field was higher than those in the VMAT plan and VMAT-like plan without magnetic field (both P<0.05). The magnetic field significantly increased the dose to the skin, tissue-lung interface, and outside the margins (all P<0.05). The optimization time of the VMAT-like plan with magnetic field was longer than that of the IMRT plan, but it required fewer MUs ( P=0.001). The quality of the IMRT plans was poor and did not meet clinical requirements. Conclusion:The quality of CSBRT plans based on VMAT-like techniques meets clinical requirements, but attention must be paid to the dosimetric effects of the magnetic field.
