Preliminary clinical application of stereotactic body radiotherapy (SBRT) for lung cancer based on MRI-guided radiotherapy system / 中华放射肿瘤学杂志

ABSTRACT

Objective:To observe the feasibility of magnetic resonance (MR)-guided stereotactic body radiotherapy (SBRT) for non-small cell lung cancer, and analyze the dosimetric differences in the presence or absence of magnetic field.Methods:Three patients with non-small cell lung cancer were prospectively treated with MR-guided linac (MR linac) for SBRT, and the dose was calculated with or without magnetic field models. The differences of dose distribution with or without magnetic field models were compared. At the same time, the target coverage, plan pass rate and treatment time were described, and the complexity of the conventional accelerator backup plan and the magnetic field model were compared.Results:The treatment time of 3 patients was (36.67±6.11) min, and the average time of online adaptive planning was (14.4±1.7) min, which was basically tolerated by patients. The treatment plan pass rate (3%/3 mm) was 98.9%, the Gamma pass rate (3%/3 mm) of the online plan during treatment was 98.5% and the target coverage was 99.1%, which met the clinical needs. The dose in the low dose area of the lung was slightly lower than that in the case without magnetic field, whereas the dose in ribs and skin was slightly higher than that in the plan without magnetic field. The number of machine unit (MU) for online adaptive plan was slightly higher than that of the reference plan, and the number of MU for the conventional accelerator standby treatment plan was significantly lower than that of the MR linac plan under the same target coverage. The follow-up results showed that there was no adverse reaction, and the short-term efficacy was partially relieved.Conclusions:In the case of considering the influence of magnetic field, the treatment plan meeting the clinical needs can be obtained. It is proven that SBRT radiotherapy for lung cancer guided by magnetic resonance accelerator is feasible, whereas the treatment time and process are complex.