Clinical application of LinaTech linear accelerator VenusX to hippocampal protection in whole-brain radiotherapy / 中华放射医学与防护杂志

ABSTRACT

Objective:To compare the dosimetric differences between the VenusX accelerator with an orthogonal dual-layer multi-leaf collimator (MLC) and the Varian′s CLINAC IX and EDGE accelerators with a single-layer MLC for hippocampus protection in the whole-brain radiotherapy (WBRT).Methods:Forty patients with multiple brain metastases admitted to the Radiotherapy Department of the Shanghai General Hospital from June 2021 to February 2023 were selected in this study. Three whole-brain treatment plans were designed based on the above three accelerators for each patient. Under the same prescription dose, radiation field, and plan constraints, the three plans were compared in terms of the dosimetric differences in target volumes, hippocampi, and adjacent organs at risk (OARs), as well as the execution efficiency.Results:For the planning target volume (PTV), there were statistically significant differences in approximate maximum dose ( D2) between the VenusX and IX plans ( t = 4.94, P < 0.05), in approximate minimum dose ( D98) between the VenusX and EDGE plans ( t = 5.98, P < 0.05), in the target conformity indices (CIs) between VenusX plan and EDGE plans, and between the VenusX and IX plans ( t = -6.84, -14.30; P < 0.05), and dose homogeneity indices (HIs) between the VenusX and IX plans ( t = 3.48, P < 0.05). For OARs, the maximum doses ( Dmax) and average doses ( Dmean) to bilateral hippocampi of the VenusX plan were lower than those of the EDGE and IX plans ( t = 8.59-17.11, P < 0.05); the maximum doses ( Dmax) to bilateral lenses, bilateral optic nerves, and optic chiasma of the VenusX plan were lower than those of the other two plans ( t = 2.10-20.80, P < 0.05); and the differences between the maximum doses ( Dmax) to the brain stem of the VenusX and EDGE plans were statistically significant ( t = 3.86, P < 0.05). In terms of plan execution efficiency, the number of machine jumps (MU) and the treatment time of the VenusX plan were higher than those of the EDGE and IX plans, with statistically significant differences ( t = -56.48, -56.90, P < 0.05). Conclusions:The doses to target volumes of the three treatment plans all meet the prescription requirements, and the VenusX plan outperforms the EDGE and IX plans in the protection of OARs. Despite the reduced execution efficiency, the VenusX plan shortens the actual treatment time by improving the dosage rate, thus meeting the clinical requirements.