Dosimetric comparison of two linear accelerators for lung cancer SBRT using IMRT dose delivery technique: VenusX vs. Edge.

BACKGROUND

The VenusX and Edge accelerators are two commercially available systems used for lung stereotactic body radiation therapy (SBRT) with Intensity-Modulated Radiation Therapy (IMRT) techniques.

METHODS

A retrospective analysis was conducted on 40 lung cancer patients treated with the Edge accelerator. Treatment plans using both the Edge (Plan) and VenusX (Plan) accelerators were generated and evaluated using various dosimetric metrics, employing statistical analyses to identify significant differences.

RESULTS

For planned target volume (PTV), Plan outperformed Plan across the entire cohort, achieving a higher D2 dose (76.84 vs 75.56 Gy, p = 0.005), and showing significant improvements in conformity index (0.84 vs 0.80), homogeneity index (0.50 vs 0.47), and gradient index (5.12 vs 5.62), all with p < 0.001. Plan also recorded a lower D (27.27 vs 27.87 Gy, p = 0.004). Subgroup analyses revealed significant enhancements in conformity index (CI), homogeneity index (HI), and gradient index (GI) for both single and multi-target lesion patients, with multi-target also seeing a notably lower D. regarding organs at risk (OARs), Plan significantly reduced lung mean dose (D) (3.85 to 3.60 Gy), V (16.88% to 15.61%), and V (5.04% to 4.63%), along with improvements in the great vessels' D and max dose (D), and esophagus' D across all patients. Single-lesion patients saw consistent lung improvements, while multi-lesion patients experienced significant lung reductions and enhancements in great vessels' and esophagus' metrics.

CONCLUSIONS

In conclusion, both Plan and Plan achieved treatment plans that met the dosimetric criteria defined by the RTOG guidelines. While Plan exhibited improved values in CI, HI, and GI, these findings reflect observed dosimetric differences rather than definitive evidence of clinical superiority. Further prospective studies are warranted to evaluate the clinical relevance of these differences.