Abstract
Purpose: The plan quality of the stereotactic body radiation therapy (SBRT) plan is affected by the patient’s planning target volume (PTV). The predictability of PTV volume and cut-off points were investigated to judge the suitability of manual and automatic plans for lung SBRT patients.Methods: The manual and automatic SBRT plans were retrospectively designed using the Pinnacle 16.2 treatment planning system (TPS) for 98 lung cancer patients. the suitability of manual and automatic plans for each patient is comprehensively evaluated. Receiver operating characteristic (ROC) analysis was used to investigate the predictability of PTV volume and determine the cut-off point. Once the cut-off point exists, all patients were divided into two groups according to this cut-off point. The Wilcoxon signed-rank test was performed for the dosimetric comparisons between the two groups. Results: ROC analysis showed that PTV volume (AUC [Area under curve]: 0.918, p= 0.005) has diagnostic power to predict the suitability of manual and automatic plans for lung SBRT patients. The cut-off points of 22.675cc were selected for PTV volume. Regardless of some comparable results, the CI, GI, V10, and V20 of automatic plans were found to be better than manual plans below the cut-off points, and the manual plan is superior to the automatic plan in HI, GI, heart d15cc, V10, V20 above the cut-off points.Conclusion: The PTV volume of cut-off points (22.675cc) are predictive of the suitability of manual and automatic plan using Pinnacle TPS for lung SBRT patients. Automatic plans were recommended for patients with PTV volumes less than 22.675cc, and manual plans can be tried for patients with larger PTV volumes.
Impact of 6-Degrees-of-Freedom Correction on Optimal Planning Target Volume Margins in Stereotactic Body Radiation Therapy of the Spine in the Era of Volumetric Modulated Arc Therapy
