Surface-guided radiation therapy combined with real-time position management-guided deep inspiratory breath-hold radiotherapy for left breast cancer.

BACKGROUND AND PURPOSE: To evaluate the efficacy of surface-guided radiation therapy (SGRT) combined with real-time position management (RPM)-guided deep inspiratory breath-hold (DIBH) radiotherapy for left breast cancer. MATERIALS AND METHODS: Twenty patients diagnosed with breast cancer, who underwent breast-conserving surgery and subsequent DIBH radiotherapy, were randomly assigned to two treatment groups: SGRT-guided (SGRT); and combined SGRT + RPM-guided (SGRT + RPM). Recorded setup and cone beam computed tomography (CBCT) validation execution Time (T1), Beam delivery time (T2). Residual vertical setup error (VRT Error), six-dimensional (6D) setup errors, and breath-hold error (BH Error) were obtained using breath hold CBCT. Correlations between BH Error and VRT Error were analyzed. Dose reconstruction was performed using velocity-generated adaptive CT to compute per-fraction and accumulated doses, with coefficient of variation (CV) analysis used to quantify interfractional dose variations in clinical target volume (CTV) and organs at risk (OARs). RESULTS: The mean (± SD) T1 and T2 times for the SGRT and SGRT + RPM groups were 452.53 ± 83.57 s vs. 299.58 ± 53.52 s (p < 0.05), and 147.85 ± 46.35 s vs. 135.3 ± 32.97 s (p > 0.05), respectively, with no statistical difference in 6D setup errors (p > 0.05). The SGRT group exhibited a mean BH Error that was 0.4 mm larger than that of the SGRT + RPM group, with a 0.7 mm reduction in stability. There was a correlation between BH Error and VRT Error in the SGRT group (r = 0.635, p < 0.05). Accumulated dose analysis revealed statistically significant decreases in CTV D98% and V95% in both groups (p < 0.05). However, maintained CTV coverage meeting clinical acceptability criteria (V95% ≥ 95%). The accumulated OARs doses demonstrated no significant differences compared with the planned doses (p > 0.05). There was no significant difference in CV values between the two groups (p > 0.05). CONCLUSION: The DIBH guided by SGRT + RPM simplify the radiotherapy workflow, improve the operation efficiency and breath-hold (BH) quality of patients. Simultaneously, it guaranteed alignment of the cumulative doses received by the CTV and OARs with the planned doses.