KEY POINTS
- Single-center study of 31 women receiving breast radiotherapy after breast-conserving surgery with deep inspiration breath-hold.
- The workflow used ExacTrac Dynamic thermo-optical surface monitoring plus stereoscopic X-ray guidance, with cone-beam computed tomography used as the independent reference.
- Valid datasets included 144 inter-fraction cone-beam computed tomography-derived setup errors, 127 intra-fraction thermo-optical monitoring plus cone-beam computed tomography datasets, and 135 intra-fraction X-ray correction datasets.
- After X-ray correction, mean six-dimensional setup errors were not significantly different from zero, and breast volume did not significantly affect setup accuracy.
- Calculated planning target volume margins using the van Herk formula were 5.10 mm lateral, 5.22 mm longitudinal, and 5.78 mm vertical.
CLINICAL TAKEAWAY
This study supports thermo-optical surface monitoring plus intermittent X-ray correction as a feasible setup and intra-fraction monitoring workflow for breast deep inspiration breath-hold radiotherapy. The potential practical value is lower imaging dose than repeated cone-beam computed tomography while preserving positional control. The evidence remains limited: small single-center cohort, no delivered-dose reconstruction, no toxicity endpoints, and no validation in post-mastectomy patients or deeper targets.