Dosimetric Comparison between Sgrt- and Rpm-Based Dibh APBI for Left-Sided Breast Patients
Abstract
Purpose
Accurate breath-hold reproducibility is critical in left-sided breast irradiation to reduce cardiac and lung dose, and differences in motion management techniques may influence delivered dose accuracy. The purpose of this study is to investigate the dosimetric differences between surface-guided radiation therapy (SGRT)-based and infrared-based deep inspiration breath-hold (DIBH) accelerated partial breast irradiation (APBI) for left-sided breast patients.
Methods
This retrospective study included twenty left-sided breast patients who underwent DIBH APBI using IMRT. Each patient’s breathing trace acquired during CT simulation was imported into a programmable respiratory motion phantom to reproduce patient-specific breathing patterns and breath-hold motion during beam delivery. An SRS MapCheck detector was mounted on the motion platform to measure delivered dose. The SGRT system evaluated was AlignRT, and the infrared marker-based system was Real-Time Position Management (RPM). Clinical treatment plans were transferred to the phantom geometry and delivered twice per patient: once using RPM gating and once using AlignRT gating. Gamma analysis comparison was performed between the planned and measured dose distributions using clinical criteria to evaluate dosimetric agreement under the two gating techniques.
Results
Gamma analysis suggests that both gating systems demonstrate comparable performance during breath-hold delivery. Preliminary data indicate that the measured dose distributions show clinically acceptable passing rates.
Conclusion
Under simulated patient-specific respiratory motion, RPM-gated delivery demonstrated dosimetric accuracy comparable to SGRT-based delivery with AlignRT. These results suggest that both motion management approaches provide similar dose delivery performance for DIBH APBI.