Comparison of heart-sparing efficacy between deep inspiration and end-expiration breath-hold in gastric MALT lymphoma radiotherapy: Spatial separation versus margin reduction.

Abstract

This study aims to explore whether spatial separation in deep inspiration breath-hold (DIBH) or margin reduction in end-expiration breath-hold (EEBH) achieves heart-sparing efficacy in the radiotherapy (RT) of gastric mucosa-associated lymphoid tissue (MALT) lymphoma patients. 51 gastric MALT lymphoma patients treated between 2023-2025 were enrolled and trained for either DIBH or EEBH. Dosimetric parameters (heart and left ventricle V5-V30 and mean doses) were compared. Geometric relationships between the heart and target volume were characterized using distance-based metrics, and their association with cardiac dose reduction was evaluated using linear regression. Overlap-based indices were reported descriptively. Fifty CBCT-based IGRT deviations from audio-visual feedback (AVFB)-assisted DIBH patients were descriptively compared with EEBH. Both DIBH and EEBH reduced cardiac doses compared with free breathing. Using relative dose reduction (Δdose) as the primary endpoint, DIBH was associated with greater reductions in low-dose parameters, particularly ΔV5. Increased spatial separation during DIBH correlated with greater low-dose reduction. CBCT-based positional analysis suggested consistent inter-fraction setup under AVFB-assisted DIBH. This exploratory dosimetric study suggests that DIBH may be associated with greater reduction in cardiac dose, particularly for low-dose metrics. Increased spatial separation may serve as a geometric indicator of dose reduction. These findings should be interpreted as exploratory, and further studies are warranted to validate their clinical relevance.