KEY POINTS
- This single-institution case involved an 84-year-old woman with a 2.1 cm renal cell carcinoma metastasis in the right lower lung adjacent to the chest wall.
- The prescribed course was 60 Gy in 8 fractions. Because an inhale breath-hold plan exceeded rib and chest-wall constraints, treatment was divided into 4 inhale breath-hold fractions and 4 exhale breath-hold fractions, each delivering 30 Gy.
- Splitting treatment across respiratory phases distributed the high dose across different adjacent ribs, reducing maximum rib dose from 67.87 Gy to 33.46 Gy and chest-wall D30 cm³ from 31.83 Gy to 16.34 Gy.
- Planning target volume coverage was maintained at 95.06% with the split-course approach versus 95.07% with the inhale-only plan. Lung and liver exposure increased slightly but remained within planning constraints.
- Treatment was delivered every other day using daily cone-beam computed tomography and surface guidance. Mild fatigue was the only reported acute complaint, and no chest-wall or rib pain was reported through 9 months of follow-up.
CLINICAL TAKEAWAY
For highly selected peripheral lung targets that shift relative to the ribs between respiratory phases, separate inhale and exhale plans may redistribute chest-wall dose while preserving target coverage. This remains a technically interesting single case with short follow-up and requires validation in a larger cohort before routine use.