KEY POINTS
- This study developed SMART-BRAIN, a novel medulloblastoma craniospinal irradiation target concept, using literature-based patterns of failure and dosimetric testing in 5 pediatric patients aged 4–16 years.
- The proposed CTV_2340 included the ventricular system, periventricular region, cortical surface, and entire posterior fossa to the foramen magnum, with a 1 mm expansion into brain.
- All proton plans met target coverage goals, including V100% ≥ 95% and V98% ≥ 97%, using robust optimization with ±2 mm setup and ±2% range uncertainty.
- Median non-target brain volume was 194.5 cc, representing 14.8% of total brain volume; proton planning reduced median non-target brain V18 Gy to 70.2%, sparing nearly 30% of non-target brain from at least 18 Gy.
- Photon planning showed inferior target coverage and minimal non-target brain sparing; meaningful hippocampal sparing was not achieved because the target overlapped the hippocampi.
CLINICAL TAKEAWAY
SMART-BRAIN is an ambitious proton-based craniospinal irradiation de-escalation concept for selected medulloblastoma patients, aiming to spare white matter and deep brain regions rather than only the hippocampi. The dosimetric signal is interesting, but the evidence is conceptual and based on only 5 planning cases with no clinical outcome validation. This should not change standard target volumes outside a carefully designed clinical trial.