Mayo Clinic Florida Models Move Dose for First US Carbon-Ion Facility

The authors model realistic beam paths including hockey-stick trajectories from unequal X-Y scan speeds, linear ramp-up intensity, and measured stochastic fluctuations. They divide each inter-spot segment into discrete move sources with analytically derived position, monitor units, and intensity, then feed these into TOPAS for a 430 MeV/u carbon beam in water. This directly tackles the gap in commercial treatment planning systems that omit intra-move dose.

Carbon-ion therapy’s higher linear energy transfer produces clustered DNA damage that improves local control in radioresistant tumors, yet the absence of any US facility has restricted access to trials abroad. Accurate move-dose modeling is therefore a prerequisite for safe, efficient delivery once Mayo’s synchrotron becomes operational. The approach mirrors methods already refined at HIMAC and HIT, where small dosimetry errors scaled with scanned fields.

Validation in a homogeneous phantom shows close agreement between simulated and reference distributions, but the study remains preclinical. Patient-specific heterogeneity, respiratory motion, and end-to-end commissioning data are still required before regulatory acceptance.

Integration of this framework into Mayo’s planning pipeline will determine whether move-dose corrections measurably alter target coverage or organ-at-risk sparing in the first US cohort.