Nuclear fragmentation cross sections for therapy beams
In plain words
Heavy ions break up when they hit nuclei in tissue, creating lighter fragments that deposit dose past the tumour. The break-up probabilities are not measured well enough.
Precise statement
Measure and model partial charge-changing and isotopic production cross sections for projectiles of Z from 2 to 10 at 100 to 450 MeV per nucleon on hydrogen, carbon, nitrogen, oxygen and calcium targets, to about 5 percent, including fragment angular and energy distributions. An answer is a cross-section set that lets Monte Carlo transport reproduce measured depth-dose tails to within 1 percent of peak dose.
What would settle it
Thin-target fragmentation experiments covering the therapeutic energy range, benchmarked against measured depth-dose and lateral profiles.
Status in the literature
Unverified note
Dedicated campaigns since about 2020 have filled gaps, yet model spread in the fragment tail remained several percent in 2025.