Validation of a track-repeating algorithm versus measurements in water for proton scanning beams

Dose distributions calculated with the fast dose calculator (FDC), a track repeating-algorithm for proton therapy, have been validated versus dose measurements in water for scanning proton beams at the University of Texas MD Anderson Cancer Center Proton Therapy Center in Houston. The dose calculated with FDC, at the position of the measured points for depth and lateral profiles, was compared to the measurements with a gamma-index analysis. It was found that 99.9% and 99.5% of the measured points had a gamma-index value smaller than unity for the 3%/3 mm and 2%/2 mm dose/distance agreement criteria, respectively.