Carbon beam dosimetry intercomparison at HIMAC

To verify international uniformity in carbon beam dosimetry, an intercompar ison programme was carried out at the heavy ion medical accelerator (HIMAC) . Dose measurements with ionization chambers were performed for both unmodu lated and 6 cm modulated 290 MeV/nucleon carbon beams. Although two differe nt dosimetry procedures were employed, the evaluated values of absorbed dos e were in good agreement. This comparison established a common framework fo r ionization chamber dosimetry between two different carbon beam therapy fa cilities.