ANGULAR DISTRIBUTION OF NEUTRONS FROM PROTON AND CARBON ION THERAPY USING AHUBO PHANTOM (MONTE CARLO SIMULATIONS WITH FLUKA)

Redona IZAIRI-BEXHETI, Mimoza RISTOVA

Abstract

Accelerated protons and C-ions are used by means of radiation therapy (RT) for cancer treatment for over 50 years. Monte Carlo simulations with FLUKA transport code were performed to simulate particle therapy with either protons or C-ions at a given radiation therapy energy. The average Human Body (AHUBO) Phantom has been used to create a human head model (sphere of 8 cm radius). The AHUBO head was placed in (0, 0, 0) the Cartesian system of the Flair graphical interface of FLUKA, and the ion source at Z=-30 cm apart from the centre. The primary beams consisted of 107 protons of 100 MeV and 107 C-ions with 190 MeV/u, energies pertaining to a Bragg peak positioned in the centre of the AHUBO head model (coinciding with the position of the pituitary). The Angular distribution of secondary neutrons with respect to the incident direction of the primaries was scored with a USRBDX for angles 0-180 degrees of solid angle (step 15 degrees). Results showed that there are three typical maxima in the neutron spectra, one thermal and two high energy (HE) peaks. The position and the intensity of the HE peaks change with the change of the solid angle for both incident particle type simulations. The neutron fluence near the margin of the 8 cm radius sphere (region inwards) for the treatment with primary protons was estimated to be in the range of 10-5cm-2, while in the case of treatment with primary C-ions, the fluence was one order of magnitude greater (10-4).

Pages: 294 - 304