Dosimetric effect of carbon fiber treatment couch in boron neutron capture therapy

This study aims to investigate the dosimetric effect of carbon fiber treatment couch on boron neutron capture therapy (BNCT). Using Monte Carlo code PHITS, the differences in normal tissue dose, treatment time, and tumor dose with and without the treatment couch were calculated for supine and lateral positions. For the lateral position, where the treatment couch was within the radiation field, the maximum dose rate difference was found to be up to 26%, the maximum treatment time deviation was up to 36 secs, and the maximum absolute deviation of the tumor dose can reach up to 1.1 Eq-Gy, and the maximum relative deviation can reach up to 12.1%. Therefore, it is inappropriate to ignore the device in dose calculation if it is within the radiation field. In practical treatment planning, efforts should be made to avoid placing the carbon fiber treatment couch within the radiation field. Otherwise, the treatment couch model should be included in the dose calculation to improve the accuracy of the results.