Note that the reason it’s nearly the same beam-on time is the gantry has sped up. So given a specific planning field width, what determines the treatment time is the treatment field length and the fraction dose – not the pitch! (Exceptions at very fast gantry periods, which corresponds to either very small pitches or very low fraction doses.)
Note that the reason it’s nearly the same beam-on time is the gantry has sped up. So given a specific planning field width, what determines the treatment time is the treatment field length and the fraction dose – not the pitch! (Exceptions at very fast gantry periods, which corresponds to either very small pitches or very low fraction doses.)