  Purpose: 3D rotational setup errors in radiotherapy are often ignored by most
clinics due to inability to correct or simulate them accurately and
efficiently. There are two types of rotation-related problems in a clinical
setting. One is to assess the affected dose distribution in real-time if
correction is not applied and the other one is to correct the rotational setup
errors prior to the initiation of the treatment. Here, we present our
analytical solutions to both problems.
