The application relates to a portable bite part (230) for correcting a motion of an object (201) in Panoramic, Computed Tomography, or Cephalometric X-ray imaging. The bite part comprises a first end (233) and a second end (234). The bite part has known dimensions. The first end is configured to be positioned in a mouth (202) of the object. The bite part further comprises markers (231, 232), which make possible to recognize positions of the markers from at least two images (237, 238) presenting the bite part and to calculate the motion of the object with respect to an X-ray imaging unit (100) by using the positions of the markers and the known dimensions of the bite part.
