The application relates to a portable bite part (230) for determining an imaging area (204) of a patient (201) in Panoramic, Computed Tomography, or Cephalometric 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 patient. The bite part further comprises markers (231, 232). The first end is configured to indicate the area inside the mouth. The markers are configured to be positioned outside the mouth. The markers make possible to recognize positions of the markers, whereupon it is possible to calculate a location (205) of the first end with respect to an X-ray imaging unit (100) by using the positions of the markers and the known dimensions of the bite part.
