A full head volume is ideal. The minimum image needed for cephalometric analysis needs to above the superior orbital rim and include the entire mandible. The minimum image for TMD needs to include the complete temporomandibular joints as well as glenoid fossae and the hyoid bone.
To properly position a patient for a cone beam CT (CBCT) scan, ensure they stand upright, align their mid-sagittal plane with the laser guide on the machine, place their chin in the chin rest, bite down on the bite block with their teeth aligned, and keep their head still while the scan is taken, making sure the Frankfort plane (line between the tragus of the ear and the orbital floor) is parallel to the floor; always reference the machine's specific positioning instructions for precise alignment. A bite block cannot be used for cephalometric analysis.