Fig. 1

Panoramic radiographs of the phantoms using PCH-2500®. The readable area was evaluated twice by the consensus of two oral–maxillofacial radiologists with over 20 years of experience. (a, b). a Horizontal resolution phantom containing 1.88 lp/mm was located in the incisor region. The readable boundary was indicated by yellow arrows. (Step number: 1 ~ 13, numbered from the lowest area). b Vertical resolution phantom containing 1.88 lp/mm was located in the incisor region. The readable boundary was indicated by yellow arrows. (Step number: 1 ~ 13, numbered from the lowest area). c Panoramic radiograph of ball phantom. The incisor, premolar, molar, and TMJ regions used for analysis were indicated by yellow boxes