1991 Volume 47 Issue 12 Pages 2009-2016
Orthopantomograph Model OP-3 (Siemens) has a rotary knob for changing the position of the locus of X-ray beam rotation center (XRC) with respect to the guide plate. A change in the point setting (AL) of the rotary knob causes variation in image formation. Theoretical analysis was conducted on the AL of the rotary knob for assessment of image formation capacity of Model OP-3 and determine an appropriate AL for clinical application. Al of 28〜38mm and 57mm for adults and 20〜28mm and 48〜57mm for children (aged 4〜10) were found to show little strain of projected images and to be most appropriate for photographing the standard dentition region and mandibular joint region, respectively.