DPT

DPT

1. Faults

   • Pt's chin too far down
     • Smile
     • Not parallel to Frankfurt plane
   • Pt chin too far up
   • Incorrect focal trough
     • Pt too far forwards
       • Front teeth will be blurred and narrowed
     • Pt too far backwards
       • Front teeth will be widened, blurred and magnified
     • Rotation of the head
       • If the patient is rotated to the left then the right hand side ramus will be more magnified and the teeth will be wider. The LHS teeth will be narrower
   • ghost image
     • Opposite side of the object
     • Def: Opaque shadow of a dense object
     • Appears larger than the object
     • Less sharp
     • Can get ghost images of mandible if it is really radio dense
   • Movement blurring
     • e.g parkinsons pt's

2. Technique

   • Ask pt to have tongue hitting roof of their mouth
   • Frankfurt plane needs to be parallel to the floor
     • Inferior orbital margin to superior border of external auditory meatus
     • Alar tragal is an estimation of frankfort
   • Focal trough has to between 2 and 3