Dental Radiology and Diagnostic Imaging
Dental Radiology and Diagnostic Imaging tests image production, selection criteria, radiation safety, technique, anatomy and interpretation.
Core concepts
- ALARA: use the least radiation that answers the clinical question. Justify every exposure.
- Paralleling technique: the receptor is parallel to the long axis and the central ray is perpendicular; this reduces distortion.
- Bisecting angle is a fallback when paralleling is impossible; it magnifies and distorts.
- Bitewings detect interproximal caries and crestal bone; periapicals show apices; panoramic images show the jaws and impacted teeth but have lower resolution.
- CBCT gives three-dimensional bone imaging; it is not for soft tissue and has metal artifacts.
- Radiographic interpretation: a well-defined corticated radiolucency suggests a benign cyst; an ill-defined ragged border suggests malignancy; a sunburst periosteal reaction suggests osteosarcoma.
Worked example
A patient has a suspected impacted mandibular third molar. A panoramic image shows position and relation to the canal; CBCT is added if the canal is close or surgery is complex. Reasoning: panoramic is the screening view; CBCT answers a specific anatomic question.
Traps
Do not retake images without checking technique and processing. Do not diagnose from one view. Do not confuse ghost images on panoramic films. Do not ignore radiation dose in children and pregnancy.