Radiology Lecture 18: Computed Tomography (CT) & Cone Beam CT

Computed Tomography (CT)

• Uses X-rays, a powerful form of electromagnetic radiation
• Evaluates the entire body
• Multi-detector CT scanners have evolved, with better clinical applications
• Applications include:
  • Osteomyelitis and space infections
  • Midfacial and mandibular trauma
  • Developmental anomalies of the craniofacial skeleton
  • Benign intraosseous cysts and neoplasms of the jaws
  • Benign and malignant neoplasms of the orofacial soft tissues
  • Soft-tissue cysts
• Advantages:
  • Provides axial, coronal, and sagittal views of tissue
  • Displays anatomically precise location of lesions and extent
  • Shows normal and pathological soft tissue structures clearly
  • Allows for selective viewing and enlargement of areas of interest
  • Images can be manipulated and stored for later viewing
• Disadvantages:
  • Sophisticated and expensive to maintain
  • High-density materials produce severe artifacts, making interpretation difficult
  • Inherent risk associated with contrast medium

Cone-Beam Computed Tomography (CBCT)

• A new medical imaging technique that generates 3D images
• Based on a cone-shaped X-ray beam centered on a 2D detector
• Components:
  • X-ray source with a rotating gantry
  • Divergent pyramidal or cone-shaped source of ionizing radiation
  • 2D X-ray detector on the opposite side
• Advantages:
  • Rapid scan time
  • Beam limitation
  • Image accuracy
  • Reduced patient radiation dose
  • Interactive display modes applicable to maxillofacial imaging
• Disadvantages:
  • Extinction artifacts
  • Beam hardening artifacts