Tomografía CBCT y Calidad de Imagen

CBCT (Cone Beam Computed Tomography)

• Invented in 1971 by Godfrey Hounsfield, at the Atkinson-Morley Hospital in London.
• Early CT (Computed Tomography) scanned only one section at a time, while CBCT produces a 3D image.
• CBCT and CBVT (Cone Beam Volumetric Tomography) are terms for the same technology.
• CBCT provides images of dental and maxillofacial regions, focusing on hard tissues.
• It is considered a more advanced diagnostic tool compared to traditional 2D x-rays.
• CBCT is especially useful in situations where a 3D visualization is essential, like identifying impacted teeth, root canals, or problems with the jaw.

Factors Affecting Image Quality

• Detector type
• Head positioning (for stability)
• Bit depth
• Software

Improving Image Quality

• Contrast: The ability to convert radiation dose into shades of gray and black. A high contrast image gives greater detail.
• Sharpness: The ability to distinguish two close structures. This depends on the sensor resolution.
• Noise: Variation in the fluctuation of X-rays. Motion of the patient during the scan can worsen noise.
• Contrast is improved with low noise levels.
• Materials that absorb more X-rays appear whiter on the image, like bone.

How Digital Images are Formed

• Voxels form the image matrix replacing pixels.
• Voxels are the three-dimensional equivalent of pixels in 2D images.
• Voxels provide more depth of information.

CBCT Principles of Radiological Protection

• Justification: Radiographic procedures should only be used when the benefits outweigh the risks.
• Optimization: Radiation exposure should be kept as low as reasonably achievable (ALARA).
• ALARA is a safety principle that advocates for the minimum dose required to perform the procedure successfully.

CBCT Advantages

• Limited X-ray beam: Decreases exposure time.
• Faster exposure times: Reduces patient motion artifacts.
• Reduced radiation dose compared to traditional CT scans, but higher than conventional dental X-rays.
• Multiplanar reconstruction: Allows visualization of structures in different anatomical orientations (axial, sagittal, coronal) improving diagnosis possibilities.
• Improved resolution in some cases, with high-resolution, small FOV (field of view) CBCT.

CBCT Disadvantages

• Soft tissue detail is often less detailed than with traditional CT scans.
• Potential for artifacts from dense materials (e.g. restorations).
• Patient must remain still.

FOV (Field of View)

• Small FOV: Useful for areas like a single tooth or a small section of the jaw.
• Medium FOV: Used for a wider area, including an entire jaw, or a few teeth.
• Large FOV: Useful for the whole skull. A larger FOV requires a larger dose of radiation.

Applications of CBCT

• Reabsorption of tooth roots.
• Fractures.
• Dental implants.
• Impacted teeth.
• Periodontal defects.
• Jaw lesions.
• Various other dental and oral diagnoses.
• Craniofacial/head trauma assessments.

Este cuestionario explora la Tomografía Cone Beam Computed (CBCT), una herramienta avanzada para imágenes dentales y maxilofaciales. Además, se discuten los factores que afectan la calidad de la imagen y las maneras de mejorarla. Ideal para estudiantes y profesionales en odontología y radiología.