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CT Scanner vs. CBCT Scanner: Key Differences Explained

ct scanner cbct scanner medical imaging radiology x-ray

This article breaks down the differences between CT (Computed Tomography) and CBCT (Cone Beam Computed Tomography) scanners, explaining how each technology works and highlighting their respective advantages and disadvantages.

What is Computed Tomography (CT)?

Traditional radiography creates 2D images by superimposing images from various body layers exposed to X-rays. This superimposition can obscure the clarity of individual layers. Tomography was developed to address this limitation.

Computerized Axial Tomography (CAT), now commonly referred to as CT, combines tomographic imaging with computer processing. Godfrey Newbold Hounsfield invented the CT scanner in England.

CT scans utilize computer processing to combine numerous X-ray images taken from different angles, generating cross-sectional images.

Computed Tomography

In CT scanning, an X-ray source and an array of detectors are positioned opposite each other. The X-ray source emits a “fan beam” that covers the entire section of the body being imaged. The radiation that passes through the patient is then detected by the array of detectors.

The patient is moved through a chamber containing the X-ray tube and detectors, which are mounted on a trolley. The detectors can move in one axial direction, hence the term Computerized Axial Tomography (CAT). The computer reconstructs images of the body layers using the data from the detectors.

For more in-depth information, you can refer to resources detailing the working principle, advantages, and disadvantages of CT scanners.

What is Cone Beam Computed Tomography (CBCT)?

CBCT is a variation of the traditional CAT scanner.

Unlike CT, it uses an X-ray tube and detector panel that rotates around the patient, capturing data with a cone-shaped X-ray beam instead of the slices acquired by a standard CT scanner.

Cone Beam Computed Tomography

The X-ray source and detector move through an arc of 180 to 360 degrees to produce multiple planar projection images. For further understanding, resources about the working principle, advantages, and disadvantages of CBCT scanners can be consulted.

CT vs. CBCT: A Detailed Comparison

The following figure illustrates the operational differences between CT and CBCT techniques:

CT scanner vs CBCT scanner

The table below summarizes the key differences between CT and CBCT scanners:

FeatureCT ScannerCBCT Scanner
X-ray Beam ShapeFan-shaped beamCone-shaped beam
X-ray TubeHigh-output rotating anode X-ray tubeLow-power medical fluoroscopy tube for continuous imaging
Image DetectorImage detector arranged in an arc; multiple rows of circular detector arraysSolid-State Area Sensor (or flat panel detector)
Image OutputSingle slice image per scan (2D slices)Complete volume image in single rotation (volumetric dataset)
Scan SpeedSlower due to spiral motion and hundreds of rotationsQuicker; requires only one or two 360-degree rotations. Average time is ~30 seconds
Radiation DoseHighLower
Image OverlapRequires overlapping of radiation for adequate image formationNo overlapping of slices
Jaw VisualizationOnly one jaw visualized at a timeBoth jaws imaged simultaneously
Contrast ResolutionHighPoor; soft tissues not easily viewed
Equipment CostHighApproximately 3 to 5 times less expensive than traditional CT
Patient ComfortCan cause claustrophobiaOpen design virtually eliminates claustrophobia, increasing patient comfort