CBCT Toolkits: Cone Beam CT Tools Create High Resolution Images with Less Dose than CT Scanning

Rick Colbeth
General Manager Vice President Flat Panel Detectors

The use of the X-ray in medical diagnosis has flourished since its discovery in 1896 in the form of 2-D snap shot imaging (radiography), 2-D video imaging (fluoroscopy), and 3-D imaging with CT or computed tomography. Flat panel detectors were first developed for 2-D X-ray applications but are increasingly used in 3-D imaging in the form of cone beam computed tomography (CBCT) systems. CBCT systems are generally targeted to specific 3-D applications, for example, foot scanning or head scans for dental. cone beam CT systems offer 3-D imaging at lower cost, and, because the systems can be targeted for specific applications, CBCT systems often use lower dose and provide higher resolution images than a general CT scanner.

Using cone beam computed tomography 3-D scanning, medical practitioners can now cost effectively scan a patient’s foot—or any other body part—within minutes in office settings. In the case of foot scanning, a flat panel-based CBCT system, unlike CT, allows practitioners to scan a patient standing and to evaluate the changes in their bones and joints in the weight-bearing position, enabling a more accurate diagnosis. Dose reduction comes from optimizing the imaging geometry and X-ray flux to the specific imaging task. At the same time, the detector pitch in flat panel systems is inherently much finer than traditional CT scanners, enabling very high resolution 3-D imaging.

Despite the benefits of cone beam CT scans, such as lower dose, reduced cost, and more accurate diagnoses, one major challenge with CBCT in medical and dental imaging is scatter, due to the open collimation of the radiation beam. Scatter can affect the quality of 3-D reconstruction by introducing artifacts and inaccuracies in the Hounsfield units (data values).

Scatter correction is a key component in our CBCT toolkit, a suite of software tools enabling CT-like image quality from cone beam computed tomography data sets. Using our CBCT Software Toolkit (CST), we’ve helped clients like CurveBeam create high-resolution, cost effective CBCT systems in a very short amount time. In dental imaging, CBCT systems are the standard of care in implant planning. Using a small fraction of the dose needed for typical CT head scans, dental CBCT systems deliver high resolution 3-D images of the jaw enabling accurate, safe dental implants. Today these scans can be done at the same dose traditionally used in 2-D panoramic imaging, which is still widely used in orthodontics and surgical planning. Regardless of the body part scanned, customers can use the algorithms in our CST image reconstruction pipeline, combine them with their own, or use a combination of our plugins and theirs to create the best 3-D imaging for their needs.

Problem-Solving Plug-ins
The most difficult 3-D imaging task is to achieve sufficient soft tissue contrast resolution. Our CST 3-D image reconstruction software, in combination with our wide dose range panel technology, enables high contrast soft tissue imaging by accurately correcting for artifacts specific to the CBCT geometry and non-idealities in the detector.

Here are a just few examples of customized CBCT plugins:

Scatter Correction:
The wide open collimation associated with CBCT systems is one of the key contributors to image artifacts, including streaks and “cupping” at the center of rotation. Scatter affects the accuracy of the 3D data sometimes by 100s of Hounsfield units. With scatter correction, the CBCT image quality can be brought back to standards expected from traditional CT scanners.

Lag Correction:
For CBCT systems based on amorphous silicon flat panels with CsI, there are lag and ghosting effects associated with both the amorphous silicon array and the CsI. The CST lag correction plugin capitalizes on 25 years of experience with these technologies to remove these effects.

Isocenter Wobble:
The isocenter in many CBCT systems moves—unlike CT imaging—because the mechanical systems are less rigid or because they are mobile systems. Less system stability decreases resolution. The CBCT toolkit contains a plugin that can correct for isocenter wobble.

Other Available Plugins
Beam Hardening Correction
FDK Reconstruction
Ring Correction
Normalization
Hounsfield Unit Adjustments
Customer-developed Plugins

For more information on our CBCT Software, download our datasheet.
CBCT Software Tools
PaxScan CBCT Software Tools_76827_2
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