Cone beam CT
Cone beam CT (CBCT) is a variant type of computed tomography (CT), and is used particularly in dental and extremity imaging. It differs from conventional CT in that it uses cone-shaped x-ray beam and two dimensional detectors instead of fan-shaped x-ray beam and one dimensional detectors.
In CBCT, a divergent cone-shaped source of radiation is directed through the target. The attenuated x-rays are detected on the opposite side by an x-ray detector, which has multiple dexels in the x and y-axis 2. Volume acquisition can thus be acquired with fewer rotations of the x-ray tube gantry. This differs from fan-beam CT, which uses a 2D fan-shaped x-ray beam in helical progression to acquire image data. Furthermore, fan-beam CT detector only has dexels in the x-axis.
The advent of CBCT has brought about several advantages over its fan-beam counterpart, but it also has its inherent disadvantages.
- decreased examination time
- decreased patient movement artifact
- increased x-ray tube efficiency 3
- increased scattered radiation
- potential for cone beam artifact if an inappropriate reconstruction algorithm is used
- 1. Diagnostic Radiology: Recent Advances and Applied Physics in Imaging (Aiims-Mamc-Pgi Imaging). Jaypee Brothers Medical Pub. ISBN:9350904977. Read it at Google Books - Find it at Amazon
- 2. Scarfe WC, Farman AG. What is cone-beam CT and how does it work?. Dent. Clin. North Am. 2008;52 (4): 707-30, v. doi:10.1016/j.cden.2008.05.005 - Pubmed citation
- 3. Miracle AC, Mukherji SK. Conebeam CT of the head and neck, part 1: physical principles. AJNR Am J Neuroradiol. 2009;30 (6): 1088-95. doi:10.3174/ajnr.A1653 - Pubmed citation
computed tomography (CT)
- CT technology
- CT image reconstruction
- CT image quality
- CT dose
- CT contrast
- patient-based artifacts
- physics-based artifacts
- hardware-based artifacts
- helical and multichannel artifacts
- CT safety
- history of CT