What is Cone Beam CT?
CT stands for computed tomography. This describes a technology that uses x-rays to map out anatomic structures. A source of x-rays is rotated around a patient, and a detector is positioned on the opposite side of the patient. A complicated algorithm is then used to reconstruct the underlying anatomy based on differences in tissue density.
Conventional CT has been around for decades. In this technology, a narrow “fan” of x-rays is generated to create multiple “slices” of information. The thickness of these “slices” can be adjusted based on the application. The closer together and thinner the slices, the higher the resolution that can be obtained.
Cone Beam CT is a newer technology that uses a single “cone” of x-rays that is rotated around the patient, instead of multiple “fans” stacked together. This information is then used to reconstruct a 3-dimensional volume of information, instead of multiple “slices.” This volume of information is made up of tiny 3-dimensional cube-shaped pixels called “voxels.”
What are the advantages of Cone Beam CT?
1) Lower radiation dose – A potential problem with all CT scans is the use of x-rays, which is a type of radiation that can be harmful in larger doses. Cone beam CT uses 3 – 6 times less radiation per scan than conventional CT. In most cases, the effective radiation dosage from a cone beam CT scan is comparable to a few round-trip plane flights (yes, we get radiated when we fly!).
2) Fast scan time – scans are typically completed in about 30-45 seconds.
3) High level of precision – resolution of cone beam CT is on the order of 0.2 – 0.25 millimeter, allowing imaging of very small structures such as the delicate bones within the middle ear.
4) Patient convenience – With the conventional way of doing things (still the way most ENT practices do it), the patient’s ENT orders a CT for a patient. The patient must then schedule an appointment at a hospital or outpatient imaging center to have the scan performed. There is then a period of time between when the scan is completed and when the ENT reviews it. The patient is then typically called back into the office for a subsequent visit with the ENT to review the scan and determine a treatment plan. With Cone Beam CT, which is available in the office, the patient has the scan performed, and within minutes has the opportunity to review this with their ENT physician. This allows a quick diagnosis to be made, as well as an immediate decision regarding a treatment plan, in a single visit.