Cone beam computed tomography (or CBCT, also referred to as C-arm CT, cone beam volume CT, flat panel CT or Digital Volume Tomography (DVT)) is a medical imaging technique consisting of X-ray computed tomography where the X-rays are divergent, forming a cone.

CBCT has become increasingly important in treatment planning and diagnosis in implant dentistry, ENT, orthopedics, and interventional radiology (IR), among other things. Because of increased access to the technology, CBCT scanners are now widely used in dentistry, such as in the fields of oral surgery, endodontics and orthodontics. Integrated CBCT is also an important tool for patient positioning and verification in image-guided radiation therapy (IGRT).

During dental and orthodontic imaging, the CBCT scanner rotates around the patient's head, acquiring up to 600 distinct images. For interventional radiology, the patient is positioned offset to the table so that the region of interest is centered in the field of view for the cone beam. A single 200 degree rotation over the region of interest acquires a volumetric data set. The scanning software collects the data and reconstructs it, producing what is termed a digital volume composed of three-dimensional voxels of anatomical data that can then be manipulated and visualized with specialized software. CBCT shares many similarities with traditional (fan beam) CT however there are important differences, particularly for reconstruction. CBCT has been described as the gold standard for imaging the oral and maxillofacial area.

In the late 1990s, Dr Yoshinori Arai in Japan and Dr Piero Mozzo in Italy independently developed Cone Beam Computed Technology for oral and maxillofacial radiology. The first commercial system (the NewTom 9000) was introduced in the European market in 1996 and into the US market in 2001, by Italian company Quantitative Radiology (also known as QR, based in Verona).

Cone beam CT using kilovoltage X-rays (as used for diagnostic, rather than therapeutic purposes) attached to a linear accelerator treatment machine was first developed in the late 1990s and early 2000s. Such systems have since become common on latest generation linacs. In the late 2010s CBCT also started to become available on-board particle therapy delivery systems.

While CBCT with X-ray image intensifiers was experimented with in the late 1990s, it was not until the adoption of flat-panel X-ray detectors, with improved contrast and spatial resolution, that CBCT became practical for clinical use in interventional radiology procedures. Many fixed, and even mobile, C-arm fluoroscopy systems are now capable of CBCT acquisitions, in addition to traditional planar fluoroscopy. CBCT provides image guidance during interventional radiology procedures for conditions such as knee osteoarthritis, benign prostatic hyperplasia, and hepatocellular carcinoma.

The most significant advantage of the CBCT in Endodontics is that it can show critical root canal anatomical features that conventional intraoral or panoramic images cannot.

According to the American Association of Endodontics, there are numerous specific situations in which 3D images produced by CBCT enhance diagnosis and influence treatment, and its use cannot be disputed over conventional intraoral radiology based on ALARA principles.