Dental Cone Beam CT

Overview

A dental cone beam CT scans the jaws, teeth and sinuses in three dimensions by sweeping an X-ray tube and a flat detector once around the patient's head. Unlike a hospital CT that builds a volume from many thin fan-beam slices, CBCT casts a single cone-shaped beam onto a flat panel and captures the whole region in one rotation, which is why it is fast and compact enough for a dental practice. The volume guides implant placement, root-canal anatomy and surgical planning.

The patient is steadied in the Patient Positioning supports, and the Rotating Gantry swings the X-Ray Source and the Flat-Panel Detector around the head on a rigid C-arm. As the gantry turns, the source fires hundreds of times and the detector records a projection at each angle; the Slip Ring passes power and the image stream across the rotating joint. The Reconstruction Computer back-projects those projections into a 3D volume, and the Control & Display lets the operator set the field of view and trigger the exposure from behind the radiation barrier. The whole assembly hangs from the Column & Covers column.

Dose scales with field of view, so the operator collimates to the smallest volume that answers the clinical question rather than always scanning the whole skull.

How it works

Once the Chin Rest & Bite Block and the Alignment Lasers have the anatomy centred, the Vertical Lift Motor drives its Ball Screw to set height and the operator holds the Exposure Switch. The Gantry Drive Motor then sweeps the C-arm through its rotation; a Helical Gear Pair gives the smooth reduction the geometry needs, and the Gantry Encoder tags every projection with the exact angle, which reconstruction depends on.

At each step the High-Voltage Generator drives the X-Ray Tube to emit a pulse, and the Beam Collimator trims the cone to just cover the panel so no dose is wasted. The beam passes through the head and lands on the Flat-Panel Detector, where the Scintillator Layer converts X-rays into light and the CMOS Image Sensor reads it; the Detector Readout Board digitises each frame and streams it across the Slip Ring. One sweep yields a few hundred angular projections.

Turning projections into anatomy is the job of the Reconstruction Computer. Its Compute SoC Module runs filtered back-projection, the cone-beam FDK algorithm, smearing each weighted projection back along its ray and summing the contributions so structures reinforce where rays from every angle agree, while an Microcontroller keeps the source pulses, gantry angle and detector frames in sync during the sweep. The resulting isotropic voxel volume appears on the Operator Touchscreen, where the clinician scrolls and reslices it. Lead shielding behind the Moulded Covers and the dead-man Exposure Switch keep the exposure contained and brief.