cone beam CE

cone beam1_2012 Fig. 1_The fan beam on which spiral computed tomography (left) is based interrogates only a slice of tissue, whereas the cone beam of cone-beam computed tomography (right) interrogates a three- dimensional region within a 360 degree rotation. (Photo/Reproduced with permission from MacDonald- Jankowski and Orpe.) Fig. 2_With conventional CT, the X-ray is produced as the gantry rotates the X-ray tube and detector around the patient. (Photos/Provided by Richard W. Greenan) Fig. 3_NewTomTM QR-DVT 9000 30 I I clinical technique _neuromuscular application _Three-dimensional imaging for dentistry is here and has already proven to be the practical alternative to traditional 2-D radiodontics, as expected. A single volumetric cone-beam com- puted tomography (CBCT) scan can now replace the conventional cephalogram, panoramic, PA skull and tomograms of the TMJs, implant sites and paranasal sinuses in one 10–20 second scan. The advent of volumetric CBCT has overtaken conventional medi- cal CT in both its reduction of radiation, significant increase in restorative detail and at a lower cost to boththeclinicianandpatient.Thisnewtechnologyis already redefining cephalometrics. _History CT was invented in 1972 by British engineer Sir Godfrey N. Hounsfield of EMI Laboratories, England, with the first “CAT-Scans” patent granted to Robert S. Ledley on Nov. 25, 1975. Most conventional medi- cal MDCT’s incorporate a fan shaped beam (Fig. 1) whereas dental CBCT systems today utilize a cone shape beam (Fig. 2). With conventional CT, X-ray is produced as the gantry rotates the X-ray tube and detectoraroundthepatient(Fig.2)producinganim- ageor“slice”witheach360degreerotationandthen stacks the multiple scans and slices. In a cone-beam CT (CBCT) geometry, the entire subject is exposed just once from a single point sourceusinganamorphoussilicon(aSi:H)flat-panel sensor, Csi, CMOS or CCD as its detector. A single rotationCBCTscanresultsinavolumetricscanofthe entire subject with complete data acquisition in just two to three minutes. In March 2001, the NewTomTM QR-DVT 9000 be- came the first CBCT system to receive FDA approval in the United States (Fig. 3). Followed in 2003 by the Imaging Sciences International i-CATTM incorporat- ing similar CBCT technology but in a sit-down and relatively affordable system (Fig. 4). In 2008, NewTom introduced the upright VG system (Fig. 5) utilizing its exclusive Smart Beam Technology with significant reduction in radiation dosage.1 Author_Richard W. Greenan Volumetric cone-beam computed tomography in neuromuscular dentistry Fig. 1 Fig. 2 Fig. 3