Cone-beam computed tomography (CBCT) systems have been designed for imaging hard tissues of the maxillofacial region. CBCT is capable of providing sub-millimetre resolution in images of high diagnostic quality, with short scanning times (10-70 seconds) and radiation dosages reportedly up to 15 times lower than those of conventional CT scans. Increasing availability of this technology provides the dental clinician with an imaging modality capable of providing a 3-dimensional representation of the maxillofacial skeleton with minimal distortion. This article provides an overview of currently available maxillofacial CBCT systems and reviews the specific application of various CBCT display modes to clinical dental practice.

/pdf/clinical-applications-of-cone-beam-computed-tomography-in-4kp8tgr2p7.pdf

Clinical applications of cone-beam computed tomography in dental practice.

Objectives: Cone beam computed tomography (CBCT), which provides a lower dose, lower cost alternative to conventional CT, is being used with increasing frequency in the practice of oral and maxillofacial radiology. This study provides comparative measurements of effective dose for three commercially available, large (12″) field-of-view (FOV), CBCT units: CB Mercuray, NewTom 3G and i-CAT. Methods: Thermoluminescent dosemeters (TLDs) were placed at 24 sites throughout the layers of the head and neck of a tissue-equivalent human skull RANDO phantom. Depending on availability, the 12″ FOV and smaller FOV scanning modes were used with similar phantom positioning geometry for each CBCT unit. Radiation weighted doses to individual organs were summed using 1990 (E1990) and proposed 2005 (E2005 draft) ICRP tissue weighting factors to calculate two measures of whole-body effective dose. Dose as a multiple of a representative panoramic radiography dose was also calculated. Results: For repeated runs dosimetry was ge...

/pdf/dosimetry-of-3-cbct-devices-for-oral-and-maxillofacial-3pq1k8mr17.pdf

Dosimetry of 3 CBCT devices for oral and maxillofacial radiology: CB Mercuray, NewTom 3G and i-CAT

Objectives This study compares 2 measures of effective dose, E1990 and E2007, for 8 dentoalveolar and maxillofacial cone-beam computerized tomography (CBCT) units and a 64-slice multidetector CT (MDCT) unit. Study design Average tissue-absorbed dose, equivalent dose, and effective dose were calculated using thermoluminescent dosimeter chips in a radiation analog dosimetry phantom. Effective doses were derived using 1990 and the superseding 2007 International Commission on Radiological Protection (ICRP) recommendations. Results Large-field of view (FOV) CBCT E2007 ranged from 68 to 1,073 μSv. Medium-FOV CBCT E2007 ranged from 69 to 560 μSv, whereas a similar-FOV MDCT produced 860 μSv. The E2007 calculations were 23% to 224% greater than E1990. Conclusions The 2007 recommendations of the ICRP, which include salivary glands, extrathoracic region, and oral mucosa in the calculation of effective dose, result in an upward reassessment of fatal cancer risk from oral and maxillofacial radiographic examinations. Dental CBCT can be recommended as a dose-sparing technique in comparison with alternative medical CT scans for common oral and maxillofacial radiographic imaging tasks.

/pdf/comparative-dosimetry-of-dental-cbct-devices-and-64-slice-ct-omz4if0pfp.pdf

Comparative dosimetry of dental CBCT devices and 64-slice CT for oral and maxillofacial radiology

http://www.endoexperience.com/documents/DeVos2009.pdf

Cone-beam computerized tomography (CBCT) imaging of the oral and maxillofacial region: a systematic review of the literature.

Patel S, Dawood A, Pitt Ford T, Whaites E. The potential applications of cone beam computed tomography in the management of endodontic problems. International Endodontic Journal, 40, 818– 830, 2007. Aim To provide core information on cone beam computed tomography (CBCT) technology and its potential applications in endodontic practice. Summary CBCT has been specifically designed to produce undistorted three-dimensional information of the maxillofacial skeleton as well as three-dimensional images of the teeth and their surrounding tissues. This is usually achieved with a substantially lower effective dose compared with conventional medical computed tomography (CT). Periapical disease may be detected sooner using CBCT compared with periapical views, and the true size, extent, nature and position of periapical and resorptive lesions can be assessed. Root fractures, root canal anatomy and the true nature of the alveolar bone topography around teeth may be assessed. CBCT scans are desirable to assess posterior teeth prior to periapical surgery, as the thickness of the cortical and cancellous bone can be accurately determined as can the inclination of roots in relation to the surrounding jaw. The relationship of anatomical structures such as the maxillary sinus and inferior dental nerve to the root apices may also be clearly visualized. Key learning points • CBCT has a low effective dose in the same order of magnitude as conventional dental

/pdf/the-potential-applications-of-cone-beam-computed-tomography-1wvvmiafet.pdf

The potential applications of cone beam computed tomography in the management of endodontic problems.

Objective The purpose of this investigation was to measure the tissue-absorbed dose and to calculate the effective dose for the NewTom 9000, a new generation of computed tomographic devices designed specifically for dental applications. Comparisons are made with existing reports on dose measurement and effective dose estimates for panoramic examinations and other computed tomographic imaging modalities for dental implants. Study design Thermoluminescent dosimeters were implanted in a tissue-equivalent humanoid phantom at anatomic sites of interest. Absorbed dose measurements were obtained after single and double exposures. The averaged tissue-absorbed doses were used for the calculation of the whole-body effective dose. Results The effective dose for imaging of maxillomandibular volume with a NewTom 9000 machine is 50.3 μSv. Conclusion The effective dose with the NewTom 9000 machine is significantly less than that achieved with other computed tomographic imaging methods and is within the range of traditional dental imaging modalities.

Radiation absorbed in maxillofacial imaging with a new dental computed tomography device.

The use of computed tomography for dental imaging procedures has increased recently. Use of CT for even seemingly routine diagnosis and treatment procedures suggests that the desire for 3-D imaging is more than a current trend but rather a shift toward a future of dimensional volume imaging. Recognizing this shift, several imaging manufacturers recently have developed 3-D imaging devices specifically for dental purposes using cone-beam computerized tomography. This technology allows for 3-D imaging similar to CT, but at lower equipment cost, simpler image acquisition and lower patient radiation dose. Herein, an overview of these devices is provided such that potential users can be better informed about this emerging technology.

3-D volume imaging for dentistry: a new dimension.

Central odontogenic fibroma: clinicopathologic features of 19 cases and review of the literature.

Objectives. The purpose of this investigation was to measure the tissue-absorbed dose and to calculate the whole-body effective dose (E) for a new generation panoramic machine (Planmeca PM 2002 CC Proline), operating in the panoramic examination mode. Comparisons could then be made with historical panoramic and intraoral radiographic dose measurement values and effective dose estimates. Study design. Thermoluminescent dosimeters were embedded in a humanoid, tissue-equivalent phantom at anatomically significant sites, representing key tissues. Absorbed dose measurements were obtained after every 5 panoramic exposures of a 25-exposure total. The measured average tissue-absorbed doses from a single panoramic exposure were used in the calculation of the whole-body E. Results. The whole-body E for the PM 2002 CC Proline panoramic examination is 3.85 μSv. This is below the panoramic average of 6.7 μSv. The PM 2002 CC Proline panoramic examination delivers approximately 5% to 12% of the E of a complete mouth intraoral radiographic examination. Conclusions. The effective dose from the PM 2002 CC Proline examination is at the low end of the range for other panoramic machines and is far below either a D-speed or E-speed film intraoral radiographic examination. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000;89:236-43)

Effective dose from radiation absorbed during a panoramic examination with a new generation machine

Complex impacted third molars present potential treatment complications and possible patient morbidity. Objectives of diagnostic imaging are to facilitate diagnosis, decision making, and enhance treatment outcomes. As cases become more complex, advanced multiplane imaging methods allowing for a 3-D view are more likely to meet these objectives than traditional 2-D radiography. Until recently, advanced imaging options were somewhat limited to standard film tomography or medical CT, but development of cone beam volume tomography (CBVT) multiplane 3-D imaging systems specifically for dental use now provides an alternative imaging option. Two cases were utilized to compare the role of CBVT to these other imaging options and to illustrate how multiplane visualization can assist the pretreatment evaluation and decision-making process for complex impacted mandibular third molar cases.

Robert A. Danforth

Papers

Radiation absorbed in maxillofacial imaging with a new dental computed tomography device.

3-D volume imaging for dentistry: a new dimension.

Central odontogenic fibroma: clinicopathologic features of 19 cases and review of the literature.

Effective dose from radiation absorbed during a panoramic examination with a new generation machine

Cone beam volume tomography: an imaging option for diagnosis of complex mandibular third molar anatomical relationships.