Reporting findings in the cone beam computed tomography volume.

The use of cone beam CT (CBCT) is common among dentists and dental specialists in North America and the world. The regions of interest captured by these machines vary in size and applications are numerous. If using the image data from this modality, clinicians are obligated to examine the entire volume and to understand and recognize all the anatomy in the head and neck region that can be portrayed and any abnormalities detected in otherwise normal surroundings. This article attempts to identify common entities found in the anatomic regions captured in a CBCT volume and those common abnormalities that must be referred.

Maintaining radiation exposures as low as reasonably achievable (ALARA) for dental personnel operating portable hand-held x-ray equipment.

Clinical experience indicates that newly available portable hand-held x-ray units provide advantages compared to traditional fixed properly installed and operated x-ray units in dental radiography. However, concern that hand-held x-ray units produce higher operator doses than fixed x-ray units has caused regulatory agencies to mandate requirements for use of hand-held units that go beyond those recommended by the manufacturer and can discourage the use of this technology. To assess the need for additional requirements, a hand-held x-ray unit and a pair of manikins were used to measure the dose to a simulated operator under two conditions: exposures made according to the manufacturer's recommendations and exposures made according to manufacturer's recommendation except for the removal of the x-ray unit's protective backscatter shield. Dose to the simulated operator was determined using an array of personal dosimeters and a pair of pressurized ion chambers. The results indicate that the dose to an operator of this equipment will be less than 0.6 mSv y⁻¹ if the device is used according to the manufacturer's recommendations. This suggests that doses to properly trained operators of well-designed, hand-held dental x-ray units will be below 1.0 mSv y⁻¹ (2% of the annual occupational dose limit) even if additional no additional operational requirements are established by regulatory agencies. This level of annual dose is similar to those reported as typical dental personnel using fixed x-ray units and appears to satisfy the ALARA principal for this class of occupational exposures.

Operator exposure to scatter radiation from a portable hand-held dental radiation emitting device (Aribex NOMAD) while making 915 intraoral dental radiographs.

Operator exposure to backscatter radiation while using an Aribex NOMAD radiation emitting device (a portable, self-contained, cordless, hand-held dental X-ray unit) was determined while the operator employed various typical and atypical use scenarios during the exposure of 715 digital and/or film-based dental radiographs and 200 study control exposures. Study data was compared to the radiation safety occupational exposure annual Maximum Permissive Dose (MPD) of 50 mSv (5000 mrem) to determine the possible exposure risk to an unprotected operator using this device. The results showed the reproductive organs received the highest dose and the thyroid the least. The average operator whole body dose for the study was determined to be 0.047 mSv (4.47 mrem) or 0.09% of the annual MPD. Extrapolating the data as an expression of averaged annual operator exposure resulted in a whole body dose of 0.4536 mSv (45.36 mrem) or 0.9% of the annual MPD, These results are well below established occupation exposure limits and are compatible with those published by the manufacturer.

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

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.

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

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.

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

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 muSv. 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.