While CT is being used in all aspects of medical diagnosis, a dramatic increase in the use of cone beam CT (CBCT), a form of CT, has occurred in dentistry during the last decade. In particular this technology has found application in orthodontic treatment planning, which is often initiated in young patients. The currently available data regarding dose and risk to patients undergoing CBCT are incomplete and underestimate the risk to pediatric patients. Moreover, current techniques for measuring patient dose/risk from CBCT examinations are either excessively complex or unreliable. To address these important issues we propose a thorough investigation of CBCT dosimetery and the development of a simple device that may be used to inexpensively and accurately determine patient dose and measure image quality. This will be accomplished through first conducting a thorough dosimetry investigation of current CBCT machines using an anthropomorphic phantom. Exposure variables such as current (mA), exposure time(s), and peak kilovoltage (kVp) will be evaluated so that the effect of each of these variables on patient risk can be estimated. Modulation transfer function (MTF) and Contrast to noise ratio (CNR) will be calculated as objective measures of image quality. This data will then be used to develop a simple and inexpensive method to accurately determine effective dose and image quality using readings from a simple Plexiglas phantom with a minimal number of dosimeters. This simplified phantom device will promote accurate and standardized reporting of dose for risk estimation of CBCT examinations.

Public Health Relevance

First, this project will produce data documenting the potential risk routine CBCT examinations may pose to pediatric patients and will be used to advise manufacturers, inform clinicians, and guide policy makers in the judicious use and improvement of CBCT technology. Second, the simplified phantom device will promote accurate and standardized reporting of dose for risk estimation of CBCT examinations. Finally, results from these studies will provide a foundation on which future research can develop clinical standards criteria for optimal levels of image quality, taking into consideration both diagnostic yield and dose.

National Institute of Health (NIH)
National Institute of Dental & Craniofacial Research (NIDCR)
Exploratory/Developmental Grants (R21)
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Oral, Dental and Craniofacial Sciences Study Section (ODCS)
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Fischer, Dena
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University of North Carolina Chapel Hill
Schools of Dentistry
Chapel Hill
United States
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Ludlow, J B; Timothy, R; Walker, C et al. (2015) Effective dose of dental CBCT-a meta analysis of published data and additional data for nine CBCT units. Dentomaxillofac Radiol 44:20140197
Ludlow, John B; Walker, Cameron (2013) Assessment of phantom dosimetry and image quality of i-CAT FLX cone-beam computed tomography. Am J Orthod Dentofacial Orthop 144:802-17