Comparison of patient dose from imaging protocols for dental implant planning using conventional radiography and computed tomography

Objectives: To compare the radiation doses from imaging protocols for dental implant planning either using conventional radiography only (dental panoramic radiography (DPR), cephalometry and linear cross-sectional tomography) or involving computed tomography (CT). Methods: Organ absorbed doses were measured using a female Rando anthropomorphic phantom loaded with lithium fluoride thermoluminescent dosemeters (TLD). Standard mandibular protocols for dental implant planning were followed using either a conventional dental radiographic unit (PM 2002 CC Planmeca, Helsinki, Finland) or CT scanner (Excel Twin Elscint, Haifa, Israel). Organ absorbed and effective doses were calculated. Effective dose was calculated using two approaches, one based on the ICRP method which excludes the salivary tissue from the remainder organs (designated E-exc), and the other with its inclusion (E-inc). Results: The greatest individual organ doses for any examination were measured in the salivary tissue. E-exc for panoramic, cephalometric and cross-sectional tomography using DPR was 0.004 mSv, 0.002 mSv and 0.002 mSv, respectively, whereas with CT it was 0.314 mSv. The value of E-inc calculated using these data was between two and five times E-exc. Conclusions: E-inc greatly increases the apparent radiation burden, especially with high dose procedures. CT techniques can provide excellent images, but at the cost of increased radiation detriment. DPR with a cross-sectional tomography facility may give adequate clinical information at a greatly reduced dose.