Effective doses from cone beam CT investigation of the jaws.

OBJECTIVES: The purpose of the study was to calculate the effective dose delivered to the patient undergoing cone beam (CB) CT of the jaws and maxillofacial complex using the i-CAT Next Generation CBCT scanner (Imaging Sciences International, Hatfield, PA). METHODS: A RANDO® phantom (The Phantom Laboratory, Salem, NY) containing thermoluminence dosemeters were scanned 10 times for each of the 6 imaging protocols. Effective doses for each protocol were calculated using the 1990 and approved 2007 International Commission on Radiological Protection (ICRP) recommended tissue weighting factors (E1990, E2007). RESULTS: The effective dose for E1990 and E2007, respectively, were: full field of view (FOV) of the head, 47 µSv and 78 µSv; 13 cm scan of the jaws, 44 µSv and 77 µSv; 6 cm standard mandible, 35 µSv and 58 µSv; 6 cm high resolution mandible, 69 µSv and 113 µSv; 6 cm standard maxilla, 18 µSv and 32 µSv; and 6 cm high resolution maxilla, 35 µSv and 60 µSv. CONCLUSIONS: Using the new generation of CBCT scanner, the effective dose is lower than the original generation machine for a similar FOV using the ICRP 2007 tissue weighting factors.

Continuing dental education in radiation protection: monitoring the outcomes.

OBJECTIVES: To evaluate an evolving radiation protection dental postgraduate course run in Wales between 2003 and 2007. METHODS: We compared three standardized course series. Course content was enhanced in 2006 to target areas of weakness. In 2007, a single best answer multiple choice questionnaire instrument superseded a true/false format. Practitioners' performance was studied pre- and immediately post-training. 900 participants completed identical pre- and post-course validated multiple choice questionnaires. 809 (90%) paired morning-afternoon records, including those of 52 dental care professionals (DCPs), were analysed. RESULTS: Mean (standard error) pre- and post-course percentage scores for the three courses were 33.8 (0.9), 35.4 (1.4), 34.6 (1.0) and 63.6 (0.9), 59.0 (1.4), 69.5 (0.9). Pre-training, only 2.4%, 3.1% and 4.9% of participants achieved the pass mark compared to 57.7%, 48.4% and 65.9% post-training, indicating a rather greater pass rate and gain in the most recent series than earlier ones. In recent series, older more experienced candidates scored slightly higher; however, their gain from pre- to post-training was slightly less. CONCLUSIONS: Baseline levels of radiation protection knowledge remained very low but attending an approved course improved this considerably. Targeting areas of weaknesses produced higher scores. Current radiation protection courses may not be optimal for DCPs.