[OA193] Patient dosimetry during cone beam ct in dental implant planning

Purpose Cone beam CT (CBCT) is an advanced imaging technique compared to panoramic radiography and of lower cost than a conventional CT procedure. Its advantages are the focused imaging of the maxillofacial region and a reduced radiation exposure with relatively low cost. CBCT produces three-dimensional information on the facial skeleton and teeth in a few seconds time. The purpose of the study was to measure patient radiation exposure in terms of Kerma Area Product (KAP) in implant planning dentistry, to estimate effective dose (Ef) and to compare patient radiation doses with corresponding values from CT and conventional panoramic radiography, in clinical practice. Methods The X-ray system used was a CS9300 Carestream system. Patient sample included 168 individuals undergoing 211 CBCT examinations. Data recorded included: KAP, tube voltage, tube current, exposure time, field of view (FOV), patient age and clinical indication. Five examination types were selected in order to keep protocol settings as similar as possible. Results Patient mean age was 55 years. Patients underwent either 1 (80.2%), 2 (14.7%), 3 (2.5%) or >3 (2.3%) CBCT examinations. Protocol details were: 80–90 kV, 4–5 mA, 8 s exposure time and fixed FOV of 10*10 cm 2 . Mean (SD) KAP was 533 (112) mGy*cm 2 . Median KAP value was 530 mGy*cm 2 . A conversion factor of 0.08 mSv/Gycm 2 was used to calculate Ef. Mean (SD) Ef was found 42.7 (9.0)  μ Sv (median 42.4 μ Sv). A broad comparison was done with international data from dental dosimetry studies using different modalities, showing that CBCT requires 4–10 times lower radiation exposure than corresponding CT images, depending on examination type. At the same time, CBCT patient radiation exposure is 3–6 times higher than panoramic radiography. Conclusions CBCT is an accurate and useful tool for many clinical oral-maxillofacial indications. Although CBCT doses are significantly lower than conventional CT, yet they are higher than those from conventional imaging used in dentistry. Therefore, a risk/benefit analysis must be carried out before a CBCT investigation is requested.