Effective dose and detriment assessment in cone beam computed tomography (CBCT)
DOI:
https://doi.org/10.7308/aodontol/2012.48.4.07Keywords:
Cone beam computed tomography, Radiation dosage, Risk assessmentAbstract
Aim: To calculate the effective dose (E) and detriment associated with cone beam computed tomography (CBCT), following recommendations set forth by the International Comission on Radiological Protection (ICRP).
Materials and Methods: The effective dose (E) was calculated by multiplying the absorbed/equivalent doses by the bone marrow, thyroid, skin, bone surface, salivary glands, brain, and remaining organs (extrathoracic region, lymphatic nodes, muscles, and oral mucosa), resulting from different equipments and imaging protocols, by tissue weighting factor of these tissues. Detriment was estimated by multiplying E by the probability coefficient for stochastic effects after exposure to low doses of radiation: 5.7 x 10-2 Sv-1. The equipment and protocols were grouped according to the irradiated volume (field of view - FOV). The mean effective doses, standard deviation, and variation coefficient of each group were also calculated.
Results: Protocols that employed a larger FOV resulted in an increase of the effective dose and detriment. The mean (standard deviation) of E for small, medium, and large FOV were 33.91 µSv (13.38), 82.85 µSv (74.26), and 107.99 µSv (43.82), respectively. The small FOV group presented the lowest variation coefficient (39%).
Conclusion: The E from CBCT are high when compared to other conventional radiography, although the detriment is relatively low. Recommendations for CBCT and the choice of protocol must be carefully justified so that the benefits of patient exposure outweigh the potential radiation detriment.
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