[A simple method for estimating effective dose in dental CT. Conversion factors and calculation examples for a clinical low dose protocol].
OBJECTIVE
An easily applicable method to estimate effective dose including in its definition the high radiosensitivity of the salivary glands from dental computed tomography is presented. Effective doses were calculated for a markedly dose reduced dental CT protocol as well as for standard settings. Data are compared with effective doses from the literature obtained with other modalities frequently used in dental care.


METHODS
Conversion factors based on the weighted Computed Tomography Dose Index were derived from published data to calculate effective dose values for various CT exposure settings.


RESULTS
Conversion factors determined can be used for clinically used kVp settings and prefiltrations. With reduced tube current an effective dose for a CT examination of the maxilla of 22 microSv can be achieved, which compares to values typically obtained with panoramic radiography (26 microSv). A CT scan of the mandible, respectively, gives 123 microSv comparable to a full mouth survey with intraoral films (150 microSv).


CONCLUSIONS
For standard CT scan protocols of the mandible, effective doses exceed 600 microSv. Hence, low dose protocols for dental CT should be considered whenever feasable, especially for paediatric patients. If hard tissue diagnoses is performed, the potential of dose reduction is significant despite the higher image noise levels as readability is still adequate.
Homolka
P
P
Institut für Biomedizinische Technik und Physik, Universität Wien.
Gahleitner
A
A
Kudler
H
H
Nowotny
R
R
D002138:Calibration; D006801:Humans; D011829:Radiation Dosage; D011835:Radiation Protection; D011861:Radiography, Dental / Q000706:statistics & numerical data*; D011874:Radiometry / Q000706:statistics & numerical data*; D012469:Salivary Glands / Q000528:radiation effects; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data*