Low-dose dental computed tomography: significant dose reduction without loss of image quality.
OBJECTIVE
To measure and reduce the patient dose during computed tomography (CT) for dental applications.


METHODS
Lithium fluoride thermoluminescent dosimeters were implanted in a tissue-equivalent humanoid phantom (Alderson-Rando-Phantom) to determine doses to the thyroid gland, the active bone marrow, the salivary glands, and the eye lens. Dental CT was performed with spiral CT and a dental software package. The usual dental CT technique was compared with a new dose-reduced protocol, which delivered best image quality at lowest possible radiation dose, as tested in a preceding study. Image quality was analysed using a human anatomic head preparation. In addition, the radiation dose was compared with panoramic radiography and digital volume tomography (DVT). Eight radiologists evaluated all images in a blinded fashion. A Wilcoxon rank pair test was used for statistical evaluation.


RESULTS
Radiation dose could be reduced by a factor of 9 (max.) with the new dose-reduced protocol (e.g. bone marrow dose from 23.6 mSv to 2.9 mSv; eye lens from 0.5 mSv to 0.3 mSv; thyroid gland from 2.5 mSv to 0.5 mSv; parotid glands from 2.3 mSv to 0.4 mSv). Dose reduction did not reduce image quality or diagnostic information.


CONCLUSIONS
A considerable dose reduction without loss of diagnostic information is achievable in dental CT. As radiation exposure of the presented low-dose protocol is expected to be in the same range as DVT, low-dose dental CT might be superior to DVT, because CT can be used to evaluate soft tissues as well.
Rustemeyer
P
P
Institute of Anatomy, University of Münster, Germany. peter.rustemeyer@uni-muenster.de
Streubühr
U
U
Suttmoeller
J
J
D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011861:Radiography, Dental / Q000379:methods / Q000592:standards*; D016037:Single-Blind Method; D014057:Tomography, X-Ray Computed / Q000379:methods / Q000592:standards*