A novel alignment device for cone beam computed tomography: principle and application.
OBJECTIVE
the aim of this investigation was to optimize the positioning and size of the scanned field of view (FOV) in cone beam CT (CBCT) scanners using a practical external alignment device fitted in the patient's mouth in order to train radiographers and reduce radiation dose to the patient. This is particularly challenging when using small FOVs to cover small volumes of interest.


METHODS
test objects were positioned and scanned using the aligner to show that the design and geometry were correct and help the radiographer to superimpose the scanner and the volume of interest axis of rotation. An in vivo study was then undertaken comparing the accuracy of patient positioning when using the aligner, instead of scouts, to position the patient for small FOV (cylinders of 4-8 cm height and 4-8 cm diameter) dental scans. The scanners used were the Accuitomo F170 CBCT scanner (Morita, Kyoto, Japan) and the iCAT Next Gen CBCT scanner (Imaging Sciences, Hatfield, PA).


RESULTS
there was no significant difference in positioning the patient when using the aligner compared with the scout images.


CONCLUSIONS
it is possible to rely on the aligner for patient positioning for a small volume scan and therefore spare the radiation dose associated with scout imaging.
Dawood
A
A
Cavendish Imazing, London, United Kingdom.
Sauret-Jackson
V
V
Patel
S
S
Darwood
A
A
D017076:Computer-Aided Design; D054893:Cone-Beam Computed Tomography / Q000295:instrumentation*; D004867:Equipment Design; D006801:Humans; D007568:Jaw / Q000000981:diagnostic imaging; D056888:Patient Positioning; D011861:Radiography, Dental / Q000295:instrumentation*; D015898:Tomography Scanners, X-Ray Computed