Can cephalometric parameters be measured reproducibly using reduced-dose cone-beam computed tomography?

Abstract

ObjectiveTo evaluate cone-beam computed tomography (CBCT) image quality via cephalometric measurement variability while reducing radiation exposure by altering the radiographic technique. Materials and MethodsA human cadaver was imaged using a Morita Accuitomo 170 CBCT machine at various technique parameters: tube voltages of 60, 70, 80, and 90 kV, tube currents of 1, 2.5, and 5 mA, and rotational arcs of 180° and 360°. From the rotation data, standard cephalogram views were generated. Point radiation dose measurements were recorded at the entry of three key radiosensitive regions. Ten examiners measured seven cephalometric parameters on the conventional cephalogram and each derived view. Measurement error and dose were compared between radiographic techniques and a standard cephalometric procedure. ResultsGenerally insignificant differences in measurement error were observed when rotation arc was reduced from 360° to 180°, when tube current was reduced from 5 mA to 2.5 mA, and when tube voltage was reduced from 90 kV to 80 kV and 70 kV. Radiation dose could be halved for either of the rotation arc or tube current reductions; reducing both yielded dose comparable to standard cephalometric imaging. Using 1 mA or 60 kV rendered nondiagnostic images. DiscussionThe study's cadaver included embalming fluid, a lack of patient-motion-induced image blur, and lesser bone density relative to a typical adolescent orthodontic patient, which can yield images not wholly representative of live patients. ConclusionOrthodontists could image with CBCT using a 180° arc of rotation, 2.5 mA, and 70 or 80 kV to reduce radiation dose while yielding images of adequate quality that are derived from three-dimensional data.