Dosimetry of Orthodontic Diagnostic FOVs Using Low Dose CBCT Protoco

Objectives: Effective doses resulting from combinations of field size and exposure parameters that might be used for orthodontic diagnosis tasks were acquired using a Promax 3D Mid CBCT unit. Specifically doses for a protocol involving reduced exposure and iterative reconstruction called “ultra low dose” (ULD) was compared with standard exposures. Contrast to noise ratio (CNR) and modulation transfer function (MTF) were calculated as quantitative measures of image quality.
Methods: Doses resulting from various combinations of field size, exposure protocol, and child or adult anthropomorphic phantoms using the Promax 3D MID CBCT unit (Helsinki, Finland) were measured with Optical Stimulated Luminescent (OSL) dosimetry using previously validated protocols (Ludlow et al.). A QUART DVT phantom was used to measure CNR and MTF. Standard and ULD image quality parameters were compared in a paired analysis.
Results: See tables.
Conclusions: An average reduction in dose of 77% was achieved using ULD protocols when compared with standard protocols. While this dose reduction was significant, no statistical reduction in image quality between ULD and standard protocols was seen. This would suggest that patient doses can be reduced without loss of diagnostic quality.