Suboptimal Positioning in Imaging -- Chin Elevation Reduces Thyroid Radiation on CBCT

Objective: To evaluate the impact of suboptimal patient positioning on effective and equivalent radiation doses during panoramic and cone-beam CT (CBCT) dental imaging. Design: Experimental study. Methods: Using an adult dosimetry phantom equipped with optically stimulated luminescent dosimeters, exposures were performed under optimal and 6 suboptimal positioning conditions: anterior shift, posterior shift, lateral shift, chin elevation, chin lowering, and head rotation. Imaging was conducted using the RAYSCAN Alpha Plus 160 system with panoramic exposures and CBCT acquisitions at medium (10 cm x 10 cm) and large (16 cm x 10 cm) fields of view (FOVs). For panoramic imaging, effective dose (E) in the optimal position was 50 μSv. Results: All suboptimal positions yielded significantly lower E, ranging from a 46% decrease (for anterior shift) to an 11% decrease (for rotation), with all changes statistically significant ( P P =0.06). Thyroid equivalent dose dropped by as much as 74% w more...