Computed tomography (CT) imaging can be used to determine bone pose, sometimes combined with skin-mounted markers. For this specific application, a lower radiation dose than the conventional clinical dose might suffice. This study aims to determine how lowering the radiation dose of a CT-scan of the ankle and foot affects the precision of detecting bone pose and marker position. Radiation dose is proportional to tube charge. Hence, an adult cadaveric leg was scanned 10 times at four different tube charges (150, 75, 50 and 20 mAs) with a Philips Brilliance 64 CT scanner. Precision of detecting bone and marker position at 50 mAs was not significantly different from 75 mAs and from the clinically used 150 mAs, but higher than 20 mAs. Furthermore, no differences of the precision in detecting bone orientation were found. These results indicate that the radiation dose can be reduced by a factor 3 compared to the clinically usual radiation dose, without affecting the precision of detecting bone pose and marker position in the foot and ankle.@en

Individuals with cerebral palsy often walk with atypical gait patterns like equinus or crouch gait. Several multi-segment foot models have been developed [1] to measure the abnormal foot kinematics of these gait patterns. The Oxford Foot Model [2] (OFM) and Rizzoli Foot Model [3,4] (RFM) are used most frequently in both clinical practice and research [1]. Their different model characteristics (e.g. marker placement and axis definitions) will likely result in different kinematic output. However, these differences have not yet been extensively compared, especially not in pathological gait patterns.@en