title: The use of a two-dimensional ultrasound time-of-flight system for location of the centre of gravity in posturography measurements.
abstract: A method has been developed for objective assessment of balance using ultrasound time-of-flight (ToF) posturography measurements to accurately locate the centre of gravity (CoG) of a subject. Two orthogonal 40 kHz ultrasound transmitters are mounted on the subject's waist at the height of the CoG. Anterior/posterior and lateral motions are detected independently by measuring variations in the ToF from the transmitters to appropriately positioned wall-mounted receivers. The motion of the CoG is accurately traced during the course of 20 second assessment periods as the subject stands on a solid surface with eyes open and eyes closed. The tests are repeated with the subject standing on a standardized soft surface. Trials of day-to-day repeatability and repeated tests on patients prior to therapy indicate there is no significant improvement to balance measures with experience of the system. Balance measures are significantly worse in patients suffering vertigo symptoms following traumatic brain injury than for equivalent normal volunteers. Repeated measures post-therapy indicate significant improvement in balance measures following vestibular therapy in patients with vertigo. CoG location using ultrasound ToF is a suitable method of tracking sway and thus assessing balance in normals and balance-compromised patients.
authors.affiliation: Medical Physics, Poole Hospital NHS Trust, Dorset, UK.
authors.forename: S
authors.initials: S
authors.lastname: Perring
authors.forename: R
authors.initials: R
authors.lastname: Jepson
mesh_terms: D004244:Dizziness / Q000000981:diagnostic imaging; D006112:Gravitation; D006801:Humans; D004856:Postural Balance / Q000502:physiology; D011187:Posture / Q000502:physiology*; D015203:Reproducibility of Results; D014463:Ultrasonography / Q000379:methods*; D014717:Vertigo / Q000000981:diagnostic imaging*