title: Detection of patient movement during CBCT examination using video observation compared with an accelerometer-gyroscope tracking system.
abstract: OBJECTIVE
  To compare video observation (VO) with a novel three-dimensional registration method, based on an accelerometer-gyroscope (AG) system, to detect patient movement during CBCT examination. The movements were further analyzed according to complexity and patient age.
  
  
  METHODS
  In 181 patients (118 females/63 males; age average 30 years, range: 9-84 years), 206 CBCT examinations were performed, which were video-recorded during examination. An AG was, at the same time, attached to the patient head to track head position in three dimensions. Three observers scored patient movement (yes/no) by VO. AG provided movement data on the x-, y- and z-axes. Thresholds for AG-based registration were defined at 0.5, 1, 2, 3 and 4 mm (movement distance). Movement detected by VO was compared with that registered by AG, according to movement complexity (uniplanar vs multiplanar, as defined by AG) and patient age (≤15, 16-30 and ≥31 years).
  
  
  RESULTS
  According to AG, movement ≥0.5 mm was present in 160 (77.7%) examinations. According to VO, movement was present in 46 (22.3%) examinations. One VO-detected movement was not registered by AG. Overall, VO did not detect 71.9% of the movements registered by AG at the 0.5-mm threshold. At a movement distance ≥4 mm, 20% of the AG-registered movements were not detected by VO. Multiplanar movements such as lateral head rotation (72.1%) and nodding/swallowing (52.6%) were more often detected by VO in comparison with uniplanar movements, such as head lifting (33.6%) and anteroposterior translation (35.6%), at the 0.5-mm threshold. The prevalence of patients who move was highest in patients younger than 16 years (64.3% for VO and 92.3% for AG-based registration at the 0.5-mm threshold).
  
  
  CONCLUSIONS
  AG-based movement registration resulted in a higher prevalence of patient movement during CBCT examination than VO-based registration. Also, AG-registered multiplanar movements were more frequently detected by VO than uniplanar movements. The prevalence of patients who move was highest in patients younger than 16 years.
authors: Section of Oral Radiology, Department of Dentistry and Oral Health, Aarhus University, Aarhus, Denmark.
authors: Rubens
authors: R
authors: Spin-Neto
authors: Section of Oral Radiology, Department of Dentistry and Oral Health, Aarhus University, Aarhus, Denmark.
authors: Louise H
authors: LH
authors: Matzen
authors: Section of Oral Radiology, Department of Dentistry and Oral Health, Aarhus University, Aarhus, Denmark.
authors: Lars
authors: L
authors: Schropp
authors: Section of Oral Radiology, Department of Dentistry and Oral Health, Aarhus University, Aarhus, Denmark.
authors: Erik
authors: E
authors: Gotfredsen
authors: Section of Oral Radiology, Department of Dentistry and Oral Health, Aarhus University, Aarhus, Denmark.
authors: Ann
authors: A
authors: Wenzel
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D054893:Cone-Beam Computed Tomography / Q000295:instrumentation; D005260:Female; D019416:Head Movements; D006801:Humans; D008297:Male; D008875:Middle Aged; D014741:Video Recording; D055815:Young Adult
keywords: CBCT; motion artefacts; movement; movement detection