Online mobile C-arm calibration using inertial sensors: a preliminary study in order to achieve CBCT

  • Imane LemammerEmail author
  • Olivier Michel
  • Hacheme Ayasso
  • Steeve Zozor
  • Guillaume Bernard
Review Article



Cone beam computed tomography (CBCT) became increasingly popular over the last years. It allows more accurate diagnosis and treatment planning with a lower effective radiation dose. However, volume reconstruction algorithms require a very precise knowledge of the imaging geometry. Due to mechanical instabilities, mobile C-arms are incompatible with existing tomography algorithms. Therefore, C-arm online calibration is essential in order to achieve an accurate volume reconstruction.


We present an online calibration method for mobile C-arms. It is based on tracking the detector and the X-ray source of the C-arm using three-axis gyroscopes and accelerometers. It aims to be precise and noninvasive. The performance of the calibration algorithm is evaluated in regard to the precision of the sensors and to whether or not dynamic models are considered. In addition, we present an algorithm which propagate the errors from the positions and orientations estimates to the 2D projections on the detector plane. Thus, we can evaluate the impact of the estimation errors on the acquired images.


The experiments are conducted on an experimental C-arm. The reached accuracy is \(\approx 0.19 ^{\circ }\) for orientation and \(\approx 3.0\,\hbox {mm}\) for position. These errors propagate as an error of \(\approx 2\,\hbox {mm}\) for the 2D projections on the detector plane.


The proposed calibration algorithm achieves an accuracy comparable to the precision of existing calibration methods. The required angle accuracy by CBCT algorithms is reached. However, improvements are needed to achieve the required position precision. The in-plane translations of the X-ray source and the detector are the most crucial parameters to estimate in order to conduct CBCT on mobile C-arms.


Mobile C-arm CBCT Pose estimation Online calibration IMU Error propagation 



This study was funded by Thales AVS France and the ANRT (Association Nationale Recherche Technologie).

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest

Human and animal rights

This article does not contain any studies with human participants performed by any of the authors. This articles does not contain patient data.


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Copyright information

© CARS 2019

Authors and Affiliations

  1. 1.GIPSA-Lab, Grenoble INP, CNRSUniv. Grenoble AlpesGrenobleFrance
  2. 2.Thales AVS FranceMoiransFrance

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