Dynamic CT scanner environment effects on a DC electromagnetic tracking system

Vaibhav Patil, R. San Jose Estepar, Connor J. Walsh, Kirby G. Vosburgh
International Journal of Computer Assisted Radiology and Surgery
Volume 4, Number Supplement 1, Pages S339-S340
2009

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Abstract

Purpose:Electromagnetic (EM) trackers provide a steady stream of highly accurate data on instrument position, needing only to be registered to imaging data to provide simple, intuitive displays to guide the operator. Also, increasing emphasis is being placed on remotely actuated interventional devices to reduce radiation exposure to the operator and also to obtain greater accuracy and consistency. Such systems require internal spatial sensors to ensure they are operating properly. Several investigators have evaluated the potential for the interference of the CT environment with the performance of electromagnetic trackers. However, there are few extant studies of the effects on tracker performance during scanning or closely integrated into the scanning operation. The purpose of this study is to evaluate the performance of current state of the art DC EM trackers during the operation of a CT scanner to measure the accuracy, induced noise, and stability of the tracker signals during different phases of a typical CT scanning procedure.

Conclusions: We have demonstrated that a CT scanner induces increased variability in EM sensor readings and that the effect is more severe when the CT gantry is rotating. There is also evidence of a baseline shift after the scout image was taken. At this point, the gantry is fixed yet the CT scanner bed is in motion. This implies that bed motion may cause a measureable shift in values that can be compensated for during clinical intervention. The implication for CT guided procedures includes the desire to always take measurements under the same CT operation conditions, in a well tested, stable protocol. We further recommend stopping the gantry motion when a precision measurement is required.

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Reference

Patil V, San Jose Estepar R, Walsh CJ, Vosburgh KG. Dynamic ct scanner environment effects on a dc electromagnetic tracking system. International Journal of Computer Assisted Radiology and Surgery 2009;4(Supplement 1):S339-S340.

Bibtex entry

@Article{patilCARS09,
  author         = {Vaibhav Patil and Raul {San Jose Estepar} and Connor J.    
                   Walsh and Kirby G. Vosburgh},                               
  title          = {Dynamic CT scanner environment effects on a DC             
                   electromagnetic tracking system},                           
  journal        = {International Journal of Computer Assisted Radiology and   
                   Surgery},                                                   
  year           = {2009},                                                     
  volume         = {4},                                                        
  number         = {Supplement 1},                                             
  pages          = {S339-S340}
}