Performance of a miniature magnetic position sensor for three-dimensional ultrasound imaging

A miniature magnetic position sensor used for three-dimensional ultrasound imaging was tested for precision and accuracy in vitro. The sensor alone was able to locate points with root-mean-square (rms) uncertainty of 1.7 mm and accuracy of 0.05 +/- 0.62 mm over its specified operating range of 50 cm, With an ultrasound imaging system, a point was located from arbitrary viewing windows with 2.4-mm rms uncertainty and 0.06 +/- 0.68 mm accuracy, If viewing windows were Limited to those representative of a typical ultrasound examination, the system could achieve rms uncertainty in point location of < I mm, Performance was not affected by operation of the imaging system when the sensor was mounted on an ultrasound scanhead. Sensitivity to metals in the operating environment was also measured, (C) 1997 World Federation for Ultrasound in Medicine & Biology.