Validation of online cardiac 3-D localization using isocenter-based biplane radiography and instrumental rotational image alignment

The present study determined the accuracy of biplane radiographic 3-D localization using primary instrumental instead of secondary computational image correction or geomagnetic image rotation. Mechanical adjustment of the alignment coils in both TV cameras was performed to compensate for geomagnetic image rotation in the preferred RAO and LAO views. Forty-nine points of a centimeter grid imaged in 14 common biplane projections were located from image pairs without (cine images) and with (video images) instrumental image alignment. The localization error of computed 3-D coordinates relative to a reference point was calculated. Radiographic 3-D localization provided an overall absolute localization error of 1.08±0.47 mm and 0.61±0.32 mm without and with instrumental alignment, respectively. Instrumental rotation improves localization accuracy markedly and may obviate interactive computational correction during online 3-D localization