The recent advance in image intensifier based volume tomographic
angiography has stirred a significant interest in the development
of accurate and efficient algorithms to correct image intensifier distortions.
An algorithm and its calibration protocol are developed to correct
the distortion caused by the image intensifier–CCD camera imaging
chain in a single step regardless of distortion sources. This algorithm first
partitions a distorted image into small quadrilateral regions, then maps
each region individually to the corrected image using the corresponding
bilinear functions. The general applicable parameters of these bilinear
functions can be obtained using a specially designed grid phantom. The
algorithm and the calibration protocol are tested using this grid phantom
on a newly built image intensifier based volume tomographic angiography
imaging system. The maximum distortion error is reduced from 5.96
mm before correction to 0.05 mm after correction. Further validation of
the proposed algorithm is performed through three-dimensional tomographic
reconstructions of a vascular phantom and animal studies. The
reconstruction results indicate that the accuracy of the algorithm and the
calibration protocol is acceptable for volume tomographic angiography.
This algorithm can also be applied to radiation therapy and stereosurgical
treatment planning where image intensifier distortions must be corrected.