Purpose: Photon-counting edge-on detectors are currently being considered for use
in clinical computed tomography (CT) systems. A method for geometric calibration
of edge-on detectors mounted in a CT gantry has been developed and evaluated.
The method is complementary to the geometrical calibration methods developed for
CT systems using flat-panel detectors and takes the extra dimension of the edge-on
detectors (along the direction of the x-rays) into account.
Methods: The method uses projection images of a simple phantom together with
geometrical arguments to accurately estimate the orientation and relative position of
the edge-on detectors. Both computer simulations and experimental measurements
were used to verify the method.
Results: It is experimentally demonstrated that the method can determine the orientation
of the detector with an accuracy of 0.08 degrees. The method is also shown
to be insensitive to errors in the modeled parameters used in the algorithm.
Conclusions: The presented method can accurately determine the orientation and
relative position of edge-on detectors mounted in a CT-gantry and can be used to
evaluate the detector mounting and to produce an accurate forward model of the
imaging system. Also, the method has potential to reduce the dimensionality of the
geometric calibration of the full CT system since the direction of the x-rays with
respect to the detector is measured.
2016. Vol. 43, no 11, 6165-6174 p.