Abstract. The combination of circular CT with a helical trajectory segment results in a mathematically complete data set. We present a reconstruction algorithm which is mathematically exact and of the filtered back-projection type. The algorithm ensures that only Radon planes which are not covered along the circle are taken into account, when data from the helical segment are back-projected. Therefore, the helical segment contributes only to low-frequency parts of trans-axial slices. Data along the helix can be obtained with a very low acquisition dose.

Print publication: Issue 1 (7 January 2007)
Received 10 August 2006, in final form 25 October 2006
Published 12 December 2006