Tomographic imaging of time-varying distributions

TLDR: In this paper, the impact of the order of acquisition of different views on the L2 norm of the image-domain reconstruction error is determined for band-limited temporal variation, and a novel technique for lowering the sampling rate requirement while preserving image quality is proposed and investigated.

Abstract: This paper addresses the tomographic imaging of time-varying distributions, when the temporal variation during acquisition of the data is high, precluding Nyquist rate sampling. This paper concentrates on the open (and hitherto unstudied) problem of nonperiodic temporal variation, which cannot he reduced to the time-invariant case by synchronous acquisition. The impact of the order of acquisition of different views on the L2 norm of the image-domain reconstruction error is determined for band-limited temporal variation. Based on this analysis, a novel technique for lowering the sampling rate requirement while preserving image quality is proposed and investigated. This technique involves an unconventional projection sampling order which is designed to minimize the L2 image-domain reconstruction error of a representative test image. A computationally efficient design procedure reduces the image data into a Grammian matrix which is independent of the sampling order. Further savings in the design procedure are realized by using a Zernike polynomial series representation for the test image. To illustrate the approach, reconstructions of a computer phantom using the best and conventional linear sampling orders are compared, showing a seven-fold decrease in the error norm by using the best scheme. The results indicate the potential for efficient acquisition and tomographic reconstruction of time-varying data. Application of the techniques are foreseen in X-ray computer tomography and magnetic resonance imaging.© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.