Tiny changes in tomographic system matrices can cause large changes in reconstruction quality. (21st May 2022)

• Record Type: Journal Article
• Authors: Khellaf, F; Clackdoyle, R; Rit, S; Desbat, L
• Is Part Of: Physics in medicine & biology. Volume 67:Number 10(2022)
• Publication Date: 2022-05-21
• Subjects: region-of-interest reconstruction -- region-of-interest tomography -- least squares; Biophysics -- Periodicals; Medical physics -- Periodicals; 610.153
• DOI: 10.1088/1361-6560/ac65d5
• Languages: English
• ISSNs: 0031-9155

Abstract

Abstract: This paper studies the impact of tiny changes in region-of-interest (ROI) tomography system matrices on the variance of the reconstructed ROI. In small-scale and medium-scale examples, the variance in the reconstructed ROI was estimated for different system matrices. The results revealed a striking and counterintuitive phenomenon: a tiny change in the system matrix can dramatically affect the variance of the ROI estimate. In one of our examples, a decrease of 0.1% in one element out of hundreds of thousands of the system matrix resulted in a systematic reduction of the variance inside the ROI, and by a factor of 5 to 10 for some pixels. Our results agree with a recently proven theorem about the ability of additional measurements to reduce the variance in ROI tomography.