Scatter Correction for Spectral CT Using a Primary Modulator Mask

• Published in: IEEE transactions on medical imaging 2020-06, Vol.39 (6), p.2267-2276
• Main Authors: Pivot, Odran, Fournier, Clarisse, Tabary, Joachim, Letang, Jean Michel, Rit, Simon
• Format: Article
• Language: English
• Subjects: Computed tomography; Computer Science; Computer simulation; Cost function; Detectors; Energy; Error correction; Error reduction; Estimation; Imaging techniques; Mathematical model; Medical Imaging; Modulation; Photon counting detectors; Photonics; primary modulator mask; Radiation; scatter correction; Scattering; spectral CT; Spline functions
• ISSN: 0278-0062; 1558-254X
• DOI: 10.1109/TMI.2020.2970296

The problem of scattered radiation correction in computed tomography (CT) is well known because scatter induces a bias, a loss of contrast and artifacts. Numerous strategies have been proposed in conventional CT (using energy-integrating detectors) but the problem is still open in the field of spectral CT, a new imaging technique based on energy-selective photon counting detectors. The aim of the present study is to introduce a scatter correction method adapted to multi-energy imaging and based on the use of a primary modulator mask. The main contributions are a correction matrix, which compensates for the effect of the mask, a scatter model based on B-splines and a cost function based on the mask structures and robust to the object structures. The performances of the method have been evaluated on both simulated and experimental data. The mean relative error was reduced from 20% in the lower energy-bins without correction to 4% with the proposed technique, which is close to the error caused by statistical noise.