Reconstruction with an alternating aperture, photon counting detector

Scott S. Hsieh; Katsuyuki Taguchi; Shuai Leng; Cynthia H. McCollough

doi:10.1117/12.3006478

1 April 2024 Reconstruction with an alternating aperture, photon counting detector

Scott S. Hsieh, Katsuyuki Taguchi, Shuai Leng, Cynthia H. McCollough

Proceedings Volume 12925, Medical Imaging 2024: Physics of Medical Imaging; 129250F (2024) https://doi.org/10.1117/12.3006478
Event: SPIE Medical Imaging, 2024, San Diego, California, United States

Abstract

The spatial resolution of photon counting detectors (PCDs) can be further improved if photons that contribute to charge sharing (leading to counts in two adjacent pixels) were detected and binned separately. These events are captured in a coincidence counting architecture, previously proposed for improving spectral imaging performance. Here, we examine the problem of using coincidence counts in a non-spectral application for the purpose of improving spatial resolution. With typical PCD parameters, the number of photons that lead to coincidence counts is 3 times fewer than photons that lead to a single count only. Effectively, the detector has an alternating aperture: channels of the detector alternate between being wide and narrow. An analytic reconstruction algorithm that simply normalizes against the air scan will be inefficient at low spatial frequencies because the narrow detector channels contribute equal weight to reconstruction but have worse statistical information. We propose decomposing the sinogram into the narrow and wide apertures components separately, zero-stuffing them, and applying frequency weights so that the detective quantum efficiency at low spatial frequencies is restored, while information content at high spatial frequencies can be accessed. The frequency weighted sinograms are then summed and backprojected. We test this approach in simulations with various detector models on numerical phantoms.

Conference Presentation

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Scott S. Hsieh, Katsuyuki Taguchi, Shuai Leng, and Cynthia H. McCollough "Reconstruction with an alternating aperture, photon counting detector", Proc. SPIE 12925, Medical Imaging 2024: Physics of Medical Imaging, 129250F (1 April 2024); https://doi.org/10.1117/12.3006478

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