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Proceedings Paper

Increased count-rate performance and dose efficiency for silicon photon-counting detectors for full-field CT using an ASIC with adjustable shaping time
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Paper Abstract

Photon-counting silicon strip detectors are attracting interest for use in next generation CT scanners. For silicon detectors, a low noise floor is necessary to obtain a good dose efficiency. A low noise floor can be achieved by having a filter with a long shaping time in the readout electronics. This also increases the pulse length, resulting in a long deadtime and thereby a degraded count-rate performance. However, as the flux typically varies greatly during a CT scan, a high count-rate capability is not required for all projection lines. It would therefore be desirable to use more than one shaping time within a single scan. To evaluate the potential benefit of using more than one shaping time, it is of interest to characterize the relation between the shaping time, the noise, and the resulting pulse shape. In this work we present noise and pulse shape measurements on a photon-counting detector with two different shaping times along with a complementary simulation model of the readout electronics. We show that increasing the shaping time from 28.1 ns to 39.4 ns decreases the noise and increases the signal-to-noise ratio (SNR) with 6.5% at low count rates and we also present pulse shapes for each shaping time as measured at a synchrotron source. Our results demonstrate that the shaping time plays an important role in optimizing the dose efficiency in a photon-counting x-ray detector.

Paper Details

Date Published: 1 March 2019
PDF: 12 pages
Proc. SPIE 10948, Medical Imaging 2019: Physics of Medical Imaging, 109481W (1 March 2019); doi: 10.1117/12.2512826
Show Author Affiliations
Christel Sundberg, KTH Royal Institute of Technology (Sweden)
Mats Persson, Stanford Univ. (United States)
Andreas Ehliar, Prismatic Sensors AB (Sweden)
Martin Sjölin, KTH Royal Institute of Technology (Sweden)
Jacob Wikner, Linköping Univ. (Sweden)
Mats Danielsson, KTH Royal Institute of Technology (Sweden)

Published in SPIE Proceedings Vol. 10948:
Medical Imaging 2019: Physics of Medical Imaging
Taly Gilat Schmidt; Guang-Hong Chen; Hilde Bosmans, Editor(s)

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