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

DOI: 10.1117/12.2512826 DOI Help

Authors: Christel Sundberg (KTH Royal Institute of Technology) , Mats Persson (Stanford University) , Andreas Ehliar (Prismatic Sensors AB) , Martin Sjölin (KTH Royal Institute of Technology) , Jacob Wikner (Linköping University) , Mats Danielsson (KTH Royal Institute of Technology)
Co-authored by industrial partner: No

Type: Conference Paper
Conference: SPIE Medical Imaging, 2019
Peer Reviewed: No

State: Published (Approved)
Published: March 2019
Diamond Proposal Number(s): 17704 , 17707

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.

Subject Areas: Physics

Instruments: B16-Test Beamline , I15-Extreme Conditions

Added On: 14/03/2019 10:39

Discipline Tags:

Detectors Physics Engineering & Technology

Technical Tags: