Characterization of a novel photon counting detector for clinical CT: Count rate, energy resolution, and noise performance

William C. Barber, Einar Nygard, Jan S. Iwanczyk, Mengxi Zhang, Eric C. Frey, Benjamin M.W. Tsui, Jan C. Wessel, Nail Malakhov, Gregor Wawrzyniak, Neal E. Hartsough, Thulasi Gandhi, Katsuyuki Taguchi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

85 Scopus citations

Abstract

We report on a characterization study of a multi-row direct-conversion x-ray detector used to generate the first photon counting clinical x-ray computed tomography (CT) patent images. In order to provide the photon counting detector with adequate performance for low-dose CT applications, we have designed and fabricated a fast application specific integrated circuit (ASIC) for data readout from the pixellated CdTe detectors that comprise the photon counting detector. The cadmium telluride (CdTe) detector has 512 pixels with a 1 mm pitch and is vertically integrated with the ASIC readout so it can be tiled in two dimensions similar to those that are tiled in an arc found in 32-row multi-slice CT systems. We have measured several important detector parameters including the maximum output count rate, energy resolution, and noise performance. Additionally the relationship between the output and input rate has been found to fit a non-paralyzable detector model with a dead time of 160 nsec. A maximum output rate of 6 x 106 counts per second per pixel has been obtained with a low output x-ray tube for CT operated between 0.01 mA and 6 mA at 140 keV and different source-to-detector distances. All detector noise counts are less that 20 keV which is sufficiently low for clinical CT. The energy resolution measured with the 60 keV photons from a 241Am source is ∼12%. In conclusion, our results demonstrate the potential for the application of the CdTe based photon counting detector to clinical CT systems. Our future plans include further performance improvement by incorporating drift structures to each detector pixel.

Original languageEnglish (US)
Title of host publicationMedical Imaging 2009
Subtitle of host publicationPhysics of Medical Imaging
DOIs
StatePublished - 2009
EventMedical Imaging 2009: Physics of Medical Imaging - Lake Buena Vista, FL, United States
Duration: Feb 9 2009Feb 12 2009

Publication series

NameProgress in Biomedical Optics and Imaging - Proceedings of SPIE
Volume7258
ISSN (Print)1605-7422

Other

OtherMedical Imaging 2009: Physics of Medical Imaging
Country/TerritoryUnited States
CityLake Buena Vista, FL
Period2/9/092/12/09

Keywords

  • ASIC
  • CT
  • CdTe
  • Photon counting

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging
  • Biomaterials

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