Photon-counting x-ray detectors for CT

Abstract

The introduction of photon-counting detectors is expected to be the next major breakthrough in clinical x-ray computed tomography (CT). During the last decade, there has been considerable research activity in the field of photon-counting CT, in terms of both hardware development and theoretical understanding of the factors affecting image quality. In this article, we review the recent progress in this field with the intent of highlighting the relationship between detector design considerations and the resulting image quality. We discuss detector design choices such as converter material, pixel size, and readout electronics design, and then elucidate their impact on detector performance in terms of dose efficiency, spatial resolution, and energy resolution. Furthermore, we give an overview of data processing, reconstruction methods and metrics of imaging performance; outline clinical applications; and discuss potential future developments.

Computed tomography recent history and future perspectives

“…The larger thickness enables photon counting to be partitioned into a larger volume to potentially mitigate the pulse pileup effect. 40 Photon-counting detectors have several advantages compared to solid-state scintillation detectors. The detector cells are defined by the strong electric field between common cathode and pixelated anodes (Fig.…”

A deep learning post-processing to enhance the maximum likelihood estimate of three material decomposition in photon counting spectral CT

“…Also, removing the non-linearity before reconstruction and hence improving the beam-hardening of the resulting images. 1 Therefore, the line integral of the basis materials…”

“…Photon-counting detectors are expected to be a great improvement for computed tomography (CT) technology. 1 One of its strong potentials is the accuracy in material discrimination in the CT image. A photon-counting detector consists of a multi-bin system with typically B > 2 energy bins, providing enhanced X-ray spectral resolution to differentiate materials.…”

The Core of Medical Imaging: State of the Art and Perspectives on the Detectors

“…As will be described in Section 7, direct detectors, able to directly convert X-rays into an electric signal, have several advantages against indirect detectors. Hence, the introduction of direct PCD would represent the next major step in the development of clinical CT [98]. As previously pointed out, despite the fact that PCD detectors are employed in other image modalities, such as SPECT and PET, PCD current technology is still not adequate for clinical CT imaging, mainly due to the low tolerance of PCD to the high X-ray flux rates typical of medical CT. Another problem is represented by the need to arrange PCD in 2D arrays composed of low-size elements.…”

“…The lowest energy threshold of CdTe/CZT detectors is 20-25 keV, with a typical energy resolution (FWHM) of 5-10 keV [98].…”