Photon-counting spectral CT

Photon-counting spectral CT

We are helping medical OEMs develop photon-counting spectral CT. There are three different uses for Kromek CZT, represented by three medical imaging applications. They represent a trade-off in performance between energy resolution (% FWHM) and gamma photon flux.

1. For SPECT gamma cameras and surgical probes, the energy resolution can be very good (< 4.0% at 140 keV) because the photon flux is less than 1,000 photons per second per square mm detector area.
2. A medium flux x-ray photon application is represented by bone mineral densitometry, where fluxes reach a few million photons per second per square mm area).
3. The highest fluxes are represented by photon-counting spectral CT where fluxes reach hundreds of millions of x-ray photons per second per square mm detector area. The energy resolution for this colour CT application is approx 15-20% in the clinical range of 80-140 keV peak.

Our photon-counting spectral CT expertise

We have achieved fluxes > 100 million pps/mm² without polarization of the CZT detector arrays. We are currently working to speed up the readout electronics to avoid pulse pileup and to compensate for inter-pixel charge sharing, including k-escape fluorescence.

What is photon-counting computed tomography (CT)

Photon-counting computed tomography (CT) is a computed tomography technique currently under research and development, both within academia and by major vendors of CT systems. Photon-counting CT has the potential both to offer significant improvements to existing CT imaging techniques and to make possible completely novel applications. A photon-counting CT system employs a photon-counting detector (PCD) which registers the interactions of individual photons. By keeping track of the deposited energy in each interaction, the detector pixels of a PCD each record an approximate energy spectrum, making it a spectral or energy-resolved CT technique. In contrast, typical CT scanners use energy-integrating detectors (EIDs), where the total energy (generally from a large number of photons as well as electronic noise) deposited in a pixel during a fixed period of time is registered. Typical CT detectors thus register only photon intensity, comparable to black-and-white photography, whereas photon-counting detectors register also spectral information, similar to colour photography.
See the full description on Wikipedia.