Evaluation of Energy Loss and Charge Sharing in Cadmium Telluride Detectors for Photon-Counting Computed Tomography
2011 (English)In: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 58, no 3, 614-625 p.Article in journal (Refereed) Published
We present estimates of energy loss and charge sharing for a pixelated cadmium telluride (CdTe) detector used for photon-counting spectral computed tomography (CT). In a photon-counting pixelated CdTe detector, several physical effects lead to detected events with reduced energies, including Compton scattering, fluorescence emission, charge diffusion, trapping of charge carriers and slow-hole-motion-induced incomplete charge collection. Charge sharing is the result of the lost energy being collected by adjacent pixels. We simulated the photon transport and the charge-collection process with a Monte Carlo-based simulation and evaluated these effects on the detector performance. The trapping effect and poor hole collection have been studied together using an analytical model. We also investigated the detector response under the influence of only the fluorescence effect. We conclude that the charge sharing effects should be taken into account when the pixel is smaller than 1 mm(2). A straightforward way to decrease the double counting of X-rays from events with charge sharing is to increase the electronic threshold. However, increasing the threshold comes at the cost of losing low-energy events, which is undesirable, at least in applications such as pediatric imaging.
Place, publisher, year, edition, pages
2011. Vol. 58, no 3, 614-625 p.
Cadmium telluride, charge sharing, computed tomography, energy loss, Monte Carlo simulation, photon counting, signal generation
Engineering and Technology
IdentifiersURN: urn:nbn:se:kth:diva-35618DOI: 10.1109/TNS.2011.2122267ISI: 000291655900005ScopusID: 2-s2.0-79959378612OAI: oai:DiVA.org:kth-35618DiVA: diva2:429612
QC 201107052011-07-052011-07-042012-11-23Bibliographically approved