Work

Detective quantum efficiency of photon-counting CdTe and Si detectors for computed tomography: a simulation study

Year: 2020

Type: article

Abstract: Purpose: Developing photon-counting CT detectors requires understanding the impact of parameters, such as converter material, thickness, and pixel size. We apply a linear-systems framework, incorporating spatial and energy resolution, to study realistic silicon (Si) and cadmium telluride (CdTe) detectors at a low count rate. Approach: We compared CdTe detector designs with 0.5 × 0.5 mm2 and 0.225 × 0.225 mm2 pixels and Si detector designs with 0.5 × 0.5 mm2 pixels of 30 and 60 mm active thickness, with and without tungsten scatter blockers. Monte-Carlo simulations of photon transport were used together with Gaussian charge sharing models fitted to published data. Results: For detection in a 300-mm-thick object at 120 kVp, the 0.5- and 0.225-mm pixel CdTe systems have 28% to 41% and 5% to 29% higher detective quantum efficiency (DQE), respectively, than the 60-mm Si system with tungsten, whereas the corresponding numbers for two-material decomposition are 2% lower to 11% higher DQE and 31% to 54% lower DQE compared to Si. We also show that combining these detectors with dual-spectrum acquisition is beneficial. Conclusions: In the low-count-rate regime, CdTe detector systems outperform the Si systems for detection tasks, whereas silicon outperforms one or both of the CdTe systems for material decomposition.

Source: Journal of medical imaging

DOI: 10.1117/1.jmi.7.4.043501

Authors: Mats Persson, Adam Wang, Norbert J. Pelc

Institutions: Stanford University, Stanford Medicine

Language: English

Topic: Advanced X-ray and CT Imaging

Subfield: Biomedical Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: bronze

Funders: National Institutes of Health, Stanford Research Computing Center, Stanford University, National Institute of Biomedical Imaging and Bioengineering

Award: G2523454737