DocumentCode :
3327354
Title :
Investigation of the capability for material decomposition in photon counting CT images
Author :
Lee, Seung-Wan ; Choi, Yu-Na ; Cho, Hyo-Min ; Lee, Young-Jin ; Ryu, Hyun-Ju ; Kim, Hee-Joung
Author_Institution :
Dept. of Radiol. Sci., Yonsei Univ., Wonju, South Korea
fYear :
2011
fDate :
23-29 Oct. 2011
Firstpage :
3004
Lastpage :
3007
Abstract :
The conventional detectors operated in the integrating mode are insensitive to the energy spectral information since the detector output is proportional to the energy fluence integrated over the whole spectrum. Recently, photon counting detectors have been considered to be an alternative device. These detectors are able to measure the x-ray photon energy deposited by each event and reduce the noise which is caused by detector leakage current using energy thresholds. Photon counting detectors with multiple energy thresholds have a significant advantage that material decomposition is possible using energy selective windows. In this study, we investigated the capability for material decomposition in images acquired from different energy window widths using the photon counting detector based on cadmium telluride (CdTe). We designed the CdTe detector and phantoms contained different materials using Geant4 Application for Tomographic Emission (GATE) simulation. To simulate the separated images of different target materials, the energy levels were chosen to be above K-edge absorption energy of target materials. For investigating the capability of material decomposition as a function of energy window width, projections were acquired from different energy windows and contrast-to-noise ratio (CNR) was calculated with constant region of interest (ROI) for target materials and PMMA in tomographic images. The CNR was increased as a function of energy window width for all target materials and decreased at above the specific energy window width. These results showed that the energy window width affects the degree of material decomposition and there are optimal window widths for target materials. In near future, we will acquire the optimal images of separated target materials using combinations of energy windows.
Keywords :
II-VI semiconductors; X-ray detection; cadmium compounds; computerised tomography; image denoising; medical diagnostic computing; medical image processing; noise; phantoms; photon counting; wide band gap semiconductors; CdTe; GATE simulation; Geant4 Application for Tomographic Emission; K-edge absorption energy; PMMA; X-ray photon energy; contrast-to-noise ratio; detector leakage current; detector output; energy fluence; energy spectral information; energy window width; integrating mode; material decomposition; multiple energy thresholds; noise reduction; phantoms; photon counting CT images; region of interest; Arrays; Biological system modeling; Gold; Logic gates; Materials; NIST; Photonics;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 2011 IEEE
Conference_Location :
Valencia
ISSN :
1082-3654
Print_ISBN :
978-1-4673-0118-3
Type :
conf
DOI :
10.1109/NSSMIC.2011.6152539
Filename :
6152539
Link To Document :
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