Detector motion method to increase spatial resolution in photon-counting detectors

• Published in: Journal of the Korean Physical Society Vol. 70; no. 6; pp. 567 - 573
• Main Authors: Lee, Daehee, Park, Kyeongjin, Lim, Kyung Taek, Cho, Gyuseong
• Format: Journal Article
• Language: English
• Published: Seoul The Korean Physical Society 01.03.2017; Springer Nature B.V; 한국물리학회
• Subjects: Detectors; Low noise; Mathematical and Computational Physics; Medical imaging; Noise reduction; Particle and Nuclear Physics; Photons; Physics; Physics and Astronomy; Pixels; Redesign; Sensors; Signal processing; Signal to noise ratio; Spatial resolution; Theoretical; X ray tubes; 물리학; Charge sharing; Signal-to-noise ratio; Detector motion; Photon-counting detector; Spatial resolution; MTF
• ISSN: 0374-4884; 1976-8524
• DOI: 10.3938/jkps.70.567

Medical imaging requires high spatial resolution of an image to identify fine lesions. Photon-counting detectors in medical imaging have recently been rapidly replacing energy-integrating detectors due to the former‘s high spatial resolution, high efficiency and low noise. Spatial resolution in a photon counting image is determined by the pixel size. Therefore, the smaller the pixel size, the higher the spatial resolution that can be obtained in an image. However, detector redesigning is required to reduce pixel size, and an expensive fine process is required to integrate a signal processing unit with reduced pixel size. Furthermore, as the pixel size decreases, charge sharing severely deteriorates spatial resolution. To increase spatial resolution, we propose a detector motion method using a large pixel detector that is less affected by charge sharing. To verify the proposed method, we utilized a UNO-XRI photon-counting detector (1-mm CdTe, Timepix chip) at the maximum X-ray tube voltage of 80 kVp. A similar spatial resolution of a 55- μ m-pixel image was achieved by application of the proposed method to a 110- μ m-pixel detector with a higher signal-to-noise ratio. The proposed method could be a way to increase spatial resolution without a pixel redesign when pixels severely suffer from charge sharing as pixel size is reduced.