Affiliations: Center for Bioengineering and School of Electrical and
Computer Engineering, University of Oklahoma, Norman, OK 73019, USA | Department of Radiology, University of Alabama at
Birmingham, Birmingham, AL 35233, USA | Department of Radiological Sciences, University of
Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
Abstract: The objective of this study is to characterize the imaging
performance of a high resolution computed radiography (CR) system. The finest
pixel pitch of the system is 43.75 μm. The Modulation Transfer Function
(MTF) of the CR system was measured on both scan and subscan directions. The
Noise Power Spectrum (NPS) and Detective Quantum Efficiency (DQE) were also
determined under different conditions. The MTF results on subscan direction
showed 90%, 45% and 10% modulation at 1, 3, and 7 lp/mm resolutions,
respectively; on scan direction the MTF values are slightly lower. The DQE
value of this CR system at low frequency under 26 kVP is as high as 45%. As a
comparison, these measurements were repeated with a CCD based system (48 μm
pixel pitch) using the same x-ray source. The unique features of this CR
system, such as its high limiting spatial resolution and detective quantum
efficiency, make it attractive in applications such as mammography.
Keywords: Digital x-ray imaging, computed radiography, CCD, noise power spectrum, modulation transfer function, detective quantum efficiency
